Category Archives: Colorado

Cloud Seeding and the Journal Barriers to Faulty Claims: Closing the Gaps

This manuscript had a close call in being accepted into the American Meteorological Society’s  Bull. Amer. Meteor. Soc. in 1998-1999.  The key reviewer that I had to satisfy (according to journal Editor  I. Abrams)  insisted that I make it clear that the cloud seeding experimenters in Colorado  and Israel did the “best they could with the tools available at that time”, paraphrasing here.

I couldn’t do it.

I had personal experience with the leaders of both those benchmark experiments; one was intransigent regarding new facts that upset a key claim he repeatedly made about the height of cloud tops in the Rockies during storms, and the other leader denied me access  to his radar to observe cloud top heights (and thus obtain temperatures).  I went to Israel suspecting that his many papers on the clouds of Israel were in major error.  (They were later proved to be in major error  on several occasions over the following 20 years.)

So, how could I agree with the key, “Reviewer B” stating that those experimenters did the best they could?  I might have “got in” by doing that.  Both cloud seeding leaders caused their respective country’s millions of dollars in wasted cloud seeding efforts.

An updated  “Gaps” manuscript was rejected a second time (!) in 2017 or so by the editor of the weather modification/cloud seeding issue of “Advances in Meteorology”, L. Xue, as “not the kind of paper we were looking for.”  Perhaps, though, it’s the kind of article YOU were looking for:

2017 Gaps-revised following comment

Review and Enhancement of “Literature Review and Scientific Synthesis on the Efficacy of Orographic Cloud Seeding”


Dr. Reynolds, the sole author of this monumental review I critique  has done a masterful job of surveying an enormous amount of cloud seeding literature in his “draft” report to his former employer, the Bureau of Reclamation.  The BOR was  the primary sponsor of cloud seeding programs throughout the West in the 1960s to the 1980s.  However, as was also seen in a recent review of the 2009 Springer book,  “Impacts of Aerosols on Precipitation,” such a task appears to be too much despite Reynold’s valiant efforts to “get it right.”   Reynold’s discussions of the benchmark randomized experiments in Colorado that led to the nation’s largest, most costly randomized orographic cloud seeding experiments, the Colorado River Basin Pilot Project, is an example of the problem of having too much to review and not enough time to scrutinize the details of so much literature.

Reynold’s review is well-written, most of the necessary citations are in it that help the reader to understand the topic.    That is,  except for those elements in his review that I am perhaps, a little too familiar with and I feel must be addressed in this VERY belated review of his 2015 draft report.

“Too familiar?”

That’s what happens to someone who has spent thousands of volunteer hours (crackpot alert!) rectifying faulty cloud seeding and cloud claims in peer-reviewed journal articles because he felt, “Someone has to do something about this!” (Second crackpot alert, with possible megalomaniacal implications).   I was employed as a weather forecaster for the Colorado River Basin Pilot Project for all of its five winter operating seasons, 1970/71 through 1974/75.  No one can know about that project and the faulty literature it was based on more than me.  I came in naive and idealistic about the scientific literature on cloud seeding;  I didn’t leave that way

I was not asked to review Reynold’s 2015  review before he posted his report to the BOR  online as a “draft,” the status it retains as of today.   I contacted Dr. Reynolds recently and informed him that I had a few comments on and corrections to his review.  He replied that he was not interested in correcting his review or making changes at this time.  This seemed odd to me, so here we are.

Also, in the spirit of “author disclosure,” I should mention that Dr. Reynolds was also an informal reviewer of my manuscript co-authored with Prof. Dave Schultz, Manchester U., on the history of the BOR-funded Colorado River Basin Project.  It was recently rejected by the J. Appl. Meteor.  due to length.  We are in the process of seeing where that manuscript can be trimmed down without losing  important parts of the story.

The comments pn Reynold’s review would have likely been unnecessary had I reviewed it beforehand, or if Dr. Reynolds  wished to consider my comments and corrections today.    I was well known to Dr. Reynolds as an expert on clouds, cloud seeding, and the weather  in Colorado and Israel ;  he had previously cited my work his 1988 article in the Bull. Amer. Meteor. Soc.   With Professor Peter V.  Hobbs in tow, I dissected those landmark experiments in Colorado and Israel and showed they were, as Foster and Huber (1997) described faulty science,  “scientific mirages.”  They were “low-hanging fruit” that poor peer reviews of manuscripts had let in, mostly, appearing Amer. Meteor. Soc. journals.  It didn’t take a genius to unravel them.

Dr. Reynold’s comprehensive  review can be found here.  It is too long to be a blog post here that includes my embedded comments.  Since I am only commenting on certain sections,  I have extracted only those portions of Reynold’s review where I have made comments.  It may be that only those familiar with this topic, orographic cloud seeding, will be interested, but, oh, well….  It has to be done even if for only ONE person!

My goal is to be objective and not short change Reynolds’ work on what is really an astounding effort.  It would take me two lifetimes to do what Dr. Reynolds has done.

I also believe Dr. Reynold’s made a great effort to be objective in discussing a topic that almost always brings controversy.  The literature in this field is filled with pro-seeding partisans that have often edited results so that cloud seeding has been presented with a happier face than it should have been.  After all, no one got a job saying cloud seeding doesn’t work (is not viable for producing worthwhile amounts of water.)

Considering his background in the cloud seeding arena, Reynolds final conclusion, copied below, must be considered an example of high integrity and his conclusion is one that this author fully agrees as of this date:

“5.3.2 Final Conclusion 

Based on both the historical evidence and the last decade of research, it is reasonable to conclude that artificial enhancement of winter snowpack over mountain barriers is possible. It is very difficult to quantify the seasonal increases to be expected both in snowpack and subsequent spring runoff. This is because each target area has to be investigated as to the meteorology of the winter clouds and their seedability, and the engineering aspects of effectively seeding the clouds to maximize increases. Winter orographic cloud seeding should thus continue to be supported both from the scientific and operational community working together to further the science and operational outcomes. It must be stated however, that as of yet, no rigorous scientific study conducted as a randomized confirmatory seeding experiment with pre-defined primary response variables and requiring an established threshold of statistical significance has demonstrated that seeding winter orographic clouds increases snowfall. As such, the “proof” the scientific community has been seeking for many decades is still not in hand. “

================THE REVIEW=================

My comments, corrections and question on Dr. Reynolds review begins below and are in a red font.   Highly relevant citations are missing  and there are citations in the Reynold’s references that do not appear in the text.  The missing ones, annotated with a “u” ,  have been added at the end of this review.

The portions of Reynold’s review that I examined begins here:


1.0 Introduction 

1.1. Introduction to Winter Orographic Cloud Seeding In its most basic form, artificial seeding of clouds for precipitation enhancement can be divided into two broad categories: 1 – cloud seeding to enhance rainfall i.e. summer convection, 2 – winter orographic cloud seeding to enhance snowfall. The scope of this paper is only concerned with the latter. Winter orographic cloud seeding occurs when very small particles, typically silver iodide, are introduced into a cloud which is below freezing. The cloud moisture collects onto the small particles, freezing the moisture into tiny ice crystals which continue to grow until they become too heavy to remain in the cloud and then fall out as precipitation (typically snow). This process can happen rapidly on the windward slopes of mountains allowing the snow to fall near the crest of the mountain which causes a local enhancement to the amount of precipitation that would have fallen naturally (Figure 1.1).

The situation is complicated if the natural crystals are becoming rimed and due to riming, fall more quickly.  Adding more ice crystals via cloud seeding may result in raising their trajectories by reducing riming and the snow may not be increased snow where it is wanted, or will evaporate in the descending, drying  air on the lee side.  The schematic below would be valid for naturally non-precipitating clouds.  

The properties of clouds that don’t naturally precipitate vary with location.  Maritime clouds along the west coasts of continents generally can precipitate without ice.  Farther inland, where the clouds become impacted by natural and anthropogenic aerosols, ice is generally required for precipitation and may not develop until cloud tops are cooler than about -12°C.  These latter non-precipitating clouds make viable seeding targets.

Figure 1.1 – Simple model of winter orographic cloud seeding. 1 – Introduction of seeding material, 2 forced ascent due to topography, 3 – enhanced precipitation falling out of cloud. 

1.3 Relevance and Need for a Reassessment of the Role of Winter Orographic Cloud Seeding to Enhance Water Supplies in the West 

Weather modification is most commonly conducted through “cloud seeding,” the introduction of chemical agents with the intent of affecting precipitation processes. A number of academic and private entities exist that offer services to states and local governments with the aim of increasing water supplies through inducing precipitation volumes above which would occur naturally. From the 1960s through the 1980s, Reclamation was involved in a variety of weather modification initiatives in the west under Project Skywater. This project included the Colorado River Basin Pilot Project, the High Plains Experiment (summer only), and the Sierra Cooperative Pilot Project. Project Skywater was terminated in 1988, but Reclamation continued to be involved with weather modification efforts. Reclamation participated in the development of the California Department of Water Resource’s design and conduct of the Oroville Reservoir Runoff Enhancement Project from 1988 until 1994. Reclamation also supported other efforts through the mid-2000s, including the Weather Damage Modification Program. 

Based upon scientific literature through 2006 and discussions with experts in the field, the efficacy of weather modification appears to be unsettled. In 2003, the National Research Council (NRC) report “Critical Issues in Weather Modification Research” (NRC 2003), concluded that “there is still no convincing scientific proof of the efficacy of intentional weather modification efforts”. The NRC goes on to state that new technology allows for potential new research to help understand the process of precipitation and if weather modification is a viable means to increase water supplies. 

The NRC 2003 review of cloud seeding cited above  did not measure up to the one the NRC published in 1973.  I reviewed NRC 2003.  If anyone cares, can be found here:         

 A Critical Review of NRC 2003 Critical issues in weather modification NATIONAL ACADEMIES PRESS

As seems to be typical of reviews, there was just too much literature to review for the scientists involved, and also likely, not a top priority for those assigned to this task having other research on their plates.   Prof. Hobbs, with my acquiescence, helped compromise this review by declining an offer by Prof. Garstang, chair of the review committee, to review before it was published, a huge mistake.  Garstang admonished  Peter to not to comment on it AFTER it came out.  But that’s exactly what Peter told me we would do if needed.  I nodded and went back to my desk.  He said we would have “more impact” by doing that.  I hope you appreciate getting stories from behind the scenes.

In 2002-2003, Reclamation funded, through earmarks, weather modification studies in the states of Nevada, Utah, California, North Dakota, and Texas. The studies did not provide convincing scientific evidence that weather modification reliably generates additional water. However, there are a number of studies, including from within Reclamation (Hunter 2004 – cited within LBAO (Lahontan Basin Area Office) EA discussed later), that indicate that cloud seeding can significantly increase precipitation amounts for targeted locations. 

Statement on the Application of Winter Orographic Cloud Seeding For Water Supply and Energy Production 

In 2005, Reclamation primarily stopped involvement in weather modification efforts at the program level. As identified within Q&As developed by the Research and Development Office explaining Reclamations abandonment of the practice: 

•Weather modification is not an operational function of Reclamation.

•In a letter dated December 13, 2005, sent to then-Texas Senator Kay Bailey Hutchison(R), the White House Office of Science and Technology Policy (OSTP) said there aresignificant concerns about liability and legal ramifications of weather modification,including whether weather modification can be demonstrated to actually be effective.

Since 2006, continuing drought conditions, and a strong interest amongst some Reclamation stakeholders, Reclamation engaged in two research projects related to weather modification in support of cold-season snowfall enhancement. 

•In 2010 the Mid-Pacific Region’s LBAO finalized an Environmental Assessment (LBAOEA) proposing to provide $1.35 million from Reclamation’s Desert Terminal LakesProgram to the Desert Research Institute (DRI) for a cloud seeding project in the WalkerRiver Basin.

•At a March 12, 2014 meeting of the Upper Colorado River Commission, weather modification was specifically identified as one of three activities that the Upper Basin states propose to include within their drought contingency plans. The Upper Basin states asked that Reclamation provide partial support for Wyoming’s eighth year (2014) of an ongoing weather modification study / program being conducted with the National Center for Atmospheric Research (NCAR). This request resulted in Reclamation’s Upper Colorado Region obligating $200,000 to the State of Wyoming for weather modification research and development efforts conducted by NCAR, with these monies obligated through an amendment to an existing cooperative agreement between Reclamation R&D and Universities Corporation for Atmospheric Research.

The Upper Basin states have noted that state and private entities in Colorado and Utah spend over $1M and $500,000 respectively on weather modification, and estimate efficacy between 6% and 20%. At the low end, the Upper Basin states identify that a benefit of 6% is inexpensive water within the Colorado River Basin. The Upper Basin states have argued that Reclamation’s documents from the 1960s – 1980s identified positive results of weather modification.

This above section needs supporting references for the assertions made about seeding results, the benefit claim, and who are those “Upper Basin States”?  Otherwise these statements should be taken with extra caution.

1.5 Brief History of Federal and State Authorizations for Weather Modification 

The following is taken from Chisolm and Grimes (1979): 

In 1968, the Colorado River Basin Project Act of 1968 (Public Law 90-537) was passed by Congress to provide for the further comprehensive development of water resources of the Colorado River Basin and for the provision of additional and adequate water supplies for use in the upper as well as lower Colorado River Basin. Under Title II of this Act, the Secretary of the Interior was authorized to prepare and implement an augmentation plan to meet the water requirements of the new projects created by the Act (Central Arizona Project and Colorado River Storage Project), existing projects and water allotments, and the 1944 water treaty with Mexico. 

Augmentation was one of the main issues in the deliberation on the Act. The Act defines augmentation as, “ ‘augment’ or ‘augmentation’ when used herein with reference to water means to increase supply of the Colorado River system or its tributaries by introduction of water into the Colorado River system, which is in addition to the natural supply of the system.” The Statement of the Managers on the part of the House with regard to augmentation stated “all possible sources of water must be considered, including water conservation and salvage, weather modification, desalinization and importation from areas of surplus.”

The Colorado River Basin Pilot Project (CRBPP) was the Bureau’s first major effort on weather modification in Colorado under the auspices of Project Skywater and P. L. 90-537. The purpose of the Colorado River Basin Pilot Project was to provide for scientific and economic evaluation of precipitation augmentation technology and to increase precipitation. The specific objectives to be achieved were (l) to establish and operate a ground-based meteorological network in and near the San Juan Mountains of Colorado to provide data input in the selection of suitable storms for seeding, and (2) to establish and operate a ground-based silver iodide seeding system to increase snowfall in the project target area. The field phase of CRBPP began with the winter of 1969-1970 (installation of gauges and seeding generator siting) while the random seeding phase began with the 1970-71 season and ran through the 1974-75 season (not the 1973-74 season as the author stated).

Date corrections are needed from the original text, not a good sign of the author’s knowledge concerning the CRBPP.  What is incomprehensible is that the goal of replicating the large percentage increases in snowfall reported in three randomized experiments by the author’s former home institution, Colorado State University, is left out of this rationale for the CRBPP.  Surely, the author knew, also as a long term BOR cloud seeding division employee, that those experiments were the primary motivation for the BOR to spend $40-50 million (in 2023 dollars) on the CRBPP.

At about the time of completion of CRBPP in Colorado, the Bureau began funding Project Snowman in Utah. Project Snowman was conducted for the Bureau by Utah State University’s Water Research Laboratory. The objective of this four-year project was to develop cold-cloud seeding technology using airborne generators and ground-based generators located in the northern portion of the Wasatch Mountains.

References are also needed here.

The Bureau’s early work on precipitation augmentation in Colorado was based on a fairly extensive background of research activities. Three major research efforts in winter seeding contributed directly to the Bureau’s CRBPP project in the Upper Colorado River Basin. These were: 

  1. The National Science Foundation sponsored research experiments by Colorado State University at Climax, Colorado, during the 1960’s.

“1” above is not a sufficient description of the motivation for the CRBPP.  The Climax experiments were reported on numerous occasions in the peer-reviewed literature as cloud seeding successes when air mass temperatures were high (i. e., high 500 hPa and 700 hPa equivalent temperatures as by Grant and Mielke 1967u, Kahan et al. 1969u, Grant et al. 1969u, Mielke et al. 1970u, 1971u, among others).  The BOR had a LOT of peer-reviewed evidence on which to base the CRBPP and in particular, in the Grant et al. 1969u Interim Report to the BOR that described the results of the Climax I results, and the preliminary results of Climax II and the Wolf Creek Pass experiments.  The findings in these three experiments, as described by Grant et al. 1969u,  were remarkably supportive of one another.  Climax II was a confirmatory experiment; nothing was changed from Climax I.

2. The operational research funded by the State of Colorado during the 1960′ s at several mountain passes, particularly Wolf Creek Pass in the San Juan Mountains, and,

The Wolf Creek Pass experiment mentioned above was a six winter season,  fully RANDOMIZED  experiment where entire winter seasons were randomized.  This experiment was critical to where the CRBPP was located since it appeared to have produced more water than seeding had in northern Colorado where the Climax experiments took place.

3. The Bureau sponsored experiments in the Park Range near Steamboat Springs, Coloradoduring the late 1960’s.

Rhea et al.’s 1969u “Final Report” to the  BOR concerning the Park Range Project  is eventually cited by Reynold’s, but is not in Reynold’s references.  This report was a “heads up” on all the problems that would be “rediscovered” during the CRBPP (e.g, as reported in Willis and Rangno 1971u).

The results of the Colorado River Pilot Project indicated the need for further verification and improvement in technology before a large augmentation program could be undertaken again.

This is a vague description of the CRBPP results, perhaps intentionally so. Why not just say what happened for the reader right here in plain language?   “The results of the earlier CSU experiments could not be replicated in the CRBPP (Elliott et al. 1978u followed by a citation to the “Comments” on Elliott et al’s findings by Rangno and Hobbs 1980-the latter reference is contained in Reynold’s references but is not discussed in his review.   Later, it was discovered that those early optimistic CSU results and the microphysical foundation on which they rested on were all ersatz leaving no real basis for the CRBPP  (e.g., Mielke 1979u, Rangno 1979u, Hobbs and Rangno 1979u, Rhea 1983, Rangno and Hobbs 1987u, 1993, 1995a, u)”

The Wolf Creek Pass seeding effort was designed to test whether a viable signal in runoff from Wolf Creek Pass could be produced by seeding all winter.  The Wolf Creek Pass experiment, conducted from the winters of 1964/65 through 1969/70 produced stunning results when the three randomly chosen seeded seasons were compared with the long historical runoff record (Grant et al. 1969u, Morel-Seytoux and Saheli 1973u).  Furthermore, the results of seeding on  individual days during the seeded winters appeared to replicate the results of Climax I.  It doesn’t get any better than this for a trifecta of apparent cloud seeding successes!  

But, it was all a mirage (e.g., Rangno 1979u), which makes this story so interesting from a scientific viewpoint.

Thus, the Bureau’s research program continued.

Winter experiments were conducted outside of the Colorado River Basin at: Elk Mountain, Wyoming (University of Wyoming) Bridger Range, Montana (Montana State University) Jemez Mountains, New Mexico (New Mexico State University) Pyramid Lake Pilot Project (University of Nevada) In addition, the Bureau continued to provide supplemental funds to Colorado State University’s NSF research and to Utah State University’s state -sponsored research project. Through the Emergency Drought Act of 1977 the Bureau granted over $2 million to six states for supplemental support of their cloud seeding projects including over $1 million to the States of Colorado and Utah for cloud seeding in the Colorado River Basin. 

1.6 Current Policy Statements from American Meteorological Society and World Meteorological Organization on Efficacy of Winter Orographic Cloud Seeding 

The two leading organizations representing the atmospheric science scientific establishment, the World Meteorological Organization and the American Meteorological Society, have both issued policy statements on the efficacy of winter orographic cloud seeding. These are relevant to review given the NRC 2003 conclusions. 

The current statement from the World Meteorological Organization (WMO 2010) on weather modification in general and relating specifically to winter orographic cloud seeding efficacy is stated below. 

“The scientific status of weather modification, while steadily improving, still reflects limitations in the detailed understanding of cloud microphysics and precipitation formation, as well as inadequacies in accurate precipitation measurement. Governments and scientific institutions are urged to substantially increase their efforts in basic physics and chemistry research related to weather modification and related programmes in weather modification. Further testing and evaluation of physical concepts and seeding strategies are critically important. The acceptance of weather modification can only be improved by increasing the numbers of well executed experiments and building the base of positive scientific results.” 

“Cloud seeding has been used on both cold clouds, in which glaciogenic seeding aims to induce ice-phase precipitation, and warm clouds, where hygroscopic seeding aims to promote coalescence of water droplets. There is statistical evidence, supported by some observations, of precipitation enhancement from glaciogenic seeding of orographic supercooled liquid and mixed-phase clouds and of some clouds associated with frontal systems that contain supercooled liquid water. “ 

The current AMS policy statement (AMS 2010) does not address specifically the efficacy of winter orographic cloud seeding but much like the NRC 2003 report identifies uncertainty and risk with much the same conclusions. These are listed below. 

UNCERTAINTY – Planned weather modification programs benefit from a comprehensive understanding of the physical processes responsible for desired modification effects. Recent improvements in the composition and techniques for dispersion of seeding agents, observational technology, numerical cloud models, and in physical understanding of cloud processes permit evermore detailed design and targeting of planned weather modification effects, and more accurate specification of the range of anticipated responses. While effects are often immediately evident in simple situations, such as when cloud seeding is used to clear supercooled fog and low stratus cloud decks, in more complex cloud systems it is often difficult to determine a seeding effect on a cloud-by-cloud basis. In these more complex situations, large numbers of events must be analyzed to separate the response to cloud seeding from natural variability in cloud behavior. Rigorous attention to evaluation of both operational and research programs is needed to help develop more effective procedures and to improve understanding of the effects of cloud seeding. Research and operational programs should be designed in a way that will allow their physical and statistical evaluation. Any statistical assessment must be accompanied by physical evaluation to confirm that the statistical results can be attributed to the seeding through a well-understood chain of physical events. It should be noted, though, that in practice large potential benefits can warrant relatively small investments to conduct operational cloud seeding despite some uncertainty in the outcome. 

The text in blue font seems like PR, Dave, and should be updated due to the lack of proof of seeding induced increases in snow we now have. Neiburger (1969u, WMO Tech Note) warned that such thinking usually excludes the idea that seeding might result in decreases in precipitation in addition to mistargeting, faulty operations.  


RISK MANAGEMENT – Unintended consequences of cloud seeding, such as changes in precipitation or other environmental impacts downwind of a target area, have not been clearly demonstrated, but neither can they be ruled out. In addition, cloud seeding materials may not always be successfully targeted and may cause their intended effects in an area different than the desired target area. This brings us to the ethical concern that activities conducted for the benefit of some may have an undesirable impact on others; weather modification programs should be designed to minimize negative impacts.. At times unintended effects may cross political boundaries, so international cooperation may be needed in some regions. Precipitation augmentation through cloud seeding should be viewed cautiously as a drought-relief measure because opportunities to increase precipitation are reduced during droughts. A program of precipitation augmentation is more effective in cushioning the impact of drought if it is used as part of a water management strategy on a long-term basis, with continuity from year to year, whenever opportunities exist to build soil moisture, to improve cropland, and to increase water in storage. From time to time methods have been proposed for modifying extreme weather phenomena, such as seeding severe thunderstorms with aerosols to diminish tornado intensity, or seeding tropical cyclones to cause changes in their dynamics and steer them away from land and/or diminish their intensity. Some experimentation has taken place in these areas, but current knowledge of these complex weather systems is limited, and the physical basis by which seeding might influence their evolution is not well understood. Weather modification techniques other than cloud seeding have been used in various areas of the world for short periods of time to achieve goals similar to those of cloud seeding. Much less is known about the effects of these other techniques, and their scientific basis is even further from being demonstrated, either statistically or physically, than it is for cloud seeding. Application of weather modification methods that are not supported by statistically positive results combined with a well-understood physical chain of processes leading to these results, and that can also be replicated by numerical cloud modeling, should be discouraged.

Other organizations such as the North American Interstate Weather Modification Council, The Weather Modification Association, the American Society of Civil Engineers, and the Western States Water Council have also adopted policy statements or adopted resolutions relating to the use of weather modification for increasing snowpack and water supply. These are referenced in Ryan (2005) and will not be repeated here. Most if not all of these statements are much more positive in their support of the application of weather modification for enhancing snowpack and runoff despite the lack of evidence as reported in NRC 2003.

To the uninitiated reader to the field of weather modification/cloud seeding, it will seem odd that there are government entities that will pay huge sums of tax payer monies for cloud seeding with no viable evidence that it does anything, evidence being in the form of randomized experiments, the “gold standard” of scientific proof.  

Why would those entities take such chances?  

If you haven’t guessed by now, it’s because those government entities are telling their constituents directly or implicitly that they are doing SOMETHING about a drought.  It’s a great ploy, and usually works except in the minds of those who know the science.  

What science?  

Two modern randomized experiments testing to see if cloud seeding can increase precipitation in mountainous regions (Wyoming and in northern Israel) ended with  no indications that cloud seeding increased precipitation.  These null findings have been published by Rasmussen et al. 2018u for Wyoming, and by Benjamini et al. 2023u for Israel.  Now you know.  

Did the “null” finding reported by Rasmussen et al. 2018 terminate cloud seeding in Wyoming?  Of course  not.  It just looks too good to the public that you’re doing something about water needs.  

1.7 Generalized Concepts of Winter Orographic Cloud Seeding 

It is useful to review the general principles of winter orographic snowfall and whether this process could be modified or enhanced by artificial means. The basic physical concepts associated with seeding winter orographic clouds are not debated even though there is considerable debate over weather modification and its efficacy. These basic physical concepts are reviewed in the following section. There are several text books and encyclopedia articles available for a more in-depth discussion or broader overview of the physical basis of cloud seeding (Hess 1974; Dennis 1980; Dennis 1987; and Heymsfield 1992). 

Dennis in his (1980) Academy Press book, “Weather Modification by Cloud Seeding,” relied heavily on the 1977 BOR Monograph Number 1 (yes, it was deemed that important by the BOR to name it as NUMBER ONE),  became outdated almost immediately when external critics (guess who?) found serious flaws in that “meta-analysis.”     The BOR study, published in 1978u (Vardiman and Moore) was retracted in 1980  by Rottner et al. 1980 as critical “Comments” on their paper by, yep, Rangno and Hobbs (1980) were being published.  Thus, Dennis (1980) might be reconsidered as a reference here.  The BOR was too willing to believe in cloud seeding success mirages that led to this major embarrassment.

Too, much of the cloud seeding literature in Hess (1974) has been overturned in reanalyses or has not been replicated, as in the recent Wyoming and Israel experiments.  But, “hey,” you can read about global cooling in Hess (1974), thought to be underway at that time.

Figure 1.2 from Ludlam (1955), reproduced below, describes the process that remains to this day the fundamental conceptual model associated with winter orographic cloud seeding. Figure 1.2 shows a shallow orographic cloud, where the liquid condensate produced by forced assent over a mountain barrier is unable to be converted to snowfall before the air descends and evaporates in the lee of the mountain. During wintertime the freezing level (height of the 0oC isotherm) varies dependent on the origin of the air mass impinging on the mountain barrier.  This varies from north to south with the freezing level being lower in altitude at the northern latitudes of the western US and the inter-mountain west where the air masses that impact this area are usually modified maritime polar or continental polar.

and height allowing the crystals to grow at the expense of the cloud water that in (a) was lost to the lee, bringing this moisture down on the windward side of the mountain.

1.2a is the non-precipitating cloud that forms the low, demonstrable end of seeding potential.

The text in blue in the body of the paragraph may be true, but….. warm air masses during times of upper level ridges along the West Coast shunt warm air mass storms into the central and northern Rockies, so this “paradigm” often does not hold.  Surface temperatures may be well below freezing, but much higher temperatures usually exist aloft in those warm aloft regions of winter storms.  The Climax I experiment, for example, had numerous warm aloft storms overrunning colder air with west-northwest flow due to this synoptic scenario.   Quantification of this claim would have been very informative and would have pinned it down for the reader…and me!

Freezing levels are usually below ground level in mountainous regions except in the warmest storms. In the Ludlum model, it is assumed the orographic cloud has a significant depth of cloud below 0 oC and thus the cloud moisture is said to be supercooled. The critical uncertainty with regard to successful conversion of the unused cloud condensate to snowfall prior to passing over the crest is the location, duration, temperature and concentration of the supercooled liquid water (SLW).

As Ludlum describes it may take as much as 1500 seconds once artificial ice crystals are initiated to grow and fall out before passing to the lee of the mountain crest.  This can vary by several tens of minutes based on SLW concentration, temperature vertical profile and winds.

The process of crystal growth is almost always much fast than “as much as” 25 minutes to fallout cited by Ludlum  (e.g., Auer et al. 1969, Cooper and Vali 1981).

So the critical factors for achieving success are getting the seeding agent into the cloud at the right location where it will generate enough ice embryos such that they will utilize the available SLW prior to passing over the crest. There are many complex interactions that have made it very difficult to demonstrate the efficacy of winter orographic cloud seeding to the satisfaction of the scientific community. These factors are described in the following paragraphs. 

So true.

 1.7.1 The Initiation, Growth and Fallout of Snow in Winter Orographic Clouds Converting Supercooled Liquid Water (SLW) to Snow

Supercooled liquid water (SLW) in the atmosphere is made up of tiny cloud droplets that are colder than 0 oC. There are two processes in nature by which SLW in the atmosphere can freeze to initiate snowfall: 1. Heterogeneous nucleation or 2. Homogeneous nucleation. Heterogeneous nucleation occurs when the supercooled liquid drop comes in contact with what is called an ice nucleus (IN) that emulates the crystalline structure of ice and causes the droplet to freeze. These can be dust particles, biological particles or a combination of the two. These aerosols can come from as far away as Asia and Africa initiating cloud ice in orographic clouds in the western US (Cremean et al. 2013). They are made of very small particles of tenths of microns in size. They are most active at cloud top and tend to activate the growth of snowflakes from the top of the cloud down. The warmer the cloud top the less percentage of ice makes up the cloud (Cremean et al. 2013).

Sidebar:  An interesting feature, first observed in the 1950s (e.g., Cunningham 1957u) and afterward was the “upside down” storm structure where few ice crystals were found at low cloud top temperatures consisting mostly of supercooled liquid water with increasing ice crystal concentrations below the top. The increasing concentrations of ice crystals were mostly due to the fragmentation of delicate ice crystals. The most recent description of this scenario was by Rauber and Tokay (1991u) and Hobbs and Rangno (1985).

Lower down, within a km of the surface, ground observations have shown that riming and and aggregation occur that increase snowfall rates. This lower region near mountains cannot be sampled by aircraft if precipitation is falling and as a result, has mainly been documented  in ground observations (e.g, Hobbs 1975). Thus, aircraft observations can often be seen as under measuring ice particle concentrations in mountainous regions.  For example, we at the University of Washington often overflew shallow orographic clouds with liquid tops at >-10C with snow falling out underneath, but we couldn’t sample them because the tops were too close to the tops of the Cascade Mountains.

When clouds are dominated by warm rain processes, the aerosol makeup of the cloud is more sea salt and biological particles which act as condensation nuclei producing larger cloud droplets which grow to raindrops via collision coalescence. Homogeneous nucleation occurs when the air temperature drops below -40 oC and the water droplet spontaneously freezes without the aid of a nucleating agent. The most basic hypothesis in winter orographic cloud seeding is that in the presence of SLW droplets, ice crystals will grow at the expense of the drops. This means the drops will convert back to vapor allowing the crystals to grow by vapor deposition unless too many ice crystals have resulted from seeding in which case they might not grow at all. The driver for crystal growth is related to the concentration of SLW and the temperature regime of the SLW (Ryan et al. 1976; Heymsfield 1992; Pruppacher and Klett 1978).

In the presence of moderately high concentrations of SLW and with somewhat preferred growth temperatures (Ryan et al. 1976, Figure 1.3) enough of the initial ice crystals can grow and then begin to aggregate into larger flakes leading to higher fall speeds and earlier fall-out. If these artificial crystals encounter additional SLW as they fall back toward the mountain crest, the individual crystals or aggregates may collect these SLW drops (called riming) which will also increase the crystals fall-speed. If the naturally created ice crystals are unable to utilize all the available SLW, and some SLW evaporates to the lee of the mountain, the cloud is said to be less than 100% efficient. This provides the opportunity for the artificial injection of a nucleating agent to create the additional ice crystals necessary to bring the residual cloud water to the ground before it is lost to the lee of the mountain. This is the basic principles described in Ludlam’s model. 

Aerial Seeding window 

Ground based seeding temperatures 

General seeding window based on Figure 1.5 and observed SLW 

As Super and Heimbach (2005) noted, the frequency of occurrence of SLW is temperature dependent with higher frequencies and amounts at (higher) supercooled temperatures. This is true for all mountain ranges where SLW has been observed. There are two main reasons for this. First, the amount of water vapor in the atmosphere can be higher at warmer (higher) temperatures. Second, as the atmosphere cools and clouds form and reach temperatures lower than -10 oC, and especially at -20 oC, an abundance of natural ice can occur that depletes the supercooled cloud water. Thus, there is less SLW available for cloud seeding to enhance the natural precipitation process as the air approaches these temperatures. It should be noted that studies (Reinking et al. 2000; Super 2005) have found significantly higher amounts of SLW (.5 to 1 mm integrated SLW) in wave clouds during winter storms and noted that others had observed such amounts during brief periods in other western mountain locations. However, the overwhelming amount of observations utilizing microwave radiometers (Heggli and Rauber 1988; Huggins 2009; Super and Heimbach 2005), in-situ aircraft observations, and mountain top icing rate meters indicate that SLW is concentrated in the lowest 1000m along the windward slopes of mountain ranges during passing winter storms. The primary SLW zone rapidly dissipates downwind of the crest because of warming produced by subsidence and by depletion from conversion to snowfall (Boe and Super 1986; Rauber et al. 1986; Rangno 1986 (the rapid dissipation of SLW, one of my main points), Huggins 1995; Super 2005; Huggins 2009).  There are observations that confirm the simple conceptual model espoused by Ludlam when natural ice does not form. The location of many of the research studies referenced in this report along with other locations that will be referenced later in this report are shown in Figure 1.4b. One can compare these locations to Figure 1.4a which shows the location where operational winter orographic cloud seeding is conducted circa 2006 per Griffith et al. 2006. Coastally influenced areas would be west of the Sierra Nevada and Cascades while the intermountain region refers to areas east of these two ranges. 

The actual temperature relationship to SLW occurrence varies geographically. For the intermountain west, where the cloud drop size distributions are more numerous at the smaller drop sizes (10 to 15 microns; what is referred to as a continental drop size distribution), lower temperatures are reached before a sufficient number of natural ice crystals develop to utilize the available SLW. Thus, SLW can exist, at least briefly, at temperatures as low as -15 to -20 oC. Super and Heimbach (2005) provide a comprehensive review of SLW climatology in the intermountain west. 

In more coastal regions, such as the Sierra Nevada and Cascades, the drop size distribution can be broad (what is referred to as a maritime drop size distribution). The drops can begin to collide and coalesce because of the varying fall speeds of the drops with a broader distribution of cloud droplets (extending into and above 30 microns diameter). This leads to larger cloud drops (approaching drizzle size) that can be carried upslope into coastal mountains like the Cascades and Sierra Nevada ranges where just a few of these droplets can freeze leading to rime splintering or secondary ice-crystal production (Hallett and Mossop 1974; Dong and Hallett 1989; Mossop 1985). This can, and has been observed to lead to high concentrations of ice crystals with cloud temperatures warmer than -10 oC (Reinking 1978; Cooper 1986; Marwitz 1986; Hobbs and Rangno 1985; Rauber 1992).

Nieman et al 2005u reported  occurrences of the “warm rain” process in Northern California and Oregon were common.  Will cloud seeding increase precipitation if nature is providing rain via collisions with coalescence?

Other factors (Rango  (sic) 1986) can lead to high ice crystal concentrations with relatively high cloud top temperatures. Mixing of very dry air into cloud tops can initiate cloud droplet freezing (e.g., Koenig 1968; Hobbs and Rangno 1985). This has been observed in the Cascades, Sierra Nevada and southern Utah. In the post-frontal airmass, where most of the shallow orographic clouds exist, very dry air can exist above cloud top. This is caused by sinking air parcels in the region behind the upper-level jet-stream that usually passes just ahead of the surface cold front  (Heggli and Reynolds 1985). Thus the coastal mountain clouds will have a lesser degree of supercooling, meaning that the clouds will be only marginally supercooled as natural ice production will utilize the available SLW within moderately supercooled clouds. Reynolds (1995) documented that over an 8 year period in the northern Sierra Nevada, 80% of the hours reporting SLW from mountain-top icing rate meters were at temperatures warmer than -4 oC. Reynolds (1996) also reported that 70% of the hours with precipitation had icing (riming?) reported. Approximately 300 hours of icing were reported per season. However, some seasons had average temperatures during icing warmer than -2 oC which may be too warm for any known seeding agent to work effectively unless seeded aloft using aerial seeding. Studies examining mountain top temperatures in Colorado and Utah revealed that SLW in clouds is mildly supercooled in a large portion of all storm passages, which means clouds are too warm for effective AgI seeding (Super 2005). Refer to Figure 1.5 for activation levels of the various cloud seeding agents currently used or proposed.

Why aren’t supercooled non-precipitating clouds’ occurrences documented for whole seasons as in Ludlams’s simple case? Seems this information would form a great starting point that could determine how much seeding can unequivocally increase snow.  The reader would like to know.

There are many studies (Heggli et al. 1983; Boe and Super 1986; Rauber and Grant 1986; Heggli and Rauber 1988; Super and Huggins 1993; Super 2005; Huggins 2009) that state SLW within a cloud varies rather rapidly with time over any given point. Due to this variability in SLW, identifying seeding potential within winter orographic storms will require identification of the proper seeding agent and delivery technique and applied at the correct time and location (Hunter 2007; Huggins 2009). Huggins (2009) suggests that any cloud seeding program will necessarily be treating clouds that at any given time may not have sufficient SLW (when the seeding agent arrives) given its variability. This begs the question as to whether seeding in these situations may have negative impacts on snowfall production. This will be further discussed in Section 1.7.4. Even though the location of SLW concentrations is known, the exact lower threshold for SLW concentrations to be sufficient for enhancing snowfall has not been quantified. It is believed to be greater than .05 mm integrated in the vertical derived from microwave radiometers (threshold used by Super and Heimbach 2005 and Manton et al 2011). However, Murakami (2013) used .2 mm as the lower threshold for determining cloud seeding feasibility and theorized that .3mm was probably the minimum threshold for viable increases in orographic precipitation enhancement.

For what durations of this SLW threshold? Did those these researchers report how long it lasted?  Did they make any seasonal estimates of these occurrences?  The reader would want to know.

This is a critical question as frequency distributions of SLW concentrations from radiometer data (Reynolds 1988) indicate that 85% of the SLW reported were at concentrations below .2 mm (Figure 1.5).What constitutes a necessary and sufficient concentration of SLW for effective cloud seeding is still in debate. 

Several studies (Rosenfeld 2000; Givati and Rosenfeld 2004; Rosenfeld and Givati, 2006; Griffith et al. 2005; Hunter 2007) have described decreases in orographic precipitation due to pollution.

The above requires some exhaustive comments:

Reynolds was unaware that when the claims of Givati and Rosenfeld concerning air pollution were examined by external skeptics they have not been substantiated.   I think this same view should be taken with Givati and Rosenfeld (2006) for pollution effects on West Coast precipitation.  We need this latter study to be validated by an external skeptic!  Yes, I am excited here.

I suspect, as in the Givati and Rosenfeld’s (2005) Israel study, where more than 500 standard gauges and 82 or so recording gauges were available to cherry-pick whatever result one wants, this may well have been  done in the 2006 study.   Kessler et al. (2006u), in an evaluation of the Israeli operational seeding program wrote: “No supporting evidence was found for the thesis of Givati and Rosenfeld (2005) regarding the decline in the Orographic (sic) precipitations due to the increase of air pollution.”

The air pollution claims, while superficially credible except for their sudden hypothesized appearance in Israel after 1990 when operational seeding produced a slight indication of decreased rainfall (Kessler et al. 2006u), were also evaluated by several independent groups and scientists: Alpert et al. (2008u, 2009u); Halfon et al. (2009u); Levin 2009u.   The Givati and Rosenfeld (2005) claims were also addressed in a review by Ayers and Levin (2009u). All these independent re-analyses and reviews of the hypothesized effect of air pollution on rainfall found the argument that air pollution had canceled seeding-induced increases in rain in Israel unconvincing.   In the few cases that Dr. Rosenfeld’s papers have been reviewed by external skeptics, they don’t hold up.  Ask Prof. Levin, Tel Aviv University, Professor Sandra Yuter, North Carolina State University, Nathan Halfon, Tel Aviv University, or me.   Hence, Caveat Emptor!

This specifically impacts the collision coalescence process and what is called warm rain, i.e. no ice processes involved. These studies discuss that pollution can slow down the collision coalescence process by narrowing the drop-size distribution. This, in turn, slows down the warm rain process and would have the largest impacts in the low-elevation coastal ranges along the west coast where the freezing level is well above the elevations of the coastal mountains, i.e. around Los Angeles where it has been proposed to reduce precipitation. Typically the decrease in orographically enhanced precipitation is greatest downwind of a major metropolitan area that is producing pollution. Givati and Rosenfeld (2004) showed precipitation losses near orographic features downwind of coastal urban centers corresponding to 15-25% of the annual precipitation.

Caveat emptor re Givati and Rosenfeld’s findings!

This loss of precipitation can be greater than the gain claimed by precipitation enhancement techniques in portions of California (Hunter 2007). Hindman et al (2006) noted that the trend over the past 20 years, from cloud droplet measurements at Storm Peak in the northern Rockies, has shown a decrease in CCN and an increase in cloud drop size. The conclusion was a decrease in upwind CCN concentrations (less pollution) but no relationship was found with precipitation rate. Thus, the change in cloud droplet spectra was not impacting riming growth efficiency (Borys et al 2003). It was noted by Creamean (2013) that pollutants, such as from human activity, were found mostly in the boundary layer and with frequently higher concentrations preceding surface cold fronts. The pollutants become trapped in the stable air as the air warms aloft and surface flows tend to be from the southeast to east tapping polluted sources from the central valley of CA. Once the front passed, the air-mass off the ocean did not contain these pollutants. It is the post–frontal cloud systems that have been identified as the most seedable in the northern and central Sierra (Heggli and Reynolds, 1985). It is not anticipated that pollutants play a significant role in these post-frontal shallow orographic clouds.

It should be noted that a more recent survey article by Tanre’ et al (2009), reviewed the impact of aerosols on precipitation and concluded: “Even though we clearly see in measurements and in simulations the strong effect that aerosol particles have in cloud microphysics and development, we are not sure what is the magnitude or direction of the aerosol impact on precipitation and how it varies with meteorological conditions. Even the most informative measurements so far on the effect of aerosols on precipitation do not include simultaneous quantitative measurements of aerosols, cloud properties, precipitation and the full set of meteorological parameters.”

Thanks to Tanre’ et al. (2009)!

The current CALWATER II experiment running this winter in California is an attempt to provide such information.

(Did it?)

The main limitation is very similar to the problems inherent in quantifying the impacts of artificial seeding of winter orographic clouds. That is the observing systems that we apply to quantifying the impacts have large measurement uncertainties and are of a magnitude similar to the expected aerosol influence on precipitation. Tanre’ notes that satellite and radar measurements have 20-30% errors in the measurement of aerosol optical depth, while aircraft sampling in-cloud can introduce changes in the cloud that can compromise the utility of the aircraft observations. In-deed measurements of surface precipitation, especially snowfall water equivalent can have 10-15% measurement uncertainty given gauge location and thus exposure to wind, minimum threshold/resolution, and such problems as capping. These types of measurement uncertainties require longer term on-going statistical analyses to reduce the random noise in the observations much like is required for cloud seeding experiments, thus reducing the influence of measurement uncertainty so as to extract the small signal that might exist. Artificial Stimulation of Snowfall by Seeding Agents

Artificial stimulation of snowfall is conducted through the application of aerosols that mimic natural ice nuclei to enhance the heterogeneous freezing of available SLW or by chilling the air below -40 oC to initiate homogenous nucleation. It is well known that the effectiveness of the heterogeneous seeding agent is highly temperature dependent. Artificial cloud nucleating substances (AgI, CO2, Liquid propane, SNOWMAX) are dependent on the presence of SLW at temperatures slightly below 0 oC for CO2, propane, and SNOWMAX (Ward and Demott 1989) or below -5 C to -8 oC for AgI mixtures (Figure 1.6). 

Figure 1.6 – Seeding activation versus temperature for seeding agents that have been used or proposed

These seeding agents act in different ways. Solid or liquid CO2 and liquid propane work by homogenous nucleation. These seeding agents need to be directly released in the presence of SLW for them to be effective. AgI and SNOWMAX work by heterogeneous nucleation, meaning they mimic the structure of natural ice nuclei. They do not have to be released directly into cloud or SLW. The aerosol can be carried aloft into clouds and when it encounters SLW at the right temperatures will begin generating ice crystals by contact nucleation. As shown in Figure 1.6, SNOWMAX works at the warmer (higher) end of the SLW temperature spectrum and its effectiveness does not vary greatly with temperature. To the author’s knowledge, SNOWMAX is not used in any operational seeding program but is used almost exclusively for snowmaking at ski resorts. The effectiveness of AgI to nucleate ice crystals increases by orders of magnitude from -5 oC to -12 oC (Super 2005). It should be noted that under transient water supersaturations, AgI can activate more rapidly and at temperatures near -5 oC through the condensation freezing mechanism (Pitter and Finnegan 1987). Chai (1993) explained the only way AgI could have been an effective seeding agent in the Lake Almanor seeding experiment (Moony and Lunn 1969) was through the fast activating condensation freezing process.

Mooney and Lunn (1969)… The westerly case where it was reported there had been large increases in snow reported due to seeding, was not reported for Phase II of the Lake Almanor experiment (Bartlett et al. 1975u). This omission should be unsettling to any objective scientist.

If the AgI is burned below cloud base or at temperatures warmer than -5 o C, the aerosol will not produce sufficient ice embryos until temperatures colder than -8 oC are reached (Super and Heimbach 2005). Huggins (2009) found the best temperatures for SLW in the Bridger Range Experiment occurred at < -9 oC using AgI, which suggests the AgI acted through contact or deposition nucleation. The central reason to explore propane seeding is its characteristic to be effective in mildly supercooled clouds that would be too warm for AgI. Propane dispensers tend to be more reliable, less complicated and less expensive than AgI generators. SLW temperatures in CO frequently range from -4 to -13 oC depending upon location and elevation (Boe and Super 1986; Rauber and Grant 1986; Huggins 1995; Super 2005; Huggins 2009). Due to the mildly supercooled nature of some CO locations, propane could be a useful alternative to AgI generators (Boe and Super 1986; Hindman 1986). The cloud base in California is often warmer than 0 oC while the top of the SLW near the mountain crest is usually > -12 oC (Heggli et al. 1983; Heggli and Rauber 1988; Huggins 2009). This is why propane was adopted by Reynolds (1995) as the seeding agent of choice in the Lake Oroville Runoff Enhancement Program (LOREP) in northern California (see Figure 1.4b). 

Cloud base altitude is an important consideration when siting propane dispensers which must be in-cloud or just below cloud base (at ice saturation) to be effective (Super 2005). Super and Heimbach (2005) indicate that even in the intermountain region, a significant number of hours with SLW are at temperatures where the release of AgI at elevations below -5 oC and out of cloud would not reach elevations cold enough to activate a sufficient quantity of the AgI to effectively “seed” the cloud and produce meaningful increases in snowfall. Thus, the 300 to 600 hours of reported SLW over the intermountain region during the 5 month snowfall season would require a mixture of seeding delivery methods including a mixture of high elevation ground released AgI and liquid propane or seeding from multiple aircraft. 

All weather helicopters with ceilings above 20,000 feet ASL  might be useful for targeting small watersheds when shallower clouds are present.

1.7.2 Transport and Dispersion of Seeding Material Ground Releases 

Flow over complex terrain is not a simple and straightforward problem therefore making targeting a challenge. Trying to disperse AgI from ground based generators has proven to be very difficult (Super and Heimbach 2005). There are two critical issues here. One is whether a parcel of air starting out near the foothills or a valley location will be carried over the mountain in the prevailing wind direction or whether it will flow around the mountain. This is determined by the static stability of the air mass and the strength of the flow perpendicular to the mountain, often noted by the Froude number. When the velocity of the flow is strong enough to overcome the air parcels static stability, a Froude number greater than 1 is produced, meaning the parcel of air will pass over the mountain and not flow around the mountain. The depth of the boundary layer is also very important as ground based cloud seeding efforts are located within this layer. If AgI is released below cloud or at temperatures warmer than -5 oC, the aerosol will have to be carried up into the cloud to a level where the temperature is colder than -8 oC. If the boundary layer is shallow and does not allow the aerosol to reach the appropriate temperature level or that level is reached very near the crest of the mountain, there will be no impact on the windward slopes of the mountain. The depth of the boundary layer is a function of low level wind shear (Xue 2014), which is the change in direction or velocity of wind with height. The stronger the wind shear, the greater the depth of the boundary layer. Strong low level flow perpendicular to the mountain, along with strong wind shear and at times weak embedded convection, will provide the mechanism for lifting the aerosol up the mountain. This allows dispersal of the aerosol to seed more cloud volume. If the temperatures are cold enough and SLW is continuous, an increase in snowfall will occur on the windward slopes and increase the precipitation efficiency of the orographic cloud. The targeting issue has been described by many weather modification researchers (Super and Heimbach 2005; Reynolds 1988; Warburton et al. 1995a and b) as the single most critical issue that has compromised the success of both operational as well as research field projects. Again, reason to emphasize that effective cloud seeding is an engineering problem. 

It has been shown that ample seeded crystals with sufficient concentration need to be dispersed so that a substantial volume of cloud over the target is treated for more than trace snowfall rates to occur (Super 2005; Huggins 2009). The seeding material must be injected into the SLW in sufficient quantities to generate 50 to 100/L or more initial ice embryos. This will then utilize the available SLW and fall out of the cloud prior to the snowflakes passing over the summit of the mountain and sublimating in the lee of the mountain. An example of the use of a rather simple targeting model (GUIDE, Rauber et al , 1988) used in the Lake Oroville Runoff Enhancement Project (LOREP ) to target ground-based liquid propane seeding effects is shown in Figure 1.7. This project used the tracer SF6 co-released with the propane from two sites to validate the GUIDE and assure accurate targeting. The GUIDE plumes as shown both horizontally and vertically along with the vertical motion field from a locally released rawinsonde. Seeding from Valley Locations Many operational cloud seeding projects have placed AgI generators in valley locations as they are easily accessible and can be manually ignited when needed. However, a considerable body of evidence indicates valley released AgI plumes are often trapped by stable air (high static stability), especially when valley-based inversions are present (Langer et al. 1967; Rhea 1969-cited but does not appear in Reynolds references; Super 2005). Often times in past projects AgI plumes from valley located generators were not tracked sufficiently to determine exactly where the aerosol plumes drifted (Smith and Heffernan 1967; Super 2005). As noted earlier, this is a recurring issue that has been raised in many winter orographic cloud seeding articles ( Elliott et al. 1978u, Rangno 1979u; Reynolds 1988; Super 2005; Hunter 2007; Huggins 2009). The aerosols may pool in the valley or may move in a direction around the mountain, only to be carried aloft when the static stability of the airmass decreases and low level winds increase. This usually occurs near and behind the surface cold fronts associated with winter storms. Thus, the AgI aerosol may travel far distances from the target but is unlikely to have appreciable effects far from a target due to the low concentrations that eventuate after many hours or days of travel. Seeding from Airplanes or Helicopters

Seeding by aircraft can be an alternative mechanism in locations where there is insufficient time to activate the seeding agent and grow the crystals to sufficient size for fallout to occur on the windward slopes of the barrier. These situations mainly occur within coastal mountains where the SLW near the crest of the mountain is only slightly sub-cooled. Typically the clouds extend up to a kilometer above and well upwind of the crest such that cloud top temperatures are -6 oC to -8 oC or lower. In these situations, the aircraft or helicopter can fly (hover above) in the tops of the clouds and either drop crushed dry ice, AgI droppable flares, or ignite AgI wing-tip generators or stationary flares that will directly inject the seeding material into the cloud. The dispersion would be especially enhanced in the downwash below a helicopter. Using crushed dry ice or droppable flares will create a curtain of ice crystals some 1000 m below the aircraft. This will spread at a rate of 1-2 m/s dependent upon the amount of vertical wind shear (Borovikov et al. 1961u, Hill 1980; Reynolds 1988). For these seeding curtains to merge together over the intended target area, the length of the seed line cannot be more than 30 to 40 km long (Deshler et al. 1990). However, the watershed of a large river basin can be several hundred kilometers wide. One aircraft will treat only a small portion of the watershed (see Figure 1.8). In addition, the duration of the seeding aircraft is usually about 2 to 4 hours, with the possibility of the aircraft having to descend to deice several times during the seeding mission. Aircraft operations are also expensive. For these reasons, many operational seeding programs use ground based seeding platforms, even if they are only viable a small percentage of the time. 

1.7.4 Extended Area Effects fromWinter Orographic Cloud Seeding (ones that have not been sufficiently investigated for lucky draws/synoptic biases)

The reason why I added this to the title is that I deem this part of the survey the weakest part.  No one talks about how low the concentrations of AgI would be in far away, so-called downwind affected regions, and god save anyone who looks at synoptics for a bias! Meltesen et al.(1978) did look at synoptic bias for the claimed downwind seeding increases from Climax and look what they found;  a synoptic bias that produced the illusion of downwind increases in snow!

Hunter (2009) prepared an extensive literature review of the current state of knowledge on extra or extended area effects from winter orographic cloud seeding. The main impetus for this report was to present any documented evidence that determined that seeding on one mountain barrier resulted in a possible reduction of the amount of precipitation downwind. This has been coined “Robbing Peter to pay Paul”. Hunter provided the following table which is reproduced here (not all references are included in Section 6). In every case, the seeding agent was silver iodide. These results indicate that once the AgI nuclei are released into the atmosphere, they can remain active for many hours, if not several days. If pooled in high concentrations, the AgI nuclei can seed areas well away from the intended target areas. However, the impacts of these extra-area effects are just as uncertain as the increase documented in the primary target areas. That is, without strong physical observations to compare with rigorous statistical analyses, there is still a significant level of uncertainty as to the efficacy of seeding with AgI to increase precipitation within large areas outside the intended target area. 

Table 1.2 here

The little bit of seeding (hour long pulses) or in six h blocks during the last season of the Park Range Project, made this claim ludicrous.  By 1979 it was recognized that a Type I statistical error (Mielke 1979u) affected both Climax experiments.  One of the interesting facets of Climax I that  prevented the seeding researchers from recognizing a Type I error was attributing heavier snow on seeded days upwind of Climax to seeding at Climax (Kahan et al. 1969u) 

1.7.5 Statistical Analyses

Statistical analyses have been a key part of assessing past cloud seeding experiments. Credence has usually only been given to those experiments that have been randomized and run as a confirmatory experiment. Key historical projects such as Climax and the series of Israeli cloud seeding experiments run as confirmatory, and meeting or exceeding the level of statistical significance set out in the experimental design, have come under further scrutiny and found to suffer from what is called Type 1 errors (Mielke 1979u; Rhea 1983; Rangno and Hobbs 1987u, 1993; Rangno and Hobbs 1995a,u,  b; Rosenfeld 1997, Rangno and Hobbs 1997a,u, b u).

Rosenfeld’s (1997) “Comments” cited by Reynolds were replied to by Rangno and Hobbs (1997a,u) in short form, and “Comprehensively” at the Cloud and Aerosol Research Group’s website. This dual approach was favored by Professor Peter V. Hobbs.

Its surprising that Dr. Reynolds did not know of our responses to Dr. Rosenfeld’s many specious comments


Some background on the Israeli work I did: these many exchanges led the Israel National Water Authority to form an independent panel to evaluate its operational seeding program targeting Lake Kinneret (aka, Sea of Galilee), Israel’s primary water source (Y. Goldreich, 2018, personal communication). The expert panel  that was constituted could find no evidence of increased rain the in the catchment of Lake Kinneret between 1975 and 2002  (Kessler et al. 2006).  The independent panel’s findings reversed the optimistic findings of Nirel and Rosenfeld (1995) of a statistically significant 6% increases in rain through 1990. The panel could also not replicate the 6% increase reported by Nirel and Rosenfeld using the same control stations.  Here is what Kessler et al. (2006) reported in graphical form. 

Why is this Israeli discussion important in Reynolds’ review?

The preliminary findings shown in this figure caused Rosenfield to immediately look for an “out,” and with more than 500 standard gauges and 82 recording gauges in Israel (!)  he found it by cherry-picking and claiming what Reynolds suggests in his review: air pollution was decreasing rain as much as cloud seeding was increasing it.  Givati and Rosenfeld’s conclusions did not stand up to independent investigators as was documented earlier, nor by the subsequent investigations for California cited by Reynolds.

This is typical in scientific statistical testing. It is considered less incorrect to not detect a relationship when one exists rather than detect a relationship when one does not exist. Other statistical methods, such as the use of covariates, can be useful in determining the statistical success of seeding operations (Dennis 1980; Mielke et al. 1981; Gabriel 1999; Gabriel 2002; Huggins 2009). A problem common to the statistical method of historical regression is the assumption that climate has been stable over many decades (Hunter 2007) which is called stationarity, and not declaring covariates in advance of experimentation.

1.8 Summary 

From the information summarized above it is worth reviewing the key questions as outlined for winter orographic clouds as listed in Table 1.1. 

What is the location, duration, and degree of supercooling of cloud liquid water in winter orographic clouds? 

•Concentrated in the lowest km on the windward slopes of mountain (Super andHeimbach, 2005)

•Highly variable in space and time given fluctuations in wind speed/direction and naturalprecipitation processes.

•Higher concentrations and higher frequency of SLW at warmer (sic) (higher) temperatures for all mountain ranges•SLW >.05 mm vertical integrated has been used as lower threshold for cloudseeding initiation.

Are their man-made pollutants or natural aerosols/particulates impacting the target clouds that could modify the cloud droplet spectra/IN concentrations to impede seeding effectiveness? 

•Pollutants acting as CCN can narrow the droplet spectrum and slow down the collision coalescenceprocess (warm rain) reducing rainfall downwind of major pollution sources.(Rosenfeld 2000; Givati and Rosenfeld 2004; Givati and Rosenfeld 2005.  See earlier discussion of the latter report.)

•It was found in SCPP that SIP (secondary ice production) produced high ice concentrations at relatively high cloud top temperatures (-5 to -10 oC)

•If pollutants narrow the droplet spectrum, then pollutants in theory should reduce SIP.

Mossop (1978u) found that increases in small (<14 um diameter) droplets combined with those >23 um diameter increased the efficiency of the riming-splintering process.  So it is possible, with the presence of larger droplets say, due to seaborne or other large aerosols combined with pollution sources, that the Hallett-Mossop riming-splintering process is enhanced.

•If high concentrations of pollution produce high concentration of cloud droplets in a narrow size range, this could reduce riming and reduce snowfall on the windward slopes of narrow mountain ranges where growth times are critical.

•A more recent survey article on the role of pollution on clouds and precipitation (Tanre’, 2009) concluded it was still uncertain as to the magnitude of the impact of pollution or whether pollution increases or decreases precipitation based on the meteorological setting.

•Dust (Saharan and Gobi desert) and aerosols (bacteria) acting as IN can enhance natural s

Are their significant enough differences in maritime influenced winter orographic clouds versus continental orographic clouds that strongly influence the natural precipitation process? 

•Yes. Maritime clouds with broader drop size distributions are subject to SIP and thus clouds are more efficient at higher temperatures.

•Continental clouds have relatively more SLW at lower temperatures given the lack of SIP.

•Evidence of this is well-documented when one compares SCPP and Washington studies with interior mountain studies.

====================End of Comments and Corrections  by ALR==========================

References that were uncited in the Reynolds review but were mentioned in this “review and enhancement.”

Alpert, P., N. Halfon, and Z. Levin, 2008: Does air pollution really suppress precipitation in Israel?  J. Appl. Meteor. Climatology, 47, 943-948.

Alpert, P., N. Halfon, and Z. Levin, 2009:  Reply to Givati and Rosenfeld.  J. Appl. Meteor. Climatology, 48, 1751-1754.

Auer, A. H., D. L. Veal, and J. D. Marwitz, 1969: Observations of ice crystals and ice nuclei observations in stable cap clouds.  J. Atmos. Sci., 26, 1342-1343.

Ayers, G., and Levin, 2009:  Air pollution and precipitation.  In Clouds in the Perturbed Climate System.  Their Relationship to Energy Balance, Atmospheric Dynamics, and Precipitation. J. Heintzenberg and R. J. Charlson, Eds.  MIT Press, 369-399.

Bartlett, J. P.,  M. L. Mooney, and W. L. Scott, 1975:  Lake Almanor cloud seeding program.  Preprint, San Francisco Conference on weather modification, Amer. Meteor. Soc., 106-111.

Benjamini, Y, A. Givati, P. Khain, Y. Levi, D. Rosenfeld, U. Shamir, A. Siegel, A. Zipori, B. Ziv, and D. M. Steinberg, 2023:  The Israel 4 Cloud Seeding Experiment: Primary Results.   J. Appl. Meteor. Climate, 62, 317-327.

Borovikov, A. M., I. I. Gaivoronsky, E. G. Zak, V. V. Kostarev, I. P. Mazin, V. E. Minervin, A. Kh. Khrgian and S. M. Shmeter, 1961:  Cloud Physics. Gidrometeor. Izdatel. Leningrad. (Available from Office of Tech. Serv., U. S. Dept. of Commerce.)

Cooper, W. A., and G. Vali, 1981:  The origin of ice in mountain cap clouds.  J. Atmos. Sci., 38, 1244-1259.

Cunningham, R. M., 1957:  A discussion of generating cell observations with respect to the existence of freezing or sublimation nuclei.  In Artificial Stimulation of Rain, H. Weickmann, Ed.  Pergamon Press, NY.,  267-270.

Elliott, R. D., R. W. Shaffer, A. Court, and J. F. Hannaford, 1978:  Randomized cloud seeding in the San Juan Mountains, Colorado.  J. Appl. Meteor., 17, 1298–1318.

Foster, K. R., and P. W. Huber, 1997: Judging  Science–Scientific Knowledge and the Federal Courts.  The MIT Press, Cambridge, MA, 333pp.

Grant, L. O., and P. W. Mielke, Jr., 1967: A randomized cloud seeding experiment at Climax, Colorado 1960-1965.  Proc. Fifth Berkeley Symposium on Mathematical Statistics and Probability, Vol. 5, University of California Press, 115-131.

Grant, L. O., Chappell, C. F., Crow, L. W., Mielke, P. W., Jr., Rasmussen, J. L., Shobe, W. E., Stockwell, H., and R. A. Wykstra, 1969:  An operational adaptation program of weather modification for the Colorado River basin.  Interim report to the Bureau of Reclamation, Department of Atmospheric Sciences, Colorado State University, Fort Collins, 98pp.

Halfon, N., Z. Levin, P. Alpert, 2009:  Temporal rainfall fluctuations in Israel and their possible link to urban and air pollution effects.  Environ, Res. Lett., 4, 12pp. doi:10.1088/1748-9326/4/2/025001

Hobbs, P. V., and A. L. Rangno, 1979: Comments on the Climax randomized cloud seeding experiments.   J. Appl. Meteor., 18, 1233-1237.

Kahan, K. M., J. R. Stinson, and R. L. Eddy, 1969:  Progress in precipitation modification.  Bull. Amer. Meteor. Soc., 50, 206–214.

Kessler, A., A. Cohen, D. Sharon, 2003:  Analysis of the cloud seeding in Northern Israel.  Interim report submitted to the Israel Hydrology Institute and the Israel Water Management of the Ministry of Infrastructure.

Kessler, A., A. Cohen, D. Sharon, 2006:  Analysis of the cloud seeding in Northern Israel. Final report submitted to the Israel Hydrology Institute and the Israel Water Management of the Ministry of Infrastructure, In Hebrew with an English abstract. 117pp.

Levin, Z., 2009:  On the state of cloud seeding for rain enhancement.  Report to the Cyprus Institute on Energy, Environment and Water, 18pp.

Mielke, P. W., Jr., 1979:  Comment on field experimentation in weather modification.  J. Amer. Statist. Assoc., 74, 87–88,

Mielke, P. W., Jr., L. O. Grant, and C. F. Chappell, 1970: Elevation and spatial variation effects of wintertime orographic cloud seeding. J. Appl. Meteor., 9, 476–488; Corrigendum, 10, 842; Corrigendum, 15, 801.

Mielke, P. W., Jr., Grant, L. O., and C. F. Chappell, 1971:  An independent replication of the Climax wintertime orographic cloud seeding experiment.  J. Appl. Meteor., 10, 1198-1212.

Morel-Seytoux, H. J., and F. Saheli, 1973: Test of runoff increase due to precipitation management for the Colorado River Basin Pilot Project.  J. Appl. Meteor., 12, 322-337.

Mossop, S. C., 1978: The influence of the drop size distribution on the production of secondary ice particles during graupel growth. Quart J. Roy. Meteor. Soc., 104, 323-330.

Neiburger, M., 1969: Artificial Modification of Precipitation. W. M. O. Technical Note 105, 33pp.

Neiman, P. J., G. A. Wick, F. M. Ralph, B. E.  Martner, A. B. White, and D. E. Kingsmill, 2005:  Wintertime nonbrightband rain in California and Oregon during CALJET and PACJET:  Geographic, interannual and synoptic variability.  Mon. Wea. Rev., 133, 1199-1223.

Rangno, A. L., 1979:  A reanalysis of the Wolf Creek Pass cloud seeding experiment.   J. Appl. Meteor., 18, 579–605.

Rangno, A. L. and P. V. Hobbs, 1980: Comments on “Randomized cloud seeding in the San Juan Mountains, Colorado,” J. Applied Meteorology, 19, 346-350. 

Rangno, A. L., and P. V. Hobbs, 1987: A re-evaluation of the Climax cloud seeding experiments using NOAA published data.  J. Climate Appl. Meteor., 26,  757-762.

Rangno, A. L., and P. V. Hobbs, 1995a: Reply to Gabriel and Mielke.  J. Appl. Meteor., 34, 1233-1238.

Rangno, A. L. and P. V. Hobbs, 1997a: Reply to Rosenfeld.  J. Appl. Meteor., 36, 272-276.;2

Rangno, A. L. and P. V. Hobbs, 1997b: Comprehensive Reply to Rosenfeld, Cloud and Aerosol Research Group, Department of Atmospheric Sciences, University of Washington, 25pp.

Rasmussen, R. M., S. A. Tessendorf, L. Xue, C. Weeks, K. Ikeda, S. Landolt, D. Breed, T. Deshler, and B. Lawrence, 2018: Evaluation of the Wyoming Weather Modification Pilot Project (WWMPP) using two approaches: Traditional statistics and ensemble modeling. J. Appl. Meteoro. Climatol., 57, 2639–2660, D-17-0335.1.

Rauber, R. M., and A. Tokay, 1991:  An explanation for the existence of supercooled water at the top of cold clouds. J. Appl. Meteor., 48, 1005-1023.

Rhea, J. O., L. G. Davis, and P. T. Willis, 1969:  The Park Range Project.  Final Report to the Bureau of Reclamation, EG&G, Inc., Steamboat Springs, CO. 285 pp.

Rottner, D., L. Vardiman, and J. A. Moore, 1980: Reanalysis of “Generalized Criteria for Seeding Winter Orographic Clouds”, J. Appl. Meteor., 19, 622-626.

Vardiman, L, and J. A. Moore, 1978: Generalized criteria for seeding winter orographic clouds. J. Appl. Meteor., 17, 1769-1777.

A Review and Enhancement of Chapter 8 in the book, “Aerosol Pollution Impacts on Precipitation:  A Scientific Review” 


Below is the impressive list of “Scientific Reviewers” of this volume before this belated review by yours truly happened, ones listed in the 2009 Springer book,  “Aerosol Pollution Impacts on Precipitation:  A Scientific Review.”  The authors of this book, including Chapter 8, had to review an enormous amount of literature which the reviewers also had to know in great detail.

From a reading of this book in those areas of my expertise, such a task is too much despite the authors’ valiant efforts to “get it right.”  Chapter 8  is an example of the problem of having too much to review and not enough time to scrutinize the details of so much literature in one topic.  Chapter 8 is well-written, most of the necessary citations are in it that help the reader to understand the topic.    It does an outstanding job of making a case about the, “Parallels and Contrasts” in deliberate seeding and aerosol pollution.  That is,  except for those elements in Chapter 8 that I am perhaps, a little too familiar with and feel must be addressed in this VERY belated review.

“Too familiar?”

That’s what happens to someone who has spent thousands of volunteer hours (crackpot alert!) rectifying faulty cloud seeding and cloud claims in peer-reviewed journal articles because he felt, “Someone has to do something about this!” (Second crackpot alert, possibly with megalomaniacal implications.)

It goes without saying that I was not asked to review Chapter 8 before it was published.  This would have made these comments unnecessary.  I was well known by the authors of this review as an expert on clouds, cloud seeding, and the weather in the two regions where landmark experiments are reviewed in Chapter 8; those in Colorado and Israel .   With Professor Peter V.  Hobbs in tow, I dissected those landmark experiments in Colorado and Israel and showed they were, as Foster and Huber (1997) described faulty science,  “scientific mirages.”  In fact, they were “low-hanging fruit” that poor peer reviews of manuscripts had let in the journals.  It didn’t take a genius to unravel them.

I read this chapter only recently after I was given the book by one of its authors.  I wondered if Chapter 8 had been reviewed at all by any of the illustrious reviewers listed by Springer since some oversights are so egregious.  However, I was pleased to see that almost all of my work with Prof. Hobbs on those benchmark experiments was cited, except the one I deemed most important.  Odd.

Some background 

Chapter 8 was originally assigned to Prof. Peter V. Hobbs, the director of my group at the University of Washington.  He was going to use portions of a rejected manuscript of mine on cloud seeding  and peer-review entitled, “Cloud Seeding and the Journal Barriers to Faulty Claims: Closing the Gaps.”  He described the segments he was going to use, the rise and fall of the Colorado and Israeli cloud seeding experiments, as, “pretty good.”   Peter was not easy to please.  That was the highest compliment I had ever received from him for my writing.   The manuscript, submitted in 1997,  was ultimately rejected in 1999 by the Bull. Amer. Meteor. Soc., I. Abrams, Editor,  and again in an updated version by  Advances in Meteorology in 2017 as “not the kind of paper we were looking for” in their issue on weather modification (L. Xue, Editor, personal communication).    But maybe its the kind you were looking for!  So, in a sense that manuscript has been rejected twice, sometimes the sign of something especially good.   (Off topic! Get Back, “Jojo,” as the Beatles sang.

Due to pancreatic cancer, Prof. Hobbs was unable to do this piece chapter and Prof. William R. Cotton, Colorado State University, who later has become a close friend,  took over with the additional “contributors” according to Springer,  Dean Terblanche, Zev Levin, Roelof Bruintjes, and Peter Hobbs, as listed by Springer, and all of whom I greatly admire, making these comments “difficult;” “Why am I doing this?”  Etc.

For review purposes, I have copied under the rubric of “fair use,” only those portions of Chapter 8 relevant to my expertise.   To repeat, overall, its a good review.  However, I have added commentaries in a red font following the original statements of the authors (black font) that need clarification, correction, or additions.  References to relevant articles that went uncited in Chapter 8 have been added at the end of this review and are appended with a “u” for uncited.  I have added after those all the references that WERE cited in this review and appear in the original text.  Mielke (1976) cited by the authors, does not appear in the list of their references.


List of illustrious reviewers of the Springer volume:

Chairperson: Dr.George IsaacEnvironment Canada.                       (Name, affiliation, country).

Ayers, Greg,  CSIRO Marine and Atmospheric Research, Australia

Barth, Mary, National Center of Atmospheric Research, USA

Bormann, Stephan,  Johannes-Gutenberg-University, Germany

Choularton, Thomas, University of Manchester, UK.

DeMott, Paul, Colorado State University, USA.

Flossmann, Andrea, Laboratoirede Mitiorologie Physique/OPGC Universiti: Blaise Pascal/C RS, France

Kahn, Ralph, Jet Propulsion Laboratory, USA

Khain, Alexander, The Hebrew University ofJerusalem, Israel

Leaitch, Richard, Environment Canada, Canada

Pandis, Spyros, University of Patras, Greece

Rosenfeld, Daniel, The Hebrew University ofJerusalem, Israel.

Ryan, Brian, CSIRO Marine and Atmospheric Research, Australia

Twohy, Cynthia, Oregon State University, USA.

Vali, Gabor, University of Wyoming, USA.

Yau,  Peter, McGill University, Canada

Zipser, Ed, University of Utah, USA


….and now, very belatedly reviewing Chapter 8, yours truly, the less illustrious,  Arthur L. Rangno,  retiree,                                                                                                                                                                                                Research Scientist IV, Cloud and Aerosol Research Group, Atmospheric Sciences Department, University of Washington, USA:


Chapter 8 in Aerosol Impacts on Precipitation:“Parallels and Contrasts Between Deliberate Cloud Seeding and Aerosol Pollution Effects”

8.1    Deliberate cloud seeding, with the goal of increasing precipitation by the injection of specific types of particles into clouds, has been pursued for over 50 years. Efforts to understand theprocesses involved have led to a significant body of knowledge about clouds and about the effects ofthe seeding aerosol. A number of projects focused on the statistical evaluation of whether a seeding effect can be distinguished in the presence of considerable natural variability. Both the knowledge gained from these experiments, and the awareness of the limitations in that understanding, are relevant to the general question of aerosol effects on precipitation. Definite proof from the seeding projects for an induced increase in precipitation as a result of the addition of seeding material to the clouds would represent a powerful demonstration of at least one type of dominant aerosol­ precipitation link in the clouds involved. Therefore, in this chapter we review the fundamental conceptsof cloud seeding and overview the parallels and contrasts between evaluations of deliberate and inadvertent modification of precipitation by aerosols. It is not our intent to provide a comprehensive assessment of the current status of cloud seeding research. We direct the reader to more compre­hensive weather modification assessments in NRC (2003), Cotton and Pielke (2007), Silverman (2001, 2003),and Garstang et al. (2005).

Deliberate cloud seeding experiments can be divided into two broad categories: glaciogenic seeding and hygroscopic seeding. Glaciogenic seeding occurs when ice-producing materials (e.g. dry ice (solid CO2), silver iodide, liquid propane etc.) are injected into a supercooled cloud for the purpose of stimulating precipitation by the ice particle mechanism (see Sect. 2.2). The underlying hypothesis for glaciogenic seeding is that there is commonly a deficiency of natural ice nuclei and therefore insufficient ice particles for the cloud to produce precipitation as efficiently as it would in the absence of seeding.

The second category of artificial seeding experiments is referred to as hygroscopic seeding. In the past this type of seeding was usually used for rain enhancement from warm clouds (see Cotton 1982 for a review of early hygroscopic seeding research).

However, more recently this type of seeding has been applied to mixed phase clouds as well. The goal of this type of seeding is to increase the concentration of collector drops that can grow efficiently into raindrops by collecting smaller droplets and by enhancing the formation of frozen raindrops and graupel particles. This is done by injecting into a cloud (generally at cloud base) large or giant hygroscopic particles (e.g., salt powders) that can grow rapidly by the condensation of water vapour to produce collector drops (see Sect. 2.3).

Static Glaciogenic Cloud Seeding

Static cloud seeding refers to the use of glaciogenic materials to modify the microstructures ofsupercooled clouds and precipitation. Many hundreds of such experiments have been carried over the past 50 years or so. Some are operational cloud seeding experiments (many of which are still being carried out around the world) which rarely provide sufficient information to decide whether or not they modified either clouds or precipitation. Others are well designed scientific experiments that provide extensive measurements and modeling studies that permit an assessment of whether artificial seeding modified cloud structures and, if the seeding was randomized, the effects of the seeding on precipitation. While there still is some debate of what constitutes firm “proof”(see NRC 2003; Garstang et al. 2005) that seeding affects precipitation, generally it is required that both strong physical evidence of appropriate modifications to cloud structures and highly significant statistical evidence be obtained.

My comprehensive, “critical” review and enhancement of NRC 2003 is here.  Compared to the 1973 NRC review, the NRC 2003 one was merely a superstructure, a Hollywood movie set, not the real deal.  

The reason?  

Too much literature to review in depth even for the illustrious authors of the NRC 2003 report.   Professor Garstang did ask my boss, Prof. Peter V. Hobbs to participate in the 2003 review, but he declined the offer telling me that it would be better if we “commented” on the 2003 review after it was published if necessary.  I nodded and went back to my desk.  Peter usually knew best.  Fate intervened.  Peter came down with pancreatic cancer and our review  of the 2003 report never happened until I got to it years later.

  • Glaciogenic Seeding of Cumulus Clouds

The static seeding concept has been applied to supercooled cumulus clouds and tested in a variety of regions. Two landmark experiments (Israeli I and Israeli II), carried out in Israel, were described in the peer-reviewed literature. The experiments were carried out by researchers at the Hebrew University of Jerusalem (HUJ), hereafter the experimenters. These two experiments were the foundation for the general view that under appropriate conditions, cloud seeding increases precipitation (e.g. N.R.C. 1973; Sax et al. 1975; Tukey et al. 1978a, b; Simpson 1979; Dennis 1980; Mason 1980,1982; Kerr 1982; Silverman 1986; Braham 1986; Cotton 1986a, b; Cotton and Pielke 1992, 1997; Young1993).

Nonetheless, reanalysis of those experiments by Rangno and Hobbs (1993-sic) suggested that the appearance of seeding-caused increases in rainfall in the Israel I experiment was due to “lucky draws” or a Type I statistical error.

The correct year for Rangno and Hobbs is 1995, not 1993 .   Having the wrong year in a reference is a not a good sign right off the bat.  

The first evidence for a lucky draw in Israeli I was presented by Wurtele (1971u) when she reported that the little seeded Buffer Zone between the two targets exhibited the greatest statistical significance in rainfall in either target on Center seeded days.  Wurtele (1971u) quoted the Israeli I chief meteorologist that the Buffer Zone could only have been inadvertently seeded but 5-10% of the time, and “probably less.”  Wurtele should have been cited.  The wind analysis when rain was falling at the launch site near the BZ in Rangno and Hobbs (1995) supports the chief meteorologist’s view.  It would have taken a very bad pilot to have seeded the BZ if he had been instructed not to.

Furthermore, Rangno and Hobbs (1993 sic) argued that during Israel II naturally heavy rainfall over a wide region encompassing the north target area gave the appearance that seeding caused increases in rainfall over the north target area.

The first evidence for naturally heavy rain over a wide region in Israel II, including both targets on north target seeded days, was presented by Gabriel and Rosenfeld (1990u), a critical article  that somehow that went uncited by the authors of Chapter 8.   Gabriel and Rosenfeld stated that the degree of heavy rain on north target seeded days in the south target, from a historical study, was “clearly statistically significant.” 

Rangno and Hobbs (1995) added to that evidence by analyzing rainfall over wide region that included Lebanon and Jordan on north target seeded days.  The Rangno and Hobbs (1995) analysis corroborated the statement by Gabriel and Rosenfeld (1990) concerning a lopsided draw on north target seeded days of Israeli II that affected most of Israel.  In fact, the greatest apparent effect of cloud seeding on north target seeded days was in the south target at Jerusalem (Rangno and Hobbs 1995)!

Deeply troubling, too,  is why the “full results” of the Israeli II experiment by Gabriel and Rosenfeld (1990u) was not cited in a supposed review of those experiments.  The null result of the “full analysis” of Israel II which incorporated random seeding in the South target,  had been omitted in previous reporting by Gagin and Neumann (1976u, 1981).  The “full” results reported by Gabriel and Rosenfeld (1990u) was an extremely important development:  Israeli II had not replicated Israeli I when evaluated in the same way.  Furthermore, the a priori design of Israeli II specified by the Israel Rain Committee mandated that a crossover evaluation be carried out (Silverman 2001).

However, the null result of Israeli II left some questions in the minds of Gabriel and Rosenfeld (1990u).  Were actual rain increases in the north canceled out by decreases in rain on seeded days in the south target resulting in a null overall result?

This idea was later posited by Rosenfeld and Farbstein (1992) as a valid explanation and the disparate results was attributed to dust/haze.  This hypothesis ignored the fact that unusually heavy rain fell on the south target when the north was being seeded.   This left little chance for the south target’s seeded days to overcome this lopsided disadvantage, thus  leaving the impression that seeding had decreased rainfall when rainfall on the control and seeded days in the south target were compared.  Why this was not clear remains a puzzle.

At the same time, lower natural rainfall in the region encompassing the south target area gave the appearance that seeding decreased rainfall over that target area. But this speculation could not explain the positive effect when the north target area was evaluated against the north upwind control area.

Levin et al. 2010u (and unavailable to these authors) also reanalyzed Israeli II and found that a synoptic bias had produced the misperception of seeding effects downwind from the coastal control region mentioned above.    Levin et al’s 2010u conclusions corroborated the Rangno and Hobbs (1995) evaluation of Israeli II described inappropriately as “speculation” by the authors of Chapter 8.  

Details of this controversy can be found in the March 1997 issue of the Journal of Applied Meteorology (Rosenfeld 1997; Rangno and Hobbs 1997a; Dennis and Orville 1997; Rangno and Hobbs1997b; Woodley 1997; Rangno and Hobbs 1997c;  Ben-Zvi 1997; Rangno and Hobbs 1997d; Rangno and Hobbs 1997e). Some of these responses clarified issues; others have left a number of questions unanswered.

The authors should have indicated for the reader what questions were left unanswered.  

However, the exchanges between pro-seeding partisans and Rangno and Hobbs (1997) were extremely important because they led the Israel National Water Authority to form an independent panel of experts to ascertain what the result of operational seeding of the watersheds around Lake Kinneret (aka, Sea of Galilee) was over the decades.  Operational seeding began during the 1975/76 rain season.

The reports of the independent panel (Kessler et al. 2002u, 2006u) were apparently unknown to the authors of this review.  Key elements of the final 2006 report were reprised by Sharon et al. (2008u):  Twenty-seven winter seasons  (75/76 through 01/02)  of operational seeding had not led to an indication that rain had been increased, due to cloud seeding,  an astounding result considering the cost of seeding for so long a period.

Below is a graphical presentation of the independent panel’s findings in their 2006 final report:

Figure 1. The results of operational seeding on the watersheds of Lake Kinneret (aka, Sea of Galilee) as reported by Kessler et al. 2006.  (a) is that result of seeding on rainfall reported by Nirel and Rosenfeld (1995), b-d are the results found for various periods, including the very same era evaluated by Nirel and Rosenfeld (1995).[1]


[1] The findings of Kessler were challenged by seeding partisans at the HUJ and who claimed that “air pollution” was decreasing rain as much as cloud seeding was increasing it.  While this was a convenient explanation, it was not found credible by many subsequent independent investigators, including by Kessler et al. (2006).

—————————continuing with Chapter 8————–

8 Deliberate Cloud Seeding and Aerosol Pollution Effects

It is interesting to note that in the Israeli experiments the effects of artificial seeding with silver iodide appeared to be an increase in the duration of precipi­ tation, with little if any effect on the intensity of precipitation (Gagin 1986; Gagin and Gabriel 1987), a finding compatible with the “static” seeding hypothesis.

The ersatz Colorado State University cloud seeding experiment results had exactly the same outcome as those described above in Israel.  In retrospect, the duration findings from both the Colorado and Israeli scientists were huge red flags that a natural bias on seeded days had occurred in these experiments as was shown in later reanalyses by external skeptics (e.g., Rhea 1983u, Rangno and Hobbs 1987).

Givati and Rosenfeld (2005) wrote, “that cloud seeding with silver iodide enhances precipitation especially where the orographic enhancement factor (see Chapter 6) was the largest. Likewise, the pollution effects reduced precipitation by the greatest amount at the same regions”. They suggestedthat this is because the shallow and short-living orographic clouds are particularly susceptible to such impacts. This suggests that attempts to alter winter precipitation should be concentrated on orographic clouds. Or interpreted in terms of inadvertent modification of clouds; winter orographic clouds may be the most susceptible to precipitation modification by pollution.

The Israeli “experimenters,” who cost their government so much in wasted cloud seeding effort, could not walk away and apologize for their misguided findings and withheld results.  So Givati and Rosenfeld (2005) generated the argument that pollution was exactly canceling out cloud seeding effects!  Of course, the air pollution argument was nonsense, the result of cherry picking amid the 500 or so Israeli rain gauges in Israel.   Here’s what the uncited Kessler et al. (2006u) report had to say about the Givati and Rosenfeld (2005) claims about air pollution:

No supporting evidence was found for the thesis of Givati and Rosenfeld (2005) regarding the decline in the Orographic precipitations (sic) due to the increase of air pollution.”

The air pollution claims by Givati and Rosenfeld (2005), while superficially credible,  except for their sudden hypothesized appearance that canceled out cloud seeding effects, were also evaluated by several independent groups and scientists in later publications not available to the authors of this review:  Alpert et al. (2008u); Halfon et al. (2009u);  Levin (2009u), Ayers and Levin (2009u).  All these independent re-analyses and reviews of the hypothesized effect of air pollution on rainfall found the argument that air pollution had canceled seeding-induced increases in rain unconvincing.

This also suggests that the conceptual model on which the Israeli cloud seeding experiments was based is not exactly as postulated. The seeding was originally aimed at the convective clouds that formed over the narrow coastal plain, with the intent of nucleating ice crystals and forming graupel earlier in the cloud life cycle (Gagin and Neumann 1974), thus leading to increased rainfall in the catchment basin of the Sea of Galilee to the east of the Galilee Mountains. However, the report of Givati and Rosenfeld (2005) concluded that “cloud seeding did not enhance the convective precipitation, but rather increased the orographic precipitation on the upwind side of the Mountains, probably by the Bergeron-Findeisen process.”

The above is not what Kessler et al. (2006u) concluded.   It was a shame that the authors did not know about Kessler et al.’s report.

To update this review, the idea posited by Rosenfeld and Givati (2005) about seeding orographic clouds, promoted by these authors, was tested in Israel-4, a seven season randomized experiment (Benjamini et al. 2023u).  Seeding in the orographic north of Israel resulted in no viable effect on rainfall.  This should not be surprising.

The lack of enhancement of the convective clouds in Israel might be explained by their tendency to mature and dissipate inland during the winter storms. Seeding of mature convective clouds cannot affect them much. The lack of enhancement is also consistent with the microphysically maritime nature of the convective clouds.

The authors seem to be unaware that for decades the cloud seeding experimenters had reported in their many publications that the clouds of Israel were “continental” in nature (e.g., Gagin and Neumann 1974, 1976u, Gagin 1975u), that is, they contained high droplet concentrations that made them extremely “un-maritime.”  This in turn helped generate scientific consensus that seeding such clouds had produced viable results on rainfall  in Israeli I and Israeli II because it was hard for them to rain and needed cloud seeding  (e.g., Kerr 1982, Silverman 1986, Dennis 1989).

This appears to be caused mainly due to the natural hygroscopic seeding by sea spray or mineral dust particles coated with soluble material (Levin et al.1996, 2005) in the winter storms that enhance the warm precipitation (Rosenfeld et al. 2001) as well as promoting the formation of ice hydrometeors that is followed by ice multiplication (Hallett and Mossop 1974).

In a surprising oversight in a supposed “scientific review,” the authors do not cite Rangno (1988) who described so long ago the clouds of Israel as we know them today; ones that rain via warm rain processes and precipitate regularly via the ice process when top temperatures are >-10°C, all contrary to the many reports of the cloud seeding experimenters (e.g., Gagin 1986).

Moreover, it has not been satisfactorily determined why the Israeli cloud seeding experimenters could not discern the natural precipitating characteristics of their clouds with all the tools available to them for so many decades.  Did the wind not blow over the Mediterranean during Israeli I and II, thus did not “maritimize” clouds when Prof. Gagin was observing them with his radars and sampling them with his research aircraft?

I spent 11 weeks in Israel from early January through mid-March 1986 studying the precipitating nature of Israeli clouds. I spoke with Israel Meteorological Service forecasters, and the chief forecaster of the Israeli randomized experiments.   Not surprisingly, they were all aware of the natural character of their rain clouds that so eluded the cloud seeding researchers at the HUJ; faulty descriptions of clouds were published by HUJ seeding researchers repeatedly in peer-reviewed journals.  How did this happen?

These suggestions are supported by the results of glaciogenic cloud seeding in Tasmania, which targeted a hilly area by seeding along an upwind coastline. The seeding in Tasmania was shown to enhance precipitation from the stratiform orographic clouds, but not from the convective clouds (Ryan and King 1997). This is consistent with the microphysical conclusions of Rangno and Hobbs (1993 sic), who asserted that, cloud seeding as done in Israel could not have possibly caused the statistically documented rain enhancement from the convective clouds there.

Again, the correct year for Rangno and Hobbs is 1995.  

The minimal amount of cloud seeding in Israeli I should have been discussed. The experimenters realized this post facto of Israel-1 and added a second seeding aircraft and no less than 42 ground generators (NRC 1973) when conducting Israel II.  The difference in released seeding material in Israeli II from the ~1000 grams released in all of Israeli I (Gabriel and Neumann (1967) has to be stupefying and raises questions.

Do the authors of this chapter really think that only 70 h of line seeding by a single aircraft upwind of each target per whole Israeli rain season could have produced a statistically significant result in rainfall in Israeli I?  Do they know that the coverage of convective clouds with rising air below cloud base is spotty,  that the rain that comes into Israel from the Mediterranean are “tangled masses” in various life cycle stages  (as described by Neumann et al. 1967)? 

Recently, Givati and Rosenfeld (2005) carried out a study in which the effects of pollution on rainfall suppression in orographic clouds were separated from the effects of cloud seeding in Israel. They concluded that the two effects have the opposite influence on rainfall, demonstrating the sensitivity of clouds to anthropogenic aerosols of different kinds. By analyzing the rainfall amounts in northern Israel during the last 53 years during days in which no seeding was carried out, they observed a decreasing trend of the orographic factor R0 (discussed in Chapter 6) with time from the beginning of the study. They associated this decrease with the increase in aerosol pollution. The same trend, but shifted upward by 12-14%, was observed for days in which seeding was carried out. Thus, it appears that the opposing effects of air pollution and seeding appear to have nearly canceled each other.

The air pollution canceling cloud seeding claims by Rosenfeld and colleagues have not been deemed credible to those who have investigated them, listed previously.  

Another noteworthy experiment was carried out in the high plains of the U.S. (High Plains Experiment (HIPLEX-1) Smith et al.(1984).Analysis of this experiment revealed the important result that after just 5 min, there was no statistically significant difference in the precipitation between seeded and non-seeded clouds, (Mielke et al. 1984). Cooper and Lawson( 1984) found that while high ice crystal concentrations were produced in the clouds by seeding, the cloud droplet region where the crystals formed evaporated too quickly for the incipient artificially produced ice crystals to grow to appreciable sizes. Instead, they formed low density, unrimed aggregates having the water equivalent of only drizzle drops, which were too small to reach the ground before evaporating. Schemenauer and Tsonis( 1985) affirmed the findings of Cooper and Lawson in a reanalysisof the HIPLEX data emphasizing their own earlier findings (Isaac et al. 1982) that cloud lifetimes were too short in the HIPLEX domain for seeding to have been effective in the clouds targeted for seeding (i.e. Those with tops warmer than -12°C). Although the experiment failed to demonstrate statistically all the hypothesized steps, the problems could be traced to the physical short lifetimes of the clouds (Cooper and Lawson 1984; Schemenauer and Tsonis 1985). This in itself is a significant result that shows the ability of physical measurements and studies to provide an understanding of the underlying processes in each experiment. The results suggested that a more limited window of opportunity exists for precipitation enhancement than was thought previously.  Cotton and Pielke (1995) summarized this window of opportunity as being limited to: Clouds that are relatively cold-based and continental; Clouds with top temperatures in the range -1O° to-25°C, and a timescale confined to the availability of significant supercooled water before depletion by entrainment and natural precipitation processes.

Today, this window would even be viewed as too large, since many cold based continental clouds with tops>-25°C have copious ice particle concentrations(e.g., Auer et al. 1969u, Cooper and Saunders 1980u, Cooper and Vali 1981u, Grant et al. 1982u.  These references were added to make them more appropriate for inland mountain locations). The HIPLEX results also indicated that small clouds make little contribution to rainfall.

This begs the question, should we expect a similar window of effectiveness for inadvertent IN pollution?

 8.1.1. Seeding Winter Orographic Clouds

The static mode of cloud seeding has also been applied to orographic clouds. Precipitation enhancement of orographic clouds by cloud seeding has several advantages over cumulus clouds. The clouds are persistent features that produce precipitation even in the absence of large-scale meteorological disturbances. Much of the precipitation is spatially confined to high mountainous regions thus making it easier to set up dense ground based seeding and observational networks. Moreover, orographic clouds are less susceptible to a “time window” as they are steady clouds that offer a greater opportunity for successful precipitation enhancement than cumulus clouds. A time window of a different type does exist for orographic clouds, which are related to the time it takes a parcel of air to condense to form supercooled liquid water and ice crystals while ascending to the mountain crest.

Missing in this discussion is the time that ice forms in orographic clouds after the leading edge forms as a droplet cloud. Ice particles have been shown to form a short distance downwind at surprisingly high temperatures as reported by Auer et al (1969u), Cooper and Vali (1981u).  

What then is the effect of introducing ice by AgI at an upwind edge where ice is already going to form immediately downwind in those situations?  Does this case represent a productive seeding possibility?  This scenario should have been discussed by the Chapter 8 authors.

The special case described here of non-precipitating clouds, where cloud seeding will be effective without question is not quantified.  How often do they occur, and how thick are they?  What is their cloud top temperature?  Are bases low enough so that the light, seeding-induced snowfall will reach the ground?  Will it be enough to justify the cost of seeding, by ground or aircraft?

The Chapter 8 authors were not aware of Rangno (1986u) who displayed the rapid changes in cloud characteristics that made seeding even orographic clouds problematic due to those changes in cloud top temperatures and in wind directions over periods of just 3-4 hours.

So many questions, so few answers by the authors, elements that point to the extreme difficulty of proper reviews in any field in meteorology!

If winds are weak, then there may be sufficient time for natural precipitation processes to occur efficiently. Stronger winds may not allow efficient natural precipitation processes but seeding may speed up precipitation formation. Stronger winds may not provide enough time for seeded icecrystals to grow to precipitation before being blown over the mountain crest and evaporating in the sinking sub saturated air to the lee of the mountain. A time window related to the ambient winds, however, is much easier to assess in a field setting than the time window in cumulus clouds.

The landmark randomized cloud seeding experiments at Climax, near Fremont Pass, Colorado (referred to as Climax I and Climax II), Colorado, reported by Grant and Mielke(1967) and Mielke et al.( 1970,1971) suggested increases in precipitation of 50% and more on favorable days (e.g. Grant and Mielke 1967; Mielke et al. 1970,1971), and the results were widely viewed as demonstrating the efficacy of cloud seeding (e.g. NRC 1973; Sax et al. 1975; Tukey et al. l978a, b; American Meteorological Society 1984),even by those most skeptical of cloud seeding claims(e.g. Mason 1980,1982). Nonetheless, Hobbs and Rangno (1979), Rangno and Hobbs (1987, 1993) question both the randomization techniques and the quality of data collected during those experiments and conclude that the Climax II experiment failed to confirm that precipitation can be increased by cloud seeding in the Colorado Rockies.

It appears that these cited critical papers by the present writer were not read by the authors of this review.  Hobbs and Rangno (1979), a study originated and carried out by the second author, demonstrated that the claims about a physical foundation for the Climax experiments were bogus.  These important findings was left out of the discussion above.   The experimenters had claimed out of thin air (Grant and Mielke 1967) that the stratifications by 500 mb temperatures were reliably connected to cloud top ones.

Moreover, the precipitation per day (PPD) does not decrease at Climax (or elsewhere in the Rockies) after a 500 mb temperature of -20°C is exceeded as the experimenters claimed (e.g., Grant et al. 1969u, 1974u, Chappell 1970u).  Rather, the PPD continues to increase at temperatures above -20°C as shown in Rangno 1979, Hobbs and Rangno (1979).   The decrease in PPD that occurred during Climax I when the 500 mb temperature was >-20° C was indicative of a bias in the draw on the Climax I control days rather than representative of PPD climatology. 

Hobbs and Rangno (1979) further demonstrated that the master’s thesis repeatedly invoked by the experimenters in support of the 500 mb/cloud top temperature correspondence claim (e.g., Grant and Elliott 1974) did no such thing,  but rather proved just the opposite.  This was due to the way that meteorological data were assigned to experimental days by the experimenters (i. e., as described by Fritsch in Grant et al. 1974u).   Critical papers were not read by the authors.  Q. E. D.

Quoting the authors from their paragraph above:  “the quality of the data collected during those experiments”.

This is a euphemism for what Rangno and Hobbs (1987) found.

The experimenters repeatedly described the NOAA-maintained recording gauge in the center of the Climax target as “independently” collected data (e.g., Mielke et al. 1970).  Rangno and Hobbs simply went to the NOAA hourly precipitation data publication for Colorado and used those data to evaluate the Climax experiments. Those published data were not the same as those used by the experimenters. 

The experimenters had, in fact, reduced the recording charts at that key gauge in Climax II themselves as revealed by Mielke 1995, and in doing so, helped the seeded day cases (Rangno and Hobbs 1987).  Climax II, not so lucky in its storm draw on seeded days as Climax I, was plagued by “helpful” errors.  Thirty-two of 43 differences in precipitation between that used by the experimenters and that in the NOAA publication helped the seeded cases.  The chance that such results came from an unbiased source can be rejected at a P value of 0.0001.

Climax I, however, benefitting from a storm draw on seeded days that favored the appearance of a cloud seeding effect in its first half of conduct,  had virtually no errors in data.

What do we make of this?  Circle the wagons? 

Or come to a logical conclusion that someone helped the Climax experiment replicate Climax II?  At this time, mid-way through Climax II, the Bureau of Reclamation’s cloud seeding division had begun spending hundreds of thousands of dollars on the planning of the Colorado River Basin Pilot Project.  There was, therefore, enormous pressure on the experimenters to have Climax II replicate Climax I.  

We let the reader decide what may have happened.


Inexplicably, the authors of this chapter omit the reanalysis of Mielke et al. (1981) by Rhea (1983u).  Indeed, this author’s own independent reanalysis of the Climax experiments (rejected in 1983) was partially because reviewers’ thought Rhea’s reanalysis, simultaneously under review and that came to the same result, was more robust.  Rhea showed that the mismatch between the time the control gauges were read and when the Climax target gauges were read resulted in the false impression that Climax II had replicated Climax I.  When the gauges were synchronized by Rhea (1983u), the Climax II seeding increases disappeared (as they also did using the published NOAA data in Rangno and Hobbs (1987).

A background note:  Grant et al. 1983u, however, strongly criticized the Rhea reanalysis before it was published.  Rhea altered his reanalysis along the lines suggested by Grant et al. prior to publication.  Nevertheless, Grant et al. did not revise their published comment to account for Rhea’s revisions.  Grant, in a personal note to Rhea at that time, did not know why he and his group had not altered their criticism of Rhea’s revised manuscript.

The published record concerning Rhea’s reanalysis is, therefore confusing; the experimenters appeared to critique Rhea’s paper while not actually doing so.

Even so, in their reanalysis, Rangno and Hobbs(1993) did show that precipitation increased by about 10% in the combined Climax I and II experiments.

First, the so-called “10% increase in precipitation for all of the Climax I and II experiments was “built in” by the choice of control stations mid-way through Climax I by the experimenters  as demonstrated in Rangno and Hobbs (1993).   We are sure the authors did not read that 1993 paper.  Control stations should have been selected prior to the Climax I experiment as good design demands.  Otherwise, the temptation to cherry-pick control stations that prove what the experimenters already believe becomes too big a temptation and that is surely what happened in Climax I at the half-way point.

If the seeding effect is real, it will continue following a cherry-picked group of control stations.  If there is no further sign of seeding, as shown in “Climax 1B,” the second half of Climax I by Rangno and Hobbs (1993) then we know that the gauges were picked because it showed what the experimenters believed before the experiment even began.  The lack of any sign of an effect of cloud seeding on precipitation continued through all of Climax II as well (Rangno and Hobbs 1993).

Finally, 1000 re-randomizations of the Climax data performed by the University Washington Academic Computer Center by Irina Gorodnoskya (unpublished data) showed that the 10% claimed increase in precipitation by the authors above was in the noise of these experiments.  It should not be quoted as an increase in snow due to seeding as the authors do here.

This should be compared, however, to the original analyses by Grant and Mielke (1967), Grant and Kahan (1974), Grant and Elliott (1974), Mielke et al. (1971), Mielke et al. (1976) and Mielke et al. (1981) that indicated greater than 100% increase in precipitation on seeded days for Climax I and 24% for Climax II.

Two other randomized orographic cloud seeing experiments, the Lake Almanor Experiment (Mooney and Lunn 1969) and the Bridger Range Experiment (BRE) as reported by Super and Heimbach (1983) and Super (1986) suggested positive results.

Of concern is that the “cold westerly” case in Phase I of the Lake Almanor experiment, where large seeding effects were reported was not reported in Phase II (Bartlett et al. 1975).   Also, the large increases (40%) in snow  reported in Phase I for cold westerly cases, is suspect since such clouds are likely to develop high natural ice particle concentrations naturally.  The Lake Almanor Phase I  is badly in need of a reanalysis by external skeptics;  its results should not be taken at face value.

 However, these particular experiments used high elevation AgJ generators, which increase the chance that the Agl plumes get into the supercooled clouds. Moreover, both experiments providedphysical measurements that support the statistical results (Super and Heimbach 1983, 1988).

There have been a few attempts to use mesoscale models to evaluate cloud seeding programs. Cottonet al. (2006) applied the Colorado State University Regional Atmospheric Modeling System(RAMS)to thesimulation of operational cloud seeding in the central Colorado Mountains in the 2003-2004 winterseason. The model included explicit representation of surface generator production of Agl at thelocations, burn rates, and times supplied by the seeding operator. Moreover, the model explicitlyrepresented the transport and diffusion of the seeding material, its activation, growth of icecrystals and snow,and precipitation to the surface. Detailed evaluation of model forecast orographicprecipitation was performed for 30 selected operational seeding days. It was shown that the model could be a useful forecasting aid in support of the seeding operations. But the model over-predictednatural precipitation, particularly on moist southwest flow days. The model also exhibited virtually no enhancement in precipitation due to glaciogenic seeding. There are a number of possiblecauses for the lack of response to seeding, such as over prediction of natural precipitation, which prevented the effects of seeding from being seen. In addition, the background CCN and INconcentrations are unknown, therefore lower CCN concentrations than occurred would make the cloudsmore efficient in precipitation production, thus reducing seeding effectiveness.

Finally, Ryan and King(1997) reviewed over 14 cloud seeding experiments covering much of southeastern, western,and central Australia, as well as the island of Tasmania. They concluded that static seeding over the plains of Australia is not effective. They argue that for orographic stratiform clouds, there is strong statistical evidence that cloud seeding increased rainfall, perhaps by as much as 30% over Tasmania when cloud top temperatures are between -10 and -l2°C in southwesterly airflow. The evidence that cloud seeding had similar effects in orographic clouds overthe mainland of southeastern Australia is much weaker. Note that the Tasmanian experiment had bothstrong statistical and physical measurement components and thus meets, or at least comes close to meeting, the NRC (2003) criteria for scientific “proof.” Cost/benefit analysis ofthe Tasmanian experiments suggests that seeding has a gain of about 13:1. This is viewed as a real gain to hydrologic energy production.

A complication revealed in the analysis of some of the Australian seeding experiments is thatprecipitation increases were inferred one to three weeks following seeding in several seedingprojects(e.g. Bigg and Turton 1988). Bigg and Turton ( I988) and Bigg ( 1988, 1990, 1995) suggestedthat silver iodide seeding can trigger biogenic production of additional ice nuclei. The latter research suggests that fields sprayed with silver iodide release secondary ice nuclei particles at intervals of up to ten days.

In summary, the “static” mode of cloud seeding has been shown to cause the expected alterations incloud microstructure including increased concentra­ tions of ice crystals, reductions of supercooled liquid water content, and more rapid production of precipitation elements in both cumuli (Isaac et al.1982; Cooper and Lawson 1984)and orographic clouds(Reynolds and Dennis 1986; Reynolds 1988;Super andBoe 1988; Super et al. 1988; Super and Heimbach 1988). The documentation of increases in precipitation on the ground due to static seeding of cumuli, however, has been far more elusive, with the Israeli experiment (Gagin and Neumann 1981) providing the strongest evidence that static seeding of cold-based, continental cumuli can cause significant increases of precipitation on the ground.  

Tukey et al. (1978b, Appendendix C, pC.1) wrote:   “The strongest evidence for rainfall enhancement involving the seven latest substantial experiments this task force has studied seems today to be that from the two Israeli experiments….”  The statement in blue (highlighted by this writer) which is almost the exact wording as that found in Turkey et al. (1978b) 30 years before the Springer book was published) is troubling indeed.    The assessment by Turkey et al. in 1978 was valid; it was not valid 30 years later when so much water has gone under the bridge concerning the Israeli cloud seeding experiments (or,  “too little water” due to cloud seeding).

Moreover,  citing Gagin and Neumann (1981) in 2009 as the strongest evidence in support of cloud seeding as they do,  demonstrated that the authors of this review were not aware of,  nor understood the literature in the topic they are supposedly reviewing.  The omission of critical literature by the authors as was proof of this assertion.

Why wasn’t I asked to review this manuscript in advance of publication since I am well-known as an expert on both the Colorado and Israel clouds, weather, and cloud seeding experiments?  Moreover, the authors of this review knew this.

The evidence that orographic clouds can cause significant increases in snowpack is far more compelling, particularly in the more continental and cold-based orographic clouds (Mielke et al. 1981; Super and Heimbach 1988).

The authors omit Rhea’s 1983u reanalysis of Mielke et al. 1981 and that of Rangno and Hobbs (1987) in remarking that “significant increases in snowpack” have been compellingly shown by Mielke et al. 1981.

Update to the orographic seeding claim above by the authors:  The NCAR Wyoming experiment, completed in 2013 (Rasmussen et al. 2018u), could find no viable evidence that seeding from ground generators had increased precipitation after six seasons of randomized seeding.

Perhaps, however, the most challenging obstacle to evaluating cloud seeding experiments to enhance precipitation, is the inherent natural variability of precipitation in space and time, and the inability to increase precipitation amounts to better than ~10%. This last obstacle puts great demands on the measuring accuracy and the duration of the experiments. Shouldn’t we expect similar obstacles in evaluating inadvertent effects of IN pollution on precipitation?

A well-stated description of the problem.


 List of references mentioned in the critical review that were uncited by the authors, or are relevant papers for an enhancement of Chapter 8 that were unavailable to these authors because they were published after Chapter 8 appeared.

Alpert, P., N. Halfon, and Z. Levin, 2008: Does air pollution really suppress precipitation in Israel?  J. Appl. Meteor. Climatology, 47, 943-948.

Alpert, P., N. Halfon, and Z. Levin, 2009:  Reply to Givati and Rosenfeld.  J. Appl. Meteor. Climatology, 48, 1751-1754.

Auer, A. H., D. L. Veal, and J. D. Marwitz, 1969: Observations of ice crystals and ice nuclei observations in stable cap clouds.  J. Atmos. Sci., 26, 1342-1343.

Ayers, G., and Levin, 2009:  Air pollution and precipitation.  In Clouds in the Perturbed Climate System.  Their Relationship to Energy Balance, Atmospheric Dynamics, and Precipitation. J. Heintzenberg and R. J. Charlson, Eds.  MIT Press, 369-399.

Bartlett, J. P., M. L. Mooney, and W. L. Scott, 1975:  Lake Almanor Cloud Seeding Program.  Preprint, Weather Modification Conference, San Francisco, 106-110.

Benjamini, Y, A. Givati, P. Khain, Y. Levi, D. Rosenfeld, U. Shamir, A. Siegel, A. Zipori, B. Ziv, and D. M. Steinberg, 2023:  The Israel 4 Cloud Seeding Experiment: Primary Results.   J. Appl. Meteor. Climate, 62, 317-327.

Chappell, C. F.,  1970:  Modification of cold orographic clouds.  Atmos. Sci. Paper No. 173, Dept. of Atmos. Sci., Colorado State University, Fort Collins, 196pp.

Cooper, W. A., and C. P. R. Saunders, 1980:  Winter storms over the San Juan mountains.  Part II:  Microphysical processes.  J. Appl. Meteor., 19, 927-941.

Cooper, W. A., and G. Vali, 1981:  The origin of ice in mountain cap clouds.  J. Atmos. Sci., 38, 1244-1259.

Dennis, A. S., 1989: Editorial to the A. Gagin Memorial Issue of the J. Appl. Meteor., 28, 1013.  No doi.

Gabriel, K. R., and Y. Neumann, 1978:  A note of explanation on the 1961–67 Israeli rainfall stimulation experiment.  J. Appl. Meteor., 17, 552–556.

Gabriel, K. R., and Rosenfeld, D., 1990: The second Israeli rainfall stimulation experiment: analysis of precipitation on both targets. J. Appl. Meteor., 29, 1055-1067.;2

Grant, L. O., DeMott, P. J., and R. M. Rauber, 1982:  An inventory of ice crystal concentrations in a series of stable orographic storms.  Preprints, Conf. Cloud Phys., Chicago, Amer. Meteor. Soc. Boston, MA. 584-587. No doi.

Grant, L. O., J. G. Medina, and P. W. Mielke, Jr., 1983:  Reply to Rhea. J. Climate Appl. Meteor., 22, 1482–1484.

Grant, L. O., C. F. Chappell, L. W. Crow, J. M. Fritsch, and P. W. Mielke, Jr., 1974:  Weather modification: A pilot project.  Final Report to the Bureau of Reclamation, Contract 14-06-D-6467, Colorado State University, 98 pp. plus appendices.

Grant, L. O., Chappell, C. F., Crow, L. W., Mielke, P. W., Jr., Rasmussen, J. L., Shobe, W. E., Stockwell, H., and R. A. Wykstra, 1969:  An operational adaptation program of weather modification for the Colorado River basin.  Interim report to the Bureau of Reclamation, Department of Atmospheric Sciences, Colorado State University, Fort Collins, 98pp.  (Available from the Bureau of Reclamation, Library,   Federal Building, Denver, Colorado 80302.

Halfon, N., Z. Levin, P. Alpert, 2009:  Temporal rainfall fluctuations in Israel and their possible link to urban and air pollution effects.  Environ, Res. Lett., 4, 12pp. doi:10.1088/1748-9326/4/2/025001

Kessler, A., A. Cohen, D. Sharon, 2003:  Analysis of the cloud seeding in Northern Israel.  Interim report submitted to the Israel Hydrology Institute and the Israel Water Management of the Ministry of Infrastructure.

Levin, Z., N. Halfon, and P. Alpert, 2010: Reassessment of rain enhancement experiments and operations in Israel including synoptic considerations.  Atmos. Res., 97, 513-525.


Levin, Z., N. Halfon, and P. Alpert: 2011:  Reply to the Comment by Ben-Zvi on the paper “Reassessment of rain experiments and operations in Israel including synoptic considerations” Atmos. Res., 99, 593-596.

Mielke, P. W., Jr., 1995:  Comments on the Climax I and II experiments including replies to Rangno and Hobbs.  J. Appl. Meteor., 34, 1228–1232.

National Research Council, 1973: Weather & Climate Modification: Progress and Problems. National Academy of Sciences, 258 pp.,

Neumann, J., K. R. Gabriel, and A. Gagin, 1967: Cloud seeding and cloud physics in Israel:  results and problems.  Proc. Intern. Conf. on Water for Peace.  Water for Peace, Vol. 2, 375-388.  No doi.

Rangno, A. L., 1979:  A reanalysis of the Wolf Creek Pass cloud seeding experiment.   J. Appl. Meteor., 18, 579–605.

Rangno, A. L., 1986:  How good are our conceptual models of orographic clouds?  In Precipitation Enhancement–A Scientific Challenge, R. R. Braham, Jr., Ed., Meteor. Monographs, 43, Amer. Meteor. Soc., 115-124. Invited paper, title assigned by A. S. Dennis.

Rangno, A. L., 1988: Rain from clouds with tops warmer than -10 C in Israel.  Quart J. Roy. Meteor. Soc., 114, 495-513.


Rasmussen, R. M., S. A. Tessendorf, L. Xue, C. Weeks, K. Ikeda, S. Landolt, D. Breed, T. Deshler, and B. Lawrence, 2018:  Evaluation of the Wyoming Weather Modification Pilot Project (WWMPP) using two approaches:  Traditional statistics and ensemble modeling.  J. Appl. Meteor. and Climate, 57, 2639-2660.

Rhea, J. O., 1983:  “Comments on ‘A statistical reanalysis of the replicated Climax I and II wintertime orographic cloud seeding experiments.'”  J. Climate Appl. Meteor., 22, 1475-1481.

Rosenfeld, D., 1998: The third Israeli randomized cloud seeding experiment in the south: evaluation of the results and review of all three experiments. Preprints, 14th Conf. on Planned and Inadvertent Wea. Modif., Everett, Amer. Meteor. Soc. 565-568. No doi.

Sharon, D., A. Kessler, A. Cohen, and E. Doveh, 2008:  The history and recent revision of Israel’s cloud seeding program.  Isr. J. Earth Sci., 57, 65-69.

Wurtele, Z. S., 1971: Analysis of the Israeli cloud seeding experiment by means of concomitant meteorological variables. J. Appl. Meteor., 10, 1185-1192.;2

Totality of References  in Chapter 8.1, “Introduction” through 8.2.2 “Seeding Winter Orographic Clouds” 


American Meteorological Society, 1984: Statement on planned and inadvertent weather modification.  Bull. Amer. Meteor. Soc., 66, 447–448.

Ben-Zvi, A., 1997:  Comments on “A new look at the Israeli randomized cloud seeding experiments.” J. Appl. Meteor., 36, 255-256.

Bigg, E. K., 1988: Secondary ice nucleus generation by silver iodide applied to the ground. J. Appl. Meteor., 27, 453-488.

Bigg, E. K., 1990:  Aerosol over the southern ocean. Atmos. Res., 25, 583-600.

Bigg , E. K., 1995:  Tests for persistent effects of cloud seeding in a recent Australian experiment.  J. Appl. Meteor., 34, 2406-2411.

Bigg, E. K., and E. Turton, 1988: Persistent effects of cloud seeding with silver iodide.  J. Appl. Meteor., 27, 505-514

Braham, Roscoe R., Jr., 1986:  Rainfall enhancement–a scientific challenge.  Rainfall Enhancement–A Scientific Challenge, Meteor. Monogr., 21, No. 43,  1–5.

Cooper, W. A., and R. P. Lawson, 1984:  Physical interpretation of results from the HIPLEX-1 experiment.  J. Climate Appl. Meteor., 23, 523-540.

Cotton, W. R., 1982: Modification of precipitation from warm clouds. A review.  Bull. Meteor. Soc., 63, 146-160.

Cotton, W. R., 1986a: Testing, implementation, and evolution of seeding concepts–a review.  In Precipitation Enhancement–A Scientific Challenge, R. R. Braham, Jr., Ed., Meteor. Monographs, 43, Amer. Meteor. Soc., 63-70.

Cotton, W. R., 1986b: Testing, implementation, and evolution of seeding concepts–a review.  In Precipitation Enhancement–A Scientific Challenge, R. R. Braham, Jr., Ed., Meteor. Monographs, 43, Amer. Meteor. Soc., 139-149.

Cotton, W. R., and R. A. Pielke, 1992:  Human Impacts on Weather and Climate. ASteR Press, 271pp.

Cotton, W. R., and R. A. Pielke, 1995:  Human Impacts on Weather and Climate, 1st edition, Cambridge University Press, 288pp.

Cotton, W. R., and R. A. Pielke, 2007:  Human Impacts on Weather and Climate, 2nd edition, Cambridge University Press, 308pp.

Cotton, W. R., R. R. McAnelly, G. Carrio, P. Mielke, and C. Hartzell, 2006:  Simulations of snowpack augmentation in the Colorado Rocky Mountains.  J. Weather Modification, 38, 58-65.

Dennis, A. S., 1980:  Weather Modification by Cloud Seeding.  Academic Press, 267pp.

Dennis A. S., and H. D. Orville, 1997: Comments on “A new look at tbe Israeli cloud seeding experiments.” J. Appl. Meteor., 36, 277-278

Gagin, A., 1986:  Evaluation of “static” and “dynamic” seeding concepts through analyses of Israeli II experiment and FACE-2 experiments.  In Rainfall Enhancement–A  Scientific Challenge, Meteor. Monogr., 43, Amer. Meteor. Soc., 63–70.

Gagin, A., and K. R. Gabriel, 1987:   Analysis of recording rain gauge data for the Israeli II experiment. Part I:  Effects of cloud seeding on the components of daily rainfall.  J. Climate Appl. Meteor.,  26,   913–926.

Gagin, A., and J. Neumann, 1974: Rain stimulation and cloud physics in Israel. Weather and Climate Modification, W. N. Hess, Ed., John Wiley and Sons,  454–494.

Gagin, A., and J. Neumann, 1981:  The second Israeli randomized cloud seeding experiment: evaluation of results.  J. Appl. Meteor., 20, 1301–1311.

Garstang, M., R. Bruintjes, R. Serafin, H. Oroville, B. Boe, W. R. Cotton, J, Warburton, 2005:  Weather Modification; Finding common ground. Bull. Amer. Meteor. Soc. 86, 647-655.

Givati, A., and Rosenfeld, D., 2005: Separation between cloud-seeding and air pollution effects. J. Appl. Meteor. Climate, 44, 1298-1314.

Grant, L. O., and R. D. Elliott, 1974:  The cloud seeding temperature window.  J. Appl. Meteor., 13, 355-363.

Grant, L. O., and A. M. Kahan, 1974:  Weather modification for augmenting orographic precipitation. Weather and Climate Modification, W. N. Hess, ed., John Wiley and Sons, 282-317.

Grant, L. O.,  and P. W. Mielke, Jr., 1967:  A randomized cloud seeding experiment at Climax, Colorado 1960-1965.  Proc. Fifth Berkeley Symposium on Mathematical Statistics and Probability, Vol. 5, University of California Press, 115-131.

Hobbs, P. V., , andA. L. Rangno, 1979:  Comments on the Climax randomized cloud seeding experiments.   J. Appl. Meteor., 18, 1233-1237.

Isaac, G. A., J. W. Strapp, and R. S. Schemenauer, 1982: Summer cumulus cloud seeding experiments near Yellowknife and Thunder Bay, Canada. J. Appl. Meteor., 21, 1266-1285.

Kerr, R. A., 1982: Cloud seeding: one success in 35 years.Science,217,519–522.

Levin, Z., E. Ganor, and V. Gladstein, 1996: The effects of desert particles coated with sulfate on rain formation in the eastern Mediterranean.  J. Appl. Meteor., 35, 1511-1523.;2

Levin, Z., A. Teller, E. Ganor, and Y. Yin, 2005: On the interaction of mineral dust, sea salt particles and clouds–A measurement and modeling study from the MEIDEX campaign.  J. Geosphys. Res.110, D20202, doi 10.1029/2005JD005810.

Mason, B. J., 1980:  A review of three long-term cloud-seeding experiments.  Meteor. Mag., 109, 335-344.

Mason, B. J.,, 1982:  Personal Reflections on 35 Years of Cloud Seeding.  Contemp. Phys., 23, 311-327.

Mielke, P. W., Jr., K. J. Berry, A. S. Dennis, P. L. Smith, J. R. Miller, Jr., B. A. Silverman, 1984: HIPLEX-1: Statistical evaluation. J. Appl. Clim. Meteor.23, 513-522.

Mielke, P. W., Jr., L. O. Grant, and C. F. Chappell, 1970:  Elevation and spatial variation effects of wintertime orographic cloud seeding.  J.  Appl. Meteor., 9, 476-488.  Corrigenda, 10,  842, 15, 801.

Mielke, P. W., Jr.,  L. O. Grant, and C. F. Chappell, 1971:  An independent replication of the Climax wintertime orographic cloud seeding experiment.  J. Appl. Meteor., 10, 1198-1212.

Mielke, P. W., Jr.,  G. W. Brier, L. O. Grant, G. J.  Mulvey, and P. N. Rosenweig, 1981:  A statistical reanalysis of the replicated Climax I and II wintertime orographic cloud seeding experiments.  J. Appl. Meteor., 20, 643-659.

Mielke et al. 1976 does not appear in the references of this volume.

Mooney, M. L., and G. W. Lunn, 1969: The area of maximum effect resulting form the Lake Almanor randomized cloud seeding experiment.   J. Appl. Meteor., 8, 68-74.

National Research Council-National Academy of Sciences, 1973:  Weather and Climate Modification: Progress and Problems, T. F. Malone, Ed., Government Printing Office, Washington, D. C., 258 pp.

National Research Council, 2003: Critical Issues in Weather Modification Research. National Academy Press, 123 pp.

Rangno, A L., and P. V. Hobbs, 1987:  A re-evaluation of the Climax cloud seeding experiments using NOAA published data.  J. Climate Appl. Meteor., 26,  757-762.

Rangno, A L., and P. V. Hobbs, 1993:  Further analyses of the Climax cloud-seeding experiments.  J. Appl. Meteor., 32, 1837-1847.

Rangno, A L., and P. V. Hobbs, 1993 (sic):  A new look at the Israeli cloud seeding experiments.  J. Appl. Meteor., 34, 1169-1193.

Rangno, A L., and P. V. Hobbs, 1997a: Reply to Woodley.  J. Appl. Meteor., 36, 253.

Rangno, A L., and P. V. Hobbs, 1997b: Reply to Ben-Zvi.  J. Appl. Meteor., 36, 257-259.

Rangno, A L., and P. V. Hobbs, 1997c:  Reply to Rosenfeld.  J. Appl. Meteor., 36, 272-276.

Rangno, A L., and P. V. Hobbs, 1997d: Reply to Dennis and Orville.  J. Appl. Meteor., 36, 279.

Rangno, A. L., and P. V. Hobbs, 1997e:  Comprehensive Reply to Rosenfeld, Cloud and Aerosol Research Group, Department of Atmospheric Sciences, University of Washington, 25pp, with a forward by P. V. Hobbs.

Reynolds, D. W., 1988: A report on winter snowpack-augmentation.  Bull Amer. Meteor. Soc., 69, 1290-1300.

Reynolds, D. W., and A. S. Dennis, 1986:  A review of the Sierra cooperative project. Bull. Amer. Meteor. Soc.67, 513-523.

Rosenfeld, D., 1997:  Comment on “Reanalysis of the Israeli Cloud Seeding Experiments”, J. Appl. Meteor., 36, 260-271.

Rosenfeld, D., Y. Rudich, and R. Lahav, 2001: Desert dust suppressing precipitation.  A possible desertification feedback loop.  Proc. Nat. Acad. Sci.98, 5975-5980.

Ryan, B. F., and W. D. King, 1997:  A critical review of the cloud seeding experience in Australia.  Bull. Amer. Meteor. Soc.78, 239-254.

Sax, R. I., S. A. Changnon, L. O. Grant, W. F. Hitchfield, P. V. Hobbs, A. M. Kahan, and J. S. Simpson, 1975 :Weather modification:  where are we now and where are we going?  An editorial overview.  J. Appl. Meteor.14, 652–672.

Schemenauer, R. S., and A. A. Tsonis, 1985:  Comments on “physical interpretation of results from the HIPLEX-1 experiment.  J. Appl. Meteor.24, 1269-1274.

Silverman, B. A., 1986:  Static mode seeding of summer cumuli-a review.  Rainfall Enhancement–A  Scientific Challenge, Meteor. Monogr., 21, No. 43,  Amer. Meteor. Soc., 7–24.

Silverman, B. A.., 2001. A critical assessment of glaciogenic seeding of convective clouds for rainfall enhancement. Bull. Am. Meteor. Soc., 82, 903-924.

Silverman, B. A., 2003: A critical assessment of hygroscopic seeding of convective clouds for rainfall enhancement. Bull. Am. Meteor. Soc., 84, 1219-1230.

Smith, P. L., A. S. Dennis, B. A. Silverman, A. B. Super, E. W. Holroyd, W. A. Cooper, P. W. Mielke, K. J. Berry, H. D. Orville, and J. R. Miller, 1984:  HIPLEX-1:  Experimental design and response variables. J. Clim. Appl. Meteor.23, 497-512.

Tukey, J. W., Jones, L. V., and D. R. Brillinger, 1978a:  The Management of Weather Resources, Vol. I,  Proposals for a National Policy and Program.  Report of the Statistical Task Force to the Weather Modification Advisory Board, Government Printing Office. 118pp.

Tukey, J. W., D. R. Brillinger, and L. V. Jones, 1978b:  Report of the Statistical Task Force to the Weather Modification Advisory Board, Vol. II.  U. S. Government Printing Office, pE-3.

Simpson, J. S., 1979:  Comment on “Field experimentation in weather modification.” J. Amer. Statist. Assoc., 74, 95-97.

Super, A. B., 1986: Further exploratory analysis of the Bridger Range winter cloud seeding experiment. J. Appl. Meteor,25, 1926-1933.

Super, A. B., and B. A. Boe, 1988: Microphysical effects of wintertime cloud seeding with silver iodide over the Rocky mountains.  Part III.  observations over the Grand Mesa, Colorado. J. Appl. Meteor., 27, 1166-1182.

Super, A. B., and J. A. Heimbach,1983:  Evaluation of the bridger range cloud seeding experiment using control gauges.  J. Appl. Meteor., 22, 1989-2011.

Super, A. B., and J. B. Heimbach, Jr., 1988:  Microphysical effects of wintertime cloud seeding with silver iodide over the Rocky mountains.  Part II.  Observations over the Bridger Range mountains.  J. Appl. Meteor., 27, 1152-1165.

Super, A. B., B. A. Boe, and E. W. Holroyd, 1988:  Microphysical effects of wintertime cloud seeding with silver iodide over the Rocky Mountains.  Part I.  Experimental design and instrumentation.  J. Appl. Meteor., 27, 1145-1151.

Woodley, W., 1997:  Comments on “A new look at the Israeli Randomized cloud seeding experiments.” J. Appl. Meteor., 36, 250-252.

Young, K. C., 1993:  Microphysical Processes in Clouds.  Oxford University Press, 335-336.


This story begins with my first full-time job after graduating from San Jose State College.  I was hired as a weather forecaster by E. G. & G., Inc.,  in Durango, Colorado in support of a massive randomized cloud seeding experiment called the Colorado River Basin Pilot Project (CRBPP).  It was intended to prove that seeding wintertime mountain storms was a viable way of adding water to western rivers over a large area.   I was to work under lead forecaster, J. Owen Rhea, an expert on wintertime mountain storm forecasting.  Paul Willis was the Project Manager.  The project was intended to replicate stunning cloud seeding successes reported in Colorado by Colorado State University (CSU) scientists, but in the CRBPP, over a much larger area than in the CSU experiments.

The Durango job was to change my life forever, and eventually lead me to Israel as a skeptic of reports of cloud seeding successes.  Ironically, that change was to involve North American Weather Consultants,  and it’s president, Mr. Robert D. Elliott, for whom I had worked in 1968 in Goleta, CA,  as a summer hire between semesters at San Jose State, and again when on loan from the CRBPP  in the summer of 1972 in statewide cloud seeding program in South Dakota.

By time the Colorado River Basin Project (CRBPP), the nation’s largest, most costly ever mountain randomized cloud seeding experiment  ended after five winter seasons,   I had become an orographic cloud seeding “apostate. ”

What caused this epiphany?

This metamorphosis from  an idealistic and naive forecaster  coming right out of college happened due to seeing what I think most scientists would term “misconduct” in the journal literature during the CRBPP in 1974 combined with misleading news releases from the BuRec sponsor of the CRBPP.  In the journal article,  the two authors were asserting things they knew weren’t true.  I personally knew that they knew this.  I decided that  I was going to do something about this deplorable situation after the CRBPP ended.

I then had come to believe that the cloud seeding successes reported by CSU researchers couldn’t possibly have been real ones  due to the many seeding impediments that turned up during the CRBPP (clouds not ripe for seeding as had been described, inversions that blocked the seeding material in the wintertime,  cloud tops not at the heights they were supposed to be, etc.)

It was very troubling to me that the many published scientists that were associated with the CRBPP and knew that false claims had been published in the 1974 journal cloud seeding paper  did nothing.  In that 1974 paper, for example, one reads that the temperature at 490 mb in the atmosphere (about 18,000 feet above sea level) above Wolf Creek Pass, a central target of the CRBPP, was representative of cloud top temperatures during storms.   Both authors, due to the hundreds of rawinsondes launched during CRBPP storms, knew this was untrue.  Robert D. Elliott was one of the two authors.

I  waited years for a correction by the authors, or a journal “Comment” by a knowledgeable, published scientist pointing out that at least this one claim in that article was untrue.  The silence on the part of those many scientists I expected to do SOMETHING was deafening.   I, too,  was part of that “silence.”

Talk Sounds of Silence slide:  a pptx that after hours of investigation I am not able to insert, thanks to changes in WP.  It downloads and then you can play the slide.  In the meantime, this poor substitute for the real thing:

The false claim/misconduct I am referring to appeared in one of the most cited cloud seeding articles of all time, entitled, “The Cloud Seeding Temperature Window.”

Robert D. Elliott, one of the two authors of that 1974 paper was intimate with the CRBPP data as the official evaluator of the CRBPP.  That CRBPP data demonstrated that the claim in his paper that cloud top temperatures over Wolf Creek Pass averaged 490 mb  was false.  In his next visit to Durango I asked him,  “How could you write that (claim)?”   He replied that he had, “just sort of gone along with Lew” (Lewis O. Grant) his co-author.

I thought of Shoeless Joe Jackson and the little kid that said to him, “Tell me it ain’t so, Joe!”, that he had cheated in the Black Sox World Series scandal.  I felt just like that little kid must have.  This was the same Bob Elliott that I had worked for in Goleta  and admired so much.

So, that was the epiphany for me.   I then thought that nothing might be true in the cloud seeding literature no matter how highly regarded that literature or experiment was by the scientific community.

I had come into CRBPP a little too naïve and idealistic, and  when the CRBPP ended, that idealism was nearly gone and replaced by suspicion of any orographic cloud seeding success unless I had personally validated it. Over the next two decades, I was to reanalyze six prior cloud seeding successes in the peer-reviewed literature and not ONE was the success it was deemed to be by the experimenters who conducted it.

This ephiphany set the stage for what was to happen a few years later concerning the scientist in Israel whose work in clouds and cloud seeding Prof. Joanne Malkus Simpson admired so much.

After the CRBPP had ended, I was asked to do an interview about it in November 1975 in the local newspaper, the Durango Herald.   In that interview, I stated exactly what I planned to do; reanalyze all the Colorado State University cloud seeding work that had led to the massive funding of the CRBPP since I now deemed that literature highly unreliable.

After living the winter of 1975-76 in Durango, living off my savings while gathering runoff and CRBPP precipitation data, I was hired for a May-August seeding project in South Dakota by Atmospherics, Inc.  I had worked for them in the summer and fall of 1975  as a radar meteorologist in Madras (now Chennai), Tamil Nadu, India.  While mountain cloud seeding was suspect, Joanne Malkus Simpson and co-authors were published results of successful cloud seeding of tropical Cumulus clouds like those in India.  That’s why I had no qualms about taking that job in India in 1975,  Joanne had influenced me again.

Near the end of the 1976 project in SD, I was interviewed for a job at  the University of Washington by Prof. Larry Radke and Prof. Peter V. Hobbs.  I joined Prof. Hobbs, Cloud Physics Group, as it was known then, in September 1976.

After unraveling bogus cloud seeding successes in Washington State (Hobbs and Rangno 19781 and in Colorado (Rangno 1979, Hobbs and Rangno 19791),  Prof. Peter V. Hobbs who saw I had an interest and skill in examining the cloud seeding literature, said to me that “if you really wanted to have an impact, you should look into the Israeli experiments.”  It wasn’t long before I began reading critically about them.

1Authorship sequences in Prof. Hobbs group, as in these cases, do not reflect who initiated the work, carried out the analyses and wrote the drafts that Prof. Hobbs improved with his great editing skills.


My Life in Cloud Seeding: Colorado to Israel

A Personal Sojourn through a Murky Scientific Field Whose Published Results Have Often Been Skewed and Unreliable


Arthur L. Rangno

(journal handle)

Retiree, Research Scientist III, Cloud and Aerosol Research Group, Atmospheric Sciences Department, University of Washington, Seattle.

Author Disclosure

I have worked on both sides of the cloud seeding fence; in research and in commercial seeding projects.

My main career job for almost 30 years (1976-2006) was with the University of Washington’s Cloud and Aerosol Research Group (CARG) within the Atmospheric Sciences Department. I was a non-faculty, staff meteorologist and part of the flight crew of the various research aircraft we had (B-23, C-131A, and Convair 580) and directed many flights concerning the development of ice in Cumulus clouds; some involved dry ice cloud seeding. Prof. Peter V. Hobbs was the director of the CARG.

After retiring from the University of Washington I was a consultant and part of the airborne crew for the National Center for Atmospheric Research (NCAR) in a test of cloud seeding in Saudi Arabia during the winter of 2006-07. That research involved some randomized seeding of Cumulus clouds.

An overview/introduction to Peter Hobbs’ group’s work in cloud seeding, as it was presented at the American Meteorological Society’s Peter Hobbs Symposium Day in 2008 can be found here. Since Peter V. Hobbs has virtually no wikipedia presence, unlike his peers of comparable stature, he deserves at least a review of his group’s work (and our collaborations) in that domain (and in a tongue-in-cheek way that I think he would have liked.) Peter Hobbs passed in 2005.

I have also worked in summer commercial cloud seeding programs in South Dakota (twice), in India, in the Sierras, and for a CARG cloud seeding program for the Cascade Mountains of Washington in the spring of the drought winter of 1976-77. I worked for North American Weather Consultants, a provider of commercial cloud seeding services, as a summer hire in 1968 while a meteorology student at San Jose State College.

Confirmation bias? Yes, I have some. You can make supercooled, non-precipitating clouds precipitate. But since those clouds are almost always shallow, the amount of precip that comes out is small. Is it economically viable? I don’t know. EOD.

Table of contents


The cloud investigation trip to Israel

  1. The background for a trip to Israel: The British, among other groups, can’t get in to study the ripe-for-seeding clouds being described in Israel
  2. The British can’t get in: Sir John Mason’s letter
  3. Why I thought I could do something by going to Israel
  4. Story board concerning an extreme act of skepticism; “Honey, I just quit my job at the University of Washington”
  5. About the clouds I was supposed to see in Israel but didn’t
  6. 1983, an early jab at “faulty towers”; a paper that questions the Israeli experimenters’ cloud reports is submitted and rejected
  7. About getting the 1986 cloud study published
  8. The best example of rapidly glaciating clouds with modest cloud top temperatures that I saw
  9. Why was the 1986 study submitted to a foreign journal?

The battle to publish “The Rise and Fall of Cloud Seeding in Israel” in the Bull. Amer. Meteor. Soc.

  1. The battle to publish a review of Israeli cloud seeding in BAMS
  2. Why I persist with BAMS
  3. Interlude: A little of the talk given in 2017 at the University of Wyoming on the Rise and Fall FYI
  4. The Israeli experiments’ chief meteorologist’s 1986 letter about omitted Israel-2 data and at what cloud top temperatures Israeli clouds rained from
  5. More on getting the Rise and Fall of Cloud Seeding in Israel published
  6. The TWO split peer reviews (reject and accept) and about BAMS decision take the reject one instead of getting additional expert reviewers to break the split
  7. The importance of controversy
  8. Israel moves on and starts over again to see if seeding works; Israel-4 and the HUJ airborne study that supported it. Comment: Don’t do an experiment based on this paper!
  9. More thoughts on the “Battle of the BAMS
  10. Science” or something else?
  11. Douglas Adams and the likely role of credentialism in the BAMS rejection
  12. Getting tough on research misconduct such as “falsification”; i.e., omitting data to improve results as happened in Israel-2
  13. The battle is on display here: the revised manuscript and the replies to the comments of the reviewers and to the BAMS editors

Where it all started: in a big randomized cloud seeding experiment in southwest Colorado in the early 1970s designed to prove orographic cloud seeding once and for all

  1. How unsettling experiences regarding journal cloud seeding literature laid the groundwork for an eventual trip to Israel as a super skeptic
  2. The “documercial” movie about the huge Colorado River Basin Pilot Project cloud seeding experiment
  3. Scientific idealism begins to slip away in Durango
  4. 1974: My first “accolade” for exceptional skepticism of cloud seeding papers, the Archie M. Kahan “Resident Skeptic” Award!
  5. The decay of idealism accelerates in Durango
  6. Conflict of interest on part of those chosen to evaluate the CRBPP 🙁
  7. The informational “black hole” during the CRBPP
  8. The 1973 NAS panel report on Climate and Weather Modification reaches Durango in 1974
  9. 1974: The University of Washington to the “rescue” of the CRBPP
  10. The final blow to idealism in Durango
  11. A regrettable personal media eruption in Durango that required an in person apology at CSU in Fort Collins
  12. The apology and the Durango Herald article’s after effects
  13. 1979: I discover that my first conference presentation is going to be addressed by the Colorado experimenters just before I give it; egad!
  14. 1983, a real no-no: a request for an investigation
  15. Tension highlight with Prof AG of Israel at the 1984 Park City weather mod conference
  16. Intermission (and a, “Get a Life!” note)
  17. Not trusting the journal literature in cloud seeding was a “fruitful perception”
  18. The payoff for decades of volunteer cloud seeding work: a monetary prize from the “people of earth”, well, those people represented by the United Nations
  19. Why am I doing all of this (and not others)?
  20. Peter V. Hobbs and his group’s work


  1. Anecdotes about my life outside of these volunteer efforts in case it doesn’t seem like I had one (the only fun part of this “blook” read if not busy)

1. Intro

What is cloud seeding/weather modification?

Cloud seeding is releasing silver iodide (AgI) or dropping dry ice pellets into clouds with liquid water at temperatures below about -5°C (23°F) to create more ice crystals than are thought to occur naturally in them. The ice crystals grow, aggregate into snowflakes and fall out as snow, or rain. At least that’s the ideal picture. Droplets of liquid water can persist in thin layer clouds and in strong updrafts to temperatures lower than -30°C (-22°F). Quite amazing, really.

But nature is perverse in ways we don’t understand fully. Completely glaciated (iced-out) clouds can occur in clouds that have never been colder than about -7°C (20°F). Such clouds have always been observed to have larger cloud droplets, drizzle or raindrops in them. Hence, there is a “problem” in assuming that clouds are lacking in ice and need MORE ice crystals via seeding; they often don’t, and seeding them will have no effect, or even could decrease precipitation.

No randomized cloud seeding experiment, followed by a necessary replication of the result to rule out flukes, has shown to have produced increased precipitation to date. An exception in the works may be an experiment in the Snowy Mountains of Australia that has recently been reported, but has not been examined rigorously by outside skeptics like me. And extreme rigor is required when cloud seeding successes are reported by those who have conducted the experiment! Read on….

About this “blook”

This is not a blog, but a “blook” (book-blog); a “blogzilla”, an autobio consisting of 50 years of experiences and observations of this field, 1970 to the present time. Thanks in advance to the two of you who actually read this whole thing! It’ll take a couple days. Its story about a journey through science and one about how it sometimes fails to catch perverse literature and won’t allow valid literature that it doesn’t like. My hope is that my path through this field was “anomalous” or we’re in deep trouble.

This blog-book (“blook”) has four main elements: 1) my cloud investigation trip to Israel and its findings; 2) about the difficulty of getting a review of Israeli cloud seeding published in the American Meteorological Society’s Bull. of the Amer. Meteor. Soc. (“BAMS“), historically the repository of cloud seeding reviews, 3) the manuscript in question itself recounting the “rise and fall” of cloud seeding in Israel (with slight revisions following peer-review) and 4), the early 1970s experiences in Colorado that led me to being an activist in closely scrutinizing cloud seeding literature, one having a strong distrust of successful reports. It is also about a “kill the messenger” attitude in science, and a test of current friendships of those once associated with institutions that will be mentioned.

For a modicum of credibility regarding what you will read:

Peter V. Hobbs and I received a monetary prize for our work in the cloud seeding arena. The award was adjudicated by experts with the United Nations’ World Meteorological Organization. Peter Hobbs had done what might be viewed as “constructive” work in this domain before I arrived.

My portion of this prize, however, was mainly for tearing down accepted structures within the cloud seeding literature via reanalyses of cloud seeding experiments, some deemed the best that been done by the scientific community, along with other published commentaries. Ironically, some “tear-downs” were ones that Peter Hobbs himself had helped build up before I arrived. Here’s the secret to my reanalyses of cloud seeding successes: sadly, I have to report that they were ALL virtually “low hanging fruit” ready to be picked off by almost any under-credentialed meteorologist like me (cloud seeding wrecking ball Rangno) who was willing to look a little closer at them; they did not require someone with a big brain or “Einsteinian” insights to unravel them.

A part of the “prize”, was also under inadvertent (and controversial) seeding effects, we discovered in the early 1980s that our own prop aircraft (a Douglas B-23) was inadvertently seeding supercooled clouds that we had flown through at temperatures as high as -8°C! I still remember bringing in a strip chart to Peter Hobbs and telling him, “I think our aircraft did this” (created spikes of ice concentrations in an otherwise ice-free Cumulus congestus cloud).

The aircraft inadvertent seeding paper was so controversial in its day due to casting a shadow on prior aircraft sampling of supercooled clouds that it was rejected twice and took two years and voluminous increases in size before being accepted (Rangno and Hobbs 1983, J. Clim. Appl. Meteor.). It didn’t help that many earlier aircraft studies of clouds had been conducted near -10°C. Now, its common knowledge and the effect must be guarded against when sampling the same cloud repeatedly for life cycle studies. Prof. John Hallett described our findings in 2008 at the Peter Hobbs Symposium Day of the American Meteorological Society, as “an embarrassment for the airborne research community.” No! Not our study, but what we found!

In short, I have been involved with a lot of destruction or compromising of prior published science. On the other hand, I did make one positive contribution to cloud seeding, suggesting that we use the CARG mm-wavelength cloud sensing, vertically-pointed radar as a seeding target (after an aircraft contrail passed over it one day). The results of our subsequent experiments were published in no less than Science mag, and that article got a hand-written accolade from “Mr. Dry Ice,” himself, Vincent Schaefer, the discoverer of that modern seeding methodology! Some of this experiment (the best part, of course) is reprised in the 2008 Hobbs Symposium Day talk here.

I begin in mid-stream in a sense by starting out about my provocative trip to Israel to investigate their clouds in 1986. This was long after my disillusion with the cloud seeding literature had taken hold in the early 1970s. I start with this chapter because I am still battling to this day to get a review of cloud seeding in Israel published; its rise and fall. This is a major science story and I won’t give up on it! There are many reasons other than science ones for the difficulty of getting this account published. They are enumerated later. No one will be surprised by them.

The Israel seeding account, too, parallels the “rise and fall” of widely perceived experiments in Colorado that were believed to have proved cloud seeding as purported by no less than the National Academy of Sciences. Those Colorado experiments and their own rise and fall cycle preceded that of the Israeli experiments.

As in Israel, the primary fault of the Colorado experimenters was that they could not get their clouds right, the “bottom line” in cloud seeding experiments. The Colorado experimenters inferred (through post-experiment statistical analyses) as did they Israeli experimenters, “ripe-for-seeding” clouds that don’t exist.

Moreover, the Colorado experimenters could not accept the idea that their experiments were compromised because nature flung heavier storms at the seeding target and surrounding regions on randomly drawn seeded days. There were also problems with the data that the Colorado experimenters had used; it wasn’t what they said they had used, and they didn’t draw random decisions when their own criteria said they should have. (An aside: “Good grief!” And, yes, I was involved in the tear-down of the Colorado experiments).

In the account of Israel’s experiments’ “rise and fall”, you will read about how the results and even the clouds described by the Israeli experimenters, mirrored what was being reported about the clouds of Colorado. This even though the clouds in Israel were winter Cumulus and Cumulonimbus clouds that rolled in off the Mediterranean Sea, and the Colorado clouds much colder, winter stratiform clouds in the mountains, of course, deep within a continent. This should have raised some eyebrows, but didn’t. I included discussions of the Colorado findings in the Israel manuscript because at the time, these disparate reports were cross-pollinating one another in a sense for the scientific community, one that was primed for cloud seeding successes to be reported after increasingly optimistic findings in lesser studies and experiments in the 1960s.

If this hasn’t piqued your interest in reading this “blogzilla”, then, oh well; move along. haha.

But, if you want to read an “important paper”, as deemed by the anonymous reviewer (one of two), and presumably one not beholden to cloud seeding, it’s here. (That reviewer wanted it less harsh, however, and felt there were “personal criticisms.”). You can decide on these latter assertions by examining the manuscript, post revisions below.

By the way, BAMS was, and is, fully aware of the 2nd, “reject article” reviewer’s conflict of interest, but for whatever reason, paid no attention to it. More about this below.

Yes, this a slog. “Bear down”, as they say at the University of Arizona in Tucson, Arizona. (I think it will be worth it.)

Perhaps, as long as this account is, it will be seen as just a diatribe, a useless expenditure of energy on a cause that has little merit except to the author, me. I fear that’s how this will be seen, but I post it anyway. Let us begin…


No scientist working in a conflicted science arena where there are strong and diverse opinions, whether its on the origin of dogs, the degree of warming ahead due to CO2, or here, in cloud seeding, will be surprised by anything in this account.

“Unreliable literature”?

An interesting provocation in the title that I now flesh out. “One-sided citing”, or “selective citing” is a frequent occurrence in cloud seeding articles (and in other conflicted domains) and can be considered one element of “skewed literature,” that is, not being candid (honest?) about the history of your subject.

One-sided citing is when peer-reviewed article only presents (cites) one side of an issue or findings when there are more that a journal reader should be made aware of. It can only result from reviews of manuscripts by “one-sided reviewers” or ones ignorant of the body of literature in the subject they are passing judgement on in their review.

It should never happen in honest, thoroughly screened-for-publication literature.

So, how often does one-sided citing occur in the cloud seeding literature?

A survey of cloud seeding literature through 2018 (article in preparation) was done that found that 39 of 82 articles in American Meteorological Society (AMS) journals and in the Journal of Weather Modification Association’s peer-reviewed segment exhibited “one-sided citing.” The survey of peer-reviewed literature concerned two sets of once highly regarded cloud seeding experiments whose findings were overturned “upon closer inspection” also in the peer-reviewed literature. The two sets of once benchmark experiments, lauded virtually by all at one time, were conducted in Colorado and Israel. The criteria that was used in this survey was that an overturned result had to be in the peer-review literature for at least a year from the date of final acceptance of a cloud seeding article before any references to the two sets of experiments in an article that mentioned them were examined and categorized. Perhaps we should be placated that a slight majority of papers did, in fact, reference the “whole story” and cited studies that compromised prior successes. I think not.

The number of instances that authors and co-authors signed on to articles that told only one side of the story (ones that referenced only the successful phases) after compromising literature appeared was over 100 representing more than two dozen institutions from universities, government agencies, certified consultants, utilities, and, not too surprisingly, commercial seeding providers.

The institutional “winners” of one-sided citing?

Colorado State University, South Dakota School of Mines and Technology, and the Bureau of Reclamation, each having more than ten one-sided “instances1.” These results tell you, not surprisingly, that institutions who have, or have had, concentrated programs in cloud seeding as these did, are the ones most likely to have authors that practice one-sided citing in cloud seeding journal literature.

What motive would there be for authors to cite only the successful phase of cloud seeding experiments that were overturned later? There are several possible answers:

Foremost in my mind is to mislead journal readers by citing only the successful phase of an experiment that was overturned, presumably hoping that their readers don’t find out about the reversal. This leads the naive reader who takes such an article at face value to believe that cloud seeding has a more successful history than it really does, the probable goal of the authors. This is tantamount to citing Fleischmann and Pons (1989, J. Electroanalytical Chem.) in support of “cold fusion,” without citing the followup studies that showed “cold fusion” was bogus. What’s the difference here?

Added to this primary reason for one-sided citing would likely be: ignorance of the literature on the part of authors; the telltale human factor; authors that have grudges against scientists that have injured their home institution’s work, or that of their friends; and authors who don’t wish to cite scientists whose work threatens their own livelihood in cloud seeding.

Cloud seeding literature with only one side of the story cited can be considered one element of “skewed” literature. It should be considered a form of scientific misconduct or really, fraud, in my opinion, even if only a “misdemeanor.” BAMS leadership disagrees with my strong position, stating that its too difficult to determine one-sided citing in recently declining a proposed BAMS essay, “Should ‘one-sided citing’ be considered a form of scientific misconduct?” BAMS felt it was too hard to determine one-sided citing. It must also be considered that my proposal wasn’t as “tight” as it could have been…

But I disagreed due to having a low threshold of misconduct/fraud. Its rather easy to determine one-sided citing, as most of you would realize who’ve been subject to these kinds of omissions of your work. Please see the AMS book, Eloquent Science; the author, David Schultz, believes that one-sided citing is “easily recognized”, contrary to the view of BAMS. Perhaps BAMS leadership didn’t read the well-reviewed book, or consult with Prof. Schultz on why he would write that.

The survey above indicates that an awful lot of misleading literature is reaching the journals, something that publishers/editors of journals probably don’t want to hear about. Ask Stewart and Feder and their experiences with Nature in getting their 1987 article, “The Integrity of the Scientific Literature” published. It took years.

Moreover, one-sided citing damages authors like myself (I am frequently a “victim”) who lose citations they reasonably should have had, and thus one’s impact in his field as measured by citation metrics is reduced.

Surprisingly, one-sided publications have originated from such well-regarded institutions as the National Center for Atmospheric Research (NCAR), the Hebrew University of Jerusalem (HUJ), and Colorado State University (CSU), among many others that could be named, thus compromising those institutions’ reputations as reliable sources of information.

That so many occurrences of one-sided citing reach the peer-reviewed literature points to a flawed peer-reviewed system, one populated by “one-sided reviewers” and/or ones ignorant of the literature they are supposed to know about in the role of a reviewer. This is not news.

The shame of this practice is that it would have only taken a single sentence containing references to “fill in the blank” for the journal reader, such as: “These results have been questioned.” Or, “overturned.”

—————————end of one-sided citing “module”————-

My whole cloud seeding story, more or less, is about the kind of lapses described above likely driven by excessive confirmation bias, vested interests; scientists presenting only part of the actual story, as happened in Israel regarding a key “confirmatory” experiment, again pointing to a weak peer-review foundation in journals.

Moreover, this “Readers Digest Condensed Book” is only a partial (!) autobio and should be considered one in development. I know changes/additions will be made over time as comments come in… I’ve tried to constrain myself for the time being to just those important-to-me science highlights/”traumas”/epiphanies that I experienced in this realm in my journey rather than present EVERY detail of my experiences in this field (though it will surely seem like I am discussing every detail).

This is also a story, too, by a person who only wanted to be a weather forecaster ever since he was a little kid, but ends up working in and de-constructing cloud seeding experiments, the latter almost exclusively on his own time due to an outsized reaction to misleading literature.

As mentioned, I joined the University of Washington in 1976, btw, long after my disillusionment with the cloud seeding literature was underway. With Prof. Peter Hobbs support when I brought in drafts concerning reanalyses of cloud seeding experiments, I had a strong platform from which to rectify misleading and ersatz cloud seeding claims. I don’t believe another faculty member at the “U-Dub” would have taken the interest that Peter did in cleaning up my drafts. Thank you, Peter Hobbs.

Peter Hobbs was also able to reverse course, as it were, when new facts came in. This was not so much seen in the cloud seeding community I went through in Colorado as you will learn in the “Where it all began” chapter.

My distrust of the cloud seeding literature was so great that I hopped a plane to Israel on January 3rd, 1986, relatively sure that the published cloud reports that were the basis for a cloud seeding success in Israel were not slightly, but grossly in error. And someone needed to do something about it!

Most of this “blook” will be about this chapter of my life because it seems so characteristic of the compromised literature in this field whose character somehow seems to escape the attention of gullible reviewers, and also demonstrates the powerful seductive forces that the thought of making it rain has on otherwise good scientists. Nobel laureate, Irving Langmuir, comes to mind.


1An author or authors on a one-sided article are each counted as an “instance.” A single author can comprise several “instances” if he repeatedly “one-sides” the issue, and a single article that “one sides” with several authors can be several “instances.” It was observed that several authors repeatedly practiced one-siding in their cloud seeding articles, practices that also repeatedly escaped the attention of those authors’ reviewers somehow.


For a comprehensive, informative, and entertaining read about early cloud seeding experimenters, crackpots, sincere, but misguided characters, and outright cloud seeding footpads, read, “Fixing the Sky: The Checkered History of Weather and Climate Control” by Prof. James R. Fleming. I highly recommend it. Coincidentally, James R. Fleming was a crew member of Peter Hobbs’ research group when I was hired in 1976, before he became the illustrious “Prof. Fleming.” I actually took his place when I started, doing some of the same things he did, like servicing our aircraft’s instrumentation after flights! Crazy, eh?

You will read in Fleming’s book about how Nobel Laureate, Irving Langmuir, became obsessed with cloud seeding and his critical faculties were diminished by an overwhelming cloud seeding “confirmation bias.” The “Langmuirs” in this field persist to this day, willing to throw up specious arguments to recoup failed cloud seeding efforts, or create publications “proving” an ersatz increase in precipitation due to seeding by cherry-picking controls mid or post-experiment. And they’re still leaking articles like that into the peer-reviewed literature due to inadequate peer-review, likely by still-gullible and one-sided reviewers, and certainly by ones ignorant of the subject they are supposed to review. Examples to follow.


The experiences I had in the realm of cloud seeding also deal with a “checkered history”, as Prof. Fleming wrote, but ones that emanated from academic settings in the modern era in form of peer-reviewed literature. One will be able to confidently conclude from my account that putting on an academic robe did not end the kind of cloud seeding shenanigans described by Prof. Fleming, though they are far more subtle, sophisticated and crafty.

So “crafty” has been such literature that it persuaded national panels consisting of our best scientists (yes, consensuses have been formed) to declare that what were really ersatz cloud seeding successes, true and valid in several cases. Namely, bogus reports of cloud seeding successes that reached the peer-reviewed literature have misled our entire scientific community and those who read those assessments by our best scientists!

(Note: Were our best scientists at fault? Not only “no”, but HELL no!” They were just too trusting of peer-reviewed cloud seeding literature and naive about the forces of confirmation bias combined with weak peer-reviewing that allowed faulty publications to reach the literature, ones that they took at face value.)

Were the cloud seeding experimenters responsible for such faulty modern literature just misguided, deluded, but sincere people?

Or were they “chefs” that “cooked and trimmed” their results to present their journal readers with ersatz successes that they themselves benefitted from? You’ll have to decide. The evidence is clear in one case.

This, too, is written as I near the “end of my own road” and thinking that the events I experienced might be useful for others to know about and, especially, to be vigilant about.

Since its a story with dark elements, it’s also one where the scientific community (like doctors who loath testifying against malfeasant doctors), has tended to “circle the wagons” in misguided efforts to protect the reputation of science and scientists rather than being concerned with the “victims” of scientific misconduct/fraud. Again, ask Feder and Stewart. I am treading in this world now with in a manuscript submission last year to BAMS and the AMS, discussed in considerable detail later. You will be able to read the manuscript itself and make up your own mind about it’s appropriateness in BAMS.

Having never been a faculty member, only a staff research meteorologist at the University of Washington with only a bachelor’s degree, I suspect that it is easier for me than for authors like Prof. Fleming to address malfeasance and/or delusion as seen in the peer-reviewed literature by well-credentialed faculty members, the “club,” as it were, some of whom were even domiciled in one of the institutions he matriculated from.


The organization of this piece is somewhat suspect. Its not my forte, as the late Peter Hobbs would know. It jumps around a bit. But you will able to do that, too, via “jump links” in the Table of Contents. Think of them as like mini-chapters of a book.

Discussions about Israel’s clouds, cloud seeding, and the battle to get my review of Israeli cloud seeding published in BAMS has a light gray background for some sorting of topics! There is repetition. This “blogzilla” is so long I’ve lost track of some statements that might be repeated. But then, if I repeated something, maybe it was real important. 🙂

The references to technical literature alluded to here, are mainly in the submitted manuscript itself, which is found later in this piece, and on my “Publications” blog page. I didn’t want to overwhelm non-technical readers with numerous inserts of citations.

The “Rise and Fall of Cloud Seeding in Israel” manuscript that I will discuss relative to BAMS, consists of a distillation of more than 700 pages of peer-reviewed and non peer-reviewed conference preprint literature scattered among various journals and conferences and has, at this point, taken a couple of years to put together. Its a sobering historical account that has not been told before, and needs to be heard by a wide audience, particularly those who are involved with cloud seeding. There are also lessons for all of us in there when it comes to researching something when you already know before you start what the result will be.


I dedicate my work to the late Mr. Karl Rosner, former “Chief Meteorologist” of the Israeli randomized experiments, who became a friend. His integrity was laid bare for all to see when he stated that the high statistical-significance in the Buffer Zone (BZ) of Israel-1 (higher than in either of the two targets!) on “Center” seeded days could NOT have been due to inadvertent seeding based on his wind analysis (quoted by Wurtele, 1971, J. Appl. Meteor.) The BZ lay between the two intentionally seeded targets.

How easy it would have been for a seeding partisan to have said, “Oh, yeah, we must’ve seeded that Buffer Zone” and perhaps have ended speculation about a lucky random draw that favored the appearance of seeding effects in the Center target of Israel-1.

His revealing 1986 letter to me about the Israel-2 experiment is included later.

2. The background for going to Israel in 1986: no one could get a research plane in to check out those ripe-for-seeding clouds described by the HUJ experimenters

By the early 1980s, the events and the journal literature I had experienced during a randomized cloud seeding experiment in Colorado caused me never again to believe in a published cloud seeding success prima facie. It didn’t matter how highly regarded it was by national panels and individual experts. And the Israeli experiments were perceived as just that; the best that had ever been done in those days of the 1980s.

The ripe-for-seeding clouds that I went to see were ones that the HUJ experimenters had described repeatedly in journals and in conference presentations. They were the foundation for the belief that seeding them had, indeed, resulted in the statistically-significant increases in rainfall that had been reported in two randomized cloud seeding experiments, Israel-1 and Israel-2. The experimenters’ ripe-for-seeding cloud reports explained to the scientific community WHY cloud seeding had worked in Israel and not elsewhere.

In 1982, Science magazine hailed these experiments as the ONLY experiments in 35 years of seeding trials that rain increases had been induced by cloud seeding. Yes, there was a dreaded scientific consensus that these experiments had proved cloud seeding. However, only half of the Israel-2 experiment had been reported by the HUJ seeding team when the Science magazine assessment was made; the half that appeared to support a successful overall seeding experiment.

At the time I went to Israel in 1986, and much of the reason for going, was that no major outside research institution, curious about those Israeli clouds, had been able to get their research planes in to check them out. At least six attempts had been rebuffed (Prof. Gabor Vali, Atmos. Sci. Dept., University of Wyoming, personal communication, 1986). The attached letter below to me from Sir John Mason, former head of the British Royal Society and author of, “The Physics of Clouds,” tells of his attempt to get the British research aircraft into Israel and coordinate such a mission with the lead Israeli cloud seeding experimenter, Professor A. Gagin (hereafter, Prof. AG) of the HUJ. You will find it illuminating about why outside researchers couldn’t get in. (Prof. AG passed in September 1987.)

3. British unable to get in

4. Why I thought I could do something

So, in going to Israel in 1986 and by then having ten years of experience under my belt in airborne cloud studies with the University of Washington’s Cloud and Aerosol Research Group (CARG), as a weather forecaster, as a former storm chaser (summer thunderstorms in the deserts of Southern California and Arizona, Hurricane Carla in 1961) and importantly, as a cloud photographer, I felt I could fill a vacuum left by those rebuffed airborne research missions. Peter Hobbs, the director of our group, put it this way: “No one’s been able to get a plane in there.” It was a very curious situation in itself.

A “story board”, Clouds, Weather, and Cloud Seeding in Israel found below is focused on my provocative, but badly needed, cloud investigation trip to Israel in January-mid-March 1986. How I got to the point of doing such an outrageous science act as going to Israel to check out their clouds in person really began in Colorado in the 1970s, as mentioned.

Let me add this: I loved my storm and cloud chasing time in Israel and my days working within the Israel Meteorological Service (IMS) on fair weather ones only, of course! I made relationships that continued over the years though most are now gone.

Since this is just a personal “blog-book” and I want to make it more “human” if you will, as well as having reliable science, I will add a couple of photos from my IMS experience. The first two photos below are some of my “officemates” in the climate division of the IMS that I had around the little table space I was given thanks to IMS Director, Y. L. Tokatly, who saw my skepticism as a natural part of science. The clouds of Israel can only be studied in Israel.

The third photo is one taken on top of a satellite campus of the HUJ where the Atmospheric Sciences Department was located (a former nunnery); photo by Prof. A. G.

Two of my “office mates” within the Israel Meteorological Service’s Climate Group
More “officemates” within the Israel Meteorological Service’s Climate Group. They were all so nice and accommodating to this intruder’s presence.
The photo taken of me by Prof. A. Gagin atop a satellite campus of the Hebrew University of Jerusalem, on January 10th, 1986, during our first cordial meeting. The building had been a former nunnery he told me. (He would not allow me to take his photo.)

5. Story board concerning an extreme act of skepticism: the 1986 trip to Israel and its results

“Honey, I just quit my job at the University of Washington, and now I am going to spend $4,000 of our savings because I think the clouds in Israel aren’t being described correctly. I want to help them figure out their rain clouds. Do you mind if I’m gone for a few months and no longer have a job when I come back? Also, I won’t be looking for a job very soon since I will have to spend the rest of the year working on a manuscript about my findings. OK? I think we’ll still have some savings left at the end of the year.”

No, you can’t do these things if you’re married. But, as a single man in those days, “oh, yeah.” And somebody had to do something!

(Hit the expand button in the lower right hand corner for a full view.)

Peter Hobbs chided me about my skepticism concerning the HUJ cloud reports just before I left for Israel; that I seemed to be indicating to him that I knew more about the clouds of Israel than those who studied them in their backyard. He added that he thought I was “arrogant.” Wow.

Peter was still mad at me for resigning from his group just before a big CARG project and raising a ruckus about why I was resigning. But, I had scrutinized the HUJ cloud reports in considerable detail, and had submitted a paper on the problems with them in 1983 when he was on sabbatical. I had a solid background for my belief that the clouds described by the HUJ cloud seeding team didn’t exist. The mystery to this day is why they did not know the true nature of their clouds with all the tools they had.

Why I resigned from a job I loved, is another long story (oh, not really; you know, it was the old “authorship/credit issue”). Peter had those issues. But it’s one that ends happily with a reconciliation a couple of years later, which doesn’t always happen! We both benefitted from that reconciliation. We needed each other.

My trip to Israel was self-funded and self-initiated. It may sound ludicrous, but I also felt that by going to Israel I was going to be able to do what those rebuffed airborne missions could not do; evaluate the clouds of Israel sans aircraft. I had flown in hundreds if not thousands of clouds using high-end instrumentation, and when you’re directing research flights as I did for the University of Washington’s research group in studies of ice particle development in Cumulus and small Cumulonimbus clouds. You visually assess those clouds before going into them and then sample the best parts and then see what your instruments have told you about the concentrations of droplets and ice particles, etc.) You get a real quantitative feel for how much ice they’re going to have in them by their external appearance.

So, by just visually assessing the Israeli clouds and estimating their thicknesses and top heights, I would know from my airborne work and background whether the reports about the ripe-for-seeding clouds were correct. Upon closer inspection, there were several odd aspects in the HUJ experimenters’ cloud reports.

Too, if I was right about the clouds of Israel, that they were starting to rain when they were relatively shallow (highly efficient in forming rain, as we would say), say, topping out at 3-4 km (roughly 10 kft to 14 kft) above sea level, the people of Israel might well be wasting millions of dollars over the years by trying to increase runoff into their primary fresh water source, the Sea of Galilee (aka, Lake Kinneret) by seeding unsuitable clouds. They had started a commercial-style program in 1975 after Israel-2, the second experiment, had been partially reported as a success in increasing rain due to seeding.

During the first daylight hours of the first showery day, January 12th, 1986, I saw shallow Cumulonimbus clouds, clamped down by a stable layer of air, full of ice rolling in from the Mediterranean onto the Israeli coast. They had been preceded by true drizzle and thick misty rain falling from thick Stratocumulus the night before in Jerusalem where I had spent the night.

I KNEW within those first hours f the first storm that the cloud reports from the HUJ experimenters were grossly in error. To be sure there was nothing strange that day, or on subsequent days, I would ask the Israel Meteorology Service, “Was there anything unusual about this storm?” Nope. In fact, one former forecaster told me, “We get good rains out of clouds with tops at -10°C,” something the HUJ experimenters said never happened.

Experiencing drizzle was a surprise to me; it was not supposed to fall from Israeli clouds because the clouds were too polluted and as a result, the droplets in the clouds were too small to collide and form larger drizzle drops. The occurrence of drizzle instead, meant they were ripe to produce ice at temperatures only a little below freezing due to having large cloud droplets capable of coalescing into bigger drizzle drops, not tiny ones due to pollution that bounce off each other.

Why was the observation of true drizzle so important? The appearance of ice in clouds at temperatures not much below freezing (say, -4°C to -8°C) has always been associated with drizzle or raindrops before it forms.

Of course, there were other experienced research flight scientists in cloud studies out there I am sure that could have done the same thing as I did. But, I was the one that went. (Spent a lotta money doing what I thought was an altruistic act, too.)

6. About the clouds I was supposed to see in Israel

So, what are clouds that are plump with seeding potential supposed to be like? Just that; fat and pretty tall. The clouds that responded to seeding were reported to be those with radar-measured “modal” tops with heights where the temperatures were (from balloon soundings) between -12°C and -21°C. The major rain increases in the Israel-2 experiment due to seeding were reported from “modal” radar tops in the lower half of that temperature range. These would be clouds rolling in off the Mediterranean that were about 5-6 km thick, topping out around 15,000 to 20, 000 feet or so above sea level. Such clouds were described as having a tough time raining, according to the experimenters at the HUJ. They either barely rained, or not even at all, until they were seeded, the experimenters inferred from the statistical analyses alone. The effect of seeding in those statistical analyses of the Israel-2 experiment was that seeding had increased the duration of rain, not its intensity. Seeding had no effect when clouds were already raining.

These findings were compatible with how the experimenters seeded and also led to the inference of deep clouds that didn’t rain until seeded, surrounded by taller ones that did. Non-precipitating clouds cannot be observed by radar, so there was no evidence that such a cloud actually existed.

The experimenters had used just a little bit of seeding agent (silver iodide) released by a single aircraft flying long lines along the Israel coastline near cloud base in showery weather, and this seeding strategy was compatible with what was reported.

It all made sense. Mostly…unless you really got into the details of their cloud reports, in which the devil resides. And I had done that by 1983. See below for a “detective meteorology” module in which the cloud reports of the HUJ experimenters are closely scrutinized.

7. 1983: A paper questioning the Israeli cloud reports is submitted and rejected; a call to action… eventually

In 1983, after plotting dozens of rawinsonde soundings when rain was falling at the time of, or fell within an hour, of the rawinsonde launch time at Bet Dagan, Israel, and at Beirut, Lebanon, (see first figure in ppt above) I came to the conclusion that the clouds of the eastern Mediterranean and in Israel were, shockingly, nothing like they were being described as by the HUJ experimenters at conferences and in their peer-reviewed papers. I also looked at their published cloud sampling reports and it was clear to me that the clouds that the experimenters had sampled were not representative of those that caused significant rain in Israel; they were too narrow, did not have enough ice particles in them. They did not sample the wide Cumulonimbus complexes that produce rain for tens of minutes to more than an hour at a time during Israel’s showery winter weather, sometimes marked by thunderstorms.

I submitted a manuscript in July 1983 to the J. Clim. Appl. Meteor. that questioned the experimenter cloud reports. It indicated that rain frequently fell from clouds with tops >-10°C which according to the experimenters’ reports, was never supposed to happen. It was rejected by three of the four reviewers (B. Silverman, personal correspondence). Peter Hobbs, the leader of my group, was on sabbatical in Germany at this time and was not happy I had submitted a journal paper without his purview. In fact, I was to submit three that year, all rejected! I might have been “Rejectee of the Year” in 1983 with the AMS.

I was undaunted by the rejection; I was pretty sure my findings were correct, which they were proved to be by aircraft measurements in the early 1990s. Note: Rejected authors, take heart! You may have something really good.

The problem for reviewers of that 1983 submission?

How could the HUJ experimenters not know about what I was reporting if it was true?

The many rebuffed outside airborne attempts to study Israeli clouds, such as that by Sir John Mason mentioned above, suggested otherwise. I was to fester over this rejection for the next couple of years before deciding to go to Israel and see those clouds for myself, becoming a “cloud seeding chaser”, maybe the first!

I have to also acknowledge that it was Peter Hobbs in 1979 who challenged me, after our/my first cloud seeding reanalyses and commentaries were published on cloud seeding in Colorado, to look into the Israeli experiments. I guess he thought I had a knack of some kind for that kind of thing. In fact, he took a series of the first questions I had to the 1980 Clermont-Ferrand 8th International Cloud Physics Conference where the lead experimenter, Prof. AG, was presenting.

8. About the publication of the 1986 cloud study

Peter Hobbs called Prof. AG a few months before he passed in 1987 to let him know that my article on the clouds of Israel, derived from my 1986 cloud investigation, was going to be published in the Quarterly Journal of the Royal Meteorological Society. The title? “Rain from clouds with tops warmer than -10°C in Israel,” something that the lead experimenter had maintained for many years never happened. In fact, to repeat, such rain was quite common, as the Israeli experiments Chief Forecaster, Mr. Karl Rosner, states in a 1986 letter to me (posted below), and as I also saw in 1986 during my investigation, and of course, as the IMS forecasters knew. Prof. AG passed three months after Peter’s call. Undoubtedly, the appearance of my paper was going to bring many questions and stress for him.

9. The best example of rapid glaciation of shallow cumuliform clouds that I saw in Israel

Shallow Cumulus congestus clouds that were transitioning to modest Cumulonimbus clouds rolled in across the coast north of Tel Aviv on January 15, 1986. This day’s scene was especially good because of the lack, mostly, of intervening clouds toward that small line of clouds. The first shot below was taken at 1556 LST and the second shot just four minutes later, 1600 LST. The rising turret peaking between clouds in the first shot had transitioned to ice in those four minutes, taking its possible load of momentary supercooled liquid water with it. This kind of speed of ice formation that I was to see repeatedly when I was in Israel.

Prof. AG had asserted in his papers that ice particle concentrations in Israeli clouds did not increase with time which was not possible in clouds converting to ice. Later, in mature and dissipitating stages concentrations will decrease as single crystals merge to become aggregates (snowflakes).

I estimated the tops of the clouds in the photos at 4 km ASL and the temperature at -14°C +3°C based on rawinsonde data. Cloud bases were a relatively warm 10-11°C; cloud bases in Israel on shower days are generally about 8°-9°C. The cloud top estimate was later verified by radar by Rosenfeld (1997, J. Appl. Meteor.); our full discussion of these photos, including an error in time by Rosenfeld (1997), is found here along with replies to his other comments. In retrospect, we erred by not publishing our full response to the comments of Dr. Rosenfeld instead of a partial one in the J. Appl. Meteor. I felt some of my best work was in this comprehensive reply, husbanded at the U of Washington:

Copies of these medium format slides, with the times above annotated on them, were sent in 1986 to Dr. Stan Mossop, CSIRO, Australia, Prof. Roscoe R. Braham, Jr., North Carolina State University, and Prof. Gabor Vali, University of Wyoming so that they could all see for themselves that there was something seriously wrong with the existing descriptions of Israeli clouds in the literature.

10. Why was the 1986 Israel cloud study submitted to a foreign journal, the British Quarterly Journal of the Royal Meteorological Society?

Ans.: Neither Professor Peter Hobbs nor myself believed that my 1987 manuscript could be published in journals under the auspices of the American Meteorological Society (AMS). So, we went “foreign.”

I believe that this also relates to the problem I have today with BAMS under its current leadership with the “Rise and Fall of Cloud Seeding in Israel” manuscript. Perhaps the BAMS editors and its leadership feel they are “protecting” Israel, its science, and the HUJ by rejecting a manuscript about faulty science, a faulty consensus, indicative of poor peer-review, with the reader likely being led to elements of misconduct. ???

My rejected manuscript in 1983 had already suggested that the AMS audience and its reviewers were not ready to hear what I was going to report, and once again I was going to report that the clouds were markedly different than was being described by the HUJ seeding researchers.

The problem with submitting to the AMS, again? Too many (gullible) American scientists had heard repeatedly in conference presentations or read in peer-reviewed journals about Israeli clouds plump with seeding potential and low in ice content to low cloud top temperatures (to -21°C) as they were being described by the lead experimenter.

It would also be seen from my report that it was likely that the clouds of Israel had little seeding potential due to how readily they rained naturally when cloud top temperatures were barely cold enough for the seeding agent to even work.

So in 1987 we believed that what I was reporting would not fly in an American journal, and Peter Hobbs, a member of the Royal Society, “communicated” my manuscript to the QJ. The major problem again for AMS journal reviewers would be, as it was in 1983:

How could the HUJ experimenters not know what I was reporting?

Overseas reviewers tabbed by the QJ, however, such as a Sir B. J. Mason, et al (I don’t know who the reviewers actually were) were likely to be more circumspect, and not at all surprised by mischaracterizations of clouds by members of the cloud seeding community that decribed them as filled with seeding potential.

And they were more circumspect.

My 1987 submitted manuscript was accepted and published in the January 1988 issue of the Quarterly Journal. My conclusions about the general nature of Israeli clouds have been confirmed on several occasions beginning in the early 1990s in airborne measurements by Tel Aviv University scientists and by others later. I had indicated to Prof. AG and several other scientists to whom I wrote to from Israel in 1986 that, from ground observations, the clouds of Israel were producing “50-200 ice particles per liter at cloud top temperatures >-12°C” and that “ice was onsetting in Israeli clouds at top temperatures between -5°C and -8°C.”

Of course, these were fantastic statements based on ground observations in 1986 for those scientists that I wrote to from Israel, but they were verified in a peer-reviewed paper reporting cloud top temperatures and ice particle concentrations in 1996 (Levin et al., J. Appl. Meteor., Table 4).

That 1996 TAU paper is the last time that cloud top temperatures and ice particle concentrations in mature clouds would be reported by Israeli scientists, though the HUJ has conducted numerous flights since then in several separate programs, but have omitted that data about their clouds stating that the instruments they carried on their research aircraft were not capable of this measurement. (I am not kidding.)

The HUJ researchers, however, could only discern the general characteristic of Israeli clouds in 2015; that precipitation onsets in Israeli clouds only a little below freezing as they come in off the Mediterranean Sea. The Israeli experiments’ Chief Meteorologist, Mr. Karl Rosner, already knew this in 1986 (see his letter), as did the Israel Meteorological Service forecasters I spoke with in 1986. What’s wrong with this picture?

Moreover, as happens in conflicted science environments, the HUJ authors of the 2015 paper could not bring themselves to cite my 1988 paper that had reported 27 years earlier what they were finally discovering about their own clouds in 2015. What does this kind of citing tell you about the science emanating from this group at the HUJ? And what is it telling their countrymen? A lot.

The cause of such high precipitation efficiency, the 2015 HUJ authors asserted, was “sea spray cleansing” of clouds coming across the Mediterranean Sea from Europe. This made them ready to produce precipitation at modest depths with only slightly supercooled cloud tops. The Mediterranean Sea is approximately five million years old. Moreover, since the cold air masses exiting the European continent are deepening, there is a “volume cleansing” effect as well that they do not yet know about; aerosols are dispersed over greater depths and in situ concentrations decrease.

In was in 1992 that the HUJ seeding researchers first discovered that shallow clouds with slightly supercooled tops rained in Israel; but they asserted, only in the specific situation when the clouds were impacted by “dust-haze.” And it happened mostly on the southern margins of showery days, they reported.

So, why did it take HUJ researchers so long to learn about their “sea spray cleansed” clouds with all the tools at their disposal? Only the current HUJ seeding leadership can tell us; he studied the clouds and storm patterns of Israel in the late 1970s and early 1980s.

11. The battle to publish “The Rise and Fall of Cloud Seeding in Israel” in the Bull. Amer. Meteor. Soc. (more slogging)

A LOT of the material in this “blook” is about getting my The Rise and Fall of Cloud Seeding in Israel manuscript published in the Bull. Amer. Meteor. Soc. (BAMS). I am an expert on the clouds and cloud seeding in Israel and have published on those topics in peer-reviewed journals. The effort to have my holistic account of Israeli seeding published began three years ago! A proposal to BAMS for such an article was declined in 2017, re-written and accepted in later 2018, the manuscript itself submitted in January 2019, and a split decision, reject and accept, received in March 2019.

BAMS chose to reject it, without allowing a response to the comments of the two reviewers, the reject reviewer, who signed his review, is with the seeding team at the HUJ, and I felt, was a “conflicted” one. The “accept, important paper, minor revisions” reviewer was anonymous. BAMS believed that the seeding issues are “not settled” and issue, “too contentious” to be published in BAMS.

I have no idea what these vague descriptions meant about “not settled” and “too contentious.” The Special Editor did not elaborate on what was meant. Here’s my paper as it stands after peer-review, in a two column format for easier reading:

I think here of Stewart and Feder’s efforts to get their 1987 article, The Integrity of the Scientific Literature published in Nature…which took several years. Those authors had found quite a few errors in peer-reviewed scientific papers and wanted the science community to know about some sloppiness in their domain. It resisted. Ditto here.

A revised manuscript of the “Rise and Fall,” for short, following peer-review, was sent in January 2020 to the chief editor of BAMS and the Special Editor, along with the case for publishing it. I also included my replies to the comments of the two reviewers. All of this material is found near the end of this “blook” if you really want to dig into it. These were items that were NOT requested by the BAMS Editors; I just hoped they would peruse them and reconsider their reject decision.

So far, BAMS et al. are unfazed/unconvinced or, more likely, didn’t bother to read my arguments for publication, or the revised manuscript, or the responses to the reviewers. They have responded with silence. Silence is not always golden.

But I remain undaunted. This kind of behavior, rather imperious, is not unusual for editors of journals–they often feel they are above being questioned concerning their decisions, or feel they are too busy to review their decisions. Some editors/reviewers of journal articles, however, often do take the time to help and advise authors (BAMS‘ Richard Hallgren, Irwin Abrams; Fred Sanders, Gary Briggs for other journals, come to mind). These above really cared about the literature, even when a paper was rejected (as in my case with Hallgren and Abrams).

12. Why do I persist in the effort to be published in BAMS?

I deem this “Rise and Fall” account the most important story concerning cloud seeding since the advent of modern seeding in the late 1940s. It’s not only about what I deem a human tragedy, but also a scientific tragedy as well for the people of Israel and the outside scientific community. If this sounds melodramatic, read on.

It’s also important because it demonstrates the seductive/corruptive power of changing the weather; that is, making it rain or snow, on otherwise good scientists who went to the “dark side”, perhaps due to confirmation bias, vested interests, or maintaining a high status in this field that overwhelmed their judgement. As Ben-Yehuda and Oliver-Lumerman (2017) have pointed out in their book studying 748 cases of fraud, becoming a “fraudster” to use their word, is often a “process.” Good scientists, as the leading characters in this drama were, didn’t go overnight to the “dark side.”

It is worth observing in view of the current rejection of my manuscript reviewing Israeli cloud seeding that BAMS has published more than 70 cloud seeding articles, some of those considerably longer than mine, since the advent of modern cloud seeding in the late 1940s. So, an article like mine reviewing Israeli cloud seeding is rather normal for BAMS to publish from its past history. BAMS is the most read, most impactful of our American Meteorological Society (AMS) journals; my piece belongs there so that those organizations, from state to private ones, who might be considering cloud seeding, know about the Israeli experiences.

So, I persist.

I have also placed a “Get a life” footnote in response to those many people who might think at this point that I need to get one after getting into this “blook.” Its not an unreasonable thought. That footnote, perhaps defensively written, has some less serious bio material about outside interests (“sports and weather”) so that it doesn’t appear that I didn’t have any life outside ruining other people’s cloud seeding work and careers. :), sort of.

13. A few ppt slides from a talk given on “The Rise and Fall of Cloud Seeding in Israel” at the University of Wyoming in October 2017

This third ppt is a glimpse of a talk given at the University of Wyoming Atmospheric Sciences Department in October 2017 on the “Rise and Fall” of cloud seeding in Israel. At this time, my proposal to BAMS for such an article had been rejected. It was accepted when re-written about a year later. BTW, I hope you like Israeli rock music. Huh?

I used a song that I really love that’s in Hebrew for “ambience” during that WY talk, and its here as well in this ppt, the title of the song being, “The Train from Tel Aviv to Cairo.” I encountered it during my 1986 trip. Yes, that train ride might have some tension in it as this song seems to imply with its minor chords, as do my talks. I let it play as I went through the early slides without comment, at least that was the plan. In this ppt, that song doesn’t start automatically, you’ll have to click on it. Boo.

14. The Israeli experiments’ chief meteorologist’s 1986 letter decrying the omission of data from Israel-2; describes the high cloud top temperatures that rain falls from

Mr. Rosner’s feelings about that omission can be seen in his letter to me the year of my visit in which he also critiques the 1981 published article by the experimenters that left out half the results of Israel-2 on superfluous grounds:

BTW, it was the Israel Meteorological Service (I was granted some work space within it) that introduced me to Mr. Rosner in 1986. He had an astounding story to tell me, someone who had come to Israel only in question of cloud reports but who then learned about omitted experimental data! Imagine my reaction. It was unbelievable, but was beginning to look like part of a “pattern of reporting”, too.

For comparison, about what was known in 1986 concerning the clouds of Israel (information contained in Mr. Rosner’s letter), and what was only recently discovered by HUJ cloud researchers, these quotes:

From Mr. Rosner’s 1986 letter:

Mr. Rosner first corrects a statement in Gagin and Neumann 1981 who had written this about Israel-2: “Cloud tops warmer than -5·C were not seeded.”

Mr. Rosner, as chief forecaster, was closer to the day-to-day operations, says this: “In fact, the threshold (for seeding) was -8°C” (for Israel-2). (Note by ALR: This is a minor correction.

Mr. Rosner added this critical cloud/rain information after that:

“There were many instances where the tops did not reach these levels and yet rained, sometimes heavily from such clouds.”

Twenty-nine years later, in 2015, HUJ researchers discover the shallow precipitating Israeli clouds described by Mr. Rosner in 1986 (and reported by me in 1988)

From Freud et al. 2015, Atmos. Res.:

The median effective radius over the (Mediterranean) sea (blue solid curve) crosses the precipitation threshold of 15 um already at -3°C, even before silver iodide can have any effect…..”

Now, if you still believe that Prof. AG and his cohorts rebuffed airborne missions by outside groups such as Sir John Mason’s to investigate Israeli clouds, or me from seeing radar echo top heights in 1986 solely because of “national” or “personal pride” …well, I have some ocean view property in Nebraska I’d like to sell you; maybe a bridge, too. Its beyond a reasonable doubt; incompetence can not be so great as to not know.

An example: I had ridden my bicycle from Tel Aviv to Prof. AG’s radar on the periphery of Ben Gurion AP for our 3rd and last meeting. He would not allow me, however, to go there during storms and evaluating echo top heights claiming his cloud reports would only be verified. The reason I couldn’t go there, he said, was due to, “airport security.”

I don’t think he realized how I had gotten to his meeting.

His behavior was consistent with having “contrary knowledge”, that is, having the same knowledge about Israeli clouds that his chief forecaster and the forecasters within the IMS had, or even his former seeding pilots had. I spoke with one of the latter, then doing tourist flights out of Sade Dov airport and he said, when I asked him, “At what heights do Israeli clouds begin to rain?”, he said, “eight to ten thousand feet” (ASL). This would be exactly where the HUJ 2015 described the onset of rain, at heights where the temperatures are a little below freezing on most shower days.

Compare, too, Prof. AG’s scientific demeanor toward me to that of Professor Lewis O. Grant of CSU described earlier who gave me, a known skeptic, the data I requested.

But why didn’t Prof. Gagin’s successors at the HUJ, ones who could go to his radars regularly long before he passed, learn about these shallow, precipitating clouds, “cleansed by the sea” and report on them in a timely manner? Surely such shallow precipitating clouds from the Mediterranean Sea were passing regularly over and around their radars winter after winter, decade after decade (one of the two radars was vertically-pointed).

I saw those same clouds, photographed them, and reported on them in the Quart. J. Roy. Met. Soc. and in Rangno and Hobbs (1995, J. Appl. Meteor.) Yet, the HUJ seeding experimenters could not discover them.

“Dust-haze” is not a significant factor in making the majority of shallow clouds rain in Israel, as was once asserted by the HUJ experimenters as the sole cause. Indeed, that spurious report in 1992 was the “acorn” from which the “oak” of Rangno and Hobbs (1995, J. Appl. Meteor.) had sprung, again driven by the thought, “someone has to do something about this!” (that 1992 paper).

To repeat, only the current HUJ seeding leadership can illuminate us on why he/they didn’t see the regular presence of “sea-spray cleansed” shallow precipitating clouds sans “dust-haze.” But will he? Perhaps, like me in the early 1970s, he was participating in the weather modification/cloud seeding culture’s de facto “Code of Silence” to stay employed and avoid retribution by his supervisor.

Taking a step back to get a perspective on what happened in Israel… it was a human tragedy that was taking place in those days. We don’t know why it happened for sure. Perhaps Prof. AG felt trapped by his early cloud reports, ones cited early on in the 1974 benchmark papers on riming and splintering by Hallett and Mossop; Mossop and Hallett in Nature and Science, respectively; each mentioned the Israeli clouds as not having large enough droplets for riming and splintering to take place. Perhaps, becoming so prominent in the cloud seeding arena as having seemingly done such careful work and in his own Sephardic community was too much to give up (Prof. AG told me in 1986 during our first cordial meeting that he was the “most prominent,” or “highest ranking”, member of that latter group).

And me, coming to check his cloud reports, a minor figure in the field, must surely have been his worst nightmare. Had someone of the stature of a “Stan Mossop” come? Maybe not so bad.

And surely, as Prof. AG would have suspected given his cloud microstructure knowledge, there was little chance that the commercial-style seeding program targeting the Sea of Galilee (Lake Kinneret) that began in 1975 would have little chance of producing usable amounts of runoff, given the realities of Israel’s clouds. That this seeding program was not producing runoff was only discovered decades later when it was looked into by a panel of independent experts inspired by the Rangno and Hobbs’ 1995 reanalysis of the experiments and ensuing commentaries. It was finally “terminated” in 2007, 32 years after it began. (The “fall” in the “Rise and Fall”).

Imagine what we are dealing with here in scope and cost for the people of Israel? The magnitude of what happened emphasizes why my account should be published in BAMS for the AMS’ widest audience. In my opinion, those who are blocking the publication of my manuscript, rejecting it on tenuous grounds, consider the people of Israel somewhere down the line when it comes to BAMS priorities.

Please do read some of Mr. Rosner’s thoughts on omitting the results of the south target of Israel-2 by Gagin and Neumann (1981) in his letter.

15. More about getting published and those “dark elements” that may be preventing it

As of this very moment in 2020, I am still fighting to get the sobering story of this “Rise and Fall” of cloud seeding in Israel published in BAMS, one having dark elements; namely, the experimenters withheld critical data that would have changed the perceived outcome of their second, “confirmatory” randomized experiment, Israel-2.

Those withheld results were eventually forced out by the Israeli experimenters’ own “Chief Meteorologist,” Mr. Karl Rosner. Mr. Rosner’s campaign to out them began after he retired in 1985 (when he felt safe from possible retribution, he told me in Israel).

Well, there it is: whistleblowers, and why we don’t have more of them though they are crucial for science. Please step forward at your earliest convenience….

Those omitted results came out when the new leadership of the HUJ seeding unit had no choice but to publish them, with former Israeli statistician, Prof. Ruben Gabriel also becoming involved. (It was troubling to learn only recently that Prof. Gabriel, whom I admired, had reviewed the original paper that had omitted half of the Israel-2 results (Gagin and Neumann 1981, J. Appl. Meteor.—see acknowledgements.)

Imagine! Mr. Rosner felt it was wrong for the experimenters not to have reported all the results of the Israel-2 experiment immediately after it ended! I do, too, but there is little support for this view in the scientific community-at-large. The silence has been deafening.

In fact, not only was there silence, the AMS and the Weather Modification Association each dedicated memorial issues of journals to the leader of the Israeli experiments who was responsible for withholding data! Those organizations had not yet absorbed what had happened, and who exactly they had honored, but you can bet that they will fail to acknowledge their error.

Mr. Rosner and I remain in a substantial minority, one that perhaps consists of only me and him since the rest of the scientific community has “yawned” at the “misrepresentation/falsification” of Israel-2 while we remain upset about it to this day, looking for closure.

Definitions of “scientific misconduct” as formulated by the U. S. Office of Research Integrity, adopted by most scientific organizations, such as the AGU and recently by the AMS!

“Falsification”, as you will read, involves omission of data, and for the Israel-2 experiment it was not just a peccadillo. (Ben-Yehuda and Oliver-Lumerman (2017) defined omission of data as “misrepresentation.” Cherry-picking data while omitting the full amount of data that does not support the cherry-picked subset would fit under this definition.

16. The two peer-reviews: (accept and reject) and the BAMS choice to reject the “Rise and Fall” manuscript

There were but two reviews of my manuscript on the rise and fall of cloud seeding in Israel, submitted in January 2019 to the Bull. Amer. Meteor. Soc. (BAMS). The reviews came in in March 2019 and I ended up, to repeat, with a split decision: “reject” (by a conflicted reviewer with the HUJ “seeding team,” hardly surprising). He was my first choice as a reviewer with me knowing full well that he would reject anything I submitted, as he had in the past.

Why would I even name an adversary as my first choice of a reviewer?

I fervently believe that adversaries make the best reviewers. No error that you have made in a manuscript will slip by them. I did not want “pal” reviews. At the same time, I presumed that BAMS would understand the conflict of interest by the “reject” reviewer and allow me to respond to his disingenuous review full of mischaracterizations though also having some minor valid points that caused me to do some rewriting. BAMS did not recognize the conflict of interest, or has ignored it, as of now, February 24th, 2020. Probably never will. How strange this is, as though only BP can explain the Deepwater Horizon explosion without anyone commenting on it.

So, perhaps there is some inadvertent humor here when I deliberately selected a reviewer who would knee-jerk reject my paper and that BAMS would choose that one over an “accept” reviewer’s decision. Sadly funny.

The fault rather lies at the feet of BAMS who knew full well about the “reject” reviewer’s conflict of interest. It did not appear that BAMS even read the adversarial review and compared it to what was in my original manuscript! BAMS, too, is at fault in not letting me reply to the conflicted review. You can evaluate my assertions down at the end of this “blook” since I post the conflicted review and my replies to those comments. You can also read what I wrote in the manuscript, revised only slightly based on the legitimate comments of the two reviewers.

The 2nd anonymous reviewer’s decision, oddly not transmitted to me by the Special Editor in charge of my submission in his terse note; “article rejected” email, was the “accept, minor revisions, important paper”! That was amazing to me.

I was so excited to read that phrase: “important paper”, but one that somehow had no effect on the BAMS editorial staff. How can that be?

However, that anonymous reviewer also deemed my manuscript too “harsh” with “personal criticisms” and wanted it “toned down.” Well, those kinds of things are a matter of personal perspective, and are minor, as he wrote (“minor revisions.”) I contend that the original experimenters earned “harshness” with their reporting malfeasance, the effects of which I address in the “Rise and Fall,” “summary” and “reflection” sections. That is the only place where perceived “harshness” can be found in the revised manuscript. What happened must be reflected upon! To ignore it would be of itself be a whitewash and an insult to the people of Israel.

Thus, I can’t tone my manuscript too much and leave with my integrity intact; no one could. And it seems odd to want to put a happy face on misconduct; i.e., falsifying the results of an experiment, an act that affected so many stake holders in and outside of Israel.

Of these two possibilities, accept (with satisfactory revisions, as one would have expected with a split), or “reject,” BAMS chose to reject my manuscript outright, the Special Editor, tilting toward “reject” in his own opinion, describing it as “too contentious” and the seeding matter “not settled.” The latter statement is not credible in the face of the Israel National Water Authority (INWA), the funder of cloud seeding, had quit seeding of the Sea of Galilee (Lake Kinneret) many years ago.

How is that seeding termination not a “settled” point? In fact, the INWA has started completely over with a new randomized experiment to see if seeding really does work. The results of the prior experiments have been, in essence, jettisoned.

The INWA quit commercial-style seeding, of course, amid the howls of the seeding promulgators at HUJ, who, while agreeing that there had been no extra runoff due to seeding, scrambled to pull out of the hat the argument that air pollution had canceled out seeding increased rain! They were both of the SAME magnitude!

Not surprisingly, this claim was not found credible by independent Tel Aviv University scientists on several occasions; the HUJ findings had been due to cherry-picking among the dense network of gauges in Israel. (There are 500 standard gauges and 82 recording gauges in Israel (A. Vardi, IMS Deputy Director, 1987, personal communication).

Nor did the INWA restore seeding based on the HUJ pollution claims, making the termination an emphatic settled point.

“Too contentious”? Not surprisingly, fessing up to having caused their own government to have wasted millions of dollars due to their faulty cloud seeding claims and the inability to assess their own clouds accurately is not in the “DNA” of the HUJ seeding group; seeding partisans within the HUJ will always believe that their experiments “proved” cloud seeding while the rest of the world, and even their own government, moves on.

Hence, disingenuous controversy with pseudo-scientific claims will always erupt from the HUJ seeders in defense of their million dollar lapses. Who is surprised by this behavior? Other scientists from Tel Aviv University who have also reanalyzed the HUJ cloud seeding claims in peer-reviewed journals have found them as faulty as Peter Hobbs and I did (details in the manuscript pdf).

Perhaps this is what the Special Editor and BAMS are afraid of in their ersatz assertion, “too contentious”: namely, that HUJ seeding partisans or others will write long “smoke screen” soliloquies to BAMS to complain about my “Rise and Fall” article should it be published, as they did similarly in 1997 after the 1995 Rangno and Hobbs reanalyses of the Israeli cloud seeding experiments was published.

17. The importance of controversy

Note: The Rangno and Hobbs 1995 reanalysis of the Israeli experiments, and the ensuing comments by several scientists and our “replies” to them in 1997, J. Appl. Meteor., “opened Pandora’s box” (Y. Goldreich, Bar-Ilan University, author of “The Climate of Israel“, 2018, personal communication). Goldreich further stated that this episode led the Israel National Water Company to hire that independent panel of experts to assess just what they were getting from the HUJ commercial-style seeding program for the Sea of Galilee. That panel could find no extra runoff due to seeding, contradicting the reports of the HUJ seeding promulgators. Why should we be surprised at this outcome given the actual high rain efficiency of the Israeli clouds that escaped the HUJ seeding researchers for SO LONG?

Controversy can be enormously fruitful. Q. E. D.

As a matter of fact, BAMS used to embrace controversial issues as they stated annually in their organizational issue and did so to help illuminate their readers on contentious scientific issues of the day. The statement about embracing controversy was dropped by new BAMS leadership. No reason was given. See below, from the 1995 organizational issue:

“Bulletin of the American Meteorological Society (BAMS) publishes papers on historical and scientific topics that are of general interest to the AMS membership. It also publishes papers in areas of current scientific controversy and debate, as well as review articles.”

Where have you gone, BAMS, that you would hide from controversy? Is it really that, “BAMS isn’t what it used to be”, as asserted by a Fellow of the AMS, a NAS member, and recipient of many honors, now retired from the University of Washington?

This further thought for the BAMS leadership: When my article is published in BAMS, why don’t you write an editorial or side bar about why you think it doesn’t belong in BAMS? This would be quite gratifying to me because you’d be laying your bias on the line for everyone to see.

18. About the new Israeli randomized cloud seeding experiment and the airborne study that prompted it

Israel, abandoning any idea that the prior cloud seeding experiments had “proved seeding”, again indicative of a terminus, has started over with a new experiment in the Golan Heights in the far north, to see, if in fact, cloud seeding works. It’s called, “Israel-4”, now its seventh season recently concluded. No preliminary results have been reported, which is odd. In contrast, the seemingly successful first two Israeli experiments had many interim reports reporting successful progress.

Unfortunately, the funder of this new experiment, the Israeli National Water Authority, hired the HUJ “seeding unit” to evaluate seeding potential in the Golan Heights region in preparation for the start of Israel-4, a mistake akin to having the fox guard the hen house.

I reviewed the published article that came out of that HUJ research in 2015 (Atmos. Res.) that described itself as the background airborne cloud study for the new experiment. After reading it, I was not sure it had even been reviewed! But, I had not seen it until two years after it came out, too late to formally comment on it.

That 2015 article clearly exaggerated seeding potential in my view; the 2015 authors could not even disclose ice particle concentrations and the rapidity at which they develop in Israeli clouds, critical information for seeding evaluation purposes. They claimed the couldn’t measure ice particle concentrations because the new, expensive probe they carried on their research aircraft, one manufactured by Droplet Measurement Technologies, Inc., could not measure ice particle concentrations accurately. Those measured concentrations by the new DMT probe, were “unreasonably high” (D. Rosenfeld, personal communication in his review, attached below.) I guess if concentrations are too high in Israeli clouds, they are not reportable by the HUJ.

DMT disputes the claim that their probe cannot measure ice particle concentrations accurately, stating that the HUJ researchers could have reported accurate ice particle concentrations if they had wanted to (D. Axisa, 2018, personal communication).

What does this tell you, again, about the reporting from the HUJ?

The reject reviewer, DR, was provably untruthful. Is there another explanation? What is it?

The above was pointed out to the Special Editor many months ago. The fact that critical data was being withheld from the INWA, the people of Israel, and the scientific community, as the prior HUJ experimenters had done with Israel-2. This knowledge had no effect on the Special Editor in reconsidering the quality of the entire “reject” review, as I think most in his position would have. Am I wrong here? Hence, my suggestion that he recuse himself from his role.

I wondered, too, why I wasn’t selected as a reviewer by Atmos. Res. of that 2015 article? My decision on the manuscript would have even been: “accept, pending MAJOR revisions”! This article had some of the best objective writing by the HUJ’s “seeding unit.” But it also had a “Jeckyl-Hyde” aspect where misleading statements kept popping up and along with over-optimized seeding scenarios.

And to the INWA? I would have implored them:

“Don’t do a cloud seeding experiment based on this paper! Get outside researchers to evaluate seeding potential!” (Yes, the larger font indicates that my voice is raised here.) 🙂

If Israel-4 fails to produce rain via seeding, the faulty HUJ assessment of seeding potential in the Golan will be the cause; the fox will have guarded the hen house as well as expected. And that faulty paper will be consistent with the work of the HUJ seeding group since the early 1970s, work that consistently exaggerated the seeding potential of Israeli clouds and seeding results.

19. Back to the battle to publish

Returning to my own case….what has been and remains shocking to me, as a well-published researcher and an expert on Israeli clouds and cloud seeding, is that BAMS has refused to get the opinions of one or more knowledgeable reviewers to break the current review split, or consider recusing the current Special Editor who is an alumnus of Colorado State University whose cloud seeding work I have, with Prof. Peter Hobbs, trashed on several occasions, even calling for an investigation of the reporting of those experiments. (See Colorado segment below–use the Table of Contents jump link to that subject).

Despite my admiration for Prof. Fleming’s secular work, a Special Editor more experienced in the technical details of the clouds and cloud seeding in Israel would have been more appropriate, such as Dr. Roelof Bruintjes of NCAR who wrote a long review of cloud seeding in 1999 that included the Israeli experiments, among several others. Other names of more qualified editors than the current one: Bob Rauber, Bart Geerts, Gabor Vali, etc.

In spite of having to question the Special Editor’s credentials for BAMS, the one who called the final shot on rejecting my manuscript, it doesn’t mean I don’t respect him and his body of historical work! Its like a court case where the prosecutor and the defense attorney can be at each other’s throats during a trial, but might be friends and socialize after work. This is the way I see it, anyway. Nothing personal intended.

As Schultz (2009) pointed out, a reject decision on the part of an editor if they have the least basis for it, is, in essence, the “easy way out.” No need to deal with troublesome authors thereafter; just ignore them. Such editors don’t have to read their responses, go over whether a revised manuscript has responded to the legitimate claims of the reviewers, etc., It can all be ignored once a “reject” decision has been made. I am quite sure the current Special Editor did not read my original manuscript and compare it to the comments of the “conflicted” reviewer from the HUJ. But you can read these below where I have posted them.

20. “Science” at BAMS? Or something else?

What does this sound like to you? Science? Or something else?

The answer is obvious. But why?????

Some thoughts on why BAMS/AMS rejected my “rise and fall” manuscript…

First, the BAMS Special Editor objected to the full title of the original submission, “The Rise and Fall of Cloud Seeding in Israel: A History with Lessons for the Future.” The word “history” is treading in the illustrious Special Editor’s domain; he deemed the use of the word “history” inappropriate in my title.

And, there are certainly lessons to be taken away from my account: 1) Never trust the experimenters to get it right when they report on their own experiment, among other lessons.


My account involves a country that people often have strong feelings about, perhaps ones wishing to protect it from the kind of negative publicity that would go with an article about leading researchers from their highly regarded HUJ that did not report all of their experimental results and couldn’t decipher the natural properties of their clouds for decades. In doing so, our scientific community, and their own government were misled.

Perhaps the country of Israel and/or its “premier research institution” (as the HUJ describes itself), are considered off limits by BAMS leadership for articles having descriptions of reporting by scientists that could be characterized as “scientific misconduct.” Yet we know if we ask ANYONE in science about fraud in science, such as the BAMS staff itself, they will tell you with great vehemence how strongly they oppose fraud, while their actual reaction to it is: “don’t tell us about it.”

I am straining for a reason here for what to me is unprecedented behavior by BAMS in its rejection of my manuscript without allowing a response to the comments of the reviewers, given a split decision.

My account, too, is also about failed science, failed peer-review, and an erroneous scientific consensus concerning the Israeli cloud seeding experiments, once deemed as the only cloud seeding success in 35 years of seeding trials according to Science magazine. The embarrassment factor is extremely high.

But again, that consensus view of the Israeli experiments that dominated the 1980s and beyond before the wheels fell off, besides not comprehending their clouds, was based on partial reporting of results of their 2nd experiment, Israel-2, as well as the HUJ researchers failure to report in a timely manner the results from a third, long-term randomized experiment that was failing to show any effect of cloud seeding.

That third randomized experiment, Israel-3, began in 1975, but was only reported on for the first time 17 long years after it began when the results of the first 15 years of random seeding were reported in 1992. Slight decreases in rain on seeded days were reported; they were not statistically significant.

Reporting those suggested decreases in rain due to seeding being logged in Israel-3 after just a few years would have had a tremendous impact on the scientific community-at-large and would have increased pressure to have outside groups study the clouds of Israel and illuminate the HUJ seeding researchers about them.

Had all these seeding related results been communicated to outside researchers in a timely manner, as our AMS “Code of Guidelines” (Ethics) demands, had the HUJ researchers discovered the high natural ice-producing aspects of their clouds early on, or if they had just allowed outside investigators like Sir B. J. Mason and his British team to discover it for them, the “damage” paid by the Israeli people would have been so much more limited.

And why was it that every forecaster with the Israeli Meteorological Service I spoke with in 1986 knew that Israeli clouds rained with tops equal to or warmer than -10°C, and as we saw, as did HUJ’s very own experiments’ “Chief Forecaster,” Mr. Karl Rosner? And yet the HUJ experimenters denied that it happened. To repeat, how could the HUJ experimenters not know this about their own clouds with all the tools at their disposal, and the cloud knowledge around them?

This is a major conundrum that only their current seeding leadership can answer, someone whose graduate work in the late 1970s and early 80s was about the clouds of Israel as seen the experimenters’ radars and in satellite imagery.

All in all, the delays in reporting results of experiments, preventing bona fide researchers with aircraft in to study their clouds, and preventing me, an on site bona fide researcher, from examining the tops of radar echoes while I was in Israel, were all abuses of science. Who wants to hear a story about scientists abusing science in a country we care so much about?

Ans. No one.

But not wanting to hear about abuses (of science) doesn’t mean its a story that shouldn’t be told. Ask Catholics.

With BAMS rejecting my manuscript on tenuous grounds, not reading the my responses to the reviewers’ comments, BAMS has now become part of the story unless it reverses course upon “further review.”

21. Has credentialism played a role in the BAMS rejection?

Without doubt. I have only a Bachelor’s degree and was a non-faculty staff member at the University of Washington. Comprehensive reviews such as mine of the Israeli cloud seeding experience, a distillation of more than 700 pages of peer-reviewed literature and conference preprints, have always in the past been accomplished by upper echelon, senior faculty. You can just imagine how repugnant, odious it might seem to have an under-credentialed mere staff member like me write a comprehensive review in a journal about the former highly regarded cloud seeding experiments in Israel. The only thing I have going for me is seniority….and having exposed various ersatz aspects of those and other experiments. As a BAMS editor observed, this latter element in his opinion, disqualifies me from writing about this subject because I am too close to the events I am writing about.

Please read my manuscript, and make up your own mind.

Imagine, too, in a thought experiment, if some of the now-passed major players in this field, such as Sir B. J. Mason, Roscoe Braham, Jr., Randy Koenig, Peter Hobbs, or Stanley Changnon, had authored my manuscript instead of me and had also reflected on the ramifications of partial reporting as I do? Surely it would “get in.”

I believe my modest status on the professional totem pole, a person with little influence, has contributed to an easy rejection of my review manuscript by BAMS. Do we need to reprise Douglas Adams’ classic Hitchhikers Guide to the Galaxy” vignette about the graduate student who discovered the “Infinite Improbability Machine” to understand this cultural aspect of science that even Adams understood? Just in case you don’t know it, from the Hitchhiker’s Guide:

“It startled (the student) even more when just after he was awarded the Galactic Institute’s Prize for Extreme Cleverness he got lynched by a rampaging mob of respectable physicists who had finally realized that the one thing they really couldn’t stand was a smart-ass.”

22. Getting tougher in science concerning fraud and misconduct, criteria just being posted by the AMS

BAMS and its current leadership represent an “old guard” science reaction when evidence of misconduct is presented: “Circle the wagons to protect science and scientists; never mind the victims.” They see ignoring misconduct as good for science. No messy investigations, no perceived decline in the reputation of science and scientists as sole pursuers of truth.

For examples of this very same kind of behavior in the culture of science, please see the 1988 PBS NOVA program, “Do Scientists Cheat?” (You’ll spend a lot of time trying to find the full version.) I believe this cultural aspect of science is the primary reason that my manuscript on the “Rise and Fall” has been rejected.

The rejection of my manuscript has nothing to do with “not settled” or “contentious” issues, as asserted by BAMS.

The Israeli people were victims, and will be again in my opinion, under the current promulgators of seeding at the HUJ who were present when the original misrepresentation of Israel-2 took place. But they did nothing when it happened. Why would they do anything different in the future?

There is a new “get tough” ethic in science concerning fraud and misconduct that new attitude has been represented by a recent editorial by Kornfeld and Titus in Nature Geoscience, 2016: “Stop Ignoring Misconduct.” A similar theme has been reprised in the comprehensive 2017 look at fraud in science, “Fraud and Misconduct in Research” by Ben-Yehuda and Oliver-Lumerman of the HUJ. They called the 748 proven cases of fraud in science that they reviewed for patterns in misconduct, the likely “tip of the iceberg.” They noted that the site, “Retraction Watch” logged more than 1500 retractions just between 2012 and 2015! Stewart and Feder were right to question the “Integrity of the Scientific Literature.” Ben-Yehuda and Oliver-Lumerman further observed that “retracting” a paper is an “out” for known misconduct, which is certain in some of those cases. In essence, Gabriel and Rosenfeld’s (1990) analysis of the FULL results of Israel-2 was a retraction of the previously reported results for Israel-2.

Ben-Yehuda and Oliver-Lumerman further chided science for euphemising what is actually fraud, terming it, “scientific misconduct.”

The AMS/BAMS needs to “listen up.” You’re not protecting the people of Israel as you may think; you’re hurting them in your misguided actions to block the publication of this review of Israeli cloud seeding that would alert them to the dangers lurking within their own prized academic institution. Cloud seeding zealots are likely to mislead them again, and have, IMO, with their 2015 “background” paper (Atmos. Res.) for the Israel-4 experiment that exaggerated seeding potential in the Golan Heights.

Ironically, I don’t even use the word “misconduct” in my “Rise and Fall” manuscript, though a reader might well be led to that thought. In this blog, I am more definitive. Not reporting all the results of your experiment, critical ones, is deemed a type of misconduct called, “falsification/misrepresentation”, or “cooking and trimming”, and that, as we all know, including everyone at BAMS, is, in fact, what happened in Israel-2; half of this second experiment’s data was not voluntarily reported by the original experimenters, and that led to a false scientific consensus that seeding effectiveness had been “proved” at the end of Israel-2.

Please, AMS, consider your own newly minted Code of Research Conduct

Those withheld results of Israel-2 were finally published, but only after the lead experimenter passed in 1987 (he was just 54, he was about to have a lot of explaining to do). The 1990 journal publication (J. Appl. Meteor.) in which this happened was titled, “The full results” of the 2nd experiment. The full result was a “null” one when using the crossover methodology that had been used to elucidate the apparently successful results of Israel-1 in their retraction of the partial successful results reported earlier for Israel-2.

Why else would you withhold data except to produce an false image of success from which you would benefit?

Later analyses by the HUJ experimenters in the evaluations of Israel-2 have suggested increased rain on seeded days in the north target and decreases in the south target when using the full dataset and invoking “dust-haze” as having interfered in the experiment; that hypothesis is addressed in my “Rise and Fall” manuscript and is shown to be of dubious validity as they were also deemed in 1995 in Rangno and Hobbs (J. Appl. Meteor.) and by independent scientists at TAU in 2010 (Atmos. Res.)

Embarrassment has to be considered as a player in this melodrama. The AMS issued memorial issues J. Appl. Meteor. to both authors (Prof. AG and J. Neumann), 1989 and 1996, respectively, the authors of the 1981 Israel-2 cloud seeding paper that omitted half of the results of that experiment.

Additionally, the Special Editor of BAMS that rejected my paper is writing a book about Joanne Simpson who wrote the most over the top praise for Prof. AG of the HUJ when he passed. In her view, Abe Gagin could practically walk on water.

Blocking my rise and fall of cloud seeding in Israel paper from being published will shield both Joanne’s memory, the Special Editor’s. book and the AMS from considerable embarrassment. Her homage:

And, who wants to read about a failed scientific consensus, though a minor one in the small niche of cloud seeding, that might trigger a surge of negativity via an “aha, moment” concerning the “Climate Change consensus”? “Maybe its wrong, too”, some might believe. Well, too bad AMS.

23. The battle is on display here:

I am posting the revised version of the manuscript here, the one BAMS refuses to examine, after having implemented the minor legitimate changes suggested by the two reviewers. Along with it, I am posting the reviewers’ comments and my replies to them as well as thoughts on the Special Editor/BAMS rejection e-mail.

It seems only fair to do this although perhaps only one or two knowledgeable people will actually bother to read all this. The reviews were long, and so must the responses to them be. So there is a LOT of material here.

Latest Rise and Fall, line numbered for review purposes

Please tell me, if you’ve somehow gotten this far, if you think the manuscript is a suitable story, and a comprehensible one, for a general magazine of “informed readers” that BAMS says it targets. I think most everyone who reads the manuscript will understand what happened, and why this is an important story that needs to be told, not buried in a low impact journal or nowhere at all but here.


24. Where it all began: Durango, Colorado, 1970-75

In 1970 I joined a large randomized cloud seeding experiment as a naive, idealistic-about-science weather forecaster; I didn’t come out that way. A lifetime of own-time “activism” regarding cloud seeding literature I deemed suspect was the result.

This section is kind of a slog about my Colorado experiences….but, I wanted to hit a FEW highlights of what was an epiphany about science for a rather naive person, me, just out of college, that occurred in Durango, Colorado. This was my very first job as a weather forecasting meteorologist after graduating from San Jose State College (as it was called then).

(Skip if busy….though if you do, you will miss some personal ridicule, a movie, accolades, a possibly libelous newspaper headline caused by me, and details of a monetary science prize ($20,000) from the United Nation’s World Meteorological Organization that me and Peter Hobbs received for our work in weather modification. Yes, in 2005 I became, “Prize-winning meteorologist”, Art Rangno… 🙂

It is sad for me to have to point out something about the above “prize”, however. Like my HS and college baseball career, (all 2nd team this; all 2nd team that), the prize described above was really a consolation one, to insert a truth-in-packaging note. Other workers got lots more than we did that year like that guy from South Africa that got $250,000. On the other hand, 32,000 Chinese weather modification workers got the SAME amount as Peter and I got that year; hah, less than a US dollar each!

OK, back to serious text…

…that Durango job was a dream come true for me, since I only wanted to be a weather forecaster since I was a little kid (even, somehow, forecasted weather for my 5th grade class–had a brass aneroid barometer in the “cloak room”). And there I was in the beautiful little town of Durango, Colorado, right out of college in 1970, forecasting weather for an important scientific experiment! My life could not have been better!

How I got to the point where I would be so skeptical of peer-reviewed cloud seeding literature that I would travel thousands of miles in question of cloud reports from the world’s leading cloud seeding scientist, however, began here during this huge Bureau of Reclamation randomized cloud seeding experiment called the Colorado River Basin Pilot Project (CRBPP). Read on.

25. The movie explaining the Colorado experiment; a tribute to its size and importance

To depart for a second, it was a project so huge that it had its own movie, the cloud seeding “documercial,” Mountain Skywater, with a soundtrack by a local Durango artist, Clarence “Gatemouth” Brown!

Departing even further from serious text, it is with extreme modesty that I point out that I was the STAR of this 28 minute movie; I never dreamed that I would be a STAR in a movie (!), but there I am, as was declared by the Commissioner of Reclamation in those days, Ellis Armstrong. He attended the 1972 release of the 1971 film in Durango and gave me an autographed photo of several of us with him in which he proclaimed on it that I was the STAR. I only speak maybe two sentences in the whole thing! It was a pretty humorous take by the Commissioner. I do cite it in my filmography, however. 🙂

Watching this movie you will get a sense of that cloud seeding era and how it was thought that a cloud seeding success in this randomized experiment was going to be a slam dunk in the San Juan mountains around Durango. There wasn’t a lot of questioning in those days about the work that this massive project was based on; namely, several stunning randomized experiments conducted and reported by Colorado State University (CSU) scientists in the late 1960s–contracts were being signed in 1968 for the CRBPP work about when the Climax II experiment was only about half completed! (And that, my friends, was a gigantic goof, as you will read.)

Also from the movie you will get a sense of the CRBPP’s scope and how well-planned it was overall. The precip measurements were made by those who didn’t know what the experiment day call was, seeded or not seeded. It doesn’t get better than that, and the BuRec deserves some mighty big accolades for that; trying to do it right. They were so confident, too, that they said that in spite of randomization (in which only half the days are seeded), that the CRBPP would produce an extra 250,000 acre-feet of water from the target watersheds.

Also in “doing it right”, and before the CRBPP began, the BuRec proclaimed in its PR literature beforehand that they would hire an independent statistical group to evaluate the results of this mega-experiment. It doesn’t get better than that, either. It was a display of confidence about the outcome of the experiment. But, that didn’t happen. Instead, the BuRec hired a group associated with cloud seeding!

Aside: For the other seeding operators out there whose films you might see, this admonishment: “Randomize, baby, randomize”. Prove your claims the right way. Also, to seeding funders: employ independent panels to evaluate what you’ve been getting from commercial seeding as the Israeli’s bravely did.


26. Scientific idealism begins to slip away in Durango

However, during the CRBPP I lived through journal peer-reviewed literature (J. Appl. Meteor.) that many of us knew was bogus but no one challenged. I, too, participated in a “Code of Silence” that kept our outside peers in the dark about important discrepancies that were being discovered in the CSU cloud and cloud seeding hypotheses during the CRBPP. These discrepancies turned out to cause the undoing of an otherwise well-planned experiment by the Bureau of Reclamation’s Atmospheric Water Resources Management Division, as it was called then (just “BuRec” in this piece). The “Management” of atmospheric water was a word that also spoke to overconfidence.

At the same time, while in awe of the BuRec’s planning, it was strange to me that the personnel with them were immune from learning from those of us in the field about problems in their interpretations of the CRBPP’s results.

An example: BuRec personnel submitted a paper to a Florida conference in 1974, several years after the CRBPP had started, purporting that “carryover seeding” effects (those days when a control day followed a seeded day) had compromised the CRBPP because heavy snow often fell on that second “control” day. They then assumed that any heavier snow on the 2nd day MUST be due to seeding effects from leftover seeds that didn’t get blown away. They then grouped such carry over days, or portions of such days, into the actual days chosen for seeding and got better suggestions of increased snow due to seeding for the CRBPP overall.

However, no seeding effects were being detected in the first few years on single days that were seeded. Therefore, it was a crazy idea that somehow the seeding agent, silver iodide, turned into super-seeds after we turned off the seeding generators.

Of course, there was a natural explanation for heavy precipitation on the second day when two days in a row were selected for experimentation.

I wrote a long letter in 1974 explaining why the findings in that BuRec preprint were bogus. When we randomly selected a second day in a row for experimentation, it was because an incoming storm was so large and heavy that it took two days for it to go by, or it was just beginning on the last hours of the first day. Not surprisingly, the heaviest part of the storm was on the second day, and usually early on.

I showed the BuRec data that control days that followed a control day, the second control day also had heavy snow, especially in the early going just like they were inferring was due to inadvertent “carryover” seeding of a control day after a seeded day. You could claim in a similar way from my examples that not seeding on a control day caused heavy snow on a following control day; silly. I had much more argumentation as well.

My explanation fell on deaf ears.

I concluded my commentary to them in 1974 about their ersatz findings with a line they couldn’t refuse to act on: I said they needed a “Resident Skeptic” at their headquarters in Denver.

A couple of weeks later, the CRBPP Project Monitor from the BuRec, Mr. Bill Douglas, presented me in person with a framed, Dr. Archie M. Kahan “Certificate of Honorary Resident Skeptic Award.” The presentation, in which he read the words on the Certificate, got a lot of chuckles from our staff who gathered around to see it. Archie Kahan, whose signature appears in the lower right, was the head of that BuRec cloud seeding division.

27. A Resident Skeptic Award from Dr. Kahan and the BuRec

Here is that “Certificate”, one really meant, I thought anyway, to ridicule someone they didn’t take seriously. Well, there were some at the BuRec, like the late Olin Foehner, who did take me seriously. I was only trying to help, guys…. You’ll have to zoom in to read the text.

Note the upside down Bureau of Reclamation logo in the lower left hand corner. It was to be prophesy for the division that sent me this “award.” Due to various missteps, of which the CRBPP was one, and a wetter period of years in the later 1970s into the 1980s, interest in cloud seeding virtually disappeared and their office was shutdown.

28. Decay of idealism accelerates in Durango

More disillusionment with the BuRec and journal literature came when their preprint about carry over effects in the CRBPP was published in 1975 in the peer-reviewed, J. Appl. Meteor. There was no mention of the synoptic situation that I had described that compromised their findings. To them, inadvertent contamination of CRBPP days was too good an argument to let go of to help boost the results for a failing 10 million dollar experiment. Nor did I comment on it; I had no experience in journal matters and it never occurred to me to do so.

29. The choice of the evaluators of the CRBPP 🙁

Another decline in confidence about the science of the CRBPP occurred when the BuRec, instead of choosing an independent group to evaluate the CRBPP as they said they would do before the project started, hired a cloud seeding group to evaluate it! While the group they hired went under the company name of Aerometric, Inc., most of the team of evaluators were really from North American Weather Consultants, led by Robert D. Elliott, President of NAWC. NAWC was largely a commercial cloud seeding company with many seeding projects and at one point was seeding commercially so enthusiastically in Utah that it contaminated some control days of the CRBPP! “Aerometric-NAWC” was chosen as the evaluator when it was clear, after just two years of random decisions, that the CRBPP was NOT going to replicate the CSU seeding results.

Perhaps the BuRec needed a friendly bailout, someone to put a happy face on a science disaster. (Footnote: I had worked for NAWC as a summer hire in 1968 and loved it and the great people there. Tor Bergeron stopped by! Still, it wasn’t a good choice by the BuRec to have them evaluate whether cloud seeding worked.)

30. The informational “black hole” during the CRBPP: important findings came in from the field but never went out to peers

In mid-stream of the CRBPP, the BuRec called a meeting in July 1973 to try to understand what was going wrong with it. Why wasn’t it going to replicate the CSU work? Mainly, it was due to a few critical CSU assumptions that were not supported by data, such as the 500 mb temperature being an index of cloud top temperatures, and therefore, as it had been assumed, a reliable index of seeding potential. After all, the CSU experiment seeding effects were stratified by 500 mb temperatures repeatedly in the published literature; they had no data on actual cloud tops. Neither of those parameters, 500 mb temperatures or cloud top temperatures, are reliable indicators of seeding potential.

Nor were there widespread non-precipitating, reasonably deep clouds ripe for seeding ahead of and behind periods of natural precipitation, clouds that CSU scientists had inferred existed because the claimed increases in snow they reported, were solely due to the greater duration of snowfall on seeded days. Seeding had no effect on natural precipitation they concluded.

No such thick, non-precipitating cloud was found to exist in the CRBPP. This was largely due to the fact that cloud tops during storms were almost always colder than -15°C in storm situations, and usually considerably colder. Those cold tops naturally produced substantial ice concentrations without being seeded. High natural ice concentrations in clouds pretty much decimates seeding potential.

In closing that 1973 meeting, consisting of a who’s who in weather modification from universities and companies around the country, the Chief of the BuRec’s cloud seeding division, Dr. Archie M. Kahan closed it by observing that, “the (CSU) physical hypotheses were not as strong as we had been led to believe.”

It was an understatement.

But these important findings presented at that BuRec conference remained husbanded with those at that meeting. The “Code of Silence” was in full display. The discrepancies were not to be “outed” until 1979 in Hobbs and Rangno (J. Appl. Meteor.) and in my reanalysis of the CSU Wolf Creek Pass experiment that same year in that journal. (The former article was originally part of the draft manuscript I brought in to Prof. Hobbs, but he deemed it something that should be reported separately.)

31. Another pivotal event in 1974

I remember how excited I was, too, when a National Academy of Sciences 1973 report, Climate and Weather Modification; Problems and Progress, came through the Durango office in 1974. The NAS Panel on Weather Modification (Malone et al.) stated that the CSU cloud seeding work had “demonstrated” cloud seeding efficacy on a “deterministic basis”.

What was exciting when I read that NAS report in 1974?

I knew by then that an assessment by our best scientists with the NRC-NAS, a scientific consensus on the CSU experiments, as we would say today, was wrong! It was interesting to me later that Peter V. Hobbs, for whom I was to work, was a co-author of that optimistic report concerning the CSU experiments.

32. 1974: The University of Washington to the “rescue”

A breath of fresh air for me blasted into Durango during the CRBPP.  The University of Washington’s Cloud and Aerosol Group, Directed by Peter Hobbs, was hired by the BuRec to study the winter storms in the San Juan Mountains and the dispersal of the ground released seeding agent during those storms; was it getting into the clouds?

By this time, it was clear that the CRBPP was not going to replicate the Colorado State University cloud seeding results in which 50-100% increases in snowfall were reported due to seeding.  By 1974, the randomly drawn control days of the CRBPP were averaging more snow than the seeded days! The U of WA group was just coming off an exhaustive seeding project in the Pacific Northwest called the Cascade Project that had incorporated extensive ground and airborne measurements.  The U of WA field research team was led by Dr. Lawrence F. Radke for the first half of its six week Colorado mission, and by Research Meteorologist, Don Atkinson during the second half.  

With the Washington team was James Rodger Fleming, who was to play the pivotal role 40 years later in rejecting my “Rise and Fall of Israeli Cloud Seeding.”  Fleming had just obtained his Master’s Degree from the Colorado State University whose work was being questioned.  

Problems with the CSU cloud seeding work had been described at the end of the first season, 1970-1971, by the seeding contractor, E. G. and G., Inc., (Willis and Rangno 1971, E. G. & G., Inc., Final Report to the BuRec).  Those reported flaws, including the often observed blocking flow during stable air mass situations, however, went nowhere with the BuRec. CRBPP’s project leadership changed and CSU student, Lawrence Hjermstad (hereafter LH), was brought in to replace the departing Project Manager, Owen Rhea who had replaced Project Manager, Paul Willis early in the first season.

Also contributing to a lack of action was that the first season of randomization had produced results suggesting that increases in snow had occurred on seeded days compared to control days, which the BuRec exulted over in news releases. I had become Acting Project Forecaster when Paul Willis’ was removed as PM. In that role, I had made every forecast of random draws in the winter of 1970-71. You can’t imagine how much I loved that challenge, though the stress of “getting forecasts right” was daunting, getting up at night to see if the clouds were moving in, heart pounding. But I felt I had been born to be a weather forecaster, as so many of us do in this field.

And, in my first forecasting season, the forecasting criteria was much easier than it would be in the following two winter seasons, and likely why I was hired in the first place. In that first season of the CRBPP, we were directed by the BuRec, as expected, to forecast a chance of measurable precipitation “somewhere” in the target in the 24 h ending at 11 AM local time. This had to be accompanied by at least 12 h of a 500 mb temperature of -23°C or higher when the precip happened. The temperature at 500 mb, or around 18,000 feet, changes rather slowly as storms come through, so it was not an extremely difficult job to predict that.

That was to change for the following two seasons after a critical visit to the CRBPP headquarters in Durango in April 1971 by Prof. Lewis O. Grant, the leader of the Climax and Wolf Creek Pass cloud seeding experiments. He was chagrined to learn that the BuRec had ordered experimental days of the CRBPP to be drawn on the basis of 500 mb temperatures, as the CSU results had been stratified by, and not rawinsonde inferred cloud top temperatures. Prof. Grant felt that actual cloud top temperatures that were -23°C or higher, would bestow better results in the CRBPP experiment. The rawinsonde inferred temperatures at cloud top would prove to be very different than the 500 mb temperature.

This would not be news to practicing meteorologists, and was not news to former PMs, Paul Willis and Owen Rhea, just off the Park Range Project at Steamboat Spring, CO. Owen Rhea, in the summer of 1970 when I queried him about the frequently used CSU expression in the design document I was assigned to study, “500 mb (cloud top) temperature” told me, “that may say its cloud top, but that’s not cloud top.” Paul Willis chuckled at the CSU claim, saying pretty much the same thing.

The confusion was sown not only in the journal literature by CSU, but also in the 1969 CSU written design document in which it was claimed that 500 mb temperature was an index of cloud top temperature during storms and had stratified the 50-100% increases in snowfall at Climax and at Wolf Creek Pass by, well, you guessed it, 500 mb temperatures. In the 1969 CSU design document, CSU and their consortium of authors used the phrase, “500 mb (cloud top) temperature” repeatedly. Hence, the BuRec’s instruction at the outset of the CRBPP to use of 500 mb temperature as the primary forecast criterion in the first season, 1970-71.

Due to Prof. Grant’s visit and return to CSU where he advised the BuRec to change to random draw criterion to rawinsonde inferred cloud top temperatures, the forecasting job became extremely difficult. There were no immediate upwind rawinsonde measurements in which to infer incoming cloud tops from, and there were no useful satellite measurements during the years of the CRBPP. The nearest, and most often upwind of the San Juan’s, was the rawinsonde profiles from the NWS at Winslow, AZ, hours away from the CRBPP target. Moreover, that site was in the lee of the Mogollon Rim Mountains where strong drying would in effect, “hide” the incoming cloud depth. It was the best site we could use, but it not very useful for clouds arriving in the San Juan Mountains.

The new PM, LH, whom had led the Climax experiment in Colorado during his later graduate years and had done some interesting work on the precipitation patterns around Climax at CSU. His work was to be important in shedding light the Climax I results (Hjermstad 1970, Master’s Thesis).

However, LH and I clashed over many elements of the CRBPP during our first couple of years there, and the office had a background of tension.    Instead of helping to write annual reports for each season of the CRBPP, as for the 1970-71 season, I was now subject to being on loans to other companies to assist in their cloud seeding efforts. The annual CRBPP reports for the remainder of the CRBPP had a much different tone, “happier” tone, and discrepancies were not dwelled upon if mentioned at all.

The internal clashes between myself and the CRBPP leadership were described to the Washington team during their airborne studies and they were sympathetic and understood the discrepancies and confusion sown by the cloud top criterion changes (hence, the “breath of fresh air”).  LH was fully onboard the criterion change to rawinsonde inferred cloud top temperatures at the beginning as Prof. Grant demanded, but went further, suggesting to the BuRec that only 3 h of a random day meeting that criterion would be enough for an experimental 24 h day to be randomly drawn.

LH was to change his mind over the “500 mb (cloud top)” temperature issue after two seasons. Following presentations of this discrepancy at a BuRec workshop at Denver in 1973, the call of a random decision reverted to 500 mb temperature (>-23°C). However, it did not return to a partitioning large portions of storms, 12 h as before, but only THREE h of a 24 h day had to meet that criterion during a storm as LH wanted. 

During the remainder of the CRBPP, that after the 1970-71 season, I had been moved to back from Acting Project Forecaster (under Owen Rhea), to my original hired position as Assistant Project Forecaster as LH brought in his well-experienced forecasting friend from Ocean Routes, Inc., Dick Medenwaldt.  While I was disappointed, it was the logical thing to do given my on-paper inexperience.

During the early years of the CRBPP, 1970-1973, the stunning, and ever-so-convincing results of both Climax I and Climax II were reaching the journals (Mielke et al 1970 for Climax I, Mielke et al 1971 for Climax II, and Chappell et al 1971, the latter examined where the seeding effects were taking place—it was by creating more hours of snowfall and not affecting the intensity, as was expected by the kind of ground releases of seeding that had been carried out.  Note: the BuRec was going on preliminary results when it started the massive funding of the CRBPP–that’s how good the CSU work looked to them.

And how convincing were those results, once having been published in the peer-reviewed journals?   Here’s what the National Academy of Science’s Panel on Weather Modification had to say about the results of the Climax experiments in 1973: 

“Hence, in the longest randomized cloud-seeding research project in the United States, involving cold orographic winter clouds, it has been demonstrated that precipitation can be increased by substantial amounts and on a determinate basis.”

Prof. Peter V. Hobbs was a member of the NAS Panel that wrote that statement. He was fully onboard with what the literature was telling him, as was virtually everyone else. (Hah. “Everyone” but me, of course, as an insider to the CRBPP mess.) The interesting sidelight to this was that instead of questioning the reliability of the original CSU experiments, attention focused on what went wrong with the CRBPP! That’s the main reason why I began a reanalysis of the Wolf Creek Pass experiment. It was crazy that no one was questioning the original reports to see if they were robust!

Nevertheless, when the Climax results were combined with those from the seasonally randomized Wolf Creek Pass experiment in the San Juan Mountains conducted in the 1960s, with its strong indications of statistically significant increases in runoff produced by cloud seeding (Morel-Seytoux and Saheli 1973, J. Appl. Meteor., the CSU seeding picture was as complete as one could possibly could be. Thus, one can’t be too hard on the BuRec for charging ahead into a costly randomized experiment, the CRBPP, instead of doing more research “before the leap.”

33. A final blow to idealism about science

The final straw, however, was a much-cited article in 1974 in the J. Appl. Meteor. titled, “The Cloud Seeding Temperature Window.” The two authors had used constant level pressure surfaces to index cloud top temperatures in several seeding projects to come up with a cloud top temperature window of -10° to -25°C for successful cloud seeding. This temperature range was thought to characterize clouds with tops this cold that were deficient in ice particles, but would have supercooled liquid water in them that could be tapped by cloud seeding. It turned out to be a too optimistic a temperature range as later research showed.

Moreover, the lead author of this article had been told by three different people on separate occasions in my presence not to use a constant pressure level as an index of cloud tops in the Rockies. Nature does not constrain cloud tops so that they can be indexed by a constant pressure level temperature in the atmosphere.

The other author of “The Cloud Seeding Temperature Window” was in the midst of evaluating the storm day rawinsondes of the CRBPP; he was the leader of the Aerometric-NAWC evaluations team chosen by the BuRec. He absolutely knew that stratifications by a constant pressure level was not a viable way to index cloud tops from our data. When I asked that 2nd author the next time he came through the Durango office about that article, “How could you write that?” He simply replied, sheepishly it seemed to me, that he had just, “gone along with” the lead author.

So that was it.

I never again trusted the cloud seeding published literature. Cynicism 1, Idealism, nil. It didn’t matter, either, how highly regarded the literature was. It still might be inaccurate, corrupt, I thought. I often wondered, too, why that “Window” article was cited so much. I presumed it must be by readers that did not know much about synoptic weather and cloud top fluctuations.

34. A regrettable personal media eruption in late 1975 that required an apology in person at CSU

I remained quiet until the CRBPP experiment ended in 1975, which also allowed me to retain my great job in the nice little town of Durango, Colorado–ah, the plight of whistleblowers……

But then I erupted in November 1975 after the CRBPP ended when it was safe and I had no job. 🙂 Here’s that whistleblowing eruption as seen in the Durango Herald, one that I feel I have to disclose in this “blook” to give an idea of my potential biases:

You will notice that I referred to “Watergate” in the Herald headline. As I left the Durango Herald office with the reporter, Mike McRae, I muttered a mistake. I said, “if what I have begun to work on turns out, it could be the Watergate of meteorology”, meaning it would make a big splash. It was a poor, if current and accessible metaphor, but it implied wrongdoing on the part of CSU scientists. I was away when the article came out and was devastated to see what Mike had written after a careful 1-2 h recorded interview in his office. He had promised to let me examine the article before it came out, but called the evening before I left and said he wasn’t able to do that, adding, “trust me.”

I left the next day for Fresno, California. I got that Durango Herald issue about a week after it came out while I was there working briefly for Tom Henderson, and Atmospherics Inc.

After I returned to Durango from Fresno, I sped off to CSU to apologize in person for my lapse to the leader of the CSU experiments, Professor Lewis O. Grant. I had also submitted a “retraction” to the Herald clarifying what I meant. I did see that reporter Mike in the Durango supermarket, and, after I only shook my head at him, he said, “Never trust a newspaper reporter.”

Q. E. D.

But Mike’s article in which I stated I was going to reanalyze ALL of the CSU prior experiments, as you will read, was to have a profound effect that neither of us could have imagined at the time.

35. The apology and the after effects of the 1975 Durango Herald article

I was able to meet with Professor Lewis O. Grant, the leader of the CSU experiments in his CSU office as soon as I got there, . I groveled and apologized for my possibly libelous newspaper gaffe. He was real nice about it, actually. And, moreover, even when I said I still questioned his seeding experiments and asked for data, like the list of random decisions, he did not hesitate. He was an idealist; questioning was a part of science and he understood that.

Professor Grant’s attitude was not shared by the leader of the experiments in Israel, I am sad to say as Sir John Mason’s letter illustrated.

I kept Professor Grant apprised of my work from Durango as I went along with it as I said I would. As the Wolf Creek Pass experiment began to fall apart in my reanalysis, he even wrote that I had found something important. He was a true scientist.

I also learned from Professor Grant’s graduate student, Owen Rhea, who had started out as the CRBPP’s lead forecaster in 1970 and, along with Paul Willis, had hired me, that the Durango Herald article got back to the National Science Foundation who asked of CSU, “What’s going on?”

According to Owen, due to that Durango Herald article in which I was claiming that I myself would reanalyze ALL of their work, CSU scientists began reassessing their Climax experiments at that time. Those, too, eventually fell apart “upon further review”; their own. Its always best if you find your own problems and report them first before someone else does.

First, in 1978, the earlier claimed evidence of inadvertent downwind increased snow due to seeding at Climax, was found to be due to a synoptic (weather pattern) bias on seeded days. Gone.

Then, in October 1979, at a joint conference of weather modification and statistics at Banff, Canada, Owen Rhea, Professor Grant’s graduate student, verbally withdrew the claims that seeding had increased snowfall in the Climax experiments. Paul Mielke, Jr., the lead CSU statistician, had already done this in a short commentary in the J. Amer. Stat. Assoc. in March of that year, also noting that the stratifications could not have partitioned seeding potential. Climax I and II, gone.

A lucky draw on seeded days had occurred in both Climax experiments; pretty remarkable, though Climax II was to receive some “help” as it turned out, exposed in later independent reanalysis in 1987 by yours truly, with Hobbs.

At that same conference at Banff in 1979, I presented my now published, “Reanalysis of the Wolf Creek Pass cloud seeding experiment” in the May 1979 issue of the J. App. Meteor.) It, too, like the Climax experiments, was the result of a lucky draw and favorable selection of controls by the experimenters, but ones chosen after the experiments had begun, a no-no for experiments because it opens to door to confirmation bias and cherry-picking.

That was my first presentation at a conference. The year before, I had played “center microphone” for a similar conference in Issaquah, Washington. That is, I ran around with a microphone for attendees that had questions for speakers. I was a real “gopher” just the year before.

All in all, the Banff conference was a devastating one for those involved in cloud seeding at CSU, and for those organizations such as the BuRec that had placed such big bets on the CSU experimenters’ original reports.

36. Pre-1979 Banff conference palpitations and why; the human part of being a science worker in a conflicted environment

The Banff 1979 program that I was going to present in was published in the Bull. Amer. Soc. in May 1979. I was shocked to see that it indicated that CSU faculty would address my paper before I gave it. Thankfully this did not happen. I was an amateur compared to the faculty at CSU, and I was sure all that time before the October Banff conference after seeing the program in May, that my work would be cut to pieces and I would get up red-faced with nothing to say. I had palpitations that whole summer of this nightmare scene, and even redid my paper. Perhaps I had made egregious errors; I was the one that was biased and couldn’t see it.

The evening before my talk in October, I ran into Professor Grant, and he informed me at that time that they were not going to address my work after all. Whew. I had even considered not going; the fear of humiliation was that bad!

Paul Mielke, Jr., also came by, and he simply said, “We screwed up.” I admired him for that and his courageous 1979 article in the J. Amer. Stat. Assoc. In essence, in that article, he had stated that there was no real basis for the 10 million dollar CRBPP the BuRec had signed up for. Can you imagine? The BuRec REALLY did need a “Resident Skeptic!”

The 1979 Banff talk went fine, even got an accolade and a laugh, and I ended by saying, “Who wouldn’t have believed all this evidence was NOT due to cloud seeding?”, trying to put the best face on the CSU seeding collapse that evening. It was an amazing trifecta of “evidence” that seeding had increased snow that CSU scientists had encountered and embraced, but was now gone.

But that was not to last.

CSU scientists began looking again at their Climax experiments and began publishing claims that they had resuscitated valid increases in snow in those experiments in 1981, though they were smaller ones, stratifying the data again by 500 mb temperatures asserting or implying that they had something to do with cloud tops and cloud seeding potential. It was quite a discouraging blow if you care about science.

Neither I, nor Owen Rhea of CSU, could let such claims go unchallenged and we each reanalyzed the new Climax experiment reports, both of us finding a second time in the following years that those claims of increased snow due to seeding by the experimenters were ersatz. There’s much more on this, but will end this discussion here for some hint of brevity. My reanalysis of the Climax experiments was rejected by the J. Appl. Meteor., B. Silverman, Ed., personal communication; Owen Rhea’s compact one, was accepted. We did not realize that we were doing the same thing at the same time.

And, so, while the story today is centered on my work in Israel, the full autobio ppt “book” has a lot of backfill to my experiences in Durango like the ones above, experiences that caused me to distrust any publication regarding a cloud seeding success without extreme scrutiny, the kind that reviewers of journal manuscripts mostly don’t have the time or inclination for.

37. 1983, a real no-no: a request for an independent panel to investigate the reporting of the Climax I randomized experiment

This was a painful chapter, but in trying to be totally candid, it has to come out. There are likely still those out there that know about it, though, as I wrote in my request for this to the Amer. Meteor. Soc., I hoped it would remain completely behind the scenes. It did not. Prof. Grant himself later told an audience that he was under investigation.

Here’s why: CSU statistician, Prof. Paul Mielke in 1979 J. Amer. Stat. Assoc., while withdrawing the claims that the Climax experiments had increased snowfall, observed that both experiments, Climax I and II, had experienced favorable draws that created the impression that snow had been increased on seeded days. It was a courageous post. Here’s what he wrote:

Very recently, in connection with design studies for a possible experiment of this type in central and northern Colorado mountains, station-by-station precipitation analyses of the Climax I and II experimental units were made for all available hourly stations in Colorado. The resulting maps of seeded to non-seeded mean precipitation amount ratios and non-parametric teststatistic values plotted over the western half of Colorado indicated (for meteorological partitions such as warm 500 mb temperatures) that the Climax experimental results were part of a region-wide pattern (emphasis by ALR) rather than an isolated anomaly produced by seeding. In particular, these recent results cast serious doubts on consistency of apparent effects associated with replicated five-year winter periods of the Climax I and Cllimax II experiments.

Later, however, while looking for something else, I ran into this statement at the very end of the article by Mielke et al. (1970, J. Appl. Meteor.), an article accepted for publication on June 30, 1969:

“In an attempt to better define the area extent of the differences between the seeded days and non-seeded days beyond the boundary of the experimental network, available data from all Weather Bureau stations in Western Colorado are currently being investigated.”

Mid-1969 was a time that large contracts were being formulated by the BuRec and signed by contractors involved with the CRBPP. One, at least, had already been signed in 1968, the one with CSU scientists for a CRBPP design document, whose interim document was released in October 1969.

What to do after I ran into what seemed to be a “smoking gun”?

It seemed inappropriate to me to have the CSU scientists answer such a profound question on which millions of dollars might depend on the answer: “What happened to the 1969 study that was “underway”? So, I stewed for quite awhile on this seeming “smoking gun.”

Millions of dollars would have been saved, of course, if the CSU scientists had discovered/reported in 1969 the evidence that Climax I had been compromised by a “lucky draw.” It can be assumed that the BuRec would have backed off their plans for the randomization of the CRBPP; perhaps had gone into a research mode with ground and air measurements, or canceled the project altogether to ruminate on what really happened in Climax I. Note: it was well known at E. G. & G., Inc, and by the BuRec that CSU scientists opposed randomization of the CRBPP on the basis that, “it’s already been done” (in their own experiments). Imagine what would have been the situation if the BuRec had listened to that CSU argument and went commercial seeding in the CRBPP!

Ultimately, in 1983, following a negative reaction to the CSU scientists’ responses to my friend, Owen Rhea’s reanalysis of the Climax II experiment, I wrote up my request and sent it in to several organizations including CSU, the AMS and NAS. The AMS didn’t know how to go about this (D. Landrigan, personal communication) and I got no response from the NAS.

There was, however, an internal investigation by a CSU faculty panel that found no problems in the reporting of the Climax I experiment. I also received a threat of legal action by then Acting Colorado State University President, Robert Phemister if I persisted in my calls for an investigation of the CSU reporting. I didn’t. I still wish that there had been a wider look besides that by CSU faculty, one of whom was a co-author of a seeding paper.

I really hated to do it, knowing the fallout. But, what would you have done if you found the 1969 Mielke et al. “smoking gun?” I just didn’t think they should answer a question with millions of dollars riding on the answer.

I let this issue go downstream, but you can only imagine how CSU and their sympathizers that found out about my unprecedented action might have felt about me. I had asked for an investigation of the most beloved persons in all of weather modification, Lewis O. Grant and Paul Mielke, Jr., both of whom I actually liked as people!

Peter Hobbs, when he found out, was livid; he was not involved because he was on sabbatical in Germany. No one was involved but me. But, I got a raise the next year, 1984. ??

I presented a paper at the Park City, UT, weather mod conference in 1984 with all those present from CSU who knew what I had done. It was the “kitchen.” Gads, how did I make it through that one! The tension was so thick. My paper, one that later became part of an AMS Monograph with the other presentations, was titled (I had been assigned this title), “How good are our conceptual models of orographic cloud seeding?


38. Tension highlight at Park City with Prof AG

It was during this conference that Prof. A.G. from Israel took me aside and sternly lectured me about how wrong I was about the clouds of Israel (from my 1983 rejected article by the J. Appl. Meteor. that asserted they weren’t being described correctly. It was also at that time that he informed me that he had been a reviewer of that submission, one of course, that helped reject it. His lecture had no effect whatsoever on what I thought about those clouds. I hopped a plane to Israel two years later.


If you have read our papers on the Climax experiments, you will know that there was suggestions of a data reduction bias that favored the appearance of a seeding effect with the key NOAA target gauge precipitation data in Climax II (Rangno and Hobbs, 1987, 1995, J. Appl. Meteor.) The values used by the CSU scientists in their analyses were not the ones that were published by NOAA for the independently maintained gauge in the center of the target; the values that the experimenters used increased the supposed seeding effect a modest 4%. There were also many other discrepancies in the 500 mb temperature assignments for storms from those published by NOAA that also “helped” the Climax II experiment “replicate” Climax I.

In contrast, errors were negligible in Climax I; all the precipitation data were the same as in the NOAA publications, for example. Climax I benefitted by a lucky draw of storms with NW flow at mountain top levels on seeded days with high 500 mb temperatures (the latter, the category where strong, 50-100%, increases in snowfall were reported due to seeding. But NW flow is also the direction from which Climax receives it greatest natural daily precipitation and the set of control stations chosen by the experimenters (halfway through the experiment), the least. Climax II had no such luck. Check it out below:

Percentage of the experimental seeding season precipitation at Climax I (a)and II (b ) for three wind direction categories using the winds at mountain top level 4 km ASL or 600 mb level, whichever was available in the NOAA publication, “Daily Series, Northern Hemisphere Data Tabulations, Radiosonde and Rawinsonde Checked Data.” The solid bar is for seeded days, and the cross hatched ones for control days with the 500 mb temperature GE -20°C. Climax receives its greatest average daily amounts in NW flow. (From an unpublished manuscript rejected by J. Appl. Meteor. in 1983, B. Silverman, Ed., personal correspondence.

To my knowledge, the results of the 1969 Mielke et al. investigation of all western Colorado precipitation gauges in the Climax I experiment was not made known to the BuRec until Mielke’s 1979 J. Amer. Stat. Assoc. comment.


Why would anyone do call for a behind the scenes investigation that would only have negative fall out for everyone involved? I felt I was representing those people outside the cloud seeding community who really paid for the CRBPP. That, too, was the way I felt about my trip to Israel. OK, I know you’re rolling your eyes now, but it was true, I really did think, “Someone has to do something about this!” If I was arrogant (“confident” is a better word) it was because I thought I could do something given my particular cloud-centric background. I think a lot of “activists” think this way; that they can do something.

39. Intermission and time for a “Get a life!” note

Following the above comments, it seems like an appropriate point for a reader to erupt with, “Get a life!” See the note at the very end of the science portions of thes piece if that’s what you might be thinking at this point, which is not an unreasonable thought at all. 🙂

I did have an outside life somehow. I was single during most of this time, too. There’s no way you could be married/have a partner, and be doing what I was driven to do. Playing baseball, doing some extracurricular forecasting on the radio and for the Washington Huskies comprised most of that outside life.

OK, enough intermission….

40. A “fruitful perception”

Not trusting cloud seeding peer-reviewed literature, no matter how highly regarded it was, was a fruitful perception. I think you can see why by now!

Over the following twenty years after Durango I reanalyzed, with Prof. Peter Hobbs as my co-author on all but one article, no less than six peer-reviewed, journal published cloud seeding experiments. Not one was the success the original experimenters claimed it to be! PDFs of these reanalyses, and other commentaries on cloud seeding in the literature can be found here:

Important Footnote: To fill out my CV even further on the above page, I have even included my rejected papers and non-submitted reviews as well to make it look bigger than it really is. Of course, those latter items REALLY don’t count in official CVs except to ME. I am hoping to one day to have, as other scientists do, a subset of my papers published: “The Collected Rejected Papers of Arthur L. Rangno.” The volume would be quite thick.

All those published reanalyses and commentaries, and articles/reviews that weren’t accepted or not even submitted, was a vast amount of material I had created, and they were accomplished on my own initiative, my own time (except one, the Skagit reanalysis, was on Peter Hobbs’ time, but my initiative). That is, I worked on these kinds of things on my weekends, evenings, before work, after work at the office, etc. , on and on over years, probably amounting to thousands of volunteer hours to evaluate and “out” faulty cloud seeding claims and to get my views of the cloud seeding arena into print. I even drafted most of my own figures. (Crackpot alert!)

I had no funding, of course, for these, well…”altruistic” efforts, as I thought of them. I just felt I had the skills to expose faulty cloud seeding literature being a forecaster and a “cloud man.” I also felt I had a duty to do it since it was likely that no one else would.

To readers: anybody down here?

41. The payoff for decades of “volunteer” work due to that “fruitful perception”

But there was an eventual payoff for all that self-initiated work that came in 2005, as seen below. My apologies in advance for my large face shot in the first link. I didn’t do it! I post these solely for a modicum of credibility.

The $20,000 prize was also for the mountains of constructive work in cloud seeding done by Peter and his “Cloud Physics Group”, starring Lawrence F. Radke, Dean Hegg, for mostly aerosol work, and John Locatelli in ice crystal studies, the former the leaders of our airborne crews in those days. The Group’s published work was supportive of cloud seeding effects in the early 1970s “Cascade Project”, though no randomized experiments were carried out.

In fact, Peter Hobbs was pretty ebullient about the possibilities of orographic cloud seeding just after his Cascade Project had ended. He had been a panel member of the 1973 National Academy of Sciences report mentioned earlier that was also so ebullient about the CSU cloud seeding work. Peter Hobbs had also gotten the panel to insert the non-randomized Skagit cloud seeding project into that report due to its stunning apparent indication of having increased precipitation. However, the Skagit Project would also fall apart in future years, “upon further review” by “you know who.”

42. Why the recurring thought: “Somebody has to do something about this, dammitall!”

A question I ask myself is WHY I was so energized, worked up, to do all this volunteer work concerning faulty cloud seeding claims in the literature when the rest of the scientific community more or less yawned at them or absorbed them; no one really dug into them the way I did with rare exceptions. I think the activism on the war in Vietnam and in civil rights in those days of the late 60s and early 70s led one to believe that you should jump in and do something when you see things that aren’t right. That was certainly a thought I had (and still have I guess, from this mighty effort!)

In Colorado the answer was simple enough.

I knew the “territory” of the CSU cloud seeding experiments, and a lot about them, and felt I had a duty to reanalyze them since I came to doubt that those results could be valid based on the experiences and data gained in the CRBPP. I was pretty sure no one else would do this, too, based on the de facto “Code of Silence” ethic in this realm. So, I took the 75-76 winter off in Durango after the CRBPP to dig into the Wolf Creek Pass experiment, living off my savings until getting a summer commercial seeding job as a “radar meteorologist” with Atmospherics, Inc., in SE South Dakota. I was running out of savings.

I should add, too, that as a kid, the printed word in journals was precious to me. I subscribed to a journal when I was just 13 (1955), “The Monthly Weather Review,” and tried to memorize all that I read even if I couldn’t really understand all that there was in one, especially if there were equations. Haha–I still skip articles with too many equations in them.

The authors of articles, and the founders of modern meteorology, like Jacob Bjerknes (whose autograph I tried to get when he was at UCLA) and “stars” like Tor Bergeron (had my picture taken with him), or Jerome Namias, etc., were heroes to me somewhat like baseball players were to other kids. And, I was already writing stuff about ice in clouds in weather diaries in the 50s.

So, was this combination of traits the reasons why I reacted so strongly to faulty literature? I dunno.

Learning how seductive and corruptive the effects of confirmation bias could be as I saw in Durango and in the commercial seeding projects I worked on, also augmented my inclination to closely examine cloud seeding papers. To claim, or believe, that you had changed the weather by increasing precipitation was a very potent euphoric.

What was the likely driver of ersatz seeding success claims that were later overturned?

Ans. 1: No one ever got a job saying cloud seeding didn’t work.

Ans. 2: Experimenters were damn sure seeding worked beforehand, by god, they were going to strangle the data until they found signs of it, or post-select controls to “prove seeding.”

Yes, almost certainly, as Donald Kennedy observed in his Science editorial, Research Fraud and Public Policy in 2003, it was mostly “career enhancement” that drove fraudulent science (or “career maintenance” as it might be in the cloud seeding realm). Of course, they could also be well-intentioned, deluded people, unreceptive to new facts.

43. Peter V. Hobbs and his group’s work in cloud seeding


44. Life beyond science volunteering: “sports and weather” with some humorous, maybe, anecdotes concerning the Seattle Mariners and some radio work

The almost fanatical activity described above can be also be seen as a “crackpot alert.” But, maybe a good one? Yes, and you might well be thinking, as noted, “get a life!”

Well, I did have some outside activities, like playing baseball in a hot semi-pro league called the Western International League, so there. Eight guys were signed off my team over the several years I played on it; one, Mike Kinunen, was pitching for the Twins the next (1980) summer and the guy that batted 3rd in front of me, made the last out of the 1980 college World Series in Omaha playing for the #5 Hawaii Rainbows (defeated by the Arizona Wildcats!) I was the oldest starting player in that league in those halcyon days of my late 30s. In case you don’t believe me:

In my last playing year, I was the recipient of the Jim Broulette “Mr. Hustle” Award in 1980. No, it wasn’t for being a great player, but rather for being an “inspirational” one, which is not as good as being given an award for being great (I had an off year..). FYI, this what I looked like during the era of ruining cloud seeding papers except I wasn’t wearing a baseball uniform when I was doing that.

In a further nostalgic sports report and waste of your time, after the WIL, I pitched batting practice for the Seattle Mariners, 1981-1983. An anecdote about that:

I showed up for a tryout at a workout they were having on the U of WA Husky baseball field in 1981 after the MLB strike had ended and, after pitching BP there, I got to be one of the regular Mariner BP pitchers in the Kingdome, an unpaid job, btw. You get tickets behind home plate. It was so much fun, but stressful. There was an uneasy quiet if you threw as many as three balls that weren’t smacked.

They released me at the end of 1983 because the “guys” were complaining that my ball had too much movement in BP; I was “cutting the ball”, giving it extra spin (private communication, Steve Gordon, backup catcher, 1983). (Unbelievable).

The Mariners of note in those days were Tom Paciorek, Dave Henderson, Bruce Bochte, Richie Zisk and Gaylord Perry, the latter who said my BP was “horrible” in 1983 after he joined the Mariners– he didn’t hit it so well. Of course, he was a washed up pitching buffoon in those days–what would he know about hitting? (Just kidding, Gaylord.) I did throw harder than normal BP pitchers and off or near the pitching rubber, just like I did for my WIL teammates who loved my BP. They wanted zip on the ball like real pitching and I thought the MLB players would, too. And they did, too, that’s why I got “hired” in the first place.


Forecasting for the Washington Husky baseball and softball teams.

I was also the de facto weather forecaster for Washington Husky baseball and softball teams calling rain delays, tarp placements and removals and such beginning in the mid-90s. I had met the Husky baseball coach during my WIL experiences and began forecasting for softball during the 1996 NCAA regional tournament in Seattle which was impacted by numerous showers and even a thunderstorm.

The weather during these spring sports seasons is occasionally showery in Seattle, lots of Cumulonimbus clouds form on those kinds of days, rather than the easy to predict day-long rains from fronts. Radar was pretty useless in showery situations. Why? Because the lifetime of showers is short, and the Huskies could play in SOME rain, just not too hard. So, an incoming shower had to be evaluated by eyeball to assess whether it was dissipating or not; was it all ice or what, and would it rain hard enough to require a tarp and a rain delay? So that’s how I did it, almost completely by eyeballing showers, their movement and growth pattern and assessing their stages.

When the tarp was on the softball diamond during showery days, it was almost harder to call when it should be removed since it took about 45 min to get the game going again; the players had to warm up, besides taking the tarp off themselves. This meant predicting whether a shower would even form in that 45 min time frame, and if so, would it affect the game? The worst possible scenario was that you said to remove the tarp, everyone warmed up again, the crowd came back into the softball stadium, and then it rained hard right after that. It was a stressful volunteer job. Fortunately, that did not happen. I was lucky.

It sounds disconnected, but this was exactly the kind of skill I took to Israel in 1986.


Before the Husky forecasting era, I had been a forecaster on two different radio stations in Seattle, KUOW-FM (1987-1992), an NPR affiliate in which I came on during “Weekend Edition”, and on a local rock station, KZAM-FM, M-F, for about six months in 1982. For both stations I was doing very short-term forecasts for Seattle using the time of day, such as “no rain through 11 AM, then rain beginning between 11 AM and 2 PM”, etc. When I started these efforts, Seattle had no dedicated weather radar! Doppler weather radar became available only in 1992. In place of radar, you had to use upwind station reports, satellite imagery, know the “territory”, and eyeball the cloud situation along with knowing what the computer model predictions were, and then evaluate how the cloudscape, obs, and how the model predictions were meshing with what the sky was doing.

Perhaps, for sophomoric entertainment, you would like to hear one for KZAM-FM in 1982. In listening to this (sorry, its not real clear), we have to remember that, as the LA Times wrote in 1981, weather forecasting at that time was an era of “clowns and computers” as they headlined. You were expected to come up with some “schtick” if you were a media weather forecaster. And I was encouraged to do so by KZAM-FM. It got a little wild, as you will hear. To stay with the theme of “sports and weather”, I reprise my “sports-like” 1982 weather forecast on KZAM-FM, one that mentioned Gaylord Perry in context with a low pressure in the Gulf of Alaska with “moisture and rotation on it.” GP was known for cheating by throwing spitballs. And damn him for criticizing my BP! It’s a little muffled, but you’ll get the idea. Remember I was forced to do this by the forecasting motif of the day…. 🙂

OK, I am having more fun now as I remember those crazy days….I still worked at the U of WA cloud group full time during these efforts, too. Good grief, how did I manage all this?

The End at last.