A Review and Enhancement of the Cloud Seeding Chapters in the 2007 book, “Human Impacts on Weather and Climate”

Another in a continuing possibly semi-useless series by this author….  This example probably indicates why I am not asked to review manuscripts in my expertise; cloud seeding and ice formation in clouds.  I try to follow in the footsteps of meteorologist and MIT faculty member, Fred Sanders, of whom it was said, “His reviews were sometime longer than the manuscript he was reviewing.”  I bet he didn’t get many manuscripts to review, either!

Oh, well, “we” trudge on.

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Comments and “enhancements” on this work by my friends, William R. “Bill” Cotton and Roger Pielke, Sr., are in red. Necessarily, I am only presenting those portions of Cotton and Pielke’s book (those on cloud seeding) that require an “enhancement” or corrections for the reader and I have attempted to do this delicately.  Fortunately, because both are major scientists, they do not respond to criticism with emotion and are quite happy to see errors in their work corrected.  🙂

For the actual, extensive text leading up to these comments, you’ll have to buy the book.  Dashes are inserted where material, usually extensive,  is skipped to avoid too much copyright infringement.

Summary

The first three chapters are an excellent overall introduction to the topic  of weather modification.  The “Reference” section alone makes it worth the purchase of this book since it covers so much of the climate domain up to 2006.  The weather modification references needed beefing up and are done so here.

Oh, some background on what the climate was doing when this book on climate came out…  

Cotton and Pielke, Sr.’s book, hereafter,  “CP07,” came out during the middle of a hiatus in global warming, discussed a few years later in Science magazine by its reporter, Richard Kerr (2009) in, “What Happened to Global Warming?”  

About the time CP07  was published it also marked a time when the phrase, “global warming” (which was no longer occurring for unknown reasons) began to recede in use and was supplanted by the phrase, “climate  change,” something that is always happening on this great planet.  It made sense to change phrases since “climate change” would always be true whereas “global warming,” as we were learning in the 2000-2010 era, might not be.  (An aside:  I am a believer that CO2 will warm the earth in the decades ahead, but not catastrophically; I am strongly influenced in this belief by “influencers,” Roger Pielke, Jr., climate and policy expert, formerly of the University of Colorado but pushed out,  and Cliff Mass, weather and climate expert, still “intact male” at the University of Washington thanks solely to tenure.

Let us begin the review of CP07 with their acknowledgments which required an insertion by this writer:

Acknowledgments for CPO7

 The study of human impacts on weather and climate continues to be a high- interest topic area, not only among scientists but also the public. Our second edition has continued to build on our funded research studies from the National Science Foundation, the National Aeronautics and Space Administration, the Environmental Protection Agency, the Department of Defense, the National Oceanic and Atmospheric Administration, and the United States Geological Survey. Our numerous research collaborators at the Natural Resource Ecology Laboratory and Civil Engineering at Colorado State University have continued to provide valuable in sight on this subject. Over our multidecadal career, the fundamental insights into weather and climate provided by our education at the Pennsylvania State University have become increasingly recognized. We also want to recognize the perspective on these subjects, and science in general, that Robert and Joanne Simpson have provided us in our careers. Their mentorship and philosophy of research, of course, is but one of their many seminal accomplishments.

Roger Pielke would like to thank everyone who contributed to compiling the information in Tables 6.2 and 11.2 especially Roni A vissar, Richard Betts, Gordon Bonan, Lahouari Bounoua, Rafael Bras, Chris Castro, Will Cheng, Martin Claussen, Bob Dickinson, Paul Dirmeyer, Han Dolman, Elfatih Eltahir, Jon Foley, PavelKabat, George Kallos, Axel Kleidon, Curtis Marshall, Pat Michaels, Nicole Molders, Udaysankar Nair, Andy Pitman, Adriana Beltran-Przekurat, Rick Raddatz, Chris Rozoff, J. Marshall Shepherd, Lou Steyaert, and Yongkang Xue. In addition, Roger would like to thank Dr. Adriana Beltran for her assistance with figures in this edition.

As is always the case, Dallas Staley’s editorial leadership and Brenda Thompson’s assistance in completing the book has been invaluable and is very much appreciated.

“However, we are unable to thank Mr. Arthur L. Rangno for his review of this book before it was published because we forgot to ask him.  Mr. Rangno is an acknowledged expert with several peer-reviewed publications on two of the cloud seeding experiments reviewed in this book; those carried out by Colorado State University (the home institution of CP07) at Climax and Wolf Creek Pass, Colorado, and those carried out in Israel conducted by the Hebrew University of Jerusalem.  Namely,  Art didn’t do sh. to improve our book beforehand since we also mostly ignored his scintillating 1997 email concerning the first edition of our book, CP95.  Nevertheless,  we are happy to have him review our 2nd edition (CP07) belatedly, i.e., provide a few review “cow pies” here and there on some of our otherwise excellent work.”  (Fake quote.)

If you would like to see how truly “scintillating” my email was to the lead author, go here

Chapter 1:  The rise of the science of weather modification by cloud seeding

Throughout history and probably prehistory man has sought to modify weather by a variety of means. Many primitive tribes have employed witch doctors or medicinemen, and human sacrifices to bring clouds and rainfall during periods of drought and to drive away rain clouds during flooding episodes. Numerous examples exist where modern man has shot cannons, fired rockets, rung bells, etc. in attempts to modify the weather (Changnon and Ivens, 1981).

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Seeding of supercooled cumulus clouds produced more controversial results. Dry ice and silver iodide seeding experiments were carried outat a variety of locations with the most comprehensive experiments being over New Mexico. Based on four seeding operations near Albuquerque, New Mexico, Langmuir claimed that seeding produced rainfall over a quarter of the area of the state of New Mexico. He concluded that “The odds in favor of this conclusion as compared to the rain was due to natural causes are millions to one.” Langmuir was evenmore enthusiastic about the consequences of silver iodide seeding over New Mexico. The explosive growth of a cumulonimbus cloud and the heavy rainfall near Albuquerque and Santa Fe were attributed to the direct results of ground-based silver iodide seeding. In fact Langmuir concluded that nearly all the rainfall that occurred over New Mexico on the dry ice seeding day and the silver iodide seeding day were the result of seeding.

The claim by Langmuir was found to be false in an analysis by the chief Weather Bureau meteorologist in Albuquerque, NM, Willis R. Gregg.

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Convinced that cloud seeding was a miraculous cure to all of nature’s evils, Langmuir and his colleagues carried out a trial seeding experiment of a hurricane with the hope of altering the course of the storm or reducing its intensity. On October 10, 1947, a hurricane was seeded off the east coast of the United States. About 102 kg of dry ice was dropped in clouds in the storm. Due to logistical reasons, the eye wall region and the dominate spiral band were not seeded. Observers interpreted visual observations of snow showers as evidence that seeding had some effect on cloud structure. Following seeding, the hurricane changed direction from a northeasterly to a westerly course, crossing the coast into Georgia. The change in course may have been a   was the result of the storm’sinteraction with the larger-scale flow field. Nonetheless, General Electric Corporation became the target of lawsuits for damage claims associated with the hurricane.

In summary, Project Cirrus launched the United States and much of the world into the age of cloud seeding. The impact of this project on the science of cloud seeding, cloud physics research, and the entire field of atmospheric science was similar to the effects of the launching of Sputnik on the United States aerospace industry.

This discussion lacks mention of perhaps the most influential paper of all those that motivated cloud seeding throughout the world; that of Kraus and Squires (1947) reporting spectacular results from an Australia seeding experiment.  The KS47 paper, appearing in the high-end journal, Science, purported that two drops of dry ice totaling 250 lbs. into a Cumulus congestus cloud at 23,000 feet spawned a massive, isolated storm that towered to possibly “40,000 feet,” lasted for hours and dropped heavy rains over “20 square miles.”  This was the only cloud that appeared to respond so impressively to dry ice seeding on that flight day.   The Kraus and Squires report was seen as evidence that drought might be alleviated with few hundred pounds of dry ice, and as a result,  widespread cloud seeding took off as entrepreneurs hastily formed cloud seeding companies such as North American Weather Consultants, Atmospherics, Inc., Irving P. Krick Associates, among many others.  The series of photographs of the apparent response of that Cumulus cloud to seeding continued to be published as proof what cloud seeding could do for almost 40 years after KS47 (e.g., Orville 1986). 

Caveat Emptor:

HOWEVER, in independent dry ice seeding tests on Cumulus clouds by the U. S. Weather Bureau (Coons et al. 1949, Coons and Gunn 1951) no explosion of a cloud occurred as KS47 had described after seeding.  Instead, they reported, the seeded Cumulus clouds generally sank back down after dropping up to 100 lbs. of dry ice into them.  Also, they reported that natural precipitation had formed in similar Cumulus clouds in the vicinity.  It wasn’t clear to Coons et al. that dry ice seeding had made a difference.

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Chapter 2:  The glory years of weather modification

• Introduction

The exploratory cloud seeding experiments performed by Langmuir, Schaefer, Kraus and Squires, and Project Cirrus personnel fueled a new era in weather modification research as well as basic research in the microphysics of precipitation processes, cloud dynamics, and small-scale weather systems, in general. At the same time commercial cloud seeding companies sprung up worldwide practicing the art of cloud seeding to enhance and suppress rainfall, dissipate fog, and decrease hail damage. Armed with only rudimentary knowledge of the physics of clouds and the meteorology of small- scale weather systems, these weather modification practitioners sought to alleviate all the symptoms of undesirable weather by prescribing cloud seeding medication. The prevailingview was “cloud seeding is good!”

• The static mode of cloud seeding

We have seen that the pioneering experiments of Schaefer and Langmuir suggested that the introduction of dry ice or silver iodide into supercooled clouds could initiate a precipitation process. The underlying concept behind the static mode of cloud seeding is that natural clouds are deficient in ice nuclei.

²For an excellent,  more technical review of static seeding, see Silverman (1986).

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The rime-splinter secondary ice crystal production process may not explain all the observations of high ice crystal concentrations relative to ice nuclei estimates but it is consistent with many of them. Still other processes, such as drop fragmentation during freezing (Korolev et al. 2004, Rangno and Hobbs 2005) and fragmentation of delicate ice particles (e.g.,Vardiman 1978) are not well quantified understood at this time may be operating operate in some cases of observed high ice crystal concentrations relative to ice nuclei concentrations.

The implication of these physical studies is that the “window of opportunity” for precipitation enhancement by cloud seeding is much smaller than was originally thought. Clouds that are warm-based and maritime have a high natural potential for producing precipitation. On the other hand, clouds that are cold-based and continental have reduced natural potential for precipitation formation and, hence, the opportunity for precipitation is much greater, although the total water available would be less than in a warm-based cloud.

This is consistent with the results of field experiments testing the static seeding hypothesis. The Israeli I and II experiments were quite successful in producing positive yields of precipitation in seeded clouds (Gagin and Neumann, 1981). The clouds that were seeded over Israel had relatively cold bases(5-8°C) and were generally continental such that there was little evidence of a vigorous warm rain process or the presence of large quantities of heavily rimed graupel particles.

This paragraph was copied verbatim from the first edition of this book,  CP95.  This paragraph should not have been copied and pasted into CP07 because it was not even valid at the time of CP95.  For example, strong evidence of ice multiplication and warm rain processes that undercut the “ripe for seeding” Cumulus descriptions that made the statistical successes of the Israeli experiments so credible (e.g., Silverman 1986) had appeared in 1988 (Rangno).

CP07 (and CP 95) were not aware of, or chose also not to cite,  Gabriel and Rosenfeld (1990) which published the “crossover” result of seeding for Israeli II for the first time. Crossovers consist of combining the results of random seeding in two targets.  The crossover evaluation had been mandated by the Israeli Rain Committee prior to Israeli II (Silverman 2001).    The important result for Israeli II was -2% effect on rainfall, not statistically significant.    Thus, Israeli II had not replicated Israeli I, as also concluded by Rangno and Hobbs (1995), and Silverman (2001).  For comparison, the Israeli I crossover result had indicated a statistically significant 15% increase in rain (e.g., Wurtele 1971).

The null crossover result in Israeli II was due to apparent increases in rain due to seeding in the north target that were canceled out by indications of a whopping 15% decrease in rainfall on seeded days in the south target.  Numerous questions about the “ripe for seeding” clouds of Israel would have been raised had the results for the south target of Israeli II been reported in a “timely manner” and not hidden from view until 1990.

CP07 acknowledge some of the evidence against the Israeli seeding successes later in this chapter, but not all.  This is an improvement over CP95 that had not cited any counter evidence regarding those experiments.   However,  in CP07 the reader will get two interpretations of the same experiments in one book.

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A number of observational and theoretical studies have also suggested that there is a cold temperature “window of opportunity” as well. Studies of both orographic and convective clouds have suggested that clouds colder than-25°C have sufficiently large concentrations of natural ice crystals that seeding can either have no effect or even reduce precipitation (Grant and Elliot, 1974; Gagin and Neumann, 1981; Gagin et al., 1985; Grant, 1986). It is possible that seeding such cold clouds could reduce precipitation by creating so many ice crystals that they compete for the limited supply of water vapor and result in numerous, slowly settling ice crystals which evaporate before reaching the ground. Such clouds are said to be overseeded.  

There are also indications that there is a warm temperature limit to seeding  effectiveness (Grant and Elliot, 1974; Gagin and Neumann, 1981; Cooper and Lawson, 1984). This is believed to be due to the low efficiency of ice crystal production by silver iodide at temperatures approaching -4 °C and to the slow rates of ice crystal vapor deposition growth at warm temperatures. Thus there appears to be a “temperature window” of about -10°C to -25°C where clouds respond favorably to seeding (i.e., exhibit seedability).

CP07 were not aware of, or chose not cite, the extensive literature that contradicted the claims of Grant and Elliott (1974) concerning a cloud top temperature range in which cloud seeding is supposedly viable. This led CP07 to “cut and paste from CP95 that there is a viable cloud seeding window for clouds (with tops) having a temperature range from -10°C to -25°C.  We note that CP07 do not use the term “cloud top” in this discussion, but that’s what the papers they reference are referring to, not just a temperature range within a cloud deck.

That a viable cloud top temperature seeding window of -10°C to -25°C exists as CP07 purport was dealt a severe blow in the Rockies by several papers in which high (10s to 100 per liter) concentrations of ice particles were reported in wintertime clouds with tops  >-25°C including even a contribution from Grant (leader of the Climax, CO, experiments) in Hobbs (1969).

Some of the overlooked papers are: Auer et al. (1969), Cooper and Vali (1981), Marwitz et al. 1976, Cooper and Marwitz 1980, and ground ice crystal concentration reports by Vardiman 1978, and by Vardiman and Hartzell (1976) in support of the Colorado River Basin Pilot Project, and by Grant et al.’s 1982 airborne study that reported no correlation with cloud top temperatures and ice particle concentrations in stable orographic clouds.   

So, the “window of opportunity” for cloud seeding was, at the time of CP95 and in CP07, known to be much more limited compared to what they were in their books.  I brought some of this counter evidence against this purported seeding window to the attention of the first author of CP07 in an email in 1997 to no avail.

There was also a serious drawback to the Grant and Elliott (1974)  study that CP95 and CP07 depended upon; they did not measure cloud top temperatures in the projects they evaluated.  Instead,  Grant and Elliott used constant pressure surfaces as proxies of cloud tops. The use of a constant pressure temperature was shown to be invalid as an index of cloud top temperatures on several occasions (Rangno 1972, 1986, Bartlett et al. 1975, Elliott et al. 1976, Hobbs and Rangno 1979, Mielke 1979, Hill 1980). These studies also went under the CP95 and CP07 “radar.”

There is a similar drawback to the Gagin and Neumann (1981) study; they measured radar tops, not cloud tops; the latter are higher, and their claim of having measured the top of “every cell” in Israeli II, was not true. It was impossible to see the tops of cells in the north end of the north target of Israeli II, nor even very close by when appreciable rain was falling on the Israel Meteorological Service’s 3-cm wavelength radar that Gagin and Neumann used for this purpose (personal communication, 1987, Mr. K. Rosner, the Israeli experiments’ chief meteorologist).  

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Physical studies and inferences drawn from statistical seeding experiments suggest there exists a more limited window of opportunity for precipitation enhancement by the static mode of cloud seeding than originally thought. The window of opportunity for cloud seeding appears to be limited to:

• clouds that are relatively cold-based and continental;
• clouds having top temperatures in the range -10°C to -25°C;

The above sentence about cloud top temperatures is profoundly incorrect because neither in CP95 and in CP07 were the authors aware of, or chose not to cite, the many publications concerning wintertime ice in clouds that contradict the assertion that this temperature range presents a viable cloud seeding window.

• a timescale limited by the availability of significant supercooled water before depletion by entrainment and natural precipitation

We must also recognize that implementing a seeding experiment or operational program that operates only in the above listed windows of opportunity is extremely difficult and costly. It means that in a field setting we must forecast the top temperatures of clouds to assure that they fall within the -10 – 5°C  to perhaps to -15°C  – 25°C  temperature window.

The temperature range above is adjusted to reflect the modern knowledge of ice in clouds in the Rockies and the improved AgI formulations that work more efficiently at higher temperatures.  However, at the higher cloud top temperatures in this range (-10°C to -15°C) in the high barriers of the Rockies the wintertime clouds tend to be too thin for appreciable modification potential.

In summary, the static mode of cloud seeding has been shown to cause the expected alterations in cloud microstructure including increased concentrations ofice crystals, reductions of supercooled liquid water content, and more rapid production of precipitation elements in both cumuli (Cooper and Lawson, 1984) and orographic clouds (Reynolds and Dennis, 1986; Reynolds, 1988; Super and Boe, 1988;Super and Heimbach, 1988; Super et al., 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.

The above statement shouldn’t have been copied and pasted from CP95 into CP07 considering the published contrary evidence available that was available prior to both editions.

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

By citing Mielke et al. 1981, CP07 indicate a lack of awareness of the published literature regarding the experiments conducted at Climax, CO.  Mielke et al. 1981 stratified their results by 500 mb temperatures, which have no meaning for cloud properties as Mielke (1979) himself reported. For those of us who follow the cloud seeding literature, this was a bizarre occurrence in peer-reviewed literature; the official journal reviewers and journal editor who were responsible for this science oxymoron, take note.

A dark cloud (no pun intended) was cast on all of the Colorado State University cloud seeding reports when Rangno and Hobbs (1987) used independent data reduced by NOAA personnel to evaluate the Climax experiments precipitation and upper-level temperature.  CSU personnel had reduced the data in Climax II to speed reporting of its results.  But this was contrary to the prior statements made by the experimenters about these having been independently made measurements (Mielke 1995).  

Rangno and Hobbs (1987) found that the CSU errors created the replication of Climax I by Climax II .  Moreover,  Climax II’s early tainted success through it’s first two years (reported to the Bureau of Reclamation’s cloud seeding division in Grant et. al. 1969,  helped spur the decision by the BOR to fund the massive seven million dollar Colorado River Basin Pilot Project as well as provide CSU and their consultants with about $500,000 to design that experiment in June 1968.   The Climax II errors had a profound effect; Climax I had been virtually error-free.

Furthermore, Rhea (1983) uncited by CP 95 or by CP07,  showed that the optimistic result by Mielke et al. (1981) for Climax II was due to a mistiming of precipitation gauge readings between the target and the control gauges, and not due to cloud seeding.  Thus Climax II did not replicate Climax I as was widely believed.  (Rhea 1983 was published AFTER he made revisions to his paper as had been suggested by Grant et al. in a “Comment” and “Reply” journal exchange behind the scenes.  However, Grant et al. (1983) did not revise their original “Comment” after Rhea made his revisions, an act that misled readers when reading the published exchange in the journal.  Rhea, in a private communication to me in 1986 considered the Grant et al. “Reply” a “smokescreen.”

But even these conclusions have been brought into question. The Climax I and II wintertime orographic cloud seeding experiments (Grant and Mielke; 1967; Chappell et al., 1971; Mielke et al., 1971, 1981) are generally acknowledged by the scientific community (National Academy of Sciences, 1975 1973; Tukey et al., 1978) for providing the strongest evidence that seeding those clouds can significantly increase precipitation.

Nonetheless, Rangno and Hobbs (1987, 1993) question both the randomization techniques and the quality of data collected during those experiments.  They and concluded that the Climax II experiment failed to confirm that precipitation can be increased by cloud seeding in the Colorado Rockies when the NOAA-published precipitation and upper level data for the Climax II experiment was used to evaluate it. Even so, Rangno and Hobbs(1987) did show that precipitation may have been increased by about 10%in the combined Climax I and II experiments

CP07 did not read Rangno and Hobbs (1993),  The 10% increase in snow  CP07 assume occurred was due to Grant and Mielke (1967) building in a huge seeding effect in Climax I in the high 500 mb temperature storm category via the choice of controls mid-way through Climax I.  This initial act caused the entire Climax experiments to suggest an ersatz 10% increase in snow due to seeding in the high 500 mb temperature category.Moreover, the 10% was not statistically significant via 1000 re-randomizations of the combined experiments CP07 refer (I. Gorodnoskya, personal communication, University of Washington Academic Computing Center, 1987, unpublished result).

Once the controls were hard-wired, no further indications of a seeding effect occurred as can be seen in the diagrams below from Rangno and Hobbs (1993).  One can assume that Grant and Mielke were sincere in their belief that a large cloud seeding induced increase in snowfall was being produced at Climax when they chose their controls at the halfway point, but had they realized that it had ended after their choices, the story of Climax I would have turned out far differently.

should be compared, however, to the original analyses by Grant et al.(1969) and Mielke et al.(1970, 1971)which indicated greater than 100% increase in precipitation on seeded days in the high 500 mb temperature category for Climax I and 24% for Climax II. Subsequently, Mielke (1995) explained a number of the criticisms made by Rangno and Hobbs regarding the statistical design of the experiments, including revealing that CSU personnel, and not independent NOAA ones,  as had been claimed on several occasions, were responsible for the errors in the precipitation and upper- level data that created a false replication of Climax I, in particular the randomization procedures, the quality and selection of target and control data, and the use of 500 mb temperature as a partitioning criteria. It is clear that the design, implementation, and analysis of this experiment was a learning process not only for meteorologists but statisticians as well.

PS to the reader: It was not a learning process for the CSU experimenters as claimed above.

Professor Grant was informed in my presence by three different people (I was not one of them) on three occasions in the early 1970s while I was the Assistant Project forecaster for the CRBPP that the stratifications by 500 mb temperatures by he and his group did NOT index cloud top ones as he was claiming.   These refutations of his claims were based on the statements of the prior Park Range Project contractor in Rhea et al. (1969),  and on the rawinsonde data from the on-going Colorado River Basin Pilot Project (e.g., Rangno 1972, Elliott et al. 1976).  500 mb and cloud top temperatures are, in general, poorly correlated.

So, Grant stopped claiming they were strongly related after he received this information in the early 1970s and learned from it?

 No.

 Grant continued to claim (as in Grant and Elliott 1974, Grant and Cotton 1979, Grant 1986) that the 500 mb temperature was representative of cloud top temperature (see Table 8 in Grant and Elliott 1974).   Strangely believe it, Mielke et al. with Grant as a co-author (1981) again stratified results of seeding in Climax I and II by 500 mb temperatures which Mielke himself knew had no physical meaning re cloud tops or cloud microstructure!

Moreover, the CSU experimenters repeatedly and falsely claimed that a graduate student, Furman (1967), had established a relationship between 500 mb and cloud top temperatures (e.g., as in Grant and Elliott 1974). Furman (1967) says nothing about such a relationship in his master’s thesis that consisted of but three days of vertically pointed 3-cm wavelength radar at Climax (Hobbs and Rangno 1979).  Another CSU graduate student, Hjermstad (1970), to refer to Furman’s study as, “scant” in coverage.  

To the outside community, the experimenters were presenting quite a different picture of what Furman had done.  What do we make of this?

For a naive, idealistic newbie into the weather modification/cloud seeding scene like me in the early 1970s in Durango, CO, this was amazing and troubling stuff to experience! CP07 (CSU folk) try to minimize what happened, I think,  by claiming it was a “learning process” when what actually happened was so counter to what we think of as “science”; i. e., that scientists change their minds when new facts come in that contradict their hypotheses.

The results of the many reanalyses of the Climax I and II experiments have clearly “watered down” the overall magnitude of the possible increases in precipitation in wintertime orographic clouds. Furthermore, they have  revealed that many of the concepts that were the basis of the experiments are far too simplified compared to what we know today. Furthermore, many of thecloud systems seeded were not simple “blanket-type orographic clouds” but were part of major wintertime cyclonic storms that pass through the region.As such, there was a greater opportunity for ice multiplication processes and riming processes to be operative in those storms, making them less susceptible to cloud seeding.

The above is a good summary.

 Two other randomized orographic cloud seeding 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. However,these particular experiments used high-elevation silver iodide generators, which increases the chance that the silver iodide plumes get into the supercooled clouds.  Moreover, both experiments provided physical measurements that support the statistical results (Super, 1974; Super and Heimbach, 1983, 1988). Using trace chemistry analysis of snowfall for the Lake Almanor project, Warburton et al.(1995a) found particularly good agreement with earlier statistical suggestions of seeding-induced snowfall enhancement with cold westerly flow. They concluded that failure to produce positive statistical results with southerly flow cases was likely related to seeding mis-targeting of the seeded material.

The reader should be aware that the results of the second randomized Lake Almanor experiment were not fully reported. The effect of seeding in the so-called “cold westerly” cases where a large seeding effect was suggested in the first Lake Almanor experiment, was omitted in the analyses of the second experiment (Bartlett et al. 1975).

Omittted results are always a sign of concern as happened in the Israeli II experiment.  Also of concern, no one has reanalyzed the first Lake Almanor experiment with its overly large percentage increases in snow, also of “concern.”  They don’t seem realistic to me, an expert in ersatz seeding reports and in cloud microstructure.  Someone gimmee that list of random decisions for Lake Amanor I and I’ll check it out!

These two randomized experiments strongly suggest that higher-elevation seeding in mountainous terrain can produce meaningful seasonal snowfall increase.

Independent scrutiny is needed for both of those experiments to strengthen this conclusion.

We noted above, that the strongest evidence of significant precipitation increases by static seeding of cumulus clouds came appeared to come from the Israeli I and II experiments…until Gabriel and Rosenfeld (1990) reported the full results of Israel II.  

Rosenfeld and Farbstein(1992) suggested that the differences in seeding effects between the north and south target areas during Israeli II that were reported by Gabriel and Rosenfeld (1990) is was the result of the incursion of desert dust into the cloud systems. They argue that the desert dust contains more active natural ice nuclei and that they can also serve as coalescence embryos enhancing collision and coalescence among droplets. Together, the dust can make the clouds more efficient rain-producers and less amenable to cloud seeding.

Note:  This “divergent effects” hypothesis began to gain early traction in the scientific community (e.g., J. Simpson, 1989).

Even these experiments have come under attack by Rangno and Hobbs doubted the Rosenfeld and Farbstein (1992) claims, and he launched a reanalysis of both Israeli experiments in 1992 that was published in 1995 (Rangno and Hobbs). That publication drew numerous critical comments from seeding partisans in 1997   From their reanalysis of both the Israeli I and II experiments, they Rangno and Hobbs argued demonstrated that the appearance of seeding-caused increases in rainfall in the Israeli I experiment was due to “lucky draws” or a Type I statistical error as had first  been “red flagged” in Wurtele (1971) for Israeli I due to the highest statistical significance on seeded days in that experiment having been located in a Buffer Zone that was meant to be unseeded between the two targets.  That it was largely unseeded was stated by the Israeli I chief meteorologist in Wurtele’s paper, Mr. Karl Rosner.  Wurtele’s paper should have been cited in CP95 and CP07.

Gabriel and Rosenfeld (1990) and  Furthermore, they Rangno and Hobbs argued showed that during Israeli II, naturally heavy rainfall fell over a wide region that included both targets on north target seeded days, with Rangno and Hobbs expanding the analysis of Gabriel and Rosenfeld (1990) to  include Lebanon and Jordan.  The widespread heavier rainfall on north target seeded days gave the appearance that seeding caused increases in rainfall over the north target area, but since the seeded days in the north were the control days for the south target  and more ordinary storms happened in the south target on its seeded days, created the impression that seeding had decreased rainfall there.   Namely, the presence of “dust/haze” as claimed by Rosenfeld and Farbstein (1992) had nothing to do with the outcome of the Israeli II experiment as evaluated by Rangno and Hobbs (1995).  The lower natural rainfall in the region  encompassing the south target area gave the appearance that seeding decreased rainfall over that target area:  

Not cited by CP07 in this segment is Silverman (2001) in his major review of numerous static glaciogenic seeding experiments, that included the Israeli experiments.  He concluded, as did Rangno and Hobbs (1995), that the two Israeli experiments no longer were credible in proving that rain had been increased by cloud seeding.

We argued above that the “apparent” success of the Israeli seeding experiments was due to the fact that they are more susceptible to precipitation enhancementby cloud seeding. This is because numerous studies (Gagin, 1971, 1975, 1986; Gagin and Neumann, 1974) have had shown that the clouds over Israel are continental having cloud droplet concentrations of about 1,000 cm^-3 and that ice particle concentrations are generally small until cloud top temperatures are colder· than-14°C. Furthermore, there is was little evidence found in those early studies for ice particle multiplication processes operating in those clouds.

See Rangno and Hobbs (1988) for a critique of those early studies by Professor Gagin listed above and why they were unrepresentative of most Israeli clouds.  Also see Rangno (1988) for evidence that those early studies were, indeed, highly erroneous as was verified on numerous occasions in later Israeli cloud studies using aircraft (e.g., Levin et al. 1996) and satellite data.  

Rangno (1988) and Rangno and Hobbs (1995) also reported on observations of clouds over Israel that strongly suggested containing they contain large supercooled droplets and quite high ice crystal concentrations at relatively warm temperatures. In addition, Levin et al.(1996) corroborated the Rangno (1988) and Rangno and Hobbs (1988, 1995) inferences when they found high ice particle concentrations, 10s to hundreds per liter, in convective clouds with tops no colder than -13°C.  presented evidence of active ice multiplication processes in Israeliclouds. This further erodes the perception that the clouds over Israel were as susceptible to seeding as originally thought.

Naturally, the Rangno and Hobbs (1995) paper generated quite a large reaction in the weather modification community. The March issue of the Journal of Applied Meteorology contained a series of comments and replies related to their paper (Ben- Zvi, 1997; Dennis and Orville, 1997; Rangno and Hobbs, 1997a,b,c,d, e, the most important of those “Replies”; Rosenfeld, 1997; Woodley, 1997). These comments and responses clarify many of the issues raised by Rangno and Hobbs (1995). Nonetheless, the image of, what was originally thought of as the best example of the potential for precipitation enhancement of cumulus clouds by static seeding has become considerably tarnished.

What have we learned from this chapter?  Caveat emptor concerning reports by those who conducted a “successful” cloud seeding experiments later telling us how ripe with seeding potential those clouds were.

Amen.  Thanks, guys, for this concluding remark largely due to the present writer’s work and skepticism.  This conclusion should have been placed earlier so the reader is not getting two versions of the of the Israeli experiments in having increased rain.

Chapter 3:  The fall of the funding science of weather modificationby cloud seeding

For nearly two decades vigorous research in weather modification was carried out in the United States and elsewhere. As shown in Fig. 3.1, federalfunding in the United States for weather modification research peaked in the middle 1970s at nearly $19 million per year. Even at its peak, funding for weather modification research was only 6% of the total federal spending in atmospheric research (Changnon and Lambright, 1987) and this amount includedconsiderable support for basic research on the physics of clouds and oftropical cyclones. Nonetheless, research funding in cloud physics, cloud dynamics, and mesoscale meteorology was largely justified based on its application to development of the technology of weather modification.Research on the basic microphysics of clouds particularly benefited fromthe political and social support for weather modification.   •

By 1980, the funding levels in weather modification research began to fall appreciably and by 1985 they had fallen to the level of $12 million. After 1985, funding in weather modification research became so small and fragmented that no federal agency kept track of it. Currently the Bureau of Reclamation has onlyabout

$0.25 million per year that can be identified as weather modification. They have operated a program in Thailand that was supported by the Agency for International Development. Basic research in the National Science Foundation that can be linked to weather modification is on the order of $1 million. Likewise, the Department of Commerce has no budgeted weather modification program but has supported a cooperative state/federal program at about the $3.5 million level. This on again- off again “pork barrel” program is supported by congressional write-insrather than a line item in the National Oceanic and Atmospheric Administration (NOAA) budget. In FY-2003, the Bureau of Reclamation administered this program,but no such funds were earmarked for either the Bureau of Reclamation or NOAA inFY-2004 or FY-2005. In this program, states having strong political lobbying support for weather modification are earmarked for support in this program.Overall the total federal program for weather modification in the United Statesis on the order of 10% of its peak level in the middle 1970s. What caused this virtual crash in weather modification research?

Changnon and Lambright (1987) listed the following reasons for this reduction in funding:

• poor experimental designs;

Changnon and Lambright, as did CP95 and CP07, did not discuss the Bureau of Reclamation’s Colorado River Basin Pilot Project, the nation’s largest, best-planned, and costliest ever randomized orographic cloud seeding experiment based on the work of CSU cloud seeders. The surviving author, Lambright, did not remember why in his reply to a recent email query by this writer.

• widespread use of uncertain modification techniques;
• inadequate management of projects;
• unsubstantiated Faulty claims of success, published in the peer-reviewed literature, ones that should have been caught in the peer-review of manuscripts.  

The “fall” described by CP95 and again in CP07 didn’t have to happen because with solid reviews; there would have been no rise!  If you would like to read about how to stop faulty cloud seeding claims from appearing in the peer-reviewed literature, go here:

https://cloud-maven.com/cloud-seeding-and-the-journal-barriers-to-faulty-claims-closing-the-gaps/

• inadequate project funding; and
• wasteful expenditures

Changnon and Lambright concluded that the primary cause of the rapid decline in weather modification funding was the lack of a coordinated federal research program in weather modification. However, there are other factors that also must

• weather modification was oversold to the scientific community, public and legislatures due to peer-reviewed literature that appeared to show that cloud seeding had worked;
• demands for water resource enhancement declined due to an abnormal wet period;

 

Clearly there is a great need to establish a more credible, stably funded scientific program in weather modification research, one that emphasizes the need to establish the physical basis of cloud seeding rather than just a”black box” assessment of whether or not seeding increased precipitation. We need to establish the complete hypothesized physical chain of responses to seeding by observational experiments and numerical simulations. We also needto assess the total physical, biological, and social impacts of cloud seeding, or what we call taking a holistic approach to examining the impacts of cloud seeding similar to those conducted during the latter stages of the Colorado River Basin Pilot Project (e.g., Marwitz et al. 1976).  E.K. Bigg, for example (Bigg, 1988, 1990b; Bigg and Turton,1988) suggested that silver iodide seeding can trigger biogenic production ofsecondary ice nuclei. His research suggests that fields sprayed with silveriodide release secondary ice nuclei particles at 10-day intervals and thatsuch releases could account for inferred increases in precipitation 1-3 weeksfollowing seeding in several seeding projects( e.g., Bigg and Turton, 1988).If Bigg’s hypothesis is verified, an implication of biogenic production ofsecondary ice nuclei is that many seeding experiments have thus been contaminated such that the statistical results of seeding are degraded. This effect would be worst in randomized cross-over designs and in experiments inwhich one target area is used and seed days and non-seed days are selectedover the same area on a randomized basis. Thus, not only is the weathermodification community faced with very difficult physical problems and largenatural variability of the meteorology, but they also are faced with thepossibility of responses to seeding through biological processes. (Bigg’s work is not credible to this reviewer.)

We shall see later that scientists dealing with human impacts on global change are also faced with very difficult physical problems, large natural variability of climate, and the possibility of complicated feedbacks through the biosphere. There is also a great deal of overselling of what models candeliver in terms of “prediction” of human impacts over timescales of decades or centuries.

End of “review and enhancement” of CP07’s weather modification chapters.

———–We interrupt this review for a brief personal presentation———

My self-funded trip to Israel (Rangno 1988) was to expose what I thought were faulty, ripe for cloud seeding cloud reports that were the foundation for the belief that seeding had increased rain.   My findings were first confirmed by Levin (1992), reported again in the journals by Levin et al. (1996) and verified in ensuing years several times in satellite imagery and in other airborne measurements.  Spiking fubball here, of course.  How often do researchers go to another’s lab on their own expense and tell him, “I don’t believe your results? Show them to me.”  Cost me a lot of money, but it was worth it.  At the time I went, the Israeli cloud reports had gone unquestioned (e.g., Silverman 1986).

Just before I hopped on a plane to Israel, my lab chief, Professor Peter V. Hobbs described me as “arrogant” for thinking I knew “more about the clouds of Israel than those who studied them in their backyard.”  But when he submitted my paper to the Quart. J. Roy. Meteor. Soc., 12 January 1987, with a copy to Professor A. Gagin, Professor Hobbs wrote to  Gagin that what I was describing  in my paper was the same as he thought about the clouds of Israel (that they were not as Professor Gagin was describing them).  

Professor Hobbs was not being truthful.  I often wonder many times Professor Hobbs might have said that to others, that what I  was reporting was what he had thought all along, robbing me of my insight, my historical trip and year long effort all paid for from my savings.  When I confronted him about this, he sent me a memo that said not to expect a job in his group in the future.  

But, he did hire me back to the job I loved via the magic of reconciliation (mostly) over past wrongs!

———————– 

The references cited in this “Review and Enhancement” that do not appear in CP07:

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

Bartlett, J. P., Mooney, M. L., and Scott, W. L., 1975:  Lake Almanor Cloud Seeding Program.  Special Regional Weather Modification Conference, San Francisco, CA, 106-111.

Coons, R. D., and R. Gunn, 1951:  Relation of artificial cloud-modification to the production of precipitation.  Compendium of Meteorology,  Amer. Meteor. Soc., Boston, MA. 235-241. 

Coons, R. D., E. L. Jones, and R. Gunn, 1949: Artificial production of precipitation. Third Partial Report: Orographic Stratiform Clouds–California, 1949. Fourth Partial Report: Cumuliform Clouds–Gulf States, 1949. U. S. Weather Bureau Res. Paper No. 33, Government Printing Office, Washington, 46 pp.

Gabriel, K. R., and D. Rosenfeld: The second Israeli rainfall stimulation experiment: analysis of rainfall on both target areas. J. Appl. Meteor., 29, 1055–1067, 1990.

Cooper, W. A., and J. D. Marwitz, 1980: Winter storms over the San Juan mountains. Part III. Seeding potential. J. Appl. Meteor., 19, 942-949.

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

Furman, R. W., 1967:  Radar characteristics of wintertime storms in the Colorado Rockies.  M. S. thesis, Colorado State University, 40pp

Grant, L. O., DeMott, P. J., and R. M. Rauber, 1982: An inventory of icecrystal concentrations in a series of stable orographic storms. Preprints, Conf. Cloud Phys., Chicago, Amer. Meteor. Soc. Boston, MA. 584- 587.

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

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.

Hill, G. E., 1980: Reexamination of cloud-top temperatures used as criteria of cloud seeding effects in experiments on winter orographic clouds. J. Climate Appl. Meteor., 19, 1167-1175.

Hobbs, P. V., 1969: Ice multiplication in clouds. J. Atmos. Sci., 26, 315-318.

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

Hobbs, P. V., Lyons, J. H., Locatelli, J. D., Biswas, K. R., Radke, L. F., Weiss, R. W., Sr., and A. L. Rangno, 1981: Radar detection of cloud-seeding effects. Science, 213, 1250-1252.

Korolev, A. V., M. P. Bailey, J. Hallett, and G. A. Isaac, and, 2004:Laboratory and in situ observation of deposition growth of frozen drops. J. Appl. Meteor., 43, 612-622.

Kraus, E. B., and P. Squires, 1947: Experiments on the stimulation of clouds to produce rain. Nature, 159, 489-490.

Levin, Z., 1992: The role of large aerosols in the precipitation of the eastern Mediterranean. Paper presented at theWorkshop on Cloud Microphysics and Applications to Global Change, Toronto. (Available from Dept. Atmos. Sci., University of Tel Aviv). No doi available

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.

Marwitz, J. D., Cooper, W. A., and C. P. R. Saunders, 1976: Structure and seedability of San Juan storms. Final Report to the Bureau of Reclamation,University of Wyoming, Laramie, WY, 324 pp.*

Rangno, A. L., 1972: Case study on some characteristics of the specially monitored storm episodes within the Colorado River Basin Pilot Project. Special Project Report to the Bureau of Reclamation, 105pp.

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

Rangno, A. L., and P. V. Hobbs, 1988: Criteria for the development of significant concentrations of ice particles in cumulus clouds. Atmos. Res., 22, 1-13.

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 .https://carg.atmos.washington.edu/sys/research/archive/1997_comments_seeding.pdf

Rangno, A. L., and P. V. Hobbs, 2005: Microstructures and precipitation development in cumulus and small cumulonimbus clouds over the warm pool of the tropical Pacific Ocean. Quart. J. Roy. Meteorol. Soc., 131, 639-673.

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.

Simpson, J., 1989:  Amer. Meteor. Soc. Banquet talk transcript on the occasion of her inauguration as president of that organization, October 4th.

Vardiman, L., 1978: The generation of secondary ice particles in cloudcrystal-crystal collisions. J.  Atmos. Sci., 35, 2168–2180.

Vardiman, L., and C. L. Hartzell, 1976: Investigation of precipitating ice crystals from natural and seeded winter orographic clouds. Final Report to the Bureau of Reclamation, Western Scientific Services, Inc., 129 pp.

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

Concluding remark:

The entire CP07 reference list, consisting of several hundred references, is  a great resource for research and demonstrated how knowledgable these two authors are.  However, the list above also indicates how difficult a review of a topic is when the amount of literature that appears in journals today can bury you with important citations being missed.