Part 2: PETER HOBBS and me (contains irony)

“Peter V. Hobbs became one of the most vociferous scientists to show that some published claims of seeding impact were exaggerated, false, or unverifiable.”

The above statement was contained in a flyer advertising the 2018 Peter Hobbs Endowed Lecture¹ at the University of Washington by a leading scientist in weather modification.  This account focuses on the word, “became” in this flyer, and why Peter Hobbs’ optimistic view of cloud seeding through the mid-1970s was reversed to the point that by 2001 he could refer to the body of cloud seeding literature as, “often unreliable.”

This account will explain how Peter came to be a critic of cloud seeding literature when he was so optimistic about seeding after his 1970s Cascade Mountains project.

I MUST write a soliloquy about my relationship with Peter V. Hobbs in the weather modification/cloud seeding domain, with the good and the bad even if nobody cares and nobody reads it but me.  Somehow doing this blog in the latter stage of life that I am now in gives me peace.  I have wrangled (“Rangno-ed”, haha) over this credit issue for decades without really doing anything.

Had criteria been in place such as that today used by Geophys. Res. Letts., shown below, authorship sequence would mean nothing.  Who did what would be right there for all to see!

At the same time, I don’t want to downgrade what Peter did, either.  I tried as hard as I could to write a draft of research findings that he could not measurably improve.  I never could.  I was crushed when my marked up draft from Peter come back, but I was able to see how he had improved it.  He performed miracles of clarity to what I wrote.  And that’s why I would add another element to the Geophysical Research Letters’ author contributions example here from the 2022 article, “Tree Rings Reveal Unmatched 2nd Century Drought in the Colorado River Basin:

“Author Contributions:

Conceptualization:

SubhrenduGangopadhyay, Connie A. Woodhouse,Gregory J. McCabe, Cody C. Routson, David M. Meko

Data curation: Subhrendu Gangopadhyay

Formal analysis: SubhrenduGangopadhyay, Connie A. Woodhouse, Gregory J. McCabe, Cody C. Routson, David M. Meko

Investigation: Subhrendu Gangopadhyay, Connie A. Woodhouse, Gregory J. McCabe, Cody C. Routson, David M. Meko

Methodology: Subhrendu Gangopadhyay,  Connie A. Woodhouse, Cody C. Routson, David M. Meko”

I would add, for situations that others might have that are similar to mine, this:

Editing; improving clarity of material:

____________________

==========================

In September 1976 when I joined Peter’s group, I brought “insider” information to him that was to impact his then optimistic views of cloud seeding experiments in Colorado conducted by Colorado State University (CSU) scientists.  From 1970 through 1975, I had been the Acting Project Forecaster and Assistant Project Forecaster with the nation’s largest ever randomized orographic cloud seeding experiment, the Colorado River Basin Pilot Project (CRBPP).  The goal of that sophisticated experiment was to replicate the large percentage increases in snow that Peter and the scientific community had believed to have been brought about by cloud seeding in randomized orographic experiments at Climax and Wolf Creek Pass, CO.

Also, when I arrived, Peter and his group were in the “afterglow” of the Cascade Mountains seeding experiments that produced a tremendous amount of information about storms published in numerous journal pages describing that experiment.  Peter had also contributed his optimistic view of cloud seeding in his “personal viewpoint” editorial in Sax et al. 1975 and in his book with Prof. Mike Wallace in 1977.

Peter, too, as a panel member of the NRC-NAS (1973) review of climate and weather modification, had seen to it that a non-randomized cloud seeding experiment in the northern Cascades, the Skagit Project, was included as a cloud seeding success into the Panel’s review.  It sure looked like one.

By 1976, however, I was a person who could no longer trust peer-reviewed published cloud seeding literature as Peter did.  Peer-review in science is supposed to eliminate false claims.  This reversal of an idealistic attitude about science occurred when I saw false claims published in a peer-reviewed journal, ones that even the authors knew were false!

What was truly troubling to me, as much as seeing false claims published, was that scientists who knew that false claims had been published, did nothing to correct them in post publication “Comments.”  The silence was deafening.

While Peter Hobbs was optimistic about cloud seeding, I was laying out the problems that were being experienced in the CRBPP, as shown in the two articles in the Appendix of this summary, one appearing in the Telluride, CO, magazine, “Deep Creek Review,” in the spring of 1974 and the second in the Durango Herald newspaper in November 1975.  In the latter article I announced that I was going reanalyze all the CSU cloud seeding experiments!  I had barely started on one when I made that overzealous statement!

In the spring of 1974, I had a chance to visit/rant “big time” about the many problems that the CRBPP was experiencing to Peter’s B-23 aircraft group during their six-week investigation of seeding plumes and of the cloud microstructure over the San Juan Mountains, the target of the CRBPP experiment.  I was the Assistant Project Forecaster with the CRBPP at that time,  and was to be the only meteorologist with that project during its entire five winter seasons.  The Washington group was led by Prof. Lawrence F. Radke during the first two weeks, and the last four weeks by Mr. Don Atkinson.[2]    One member of Peter’s group was James Rodgers Fleming (who was to make a name for himself writing a history of early cloud seeding in the United States (Fixing the Sky) and writing a biography of the life of Joanne Malkus Simpson).

The Washington group had been contracted to do this work by the sponsor of the CRBPP, the Bureau of Reclamation’s Division of Atmospheric Water Management, its cloud seeding arm, to find out just what was going wrong with the attempt to replicate the Colorado State University cloud seeding experiments.  The Washington group issued their report the following year (Hobbs et al. 1975).

One of the major conclusions in that report was that the ground released seeding material was not reaching the clouds on stably layered days or reached the clouds too close to the target to effect a snowfall on it.

The problem of deeply stabled layering during storms whose properties matched thos for an experimental day in the CRBPP had already been called out for the BOR in the seeding contractor’s report at the end of the very first season (Willis and Rangno 1971).

The presence of those deep stable layers was one of the issues that led me to believe that the increases in snow reported by CSU scientists from the published results of their experiments could not have happened.  Rather, it seemed more likely to me that a lucky draw of storms on seeded days must have produced the appearance of seeding-induced increases in snow in those benchmark experiments.

Irony

After joining Peter’s group, I was quickly sensitized to an appropriation of credit issue within his group that led to bitterness in some members.  One member pawed a sole authored Cascade experiment by Peter Hobbs, titled, “Natural Conditions”, and muttered, “all my work.”  Next, in reading another paper about the Cascade experiment, he erupted with, “That’s not what we found!”

Oh, me.

Here I was coming from the dark side of weather modification I experienced in Durango, to another form of the “dark side” of science.  How ironic this seemed at the time, from one frying pan and into another.

I was to overturn, usually with Peter Hobbs as a co-author, faulty claims of cloud seeding successes in Colorado and Israel, and the false hypotheses behind them in the published literature over the next 20 plus years.

Even today, yours truly has a manuscript on the history of the CRBPP cloud seeding experiment, co-authored with Dave Schultz, Chief Ed., Monthly Weather Review, currently in review at the J. Appl. Meteor.

More irony

Every experiment that I exposed as faulty, Peter Hobbs had previously passed positive judgment on the Climax experiments, the Wolf Creek Pass experiment, the Israeli experiments, and the Skagit Project.  Peter read journals, believed what they said, and took those findings prima facie, as most scientists would do.  I had left that motif behind in Durango; the cloud seeding literature just could not be trusted if a success was reported.

That last experiment in the list above, the Skagit, a non-randomized one, was one that Peter himself had interjected into the NAS-NRC 1973 review of cloud seeding because he thought it so legitimate a seeding success.   It certainly looked that way in the journal article about it by Hastay and Gladwell (1969).

In 1977 or so, we were going to propose a randomized cloud seeding experiment I had designed in the Cascades to the National Science Foundation using aircraft to seed a small watershed.  Since airborne seeding would be far more expensive than ground seeding, I figured I had better look into the ground seeding effort of the Skagit Project, that appeared to have produced such a tremendous success in a small region of the Skagit River watershed.

Result:  I overturned the Skagit Project that Peter thought so highly of in less than three days!

The reanalysis of the Skagit that I produced with its many river plots, however, was published as “Hobbs and Rangno (1978),” leading one faculty member within his to say to me that, “Peter stole that paper.”  This was the first appropriation of credit that I was to experience of several that followed.  Peter, of course, as a great editor, improved the organization and drafts I brought him, always.

But why would a leading scientist and faculty member at a prestigious atmospheric sciences department, like Peter Hobbs was, want to do this; take from his staff members and graduate students in his group and make it appear that he did things he didn’t do?  My reanalysis of the Wolf Creek Pass experiment had yet to be published although it had been accepted by the Journal of Applied Meteorology prior to the journal appearance of, “Hobbs and Rangno” Skagit reanalysis.  Since the Skagit reanalysis came first, I wondered whether it would it look like Peter had instructed me how to do the Wolf Creek Pass reanalysis?

The good in working with Peter Hobbs was that he supported my research, most of it unsettling the paradigms of the day, whether it was in the cloud seeding arena or in the formation of “secondary” ice, or reporting that an aircraft can produce ice in clouds at temperatures around -10°C, or in suggesting a previously unused tool (mm-wavelength radar) for the detection of cloud seeding effects.  Peter seemed to like it when his workers produced research that questioned the existing paradigms, and he was good at seeing that those controversial manuscripts got published.

The bad was that Peter took credit for the original work that I did during my first nine years in his group.  Here is clear example that occurred in a sole-authored paper Peter presented in 1980 at Clermont-Ferrand, titled, “Lessons to be learned from the recent reanalyses some cloud seeding experiments,” my reanalyses in fact.   From this paper is his Figure 2 with his appropriation of credit highlighted, similar to that concerning my Skagit Project reanalysis two years earlier:

I initiated and carried out the precipitation-per-day (PPD) climatology at the Colorado stations shown in Figure 2b and 2c most of that on my own time at home.  But here, Peter Hobbs takes credit for those datasets!   Why, oh, why couldn’t he be truthful about the origin of these “expanded data sets”?  Why wouldn’t he want to tell his audience, proudly, that a member of his staff did these studies, perhaps even mention his name?  Its incomprehensible to me.  I only discovered this appropriation recently.  As a forecaster with the CRBPP, I came to see “in person” how those PPD graphs by CSU scientists were not representative of the true PPD climatology.  And, of course, why wasn’t I at least a co-author of this pre-print?

Sure, its ONLY a pre-print that probably no one remembers but me, but still……

Returning to the CRBPP and my background before arriving in Peter’s group

The CRBPP was a sophisticated experiment that attempted to replicate the results of those earlier Colorado experiments Peter so highly regarded.  And I had information that cast doubt on the prior experiments that was not getting out to the science community (but should have).  Instead of questioning the original experiments, the scientific community was told that the CRBPP was operated incorrectly, and that was what caused the failed replication of the CSU successes (e.g, Elliott et al. 1978).

Before coming to Peter’s group, and after the CRBPP ended, I began working on a reanalysis of one of the Colorado experiments in the winter of 1975-76, the one at Wolf Creek Pass that led to the location of the CRBPP in southwest Colorado.   I lived off my savings in Durango to do so (hah, no skiing, either!)

I felt that I had the skill to reanalyze one or all the prior experiments on which the CRBPP was based with my background knowledge of weather patterns in the Southwest; from what I had learned about orographic precipitation from J. O. Rhea, the first Project Forecaster of this large experiment whom I worked under in my first season.   Rhea’s orographic model work eventually formed the basis of today’s PRISM graphics for average precipitation in the US and his work also formed the basis of flood forecasts by the California and Nevada River Forecast Center.

Because Peter Hobbs was malleable when new facts came in, he was able to move away from his position concerning those Colorado cloud seeding “successes” after I arrived in his group.  The change in Peter’s opinion was due to the drafts of the reanalysis of one of the so-called successes, that at Wolf Creek Pass, which also included an exposé of the faults in the hypotheses of the CSU scientists (Rangno 1979, Hobbs and Rangno 1979) that seemed to have explained why cloud seeding had increased snow in their experiments.

With Peter almost always as a co-author, I was to publish cloud investigations, and several reanalyses that eviscerated seemingly solid cloud seeding successes  them until the mid-1990s.  All these papers that concerned overturning cloud seeding “successes” were almost all unfunded, done on my own “time and dime,” not on university grant monies with the exception of the Skagit reanalysis.  Perhaps due to so much of my own private time that was sacrificed in these efforts, ones I deemed altruistic, I have a great sense of ownership about them.

Investigating the high concentrations of ice sometimes found in clouds with slightly supercooled tops (~-4°C > -10°C): going against the consensus

Peter also supported my “outlier” conclusions on another topic: the main cause of the development of “secondary” ice in clouds.  The explanation that has the most credibility even today is called Hallett-Mossop, “riming and splintering” process.   However, it did not appear to explain the rapidity of ice development in the slightly supercooled clouds that I sampled in the coastal waters of Washington State, though it surely played a significant role.

This mechanism was discovered in laboratory experiments by Hallett and Mossop 1974; Mossop and Hallet 1974, and confirmations of its effect in real clouds are innumerable, hence, “going against the grain.”  In fact, those findings were so outrageous and controversial that two of the best cloud scientists in the field, Prof. John Latham and Alan Blyth, the latter a friend, couldn’t take it any longer.  They posted a brief journal criticism concluding that me and Peter were wrong in those conclusions that downplayed the Hallett-Mossop riming splintering phenomenon as the major cause of the ice we saw.  The 1998 journal article by Latham and Blyth was titled, “The glaciation papers of Hobbs and Rangno.”  (I was so excited to see a journal title with my name in it I sent a copy of it to my mom! ) We (Hobbs and Rangno) did respond to the comments of Blyth and Latham in the same journal issue, defending our position.

I flew research flights as the Flight Scientist or Flight Meteorologist into hundreds, perhaps thousands, of shallow Cumulus clouds that formed lots of ice and wrote drafts of my findings that Peter enhanced.  Peter rarely flew on research flights until after 1990, especially the turbulent Cumulus flights, but rather worked on drafts of science papers by his staff and graduate students so that journal articles were churned out as efficiently as possible.  Peter acted as a sort of filter for all the many papers that were specialties of his group:  synoptics and rainbands, aerosols, and cloud microstructure.  Peter put his staff and students’ manuscripts in the best possible shape for journal acceptance.

Peter also did not allow papers to go out of his group without his purview.  But I did do that on several occasions when he was on sabbatical in 1983.  Doing that caused problems between us.  The motivation for me was that I felt it was a time I could have a real impact and could get away from the impression that Peter was directing my work.  I submitted no less than three manuscripts in 1983; on the clouds and cloud seeding in Israel, a reanalysis of the Climax experiments starting from raw data, and a “Comment” on the reporting of the Climax experiments.  All three were rejected or asked to be withdrawn (the “Comment” manuscript), but significant elements of them were published later under Peter’s purview (e.g., Rangno and Hobbs 1987, 1993, 1995a, 1995b).

My job sampling clouds to explore the development of ice in them was perfect for me.  I had been writing about visible ice in clouds, keeping diaries of clouds since I was a little kid and had learned about the importance of ice in rain formation from books my mom bought for me when I was growing up. Too,  I chased desert thunderstorms in the high desert of southern California, and even Hurricane Carla in 1961.

So, being in that research aircraft of Peter’s, a B-23 Dragon with a viewing dome on top of the fuselage, chasing small ice-forming Cumulus and Cumulonimbus clouds in the Washington coastal waters and elsewhere, was exactly right for me.  I loved my job, with one exception that was to be a growing problem over my first nine years.

Peter’s Science Training in Britain: How It May Have Caused His Problematic Authorship Determinations

Peter Hobbs trained at Imperial College in England under Sir B. J. Mason, a renowned cloud physics expert whose book, “The Physics of Clouds,” is standard reading for those interested in that topic like me².  Peter had a methodology of authorship and appropriation of credit for the research done in his lab group that was said to have been one that was practiced in England, perhaps under Mason.  Peter often automatically took first authorship on papers that exited his group to journals.  That practice caused problems with the faculty, students, and staff periodically over the years.  And, eventually for me.  Some left his group in bitterness, and to this day, one faculty member doing a review of rainbands,  could not cite a Hobbs paper that he knew was mainly done by someone else.

Peter often took first authorship, too, on work that he did not personally analyze, though it was usually collected during field programs under National Science Foundation grant proposals that he and his faculty staff wrote and got funding for.  This was a factor in Peter taking first authorships.  Moreover, the data gathered that his students or faculty in his group used was obtained by the aircraft that Peter had gotten funding for through the NSF.

English astronomer, Anthony Hewish comes to mind and the story of the discovery of quasars for which Hewish got the Noble Prize, leaving without mention, the actual discoverer, Jocelyn Bell, who worked for Hewish and used his equipment in that discovery.  The “lab chief” problem of credit issues has also been long discussed as a problem in the US in books about science (e.g., Broad and Wade 1982, in their chapter, “Masters and Apprentices.”)

I eventually resigned in protest over the issue of credit after more than nine years in Peter’s group from a job, a university, and the people I worked with that I loved seeing every day I went to work.  It was a painful loss for me, but I felt I had to make a strong statement.  Ironically, we had reconciled over a paper via mediation by Department Chairman, Mike Wallace.

But then there was another credit issue just weeks after that which ended up being the final straw.   I resigned, submitting a 27-page letter describing all the issues that had troubled me, but had internalized over the years since I joined his group.

But, over a two-year period, Peter and I slowly reconciled.   I was hired back in December 1987 and worked with Peter for another 18 years!   Such reconciliations probably don’t happen too many times in real life, but I loved what I had done before, and jumped at the chance to return and fly into clouds once again when a graduate student suddenly quit Peter’s group.    Peter and I went on to publish several significant papers in ice formation (I think), and a comprehensive look at the cloud seeding experiments in Israel that drew a lot of journal attention.

Authorship sequence was never an issue again after I was rehired.   Sometimes we just alternated lead authorship for no particular reason even though I was the “grinder,” producing results from project research flights.  I wasn’t so concerned about credit anymore for those papers, at least outside the Cumulus cloud realm that was my specialty.

The last conflagration before being re-hired; it was a doozie

That last conflagration was in January 1987.  Peter tried to usurp my long held view on the clouds of Israel being incorrectly described in a letter to Prof. Abe Gagin, leader of the Israeli experiments.    In his letter to Prof. Gagin in, he indicated to him that he already knew what I was reporting in the accompanying manuscript that was sent.

This was blatantly untrue, as were several elements.  Here is his letter to Prof. Gagin on 12 January 1987.  It should be note that I am NOT an employee in his group, nor of the University of Washington at this time.   I was therefore livid about his statement concerning my communications  with S. C. Mossop, Roscoe R. Braham, Jr., Gabor Vali, and to Peter himself and Prof. Larry Radke during my time in Israel and afterwards.

In fact, a few days before I left for Israel on my cloud investigation in 1986, I met with Peter, and he accused me of being “arrogant” for thinking I knew “more about the clouds of Israel than those who studied them in their backyard.”

His statement was humorous and sad at the same time, but it also made me angry that Peter would lie to Prof. Gagin that he suspected what I found out about the clouds of Israel was what he already knew; that those clouds were not as Prof. Gagin had been describing them.

But again, why, oh, why would Peter want to do this to someone who has spent so much his own time and money in an altruistic effort to correct a faulty cloud assessments?  That 11-week trip to Israel cost me about $4,000 in 1986 dollars!

Once arriving home from Israel, I worked on producing a manuscript with figures I myself drafted the rest of 1986, living solely off my savings; in other words, a year of sacrificed income as well!  I was driven to expose those faulty cloud reports that was costing Israel so much in wasted cloud seeding efforts as I saw it.

Too, Peter had apparently forgotten about my manuscript on the clouds and cloud seeding in Israel that was submitted in 1983 while he was on sabbatical in England.  That short paper concluded the clouds of Israel were not as they were being described by the leader of cloud seeding program in Israel.  I had done my homework on his cloud reports in the literature independent of Peter, at home, on my own time.  But what I was reporting in 1983 was unconvincing and inconceivable to three of the four reviewers and it was rejected (Prof. Gagin himself was one of the “reject” reviewers he told me in 1984.)

In his January 12, 1987, letter to Prof. Gagin, Peter reminded him that he had raised questions with him at his 1980 presentation (in Clermont-Ferrand, France).  Peter does not mention that he had asked ME to write down some questions for Prof. Gagin before he went to that conference!  I had just begun reading critically about those experiments after the dust had settled on the Wolf Creek Pass reanalysis and a journal “Comment” paper.   At this time, Peter challenged me by saying, “if I really want to have an impact you should look into the Israeli experiments.”

So, I did.  He must have realized that I had an interest and skill in seeing through successful cloud seeding mirages.

Why is this chapter of going to Israel to expose faulty cloud reports so important to me, you may ask?

I considered my trip to Israel “historic” in the world of science.  Sounds crazy?  Here’s why.

I felt that what I was going to do when I went to Israel was analogous to what American physicist, R. W. Wood, had done concerning a new kind of radiation called, N-Rays that was being reported after the turn of the 20^thcentury from a French scientist, Prosper Rene Blondlot.  Prof. Wood had gone to France, believing N-Rays to be a possible product of delusion and if so, expose it.  And that is what it was, N-Rays was product of delusion.

What Wood did is described in many books on science history, and was thus, “historic.”  This is because the N-Ray episode is considered by some as the greatest mass delusion in science history due to the number of published “confirmations” of a non-existent radiation.    I thought what I did in going to Israel paralleled Wood’s story.

The clouds described in support of cloud seeding successes in Israel, like “N-rays,” were, I believed, also non-existent.  And those, “fictitious” cloud reports from Prof. Gagin were accepted within the world of our best cloud seeding scientists!

And that’s what I felt I was doing in Rangno 1988, Quart. J. Roy. Meteor. Soc.) in my cloud exposé.   My findings that indicated that “ripe for seeding” clouds do not exist in Israel have been confirmed on many occasions since they were published.

Moreover, seeding to increase Israel’s water supplies ended in 2007 (2013?) after no increase in rainfall was found after 27 years of cloud seeding that targeted the watershed of their largest natural water supply, Lake Kinneret (Sea of Galilee).  A fourth long term, randomized experiment in Israel, Israel-4, ended after seven seasons with a null result in 2020.³  That spectacular null result after so much effort proved once again that the clouds of Israel contain too much natural ice for cloud seeding to be a viable method for increasing water supplies.

Thus, I couldn’t let Peter Hobbs’ claims go unchallenged.   After I reminded him about where his doubts came from about the clouds of Israel (me!), he replied formally to me in a letter that I was not to expect to work for him again.

I replied to his letter with my own long letter detailing what I had been telling him all along about the clouds and cloud seeding in Israel since the late 1970s!  His outgoing letter to Professor A. Gagin, the person responsible for describing fictitious, ripe for cloud seeding clouds, his letter to me in response to my reminding Peter where his information came from and that he had been clueless about the clouds of Israel before my trip, and my comprehensive letter to Peter reminding him of this.  These are displayed here for the purpose of documenting what happened.

Nevertheless, despite of Peter’s “won’t be hired again” letter in January 1987, I was hired back into his group in December 1987 when a grad student in his group working on ice in clouds suddenly left to take gainful employment.

We both realized that we made, for all our conflagrations, a good team.

===============FOOTNOTES====================

¹I had volunteered to present this lecture with the subject being,   “The Rise and Fall of Cloud Seeding in Israel,” but was turned down.

²I bought the 1971 edition of B. J. Mason’s book while I was in Durango, CO and read it avidly.

³Journal results for this experiment, Israel-4, were published by Benjamini et al. 2023) .  The results of Israel-4 were reported to me in February 2021 from a media article in Hebrew prior to the appearance of Benjamini et al.  by Prof. Emeritus, Z. Levin, Tel Aviv University.

==============REFERENCES========================

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.  https://doi.org/10.1175/JAMC-D-22-0077.1

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

Hobbs, P. V., 1975:  The nature of winter clouds and precipitation in the Cascade mountains and their modification by artificial seeding.  Part I.  Natural conditions.  J. Appl. Meteor., 14, 783-804.

Hobbs, P. V., 1980:  Lessons to be learned from the reanalysis of several cloud seeding experiments.  Preprints, Intern. Cloud Physics Conf., Clermont-Ferrand, France, Amer. Meteor. Soc., Boston, MA, 02108, 88-91.

Hobbs, P. V., 2001:  Comments on “A Critical Assessment of Glaciogenic Seeding of Convective Clouds for Rainfall Enhancement.”  Bull. Amer. Meteor. Soc., 82, 2845-2846.

Hobbs, P. V.,  and A. L. Rangno, 1978: A reanalysis of the Skagit cloud seeding project.  J. Appl. Meteor., 17, 1661–1666.

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

Hobbs, P. V., L. F. Radke, J. R. Fleming, and D. G. Atkinson, 1975: Airborne ice nucleus and cloud microstructure measurements in naturally and artificially seeded situations over the San Juan mountains in Colorado.  Research Report X, Cloud Physics Group, Atmos. Sci. Dept., University of Washington, Seattle, 98195-1640.

Mason, B. J., 1971: The Physics of Clouds. Oxford University Press, 671pp.

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

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 cloud seeding? In Precipitation Enhancement–A Scientific Challenge, R. R. Braham, Jr., Ed., Meteor. Monographs, 43, No. 21, Amer. Meteor. Soc., 115-124.

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

Rangno, A. L., 2000: Comments on “A review of cloud seeding experiments to enhance precipitation and some new prospects“. Bull. Amer. Meteor. Soc., 81, 583–585.

Rangno, A. L., and L. M. Hjermstad, 1975: views on the CRBPP, Durango Herald newspaper interviews.

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

Rangno, A. L., and P. V. Hobbs, 1980b: Comments on “Generalized criteria for seeding winter orographic clouds.” J. Appl. Meteor., 19, 906-907.

Rangno, A. L., and P. V. Hobbs, 1981: Comments on “Reanalysis of ‘Generalized Criteria for Seeding Winter Orographic Clouds’”, J. Appl. Meteor., 20, 216.

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, 1995a: A new look at the Israeli cloud seeding experiments. J. Appl. Meteor., 34, 1169-1193.

Rangno, A. L., and P. V. Hobbs, 1995b: 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.

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

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

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

Rangno, A. L., and P. V. Hobbs, 1997e: Reply to Woodley. J. Appl. Meteor., 36, 253-254.

Rangno, A. L., and S. Suloway, 1974:  Pre-empting God, Deep Creek Review article on cloud seeding.

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.

Willis, P. T, and A. L. Rangno, 1971: Colorado River Basin Pilot Project, Comprehensive Atmospheric Data Report, Phase II, Winter Season of 1970-71, Vol. I, Report to the Bureau of Reclamation, 71 pp.