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Memories of Peter Hobbs. A Cloud Physicist Who Studied Fronts and Cyclones. He and his group either organized or were major players in a number of field programs that contributed immeasureably to our understanding of cyclones and fronts :. Peter: The Renaissance Man. Voracious reader
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A Cloud Physicist Who Studied Fronts and Cyclones • He and his group either organized or were major players in a number of field programs that contributed immeasureably to our understanding of cyclones and fronts:
Peter: The Renaissance Man • Voracious reader • Opera fanatic (especially Wagner)
Peter Hobbs, Professor of Atmospheric Sciences at the University of Washington, passed away on July 25 after a long struggle with pancreatic cancer. A leader in cloud and aerosol physics and a pioneer in the use of airborne observing platforms, his research also spanned areas such mesoscale precipitation structures, frontal evolution, atmospheric chemistry and radiation. Hobbs was a prolific writer with hundreds of refereed articles and several books, including a highly popular introductory text. • Born in 1936, Hobbs was "a wild, adventurous youth” who engaged in competitive swimming and held the title Junior Boxing champion of the County of Surrey. It was also during these years that developed a keen interest in science. At age 12 he attended a public lecture entitled "Clouds and Rainmaking" by the renowned cloud physicist, John Mason, a professor at Imperial College of Science and Technology, London University. After the lecture, Hobbs asked Mason how he might join his research group. Mason replied, "Come back and see me when you have a degree in Physics". Fourteen years later (in 1960), Hobbs appeared at his door with degree in hand and Mason took him on as a graduate student on the spot. Mason went on from Imperial College to head Britain's Meteorological Office and later was knighted for his efforts. • Hobbs completed his Ph.D degree in Physics at Imperial College in 1963 and joined the atmospheric sciences department at the University of Washington later that same year. As a young faculty member he established the Cloud and Aerosol Research Group, which grew to be the largest group in the department and maintained its vitality for nearly 40 years. • Hobbs' early research focused on laboratory and theoretical studies of cloud processes including diffusion, collision/coalescence, freezing, fragmentation, and electrification of ice particles. By the late 1960s his research group had expanded and become engaged in ground-based field studies of aerosols and clouds, including measurements from a nearby field station at 8000 ft in Olympic National Park. • Peter dreamed of creating an airborne cloud physics laboratory and in 1970 his group acquired their first research aircraft: a World War II-vintage Douglas B-23, previously owned by Howard Hughes. With instrumentation carried on the aircraft it was possible to obtain images of ice particles, to sample aerosols and gases, and to measure ice particle concentrations in real time as they flew through clouds. Between 1970 and 1984 Peter and co-workers flew thousands of hours on the B-23. Data collected on these flights provided the basis for some eighty scientific papers and thirty student theses, on subjects ranging from atmospheric aerosols and cloud chemistry to cloud physics and mesoscale meteorology. During this period Hobbs lead a number of major projects that made use of the aircraft, including the Cascade Project (1970-1974) which studied the structures of clouds, the formation of precipitation over the Cascade Mountains, and the effects of cloud seeding; and the CYCLES Project (1973-1986) which was concerned with cloud microphysics and the mesoscale organization of rainfall in cyclonic storms over the Pacific Northwest. That Doppler radars can be used to determine temperature advection was first demonstrated in the CYCLES Project. Hobbs called attention to and helped to explain the phenomenon of "ice enhancement" (also referred to as ice multiplication) in natural clouds. In aircraft observations taken over the state of Washington during in the 1970s he found that ice particle concentrations in real clouds typically exceeded the concentrations of active ice nuclei by orders of magnitude. On the basis of subsequent measurements it is now well established that ice enhancement occurs in both convective and frontal clouds, over both land and ocean, and at all latitudes. The B-23 was also used in some of the first airborne studies of volcanic effluents: Mt. Baker (in 1975), several volcanoes in Alaska and, most spectacularly, the major eruption of Mt. St. Helens in 1980. • In 1984 the B-23 was replaced by the considerably larger Convair-131A, which was equipped with extensive instrumentation for studying atmospheric aerosols, clouds, atmospheric chemistry and radiation. Using the C-131A, Hobbs and colleagues examined the structures of clouds (with emphasis on the ice phase), the effects of clouds on solar radiation, pollution in the Arctic, the properties of smoke and its effects on climate, the chemistry of the marine atmosphere, and aerosol-cloud interactions. Of particular note were their studies of smoke from the 1991 Kuwait oil fires, and an extensive study of smoke from biomass burning in the Amazon Basin in 1995 (SCAR-B).On the basis of these measurements, Hobbs and his colleagues showed that the particles in smoke are blacker, and hence have less cooling effect on climate, than previously believed. Also during this period, Peter’s group studied cloud structures and the organization of precipitation over the East Coast and the Central United States. The latter studies documented non-standard structures west of the Rockies and led to a new conceptual model for cyclones and their attendant fronts. • In March 1997 Hobbs' group acquired an even more capable Convair-580 aircraft and transformed it into perhaps the world’s most capable platform for measuring trace gases, atmospheric aerosols and clouds. Peter took the Convair-580 to Alaska in 1998 for the FIRE-ACE/SHEBA to study Arctic clouds, the Marshall Islands in 1999 for the KWAJEX project to examine mesoscale convective systems, and to southern Africa in 2000 for SAFARI-2000 to investigate the effects of biomass burning. Next in line were the extensive IMPROVE-I and IMPROVE-II projects over the U.S. Pacific Northwest in 2001, which were directed to producing unique datasets that would allow improvement of model cloud physics parameterizations, and finally the CLAMS project, on the U.S. East Coast in 2001, whose goal was to understand radiative effects of aerosols over a marine environment. The world's largest raindrops, with diameters ranging up to nearly 1 cm were collected by Hobbs' group in aircraft flights over Brazil and the Marshall Islands, and are listed in the GuinnessBook of World Records. At the end of 2001, the Peter sold the Convair in order to concentrate his group’s efforts on the analysis of the large amounts of airborne data it has collected.
Hobbs also earned distinction as an educator and writer. His projects provided a generation of students and researchers with the opportunity to do cutting-edge experimental research. He supported and supervised 34 M.S. students and 29 Ph.D. students, a number of whom have gone on to leadership positions in university departments and national laboratories. He authored or co-authored over 340 refereed papers and four books: Ice Physics (Oxford University Press, 1974), Basic Physical Chemistry for the Atmospheric Sciences (Cambridge University Press, 1995, 2000), Introduction to Atmospheric Chemistry (Cambridge University Press, 2000), and Atmospheric Science: An Introductory Survey (co-authored with J.M. Wallace, Academic Press, 1977). The latter book has sold over 50,000 copies and has been the dominant upper-level introductory atmospheric sciences textbook for decades. One of his last acts, heroic in nature considering his illness, was to complete his sections for a second edition, which should be available early next year. Finally, his lectures were known for their rigor and clarity. One of his teaching innovations was to require that students solve problems on the board in front of the class: a highly effective motivator, indeed. • Beyond atmospheric sciences, Peter’s interests were eclectic and wide ranging. A regular runner until his final year, he also was an avid golfer who took his clubs on many a field program. But his greatest outside passion was music. Peter loved opera and was particularly fond of Wagner, with the Ring Cycle being his favorite entertainment. He served as the outside graduate representative on a number of UW School of Music masters and doctoral committees. • Peter’s honors and awards include the Jule G. Charney Award and honorary membership in the AMS, and the Senior Alexander von Humboldt Award of the AAAS. Recently he and Art Rangno were awarded the WMO/UAE prize in recognition of their work on weather modification. He is a Fellow of the AGU. • In addition to his wife Sylvia, Peter is survived by his three sons—Stephen, Julian and Rowland—and three grandchildren. More information about Hobbs' professional career, including pictures, news articles and personal reminiscences, can be viewed at http://carg.atmos.washington.edu/.
