Speaker: Prof. Bart Geerts, University of Wyoming
Title: The history of cloud seeding to enhance precipitation, and prospects for the future
Location: Kane 220
Register for free here: http://events.uw.edu/Hobbs2018
Questions: atmos@uw.edu

Abstract: Cloud seeding is conducted in most states in the western United States, and in other arid regions around the world, in order to enhance precipitation. The main target is winter storms over mountains. The history of cloud seeding is long, and many cloud physicists, including Peter V. Hobbs, built their early career on researching seeding efficacy in the 1960s-1980s. Federal support for weather modification research ceased about three decades ago, not because of environmental or ethical concerns, but rather because of the difficulty of signal detection in the “noise’ of natural variability. Peter V. Hobbs became one of the most vociferous scientists to show that some published claims of seeding impact were exaggerated, false, or unverifiable. Operational seeding, meanwhile, has continued unabated, especially in dry years. We are now in a far stronger position to study changes in mountain clouds following injection of artificial ice nuclei, by means of both detailed observations using new instruments, and high-performance computing efforts that simulate the flow, cloud, and snowfall over the mountains. Thus the National Science Foundation recently supported some field work to re-examine this issue. We now have definitive proof that cloud seeding can have a modest impact on precipitation, but it remains very difficult to detect and target the “right” clouds.

The purpose of the Peter V. Hobbs Memorial Endowed Lectureship in Experimental Meteorology shall be to sponsor open lectures in the field of experimental meteorology. Peter Hobbs felt strongly that the furthering of science must be nurtured through the open exchange of ideas amongst scientists. To that end, he planned to fund an Endowed Lectureship in Experimental Meteorology for the Atmospheric Sciences Department at the University of Washington where he had worked for 42 years.

Peter Hobbs was deeply involved all his working life in the field of experimental meteorology which ranges from the microscale, through the mesoscale, up to the global scale, and includes both the physics and chemistry of the atmosphere. The common threads in this field are the ubiquitous roles played by aerosols, clouds and precipitation in the atmosphere.

The gift to establish this endowed lectureship was made in loving memory of Peter by his wife and three sons.