The cover article of the April 2012 issue of Discover Magazine, entitled "Life at the Edge of Space: Do high-flying microbes control Earth's weather?", features the impact of biological aerosol on what is perhaps the most chemically sensitive cloud process: ice crystal formation.
The chemical influence of atmospheric aerosols on ice nucleation in clouds has been a significant focus of the Prather Research Group over the last 5 years, beginning with the ICE-L field campaign in 2007, where ice cloud particles were sampled directly into an ATOFMS for the first time -- this was also the first deployment of an ATOFMS on an aircraft platform (NSF/NCAR C-130). Since that first deployment, our Aircraft ATOFMS (a.k.a. - Shirley) has been included on 4 more aircraft-based field campaigns, including two focused on the influence of atmospheric aerosol chemistry on cloud ice nucleation: CalWater 2011 and ICE-T. Through these studies, and the work of others in our field, we are coming to understand the importance of biological material on the formation of ice particles in clouds -- a crucial element in understanding, for instance, the amount of precipitation that a storm will produce.
A few key Prather Resarch Group references (for others, see our Publications page, links may require subscription for full access):
Pratt KA, DeMott PJ, French JR, Wang Z, Westphal DL, Heymsfeld AJ, Twohy CJ, Prenni AJ, Prather KA. In situ detection of biological particles in cloud ice crystals. Nature Geoscience (2009), 2, 398-401.
Ault AP, Williams CR, White AB, Neiman PJ, Creamean JC, Gaston CJ, Ralph FM, Prather KA. Detection of Asian Dust in California Orographic Precipitation. Journal of Geophysical Research - Atmospheres (2011), 116, D16205.
Twohy CH, DeMott PJ, Pratt KA, Subramanian R, Kok GL, Murphy SM, Lersch T, Heymsfield AJ, Wang ZE, Prather KA, Seinfeld JH. Relationships of Biomass-Burning Aerosols to Ice in Orographic Wave Clouds (2010) Journal of the Atmospheric Sciences 67 (8) 2437-2450.