Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 4, 1059-1071, 2007
© Author(s) 2007. This work is licensed under
the Creative Commons Attribution-NonCommercial-ShareAlike 2.5 License.
03 Dec 2007
Microbiology and atmospheric processes: the role of biological particles in cloud physics
O. Möhler1, P. J. DeMott2, G. Vali3, and Z. Levin4 1Institute for Meteorology and Climate Research (IMK-AAF), Forschungszentrum Karlsruhe, Germany
2Department of Atmospheric Science, Colorado State University, Fort Collins, CO, USA
3Department of Atmospheric Science, University of Wyoming, Laramie, WY, USA
4Department of Geophysics and Planetary Science, The Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Israel
Abstract. As part of a series of papers on the sources, distribution and potential impact of biological particles in the atmosphere, this paper introduces and summarizes the potential role of biological particles in atmospheric clouds. Biological particles like bacteria or pollen may be active as both cloud condensation nuclei (CCN) and heterogeneous ice nuclei (IN) and thereby can contribute to the initial cloud formation stages and the development of precipitation through giant CCN and IN processes. The paper gives an introduction to aerosol-cloud processes involving CCN and IN in general and provides a short summary of previous laboratory, field and modelling work which investigated the CCN and IN activity of bacterial cells and pollen. Recent measurements of atmospheric ice nuclei with a continuous flow diffusion chamber (CFDC) and of the heterogeneous ice nucleation efficiency of bacterial cells are also briefly discussed. As a main result of this overview paper we conclude that a proper assessment of the impact of biological particles on tropospheric clouds needs new laboratory, field and modelling work on the abundance of biological particles in the atmosphere and their CCN and heterogeneous IN properties.

Citation: Möhler, O., DeMott, P. J., Vali, G., and Levin, Z.: Microbiology and atmospheric processes: the role of biological particles in cloud physics, Biogeosciences, 4, 1059-1071,, 2007.
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