Articles | Volume 4, issue 6
Biogeosciences, 4, 1059–1071, 2007

Special issue: Properties of biological aerosols and their impact on atmospheric...

Biogeosciences, 4, 1059–1071, 2007

  03 Dec 2007

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 O. Möhler et al.
  • 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.

Final-revised paper