ACP Atmospheric Chemistry and Physics ACP 1680-7324 Copernicus GmbH Göttingen, Germany 10.5194/acp-7-309-2007 Technical Note: The heterogeneous Zeldovich factor Vehkamäki H. 1 Määttänen A. 1 Lauri A. 1 Napari I. 1 Kulmala M. 1 Department of Physical Sciences, Division of Atmospheric Sciences, University of Helsinki, Helsinki, Finland 19 01 2007 7 2 309 313 This is an open-access article ditributed under the terms of the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited. This article is available from http://www.atmos-chem-phys.net/7/309/2007/acp-7-309-2007.html The full text article is available as a PDF file from http://www.atmos-chem-phys.net/7/309/2007/acp-7-309-2007.pdf

In this technical note we present the exact form of the Zeldovich factor for heterogeneous nucleation on spherical pre-existing particles. We study the error caused by planar pre-existing surface approximations, which have been used in our earlier heterogeneous nucleation model and elsewhere in the literature. We also test the significance of widely used approximations for cluster surface area and circumference. We conclude that the approximations do not affect the predicted onset saturation. Especially for small pre-existing particles the nucleation rates calculated with the exact and approximative models differ significantly.

 References Laaksonen, A., McGraw, R., and Vehkamäki, H.: Liquid-drop formalism and free-energy surfaces in binary homogeneous nucleation theory, J. Chem. Phys., 111, 2019–2027, 1999. Määttänen, A., Vehkamäki, H., Lauri, A., Merikallio, S., Kauhanen, J., Savijärvi, H., and Kulmala, M.: Nucleation studies in the Martian atmosphere, J. Geophys. Res., 110, E02002, doi:10.1029/2004JE002308, 2005. Ono, S. and Kondo, S.: Encyclopedia of Physics, p. 134, Springer, Berlin, 1960. Pruppacher, H R. and Klett, J D.: Microphysics of Clouds and Precipitation, Kluwer Acad., Norwell, Mass., 1997.