Atmos. Chem. Phys., 12, 1189-1201, 2012
www.atmos-chem-phys.net/12/1189/2012/
doi:10.5194/acp-12-1189-2012
© Author(s) 2012. This work is distributed
under the Creative Commons Attribution 3.0 License.
Deposition nucleation on mineral dust particles: a case against classical nucleation theory with the assumption of a single contact angle
M. J. Wheeler and A. K. Bertram
Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada

Abstract. Deposition nucleation on two mineral species, kaolinite and illite, was studied using a flow cell coupled to an optical microscope. The results show that the Sice conditions when ice first nucleated, defined as the onset Sice (Sice,onset), is a strong function of the surface area available for nucleation, varying from 100% to 125% at temperatures between 242 and 239 K. The surface area dependent data could not be described accurately using classical nucleation theory and the assumption of a single contact angle (defined here as the single-α model). These results suggest that caution should be applied when using contact angles determined from Sice,onset data and the single-α model. In contrast to the single-α model, the active site model, the deterministic model, and a model with a distribution of contact angles fit the data within experimental uncertainties. Parameters from the fits to the data are presented.

Citation: Wheeler, M. J. and Bertram, A. K.: Deposition nucleation on mineral dust particles: a case against classical nucleation theory with the assumption of a single contact angle, Atmos. Chem. Phys., 12, 1189-1201, doi:10.5194/acp-12-1189-2012, 2012.
 
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