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Atmos. Chem. Phys. Discuss., 11, 21171-21200, 2011
www.atmos-chem-phys-discuss.net/11/21171/2011/ doi:10.5194/acpd-11-21171-2011 © Author(s) 2011. This work is distributed under the Creative Commons Attribution 3.0 License. |
Deposition freezing on mineral dust particles: a case against classical nucleation theory with the assumption of a single contact angle
Department of Chemistry, University of British Columbia, Vancouver, BC CAN V6T 1Z1, Canada
Abstract. Deposition freezing on two mineral species, kaolinite and illite, was studied using a flow cell coupled to an optical microscope at ∼240 K. The results show that the onset Sice (defined as the Sice conditions when ice first nucleated) is a strong function of the surface area available for nucleation, varying from 100 % to 125 %. 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 onset Sice 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 normal 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 freezing on mineral dust particles: a case against classical nucleation theory with the assumption of a single contact angle, Atmos. Chem. Phys. Discuss., 11, 21171-21200, doi:10.5194/acpd-11-21171-2011, 2011.