Department of Chemistry, University of British Columbia, Vancouver, BC V6T 1Z1, Canada
Received: 21 Jun 2011 – Published in Atmos. Chem. Phys. Discuss.: 27 Jul 2011
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.
Revised: 02 Jan 2012 – Accepted: 03 Jan 2012 – Published: 30 Jan 2012
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.