Deposition ice nucleation via homogeneous freezing of adsorbed water

Deposition ice nucleation (DIN) occurs when water insoluble particles (that are not immersed in water or aqueous solution droplets) initiate the growth of ice crystals in water vapor supersaturated with respect to ice. The classical view (Fletcher, 1959) of DIN is similar to that of the heterogeneous nucleation of liquid droplets: a sufficient number of water molecules originating from the vapor phase come together at a surface within a sufficiently short period of time, forming a critical cluster that is large enough so that it does not decay but starts collecting more vapor molecules and growing. In addition to being large enough, the ice cluster must also organize into a crystalline configuration, which obviously drastically decreases the probability of a nucleation event. It therefore seems likely that an intermediate liquid phase (Ostwald, 1897) is involved in the DIN process. During the past decade, the pore condensation and freezing mechanism (Marcolli, 2014), in which liquid water condenses in the pores of insoluble aerosols and subsequently freezes, has been considered a candidate for the mechanism of atmospheric DIN events. However, it is known from laboratory studies that DIN can also occur on nonporous aerosols. In this work, we have developed a theoretical framework for describing DIN as homogeneous freezing in multilayer adsorbed water. We compare the predictions of the theory to laboratory data of critical supersaturations for DIN on nonporous silica particles at temperatures down to 208 K and find very good agreement.     

Fletcher, N. H. (1959). On ice-crystal production by aerosol particles, J. Atmos. Sci., 16, 173–180.

Marcolli, C. (2014) Deposition nucleation viewed as homogeneous or immersion freezing in pores and cavities, Atmos. Chem. Phys., 14, 2071–2104,

Ostwald, W. (1897). Studien über die Bildung und Umwandlung fester Körper. 1. Abhandlung: Übersättigung und Überkaltung. Z. Phys. Chem., 22, 289-330.