The Mechanism of Ice Crystal Growth and Habit Formation

Abstract

The formation of multiple layers of adsorbed water molecules on the basal and prism faces of ice may be responsible for the remarkable temperature dependence of all growth variables (linear growth rate, step velocity, and mean migration distance). This effect results from an increased residence time of molecules in the adsorbed state as the melting point is approached. A quantitative treatment based on the Brunauer, Emmett and Teller model of multi-layer adsorption exemplifies these concepts and appears to explain the measured trends with temperature. When the theoretical treatment is used in conjunction with a growth model based on the propagation of spiral steps, reasonable values for the condensation coefficient emerge. The alternation of the primary habit of ice crystals with temperature is explained when the theoretical treatment is applied to the basal and prism faces, respectively.