Formation of patterns during growth of snow crystals

Abstract

We discuss recent progress in the understanding of the formation of patterns of snow crystals. In particular, we concentrate on the transition from hexagonal to dendritic patterns that occurs with an increase in the degree of supersaturation. Our numerical results demonstrate that the anisotropy of surface kinetics plays a very important role in the formation of faceted shapes of snow crystals in the form of hexagonal prisms and of facets seen at the tips of dendrites. Furthermore, it is shown that the conditions for the transition from a hexagonal to a dendritic pattern are given by the supersaturation and the dimensionless crystal size relative to the mean free path of a water molecule in air.