Frazil-Ice Nucleation by Mass-Exchange Processes at the Air-Water Interface

Abstract The physical requirements for proposed frazil-ice nucleation theories are reviewed in the light of recent observations on frazil-ice formation. It is concluded that spontaneous heterogeneous nucleation in a thin supercooled surface layer of water is not a viable mechanism for frazil-ice nucleation. Efforts to observe crystal multiplication by border ice have not been successful. The mass-exchange mechanism proposed by Osterkamp and others (1974) has been generalized to include splashing, wind spray, bubble bursting, evaporation, and material that originates at a distance from the stream (e.g. snow, frost, ice particles, cold organic material, and cold soil particles). It is shown that these mass-exchange processes can account for frazil-ice nucleation under a wide range of physical and meteorological conditions. It is suggested that secondary nucleation may be responsible for large frazil-ice concentrations in streams and rivers.