Ice Crystal Breeding

Authors

  • Richard L Pitter Atmospheric Sciences Center Desert Research Institute University of Nevada System Reno, NV
  • William G Finnegan Atmospheric Sciences Center Desert Research Institute University of Nevada System Reno, NV

Abstract

When ice crystals rapidly grow and aggregate in the Desert Research Institute (DRI) cloud chamber, they frequently produce new ice crystals wlthout the precence of ice forming nuclei. Ammonium salts, initially present in the cloud water and later detected in the ice crystals, enhanced this phenomenon. The continual ice crystal production was observed at temperatures from -4 C to -30 C, although it occurred more frequently when the ice crystals were long needles or dendrltes--hlghly non-spherical. Ice multiplication and secondary ice formation are commonly used in the meteorological literature to describe the phenomenon. The chemical literature (crystal growth) predates the meteorological literature and describes a similar process that occurs in systems of crystals growing in solution. The chemical literature calls the phenomenon crystal breeding. This paper describes the similarity between the systems and advances two postulated mechanlsms, both of which are consistent with our observations of ice crystal breeding and other observations of crystal breeding in solution.

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Scientific Papers