Drs. Pitter and Finnegan will investigate the effects of included inorganic, ionizable salts on the morphology of ice crystals growing in a supercooled liquid water cloud. The hypothesis to be tested is that the freezing potential, previously studied for bulk freezing of aqueous solutions, is applicable to vapor growth of ice crystals, and that the electrostatic forces that result from the freezing potential interact with the ice surface tension to determine how the ice crystals grow. The ice crystals are nucleated in a cloud chamber and grow in free-fall, collecting inorganic salt chemicals by the same mechanisms that are operable in atmospheric clouds. The work is also of potential importance to crystal growth science in general. Since ice crystal morphological detail is an intrinsic and important factor in ice crystal growth rate and hence the time for crystal development prior to the onset of aggregation and/or riming, this research has significance in the understanding of the formation of precipitation in clouds with a mixture of ice and water.
