Laboratory Studies of Selected Cloud Microphysical Processes

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This project is centered on experiments using a cloud chamber with an electrodynamic balance that permits the observation of individual, levitated ice crystals for long periods of time as they grow or evaporate in controlled conditions of temperature, pressure, and humidity. The pressure and temperature can be set low enough to simulate the conditions in cirrus clouds in the atmosphere. Three sets of experiments will be performed: (1) measurement of the growth, evaporation, and light-scattering properties of ice crystals typical of cirrus clouds; (2) study of the freezing of liquid droplets and the rapid evolution from spherical to crystal shape; (3) measuring the transfer of mass and electrical charge between pairs of crystals as they collide. This work will contribute to fundamental questions such as crystal habit and its dependence on environmental conditions, to current concerns about climatic effects of cirrus clouds, and to a better understanding of the growth and evaporation of ice crystals under different environmental conditions.