Laboratory Studies of Selected Cloud Microphysical Processes

该项目的重点是使用带有电动天平的云室进行实验，该天平允许长时间观察单个悬浮冰晶，因为它们在温度，压力和湿度的受控条件下生长或蒸发。 压力和温度可以设置得足够低，以模拟大气中卷云的条件。 将进行三组实验：（1）测量卷云典型冰晶的生长、蒸发和光散射特性;（2）研究液滴的冻结和从球形到晶体形状的快速演变;（3）测量晶体对碰撞时质量和电荷的转移。 这项工作将有助于基本问题，如晶体习性及其对环境条件的依赖性，对卷云气候效应的当前关注，以及更好地了解不同环境条件下冰晶的生长和蒸发。

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.