A Laboratory investigation is proposed to explore the hypothesis that some collisions between supercooled precipitation drop result in freezing and that a collision-ice nucleation mechanism may account for the kind and number of first ice particles in warm-based midwestern convective clouds. An apparatus will be constructed that will produce isolated collisions between supercooled drops initially falling freely at terminal velocity. Experiments will be conducted over a range of collector drop sizes and size ratios. Collisions will be recorded photographically to measure the possible dependency of freezing on impact angle and occurrence of coalescence, bounce or temporary coalescence. Data will first be collected for minimally charged drops created from distilled deionized water. By exploring a relatively overlooked but prevalent microphysical process, the goal of this research is to provide a better understanding of the role of supercooled drop collisions in the production of ice in clouds and the consequent influence these may have on the production of rain in the warm-based convective clouds of the midwestern United States. //
