The Generation of Secondary Ice Particles in Clouds by Crystal Collision

Evidence has accumulated over the last twenty years that in some clouds the concentration of ice crystals may be a factor of four or five orders of magnitude greater than the concentration of observed ice nuclei apparently available to the cloud. A large number of physical mechanisms have been proposed to explain this disparity between the concentration of ice nuclei and ice crystals. This dissertation describes the investigation of one of these mechanisms the generation of secondary ice particles in clouds by crystal-crystal collision. The number of fragments generated by crystal collisions in a cloud is a product of the number of fragments produced per collision and the collision frequency. The first term, called the fragment generation function was obtained experimentally by photographing at high speed, collisions of natural ice crystals with a fixed plate. The number of fragments in a collision was found as a function of th