Collaborative Research on Aircraft Icing and Charging Processes in Ice

摘要

This study is into the electrification processes that occur when ice crystalscollide with other bodies. The work is of relevance to the charging of ice pellets falling in thunderstorms when they collide with ice crystals, and to the charging of aircraft when they fly through ice phase precipitation. The study relates the thunderstorm field measurements made over recent years to the laboratory simulations of thunderstorm conditions. Charging is shown to be dependent on the water content in the cloud, on the ice crystal sizes, on the speed of impact, and on the temperature. Several theories to account for this charge transfer behavior are discussed, including measurements of a charge layer at an ice interface that may be indicative of charge being available for transfer during ice particle collisions. The major conclusion is that all the proposed mechanisms have problems in accounting for the observed charging behavior. Further field studies are needed in which the growth or sublimation state of ice pellets in thunderstorms may be identified so that laboratory simulations can be made more relevant.