THE MICROPHYSICAL AND ELECTRICAL PROPERTIES OF SPRITE-PRODUCING THUNDERSTORMS

摘要

Sprites and elves are caused by exceptional lightning flashes in storms distinguishable in both size and structure from ordinary thunderstorms. An ice-based mechanism for charge separation known as the non-inductive process is capable of explaining macroscopic features of both ordinary and sprite-producing thunderstorms. Accordingly, the microphysical basis for this mechanism is reviewed. A key distinction for the sprite-producing storm in summer is the development of a large and laterally-extended reservoir of positive charge in the lower portion of the cloud, favorable to the occurrence of positive ground flashes with exceptional charge moments (>500 C·km). The electrical structure of sprite-producing storms in summertime is presently better resolved than wintertime scenarios.