The electric field alignment of ice crystals in thunderstorms

The re-orientation of ice crystals in cirrus anvils following a lightning stroke is often visible from the ground with a sudden change in cloud brightness. Vonnegut suggested that this effect was due to electric field orientated ice crystals relaxing their orientation upon the removal of the field. Laboratory measurements of the electric field strength required to orientate ice crystals typical of those in thunderstorm anvils have now been made. The particular distribution of visible laser light scattered by a cloud of ice crystals orientated in an electric field is used to identify the types of ice crystal present.