Electrification experiments on Elk Mountain

Abstract

During the winter of 1976, along with the continuing studies of ice crystals in the cap cloud on Elk Mountain, measurements were made of ice crystal charges and the atmospheric electric field strength. The electric field was, in general, found to be of the same sign as the fair weather field. The net particle charges were predominantly positive with mean values of the order of ±10−14 C with fairly symmetrical distributions of positive and negative charges. The ‘mirror image’ effect was seldom observed perhaps because of the small extent and short lifetime of the cap cloud. The absence of large negative charges suggests that the particles and particle charges do not originate from blowing snow. A mechanism of charging which may explain the symmetrical charge distributions is inductive charge transfer between particles which contact and then separate in random directions relative to the electric field.