The spectra of charging events due to the collision of natural ice particles with an ice surface

Abstract

AbstractA sensitive, solid state electrometer has been built which is capable of measuring the individual charges acquired by an ice surface exposed to precipitation or cloud particles. Measurements made in natural snowfall show that the individual charges fluctuate widely both in sign and magnitude. Individual charges ranging from ‐10−2 e.s.u. to 10−2 e.s.u. have been recorded within an interval of a few seconds. In most cases the ice surface received a net positive charge, and the median charge per collision was about 2 × 10−4 e.s.u. The charging spectra commonly followed a log‐normal distribution.It is suggested that two important mechanisms for the charging were the direct transfer to the ice surface of some of the charge residing on the ice particles in the air and the fragmentation of the ice particles as they collided with the ice surface.