Abstract
Results are described of measurements of the electric charge of individual cloud particles of diameter ranging from 15μ to 200μ carried out at the top of Mt. Teine from 1957 to 1959. The cloud particles are classified into warm cloud particles, supercooled cloud particles, frozen cloud particles and ice particles.
Both positive and negative cloud particles were observed but the portion of negative cloud particles was larger than that of positive ones through the cloud particles of all types. Mirror image relation like that in rainfall held in most cases. The magnitude of charge of cloud particles was roughly proportional to the cube of their diameters. In liquid state, charged cloud particles were considerably larger than non-charged ones.
Considering those results, the mechanism of electrification of relatively large cloud particles was considered to be as follows. In initial state of electrification, cloud particles are charged to the sign opposite to that of the prevailing electric field as a result of Wilson's ion capture process. Then larger cloud particles grow by uniting with smaller charged cloud particles of same sign produced by Wilson's process. After freezing of cloud particles, further charge generation by mutual friction will occur.
