降雪による地表電場の擾乱について

Abstract

Simultaneous observation of surface electric field, charge on snow particles, rate of snowfall, crystal type of snow crystals was made during snowfall in four winter seasons from 1956 to 1960 in Sapporo. Various patterns of the surface electric field occurred during the observation.From the observational results obtained, the following conclusions were obtained.1. In the case of quiet and light snowfall from higher clouds of layer type, non-rimed snow crystals are charged negatively by a mechanism similar to Wilson's induction mechanism, and the so called inverse relation between positive surface electric field and negative charge on falling snow crystals is observed.2. In the case of heavy snowfall from such as nimbocumulus clouds, graupel or rimed snow particles are charged positively at temperature higher than -10°C by friction with non-rimed snow crystals which are charged negatively. A negative surface electric field is formed by the removement of positive charge on falling graupel from cloud layer, and thus inverse relation (positive snowfall under negative surface electric field) is observed.3. In the case of showery snowfall, negative and positive sharp peaks occur in the electric field record. These peaks are produced by the change of local space charge near the observation point. The mechanism of charge generation is the same as in 2.