The influence of rain on the atmospheric-electric field

Abstract

Photographic records of the atmospheric-electric field variations at times of rain are examined along with pluviograms covering these periods. It is found that the normal effect of rain is to abruptly reverse the normal positive field in the early stages, while in a few cases it results in a sudden reduction without change of sign. This abrupt change disappears speedily when the disturbing shower is of short duration. An analysis of the results of G. C. Simpson at Simla (1908-1909) in regard to the charge brought down by rain is given. It is shown that in the earliest stages of charged rain, in more than 85 per cent of the cases, the net charge brought down by rain is positive. It is then shown that the effect of rain on the field is due to the transfer of charge by the rain from the upper air. Calculation shows that the charge transferred by the rain is of the order necessary to produce the observed changes of potential. The explanation covers the cases of heavy rain attended with frequent reversals and very high values of the field.