XV. On the electricity of rain and its origin in thunderstroms

Abstract

Since Franklin first showed that thunder and lightning are caused by electrical discharges, there have been numerous theories to account for the production of electricity in thunderstorms, but none has been generally accepted by meteorologists. When attacking the problems of thunderstorm electricity, two methods naturally present themselves: we may either investigate the actual phenomena in the atmosphere, or try to repeat on a small scale in the laboratory the processes which may be supposed to take place during thunderstorms. During 1907-8 an investigation was undertaken on both these lines at the Meteorological Office of the Government of India in Simla. A systematic record was obtained by automatic instruments of the electricity brought down by the rain during practically the whole of one rainy season, and laboratory experiments were made to find the origin of the electricity of thunderstorms. The work has resulted in the formation of a new theory, which appears to account in a satisfactory manner for the electrical effects observed during thunderstorms. The following paper is divided into three parts:—Part I deals with the measurements of the electricity of the rain, Part II with the laboratory experiments, and Part III contains the new theory based on the results detailed in the previous parts.