THE ATMOSPHERIC ELECTRICITY PARADIGM

Remarkable aspects of the thundercloud are its intense electrification , precipitation, and convection. A satisfactory understanding of how a thunderstorm works will require a continuing series of investigations to explore the complicated interrelationships among these phenomena. Until now the major effort has been devoted to studies of how precipit ation causes electrification. For a century, investigations of thunder storms have been dominated by the idea that lightning is produced by a charge-separation process within the cloud caused by falling precipit ation. The origin of this idea, its implications, present status, and probable future are examined in the light of T. S. Kuhn's views on the nature of scientific progress. Despite some achievements, the results of research based on the precipitation theory have proved disappointi ng. For example, they have shed little light on important problems suc h as the factors that determine the polarity of the cloud electric dip ole and the role that electricity plays in meteorological processes. D uring this century, with the discovery of cosmic rays and the ionizati on they produce in the air above the cloud, it has become apparent tha t other processes, which do not involve contact charge separation orf ailing precipitation, are also causing electrification. Thunderstorms exercise great influence, for both good and bad, on many human activit ies. In view of their great environmental importance, it is surprising how little is known about them and how little effort is being made to understand how they work. It is urged that the present limited thunde rstorm research activities be expanded to include new, and possibly mo re productive, approaches.