The Balloon Observation Techniques Utilized for the Studies of Electric Structure

In order to investigate the role of precipitation particles in the electrification mechanism in winter thunderclouds, corona discharge current and electric charge on precipitation were measured simultaneously by a specially designed electric sonde. Since the corona discharge current varies over a wide range in clouds, input sensitivities were changed in succession. The measured values of corona discharge current were translated into electric potential gradient using calibrations, and the total space charge was deduced by Poisson's equation from the electric field under some assumptions. In several test balloon flights, three complete sets of profiles of two electric elements were obtained although they contained some complicated cases. The measurable range of corona discharge current was 2 x 10-10 to 2 X 10-5 A, which corresponds to 10 ' to 10 ' V 1m of electric potential gradient, and sufficiently large compared with the variation of corona discharge current in the cloud. The detectable amount of electric charge on precipitation was 10-3 e.s.u.. 1