Remarkable Characteristics of Cloud-to-Ground Discharges Observed in Winter Thunderstorms in Hokuriku Area, Japan

Abstract

During the winters from 1972/73 to 75/76, we have observed winter thunderstorms in Hokuriku Area, Japan and we have found from the observations that most of return strokes neutralized positive charge in the thunderclouds contrary to the strokes in summer which neutralized negative charge in the clouds. Though only one, we have observed a cloud-to-ground discharge initiated by a upward streamer from a structure lower than 15m. The study of such upward streamer in winter seems to be very important for protection of transmission lines against damage by lightnings.