Electrification of convective clouds is associated with the interaction of large ice particles, so studying the distribution patterns of graupel and hail in a cloud is a crucial task of cloud physics. The authors examined the radar characteristics of 10 thunderclouds near Saint Petersburg during the period of the highest flash rate. The data showed that a sharp increase in the frequency of lightning (“lightning jump”) was observed in some clouds. Statistical characteristics of clouds indicate that the volumes of hail, low- and high-density graupel in such clouds were significantly greater than those in clouds without a lightning jump. The assumptions about an increase in the electrical activity of clouds with an increase in the content of graupel and hail, as well as the obtained data on the lightning jump in the study region, can be used in constructing physical and statistical models of cloud electrification.
Sin’kevich et al. (Sat,) studied this question.