Field Generation and Dissipation Currents in Thunderclouds as a Result of the Movement of Charged Hydrometeors

Abstract

The calculations of Gay et al. of the terminal velocities of charged hydrormeteors in the presence of electric fields have formed the basis of computations of the charging current density J flowing through a thunder-cloud as a result of the operation of a precipitative mechanism of cloud electrification. Values of J were calculated for a range of values of field strength E, precipitation rate pO, precipitation content L, cloud water content C, charge distribution, total separated charge, and the fraction of the small particles that have undergone a charging event. It is found that the estimated field required for the initiation of a lightning stroke (σ3.5 kV cm?1 can be achieved only over a narrow range of conditions. The ease with which precipitative mechanisms can produce breakdown fields is considerably increased, however, if account is taken of spatial inhomogenities in the field.