Rates of growth of the electric field by the induction charging mechanism of charge generation in thunder-clouds have been calculated for various precipitation rates. It is concluded, in addition to point-discharge currents below the thundercloud and the conduction currents inside the thundercloud as leakage currents, that the electrical forces acting on precipitation and smaller size particles are important in determining the maximum electric field and the rate of charge separation in thunderclouds. The results have been qualitatively generalized for any charge generating mechanism based on the failing precipitation mechanism of charge separation in thunderclouds.

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