Duration of Lightning Strokes and Occurrence of Multiple Strokes

It is shown that the total duration of lightning strokes, the occurrence of multiple strokes and the time interval between them are partially influenced when measurements are made on direct strokes to tall objects. By recording the radiated electromagnetic field of lightning discharges in antenna circuits with cathode ray oscillographs at great distances from the lightning paths it was possible to obtain extensive data on the variation characteristics of lightning. Special methods were developed in order to analyse the lightning discharges with regard to the sequence of multiple strokes and the slow moving after-variation. A comparison of the discharge characteristics of lightning in Sweden with corresponding results from lower latitudes leads to the assumption that the intensity of thunderstorms is greater in low latitudes than in high latitudes. This involves researches of a geophysical problem of greatest interest from different points of view.