Lightning, Solar Flares and Radio Galaxies

Abstract

IN 1925, when it was still believed that a potential of n × 10⁹ V was necessary to cause a lightning flash^1a, C. T. R. Wilson put forward the suggestion that the soft cosmic rays up to about 10⁹ eV might be accounted for by runaway electrons in thundercloud fields^1b. When it was pointed out that a lightning flash can occur with a total thundercloud potential of n × 10⁷ V (refs. 2^a,b), the suggestion ceased to have much significance as applied to thunderclouds. However, in presenting a paper on these long leader strokes at the Belfast meeting of the British Association in 1952, I pointed out^2c that the Wilson mechanism might apply in the much longer cosmic electrical discharges, in which relatively large electric fields must be built up by the short-circuiting of these much more extensive electric fields by the leader stroke of such discharges as solar flares.