Lightning initiation by simultaneous effect of runaway breakdown and cosmic ray showers

The combined action of cosmic ray showers (CRS) and runaway breakdown (RB) on thunderstorm atmosphere is studied. The ionization of atmosphere produce d by CRS core being strongly amplified in RB conditions is shown to be suff icient to generate a highly ionized plasma region. Electric polarization of this plasma region is manifested in a significant local amplification of a thunderstorm electric field, what could result in a local electric breakdo wn and lead to initiation of lightning. Experiments which could check the p redictions of the theory are proposed. (C) 1999 Published by Elsevier Scien ce B.V.