WAVES OF IONIZATION IN LIGHTNING DISCHARGE

The formation of lightning channels overlapping the cloud-to-ground ga p is considered. The consideration is based on the general properties of an ionization wave propagating in a gas. The wave development is ca used by a local strengthening of the electric field at the wave front due to its own space charge. Simple simulation models are proposed to estimate the parameters of the wave processes that develop in the heat ed track of the grounded channel after its contact inside the cloud wi th a new spark channel originating from a distant lightning center. Th e influence of the initial channel conductivity and of the value of th e contact potential drop, which is of the order of megavolts, is studi ed. A model describing both the M-component and dart leader of the mul ticomponent lightnings like the wave processes is proposed. The high v elocity of the dart leader propagating in the preheated channel track is comparable to the velocity of the electromagnetic waves. Such a vel ocity of the dart leader is shown to be provided by only the one-stage gas ionization that is usual for the streamer-type process.