title: Fractal dynamics of electric discharges in a thundercloud.
abstract: We have investigated the fractal dynamics of intracloud microdischarges responsible for the formation of a so-called drainage system of electric charge transport inside a cloud volume. Microdischarges are related to the nonlinear stage of multiflow instability development, which leads to the generation of a small-scale intracloud electric structure. The latter is modeled by using a two-dimensional lattice of finite-state automata. The results of numerical simulations show that the developed drainage system belongs to the percolation-cluster family. We then point out the parameter region relevant to the proposed model, in which the thundercloud exhibits behavior corresponding to a regime of self-organized criticality. The initial development and statistical properties of dynamic conductive clusters are investigated, and a kinetic equation is introduced, which permits us to find state probabilities of electric cells and to estimate macroscopic parameters of the system.
authors.affiliation: Institute of Applied Physics, Russian Academy of Science, 46 Ulyanov Street, Nizhny Novgorod 603600, Russia.
authors.forename: D I
authors.initials: DI
authors.lastname: Iudin
authors.forename: V Y
authors.initials: VY
authors.lastname: Trakhtengerts
authors.forename: M
authors.initials: M
authors.lastname: Hayakawa