NUMERICAL SIMULATION OF HIGH-CURRENT ATMOSPHERIC DISCHARGES WITH CONSIDERATION OF PLASMA CHANNELS THERMODYNAMICS. PART 2. ANALYSIS OF SIMULATION RESULTS

The article presents the second part of the study devoted to the modeling of high-current lightning discharges. The first part [part 1] describes a model approach taking into account discharge channels thermodynamics that allows us to relate conductivity and the current-carrying radius of leader segments to their temperature. The study presents and analyses simulation results covering all stages of the high-current lightning development. It is shown that the model is capable of reproducing currents characteristic of high-current lightning discharges with amplitudes up to tens of thousands of amperes. Simulation results let us formulate a new scenario of development of compact intracloud discharges and initial breakdown pulses based on collective dynamics of a system consisting of a large number of interconnected discharge channels developing in a parallel. In particular, it is demonstrated that current pulses characteristic of compact intracloud discharges and initial breakdown pulses can form as a result of evolution of a network of low-temperature (streamer) plasma channels. Inside this network, a hot well-conducting leader frame forms drawing the system currents onto itself. At the same time, at all the stages of discharge development the relative fraction of leader sections does not exceed a few percent of the total number of channels in the current system.