Physical mechanisms for the development of lightning discharges between a thundercloud and the ionosphere

An investigation is made of the influence of changes in atmospheric pressure with altitude and the thundercloud geometry on the development of lightning propagating upward to the ionosphere. It is shown that the mechanism for the development of high-altitude lightning does not differ from that for the formation and propagation of ordinary lightning between a thundercloud and the ground. It is established that high-altitude lightning forms as a result of a reduction in pressure with altitude and can only take place from thunderclouds located at high altitudes. (C) 1999 American Institute of Physics. [S1063-7842(99)02804-4].