Physics of lightning: new model approaches and prospects of the satellite observations

Fundamental problems of lightning physics are reviewed, and recent advances in the instrumental (primarily satellite) detection of atmospheric discharge phenomena are discussed. The formation of plasma spots with the parameters necessary for the initiation and development of a lightning discharge in a thundercloud is regarded as a nonequilibrium phase transition induced by electrostatic noise. The noise is caused by the collective dynamics of charged hydrometeors, i.e., ice particles and water drops suspended in a convective flow. The interaction of plasma formations and their polarization in a large-scale intracloud electric field ensure the efficient generation of streamers, whose description in terms of random graphs and percolation theory forms the basis for the phenomenological representation of discharge as a fractal dissipative structure. This approach enables solving a number of key problems surrounding thunderstorm electricity, including the lightning initiation mechanism in essentially subthreshold electric fields, the properties and morphology of various types of lightning discharges, and a self-consistent description of the broadband electromagnetic radiation they emit. Prospects for the further development of the model are discussed and the role of forthcoming satellite experiments in the observation of intense electromagnetic radiation from thunderstorm clouds is examined.