Kinetic theory of runaway breakdown in inhomogeneous thundercloud electricfield

Kinetic theory of runaway breakdown in inhomogeneous thunderstorm electric field is developed. The kinetic equation, boundary and initial conditions a re formulated. Spectrum of X-ray emission generated by runaway electrons is calculated. It has quite a specific form: a sharp maximum at energies 50-6 0 keV and a rapid fall both to the smaller and higher energies. The intensi ty of the emission is growing effectively with the relation E-m/E-c (of max imal electric field E-m to critical field E-c) and falling down sharply wit h the distance near the point; where electric field E(z) is equal to critic al field E-c. (C) 2001 Published by Elsevier Science B.V.