This book reviews the approach to the kinetic simulation of nonequilib- rium processes in the planetary atmospheres which the authors developed and dealt with since the 1970s. The results of this study, which are focused on the nonequilibrium collisional processes in the atmospheres of planets and comets, are thoroughly reviewed and discussed. Many specific problems of atmospheric modeling, involving numerical evaluation of aeronomic pro- cesses, are addressed and compared with the available experimental data. The kinetic approach proved to be especially effective to model the in- teraction...