Laser beam propagation through the turbulent atmosphere with precipitation

Equations of the Markov approximation method for the problem of laser beam propagation in the turbulent atmosphere with precipitation have been obtained by replacing precipitation particles with spatially disordered finite black screens and by replacing turbulent inhomogeneities with analogous phase screens. Solution of the equation for the mutual coherence function is represented as a convolution of the three functions using the Wigner function. The results of simultaneous measurements of laser irradiance fluctuation along the 200-m, 2.5-km, and 5-km paths during rain are presented. A qualitative model of irradiance fluctuations at multiple scattering owing to shading of a receiver by an adjacent particle layer is suggested. A saturation phenomenon of the laser radiation scintillation index in the turbulent atmosphere with precipitation is suggested and observed.