Wind refraction of a partly coherent light beam

The method of successive approximations is used in a theoretical study of the self-interaction and defocusing of a partly coherent light beam in a moving medium. Formulas are obtained for the broadening of the beam and its displacement in the upwind direction. The latter is independent of the initial spatial coherence of the radiation. The conditions under which the spatial coherence radius decreases during the initial self-interaction stage are identified.