Optical vortices occur at light propagation in an inhomogeneous medium, disturbing the operation of adaptive optical systems and assuring a priori continuity of the phase fluctuation function. It is clear that the physical process of the light wave propagation has a threshold of complexity relative to the description and measurement of this process, after which the light wave contains points with zero intensity and there is no continuous wavefront. The appearance of zeros indicates the transition of phenomenon in a new condition. The results of numerous studies of phase fluctuations of optical waves in the atmosphere, first of all, provide a basis for estimating the efficiency of operation of adaptive optical systems, second, make it possible to determine the requirements on the wavefront sensors and adaptive mirrors, and, finally, make it possible to determine the structure and properties of phase-conjugated adaptive optical systems.