Abstract
It is experimentally shown that if in gas mixture there are more than two components, the system becomes instable even when density of mixture in upper part is lesser than in the lower one. A conducted research reviled, that the transition from the area of diffusion into the area of the convective mixing is determined by the following critical parameters: pressure, temperature, viscosity of mixture, its initial composition, factors of diffusion of components, geometrical characteristics of the channel and its orientation concerning a vertical, frequency of rotation. Existence of structural formations at this process was shown by Tepler's shadow method. Change of convective regimes was registered also by the quick-response sensors measuring local heat conductivity of gas. Linear analyses of stability can explain reasons of this "paradox of stability".