Аннотация:The paper is devoted to the study of the formation of stratification in an incompressible fluid due to convective laminar flows in horizontal layers heated from the side. Medium and intensive modes of stationary laminar thermal, concentrational and thermo-concentrational (in particular thermohaline) convection are considered, in which nonlinear flow features are manifested, which can radically change the flow structure and the characteristics of heat and mass transfer. The solutions of the problems of laminar problems of convection show the features of the formation of layered structures, vertical temperature and concentration stratification depending on the determining dimensionless parameters. The metastable instability of the direction of the stratification vector (the location of the phase interface for two-layer «air–water» system) in weightlessness in the presence of capillary convection was shown.