Convective instability of a system of horizontal layers of slightly compressible liquids

The convective stability of a system of two immiscible liquids with close densities is studied. The densities of the liquids depend nonlinearly on temperature and pressure. It is shown that the state of mechanical equilibrium is unstable. Neutral curves are plotted, and the critical values of the Rayleigh number are found. The calculations are performed for physical parameters characteristic of various northern, central, and southern zones of lake Baikal.