Schlieren system was built to visualize the phenomenon of Rayleigh convection perpendicular to the gas-liquid interface during the absorption of carbon dioxide into pure ethanol in the special mass transfer device. As the absorption progressed, the stability of liquid layer weakened and disturbances aggravated the instability, which led to turbulence in the interfacial vicinity and went on to develop plume convection down to the bulk liquid with the growth and integration of convective cells. Quantitative m...