Thermal Instability

This paper discussion the thermal instability when a fluid is heated form below. The classic example of this, is a horizontal layer of fluid with its lower side hotter than its upper. The basic state is then one of rest with light fluid below heavy fluid. When the temperature difference across the layer is great enough, the stabilizing effects of viscosity and thermal conductivity are overcome by the destabilizing buoyancy, and an overturning instability ensues as thermal convection. and an overturning instability ensues as thermal convection.