Response of a stably stratified flow to cooling

The spreading of the low-level cold pool produced by evaporation of precipitation is generally acknowledged to be an important mechanism for the regeneration of moist convection. We show that cooling a stably stratified nocturnal boundary layer produces very different results from the corresponding daytime case in which the boundary layer is neutral. In particular, dynamic behavior is sometimes closer to that of a gravity wave than to a density current. The gravity wave speed defines a minimum propagation speed for a self-regenerating convective system. -Authors