A simple model of large-scale tropical convection variations is constructed around a radiative-convective equilibrium climate, with an observed mean sounding as its thermodynamic basic state. Convection intensity is assumed to be modulated by CAPE, while occurrence frequency is modulated by convective inhibition and the statistics of subgridscale triggering energy. The model produces large-scale waves by an instability mechanism involving stratiform precipitation generated by convection. Model waves have wavelengths, speeds, and temperature structures similar to observed waves.
Convective downdrafts cool and dry the mean conditions in the boundary layer, but also generate subgridscale variability which helps future convection to overcome convective inhibition. The relative importance of these two effects determines the character of the waves