A hydrological cycle is explicitly included in a one-dimensional radiative-convective equilibrium model which is coupled to a ''swamp'' surface and tested with various cumulus convection schemes: the hard and soft convective adjustment schemes, the Kuo scheme, the Goddard Institute for Space Studies (GISS) (1974) model 1 scheme, the GISS (1983) model 2 scheme, and the Emanuel scheme. The essential difference between our model and other radiative-convective models is that in our model the moisture profile (but not cloudiness) is interactively computed by the cumulus convection scheme. This has a crucial influence on the computation of the radiative fluxes throughout the atmosphere and therefore on the model's sensitivities. Using the Emanuel scheme, we show that the climate equilibrium is very sensitive to cloud microphysical processes. Clouds with high precipitation efficiency produce cold and dry climates. Clouds with low precipitation efficiency lead to moist and warm climates. Since climate equilibrium can be very sensitive to the cloud microphysical processes, any cumulus convection scheme adequate for use in general circulation models (GCMs) should be strongly based on them. The cumulus convection schemes currently in use in GCMs bypass the microphysical processes by making arbitrary moistening assumptions. We suggest that they are inadequate for climate change studies. ¿ American Geophysical Union 1994