Cumulus clouds are ubiquitous over the tropics and over mid-latitude continents in summer, and thus could be potentially as important to the radiation budget as marine stratus. This view is shared by Stull [1992] who found that a third of the low clouds observed over Madison, Wisconsin in 1990 were fair-weather cumulus clouds or other scattered PBL clouds. Nevertheless, we found only a single example of an LES study (between 1991 and 1994) of a cumulus-topped boundary layer, by Cuijpers and Duynkerke [1993], who simulated an observed trade-wind cumulus case documented in 1972 north of Puerto Rico. They present profiles of variances, fluxes, and turbulent-kinetic-energy budgets, and showed that the layer-averaged moisture variance and buoyancy flux are linear functions of the total amount of cloud water.