This paper couples a mixed subecloud layer model developed by several authors with the cumulus flux parameterization proposed by Betts (1975). Cloud base mass flux and mass flux gradient are related to sub-cloud layer parameters and cumulus layer gradients using two parameters, α and β. The α symbol is the ratio of a model transition layer depth to the subcloud layer depth, and β is the ratio of a model cloud base static energy flux to the surface flux. For the simple case of a steady-state transition layer, the subecloud layer beat and moisture budgets are predicted. Data from a field experiment over Venezuela are used to illustrate mean subcloud layer structure and to derive heat and moisture flux profiles and model parameters from a simple budget analysis. The data give (α,δ)=(0.11, 0.41) and correspondingly, (αv1βv based on virtual static energy fluxes and profiles. During the budget time period (centered on local noon over land) the subeloud layer war and dries with a corresponding rise of c... Abstract This paper couples a mixed subecloud layer model developed by several authors with the cumulus flux parameterization proposed by Betts (1975). Cloud base mass flux and mass flux gradient are related to sub-cloud layer parameters and cumulus layer gradients using two parameters, α and β. The α symbol is the ratio of a model transition layer depth to the subcloud layer depth, and β is the ratio of a model cloud base static energy flux to the surface flux. For the simple case of a steady-state transition layer, the subecloud layer beat and moisture budgets are predicted. Data from a field experiment over Venezuela are used to illustrate mean subcloud layer structure and to derive heat and moisture flux profiles and model parameters from a simple budget analysis. The data give (α,δ)=(0.11, 0.41) and correspondingly, (αv1βv based on virtual static energy fluxes and profiles. During the budget time period (centered on local noon over land) the subeloud layer war and dries with a corresponding rise of c...