Condensation–mass flux connection in warm convective clouds: theory and implications for cloud supersaturation

Abstract

The study focused on the relationship between Condensation Rate (CR) and the upward/Plus Mass Flux (MFP) in a system of trade wind cumulus clouds simulated by an LES model. The model was initialized with data observed during the RICO field project, and simulated in a 50.0×50.0 km horizontal domain. In our previous study (Kogan, 2021) we showed that a nearly perfect correlation exists between CR and MFP (correlation coefficient R=0.99). As a result, condensation rate can be highly accurately expressed as a linear function of upward mass flux. This LES derived finding was explained using condensation theory and concept of quasi-steady supersaturation. The obtained from the LES model slope of the CR–MFP linear fit was in excellent agreement with its theoretical value (error less than 5 %). The theory also showed that the equality between the LES and theoretical values of the slope follows from the equality between supersaturation and its quasi-steady value. The study results suggest that condensation rates, for a variety of cloud conditions, can be precisely estimated using the single variable–upward mass flux. Possible implications of the results for evaluating supersaturation and degree of non-adiabaticity in clouds are discussed.