Rates of Entrainment and Detrainment of Momentum of Cumulus Clouds

Abstract

The horizontal momentum exchange process between cumulus clouds and their environment are examined. A general formula is also derived for the rates of entrainment and detrainment of momentum of a cumulus cloud ensemble. These general entrainment and detrainment rates are found to depend on the cloud mass entrainment/detrainment rate and cloud dynamic properties in a way quite different from that assumed in previous parameterization studies. The formula is applied to two simple cloud models. It is shown that even in the context of these simple models, the general formulation gives substantially different results.