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Abstract The structure near the top of stratocumulus clouds is investigated with the aid of aircraft data to determine possible processes influencing entrainment. An expression is derived to predict the buoyancy fluctuations which can be produced by mixing at the interface due to evaporative cooling, and the relative influence of cooling by radiation and by evaporation near cloud top is discussed. It is argued that the effects of evaporative cooling are not properly considered in current assessments of the stability of inversions to entrainment. A method for taking this into account in a more realistic manner is proposed. Entrainment rates derived directly from aircraft flux measurements are compared with various prediction methods. These include the predictions from four entrainment models. These predictions are found to vary widely for a given set of conditions but are generally smaller than the observationally derived values. Some of the consequences of underestimating entrainment and various other shortcomings of the models which are exposed by the comparisons are also discussed.
Nicholls et al. (Tue,) studied this question.