An Empirical Examination of Cumulus Entrainment

Abstract

Most analytic theories and laboratory models of cumulus entrainment predict that the rate of influx of ambient fluid into a convective element depends inversely on the diameter of the updraft zone. A study of 15 continental cumulus congestus clouds containing apparent bubble-like rising elements failed to demonstrate the predicted radius dependence. Application of a standard one-dimensional entrainment computation to the measured cloud and environment conditions revealed no significant correlation between cloud dimensions and entrainment.