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The effects of entrainment on the growth of droplets in continental cumulus clouds
Author(s) -
Bower K. N.,
Choularton T. W.
Publication year - 1988
Publication title -
quarterly journal of the royal meteorological society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.744
H-Index - 143
eISSN - 1477-870X
pISSN - 0035-9009
DOI - 10.1002/qj.49711448404
Subject(s) - entrainment (biomusicology) , supersaturation , atmospheric sciences , adiabatic process , evaporation , environmental science , liquid water content , convection , precipitation , meteorology , troposphere , mechanics , materials science , cloud computing , thermodynamics , geology , physics , rhythm , acoustics , computer science , operating system
In this paper data are presented from aircraft passes through continental cumulus clouds obtained during the Cooperative Convective Precipitation Experiment. The effect of evaporation of liquid water from the cloud following the entrainment of free tropospheric air is to totally remove a fraction of the droplets of all sizes rather than partially evaporate most of the droplets. Supersaturations in the cloud are found on average to be considerably higher than those predicted for an adiabatic cloud and the supersaturation is not closely tied to the vertical wind. These observations are found to have a number of important consequences for cloud droplet growth: 1. The average lifetime of individual droplets is considerably less than the age of the cloud and is not expected to exceed about five minutes. This has important consequences for the oxidation of SO 2 to sulphate. 2. Statistically favoured droplets that avoid evaporation are observed to grow much larger than average droplets and to sizes larger than would occur at the same altitude in an adiabatic cloud.