An airborne study of the microphysical structure of cumulus clouds

Data are presented from aircraft passes through cumulus clouds studied during a cooperative convective precipitation experiment on the plains of Montana in 1981. It is found that small concentrations of large drops are produced which exceed the size predicted by growth in a closed parcel model. These concentrations are higher in young, rapidly ascending turrets than in older clouds and coalescence‐size drops are found in turrets less than ten minutes old. It is concluded that dry air entrainment is responsible for the production of these large drops in ascending turrets.