A survey of Waterdrop Interaction Experiments

The growth of waterdrops by inertial capture and coalescence induced by the size‐dependent terminal velocities in the earth's gravitational field is an important process in the formation of rain. The extensive experimental data on this fundamental process are reviewed and organized into a coherent summary of the collection efficiencies applicable to natural clouds, in the following circumstances: negligible effects of electric charges and fields, normal laboratory temperatures and pressures, and relative humidities between 50 and 100%. The judgments required to reduce the experimental data to the brief summary form are documented.