Collision, coalescence and breakup of raindrops. Part I: experimentally established coalescence efficiencies and fragment size distributions in breakup.

Abstract

The collision, coalescence and breakup of single raindrop pairs were studied at terminal velocities and laboratory pressure (100kPa) in 761 collision experiments (out of 14 000 attempts). Six size combinations were used with drop pair diameters of (0.18; 0.0395cm) , (0.40; 0.0395cm), (0.44; 0.0395cm), (0.18; 0.0715cm), (0.18; 0.10cm) and (0.30; 0.10cm). For averaging purposes the experiments were repeated over one hundred times for each pair. The new coalescence efficiencies and fragment size distributions in breakup turned out to be consistent with those of McTaggart-Cowan and List (1975) and permitted the combination of the two data sets into a single data bank spanning essentially the entire range of raindrop sizes.-from Authors