Oscillation Energies of Colliding Raindrops

Abstract When raindrops collide, some of the kinetic energy involved in the collision will be available to initiate or sustain oscillations in the surviving drops. This paper presents results of a simple model of drop collisions that generates an estimate of the expected distribution of energies in an ensemble of colliding raindrops as a function of drop size and rain intensity. The results indicate that drop collisions can be an effective source of raindrop oscillations and that within any one rain shaft, it tends to produce a range of oscillation energies from intense to imperceptible. In every case, however, the fraction of drops oscillating and the severity of the oscillations increase with increasing drop size and rainfall intensity.