Field Observations of Raindrop-Raindrop Collisions

Abstract:

Raindrop-raindrop collisions were observed in natural rainfall for the first time. The High-speed Optical Disdrometer (HOD), a new instrument that we developed for precipitation microphysical observations, made these field observations of colliding raindrops possible. Raindrop collisions have long been hypothesized as the governing process in shaping of the raindrop size distribution (DSD), a key quantity for various meteorological and hydrological applications. These first time field observations of raindrop collisions provide a strong support for the hypothesized governing role of raindrop collisions in determining DSD shape evolution. These observations will be presented along with a discussion on the role of raindrop collision process for the DSD evolution. This material is based upon work supported by the National Science Foundation under Grant No. AGS-1144846.