We have developed a model for computing time-dependent behavior in raindrop size distributions for a variety of initial conditions. The model permits the inclusion of a spatially varying atmospheric profile and takes evaporation and coalescence of raindrops into account on a dynamic basis. We have applied this model to the washout process by rain, whereby small airborne particles are scavenged below a rain cloud. In comparing our results with those of previously published time-independent models, we found that the time-dependent effects greatly altered washout at lower elevations.
Note: The Institute of Electrical and Electronics Engineers, Incorporated is distributing this Article with permission of the International Business Machines Corporation (IBM) who is the exclusive owner. The recipient of this Article may not assign, sublicense, lease, rent or otherwise transfer, reproduce, prepare derivative works, publicly display or perform, or distribute the Article.