On the Study of Collision between a Falling Paper Fragment and Rain Droplets

Abstract

In order to consider the effect of random walking on the process of coalescence, the blotting paper fragment (2×2cm2) coated with soluble blue is dropped through the rain from about 9 meter height above ground.
The number of rain droplets collected by the paper fragment increases proportionally to the falling duration of the paper fragment and the spacial concentration of rain droplets, but this number has no relation to the size of rain droplets or the relative velocity of paper fragment with respect to rain droplets.
The rate of collision is about twice the expected value, which is calculated under the assumption that the paper fragment falls vertically with constant cross-section and average speed.