rain out

in atmospheric chemistry
https://doi.org/10.1351/goldbook.R05123
The mechanism by which small particles in the clouds are removed by the formation of raindrops; this is a different mechanism from wash out which is a process which occurs below cloud level. Both the terms rain out and @[email protected] have not always been used in accordance with these definitions. For clarity they should be replaced by the terms, in-cloud @[email protected] and below-cloud @[email protected], respectively.
Source:
PAC, 1990, 62, 2167. (Glossary of atmospheric chemistry terms (Recommendations 1990)) on page 2209 [Terms] [Paper]