411 REFERENCE · Wikibooks
Movie Making Manual/Rain
Reference material by Wikibooks contributors. This retains its source identity and is not 411 news reporting.
Photographing Rain
Backlight it
Use LOTS of rain! It's surprising just how much you need to show up.
Sometimes milk is added to water to increase its visibility.
Use Large droplets. Misting the source will only look like haze.