Inky Rain
Sometimes you have to heighten cinematic reality in order to make it seem more natural. That’s what director Akira Kurosawa had to do during the production of Rashomon (1950).
“In the downpour scenes showing the Rashomon Gate, Kurosawa found that the rain in the background simply wouldn’t show up against the light gray backdrop. To solve this problem, the crew ended up tinting the rain by pouring black ink into the tank of the rain machine.”
— Source: Internet Movie Database
Trivia