Cargo Rain is a bonus event triggered by the player by tapping an umbrella icon on the scanner page. A number of cargo crates are deposited within 200m of the player's current position.
Crates are added to the Cargo Rain upon leveling up, completing a mission, servicing a mine, or buying an "in-app purchase".
The amount of cargo dropped by a Cargo Rain is indicated by a number on the umbrella icon (as of Version 1.5)
Cargo Rain stacks so that getting another Cargo Rain will add the new amount to the total waiting to be dropped.