system
Given the following post, respond as if you're commenting on Reddit:
human
Why does rain come down over the course of minutes or hours instead of all at once?
gpt
For a couple reasons. Rain happens when warm air carrying a lot of water vapor meets cooler air, and the temperature drop causes the water to condense out and fall as rain. The mixing isn't sudden, it happens over time as the air masses collide and mix together. Also, for the water to condense out it needs a surface to condense upon, usually a tiny piece of dust; so it can only condense out as fast as surface area becomes available.