system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5 why do we smell rain coming/ what makes up the smell that is "rain"?
gpt
The smell is mostly geosmin, which is released from soil bacteria when rain hits them. They produce the chemical as part of their metabolism, and once they get damaged it's kicked up into the air and people smell it. It has such a strong, nice smell because it's a sign of fresh water in an area so people and many other things need to be able to find it quickly.