system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why are fumes from gasoline visible to us in the air?
gpt
We don't actually see the fumes themselves.  Light waves travel at slightly different speeds when traveling through the vapor as it does through the atmospheric air which is what gives it that wavy appearance.  It's the same effect as when looking at pavement in a very hot day.