system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: When filling up the car with petrol, how come you can see shadows of the fuel gases, it not actually see the gases with the naked eye?
gpt
Pretty sure the vapors are colorless but it they have a different density than air, which causes light to warp as it passes through them. I’m guessing if you got your head down there and really tried to look directly through the vapors, you’d see distortion similar to a heat shimmer.