system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why is it sometimes a flame does not emit any smoke, but after the flame is extinguished there is a lot of it?
gpt
Smoke happens when the fuel doesn’t completely burn. The flame appears because the fuel is burning at full temperature with proper air flow. If either of those is removed, the flame will be extinguished, but residual heat continues to inefficiently burn the fuel, which creates smoke.