system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is it that if you shape your mouth like an "o" you breathe cold air but if you shape your mouth like a "0" you breath warm air?

The title is self-explanatory.
gpt
An "o" mouth forces the air to move out faster than an "O" mouth.

Both kinds of air technically have the same temperature, but the "o" breath is moving fast enough to evaporate moisture on the skin, causing it to feel cold.