system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5:Why is it when I blow on my hand the air is cool but when I make a haaaaaaaa sound the air is warm?
gpt
The air is the same temperature either way.  The difference is that quickly-moving air can "entrain" surrounding air, essentially pulling it along for the ride.  So when you blow out through pursed lips, the air you feel is a combination of air from your lungs and air from the surrounding environment.

Try cupping your hands around your mouth (to prevent ambient air from becoming entrained) and blowing both ways, and you'll feel that they're both the same temperature.