Why is it you can blow either warm or cool air out of your lungs?
I think that all air from your lungs is hot (You are fairly warm inside, after all), but when consetrated it feels cool, like a fan in a hot room (it SHOULD be blowing hot air, right?), but when the speed is lowered, it feels hot, like it should.
BTW, that whole thing was a huge WAG
When a gas expands suddenly, it always cools. This is what happens with your breath when you have your lips close together and blow. It is also the reason air from an air compressor feels so cold. Incidentally, it is also the reason some clouds form: When damp air rises, the air cools because the air pressure decreases with altitude. When the temperature cools enough, the water vapor condenses.
Hey, slow down, slow down, I’m still working on the part about “blowing either warm air or cool air out of your lungs”. All the air that’s coming out of my lungs seems to be about the same temperature–what has Omni-not got that I haven’t, that he can switch over from “cool” to “hot”?
I demand an upgrade!
(Are you talking about pursing your lips to blow cool air over your pizza, as opposed to huffing your bad breath in someone’s face just to show him? That air would still all register as the same temperature on a thermometer, wouldn’t it?)
This is like asking how does a thermos bottle know what to keep hot and what to keep cold. How does it know?
Duck Duck Goose: - open you mouth wide and blow onto your hand. Hot air, right?
Now, try blowing a stream of air through as small a hole as you can make with your lips onto your hand. It should feel cooler.
I don’t know if the reason is cooling by expansion as suggested by bibliophage, or because the air is moving faster and evaporates sweat more effectively in the second case. Maybe it’s both. Or maybe it’s some subjective illusion and the thermometer would clear this up!
Thanks bibliophage: your explanation sounds…cool to me. Ate a good book lately?
DDGoose: How did you know I have bad breath?