Blowing hot then cold ???

[RavenD]

When in a warm room, if you switch a fan on it blows cool air and not warm air as you are in a warm room, why is this ???

[Space]

it blows warm air.
it feels cool because that air is still cooler than your face. (usually)
So it still cools you down.

Try the same experiment in a hot sauna and it will be the opposite: the fan will make the air feel hotter.

[ugly_bob]

the fact that the aire is moving makes it feel colder. It's called 'wind-chill'

[babydollkiss]

wow, that is a very interesting question

[lightoftruth]

basically when you turn a fan on its not pushing cold air against your face its just re-circulating the hot air. i think iif your sweating it helps cool you down by increasing the rate of evaporation.

[Toureman]

The fan just causes a wind to blow over you and as LofT says it is the moisture or sweat on your body evaporating that makes you feel cooler.

"wind chill" is a different thing altogether.

[RavenD]

But it still feels cooler when you have no moisture/sweat on your skin.

I thought it may have to do with it " pushing " the warm air molecules away and off your body and replacing them with normal temperature air molecules.

[BillyBB]

A moving air stream has lower pressure than the surrounding air. Therefore the air will actually cool very slightly as it expands. Not sure if you could feel the difference in temp though.

[qapmoc]

And it IS windchill, just not the way it is normally stated by metrogolists.