how do fans work

[3Styler]

floor fans, how do they actaully make you cooler.  is it to do with increasing the amount of evaporation from your body by removing heat as soon as it is evaporated, or is it to do with simply blowing cold air onto the surface of your skin thus cooling by removing you body heat by radiation; but surely if this was the case then if the room contained only warm air, the fan would not work??   

[Clanad]

You're generally on the right track... it has mainly to do with evaporation of moisture present on your skin.  Even if the air is warm in the room the evaporation will produce some cooling...

[Tim Baxter]

Your'e mostly right in both cases.  Evaporation will cool you.  The wind is air with a low vapour pressure evaporating the sweat as it passes over you, the faster the air passes then more sweat it will evaporate making you cooler (latent heat of vaporisation).  The second reason is that as long as the air temp is lower than your skin temp it will cool you.  Simple thermodynamics, heat transfer, but this is by conduction, so the faster air flows past you the more heat it will remove from your skin.  Thirdly, you are radiating heat independently of whatever other mechanism is cooling you and it does not depend on air temp, pressure or speed.

[BillyBB]

See Bernoulli Principle. Because the pressure has dropped the temperature of the air is lowered slightly.

[justineo]

Well first, find a football team or famous person that you like, buy anything linked to them and follow all their moves in the papers and on TV, you could even join a club dedicated to them.  How cool you will be depends on who you are a fan of eg Chelsea, Cool, Man U, not cool.....Andrew Murray, Cool, Timbo, not cool........Keith Richards, Cool, Cliff Richard, not cool.  Hope this helps :)

[3Styler]

i knew someone would try a joke like that so i deliberately said 'floor fans'.  It is quite glaringly obvious at the beginning of the question, though evidently not obvious enough

[justineo]

Sorry 3Styler, your question is entitled 'how do fans work" it was intended to make you smile, please delete it immediately, if not before.

[Hamish]

The reason for cooling is to do with evpouration but not as mush to do with a pressure drop.

Moisture on the surface of you skin has a few molecules in the vapour above the liquid, this is a state of equilibrium wich has to be maintained. If the surface layer of moist air is removed more water will eveouprate, but to do this it needs energy. The energy is drawn form you as heat (so you feel cooling).

You can make ice by bubling air through ether in the same way.

[DaiB]

Technically as the motor in the fan is usually electrically powered it will give off some heat in operation and actually make the room temperature warmer :)

The answer is evaporation as previous people have said.

[JSant]

I agree that evaporation of moisture on your skin will lower your skin temperature.
But what if your not sweating? Granted, there is still a lot of moisture on your skin; however,
one of the major reasons sweeping air across the surface of your skin cools you off is because of
turbulance. Turbulance promotes heat transfer. Since heat energy always flows from hot to cold, as long as there
is any temperature difference between the ambient air and your skin temperature (usually the case), turbulance from
fanning yourself will always increase the rate of heat transfer. If you are sweating profusely this affect will be increased
drastically by the moisture evaporating into the air, which is also increased by the turbulence.