Why does air coming from a fan feel cooler?

Answer 1

There are two major effects that make moving air seem cooler (in general).

The first effect is evaporation, and is by far the most significant. Any amount of moisture on the surface of your skin, primarily from sweat, will remove heat from your body when it evaporates. The motion of the air around you greatly increases the rate of evaporation, and thus your body cools much faster than it would if you were to depend upon evaporation in still air. To greatly increase the cooling effectiveness of a fan, you can occasionally moisten your skin, say with a damp cloth or even pouring water onto yourself (though this can get messy). Of course, use cooler water to do this; if the temperature of the water were above your body's surface temperature, then you would initially be adding heat which you would later have to remove.

The second effect is convection. This will only work if the air itself is cooler than your body's surface temperature. In this situation, your body is slowly transferring some of its excess heat to the air itself, thereby warming it. The fan helps to more quickly move this slightly warmer air away from your body so that more of the cooler air is in contact with your skin, and then the heat transfer continues.

If the air is warmer than your body, then obviously convection is undesirable. The fan would simply be bringing more and more warmer air to your body, and you would absorb more of this heat. But as stated above, the cooling effects of evaporation greatly counteract this. Thus, even on very hot days, a fan blowing upon you will still cool you down, as long as your skin maintains moisture through sweating or through you dampening it on your own.

Answer 2

Multiple Reasons:

1: Rate of heat transfer away from your body (if the air is cooler than your body) will be faster because there is always air that is less than the temperature of your body against your skin.

Ex: If you sit still in a stangant air room, the air around your body will warm up... but if there is a fan blowing, the air you warm up will be blown away from you

2: If you are sweating, or your skin is moist at, then there will be a much greater amount of evaporation happening with the fan moving the air. (because when you sit still, the air close to your skin gets humid from the evaporation that was taking place) and with air moving past, it will always be dry (well... as dry as it gets) air.

Answer 3

Because moving air has less pressure than air that is "still."

This lowered pressure results in a higher transfer of heat from your skin to the surrounding air and since this air moves it is continually replaced by air that has not yet been heated, thereby continuing the cycle and generally making your skin feel "cooler."

This is also why fans blowing hot air still tend to feel cooler than no fan at all.

Answer 4

No it isn't. Try this to prove it: go to a sauna, then just blow on your arm, you'll find that the air blown by you (acting as a fan) will actually be very hot, 'cause your body is cooler that the surrounding air around you.

Answer 5

it only feels cooler if the air itself is cooler than you - ever rolled down the window of a fast moving car in a belting hot day only for more hot air to blast in and u wish u could afford air conditioning?

Answer 6

The air itself is the same temperature, as you seem to acknowledge. It "feels" cooler because of convection. The movement of air removes the warmer air around your body (heated by your relatively hot temperature, 98.6), so it is as if you are in "cooler" air.

Hope that explains it!

Answer 7

I thought it was from the moving air it produces causing the water to evaporate off your skin, causing you to feel cooler...

Answer 8

actually,air coming from a fan is not cooler.we feel it cooler because it is at a high speed .being at a high speed when our body skin water evaporates in it ,it is quicker evaporation.(evaporation being the change of water into its vapour form needs heat which it takes from our body and hence makes us feel cool).thus more the rate of evaporation,cooler we will feel.
in a high speed air.the air changes v.fast.it quickly takes up water vapour and then goes.

hope i helped

Answer 9

The air itself is not cooler than the air around: it feels cooler because you heat a thin layer of air around your body, and it becomes harder to give it more energy, so it feels hot. If you blow it away, it is replaced by air which wasn't heated by your body and you can continue to heat it to coolen yourself.

also, perspiration means you give energy to sweat for it to vapourize, thus cooling you off. if there is no wind, the thin layer around you is saturated, so sweating works no longer and you feel hot. Blowing the air off makes sweating function normally.

Answer 10

It evaporates sweat on your skin more effectively, making you feel cooler.