how does waving a piece of paper or turnin on a fan make warm air in the room go cool if the air in the room is already warm
2006-12-10 00:37:20 · 15 answers · asked by francy 1 in Science & Mathematics ➔ Other - Science
Body heat loss modes:
radiation =60%
convection = 15% (that's the fan)
conduction through objects = 3%
evaporation 22%
2006-12-10 00:45:04 · answer #1 · answered by coldflesh 3 · 1⤊ 0⤋
A fan will just move the air around and not affect the temperature. It will however increase the cooling affect of evaporation of moisture from the skin, which will cool the body - exactly as the sweating process is designed to do. Hence the wind chill affect that we hear about on weather reports.
2006-12-10 00:45:04 · answer #2 · answered by Never say Never 5 · 0⤊ 0⤋
I actually know what i'm talking about here.
I studied this at uni.
It sets up a 'wind chill' type scenario.
there is a formula for determining the effect
of certain wind/air speeds on the body.
the greater the eddy currents set up in the room,
the more cooling it becomes.(circulation) it is
also to do with saturated vapour pressure. where air over the skin
assists evaporation.the greater the movement, the more drier air passes over the skin.
hence the different speeds on the fan.
it also makes loose bits of paper fly around faster
which is irritating
and funny.
2006-12-10 00:44:45 · answer #3 · answered by Anonymous · 0⤊ 0⤋
1) Our bodies (36.9 degrees) are generally warmer than the environment. The air in contact with our body will gain the heat from our body and become warmer than the air from elsewhere. If a fan is turned on, it will blow this warmer air away from your body, and slightly cooler air will take its place.
2) If the temperature is warm enough for perspiration to occur, then the fan will accelerate the rate of evaporation of perspiration from our skin. For evaporation to occur, energy, in the form of heat, must be taken in by the perspiration (the part that's water) so as to become a vapour. This heat energy comes from our skin and so we will feel cooler.
2006-12-10 10:45:40 · answer #4 · answered by Kemmy 6 · 0⤊ 0⤋
It doesn't. The increased flow of air over exposed body areas, lowers the humidity of the air just above the skin which in turn causes sweat to evaporate faster, hence cooling the body.
2006-12-13 20:48:40 · answer #5 · answered by Daedalus 3 · 0⤊ 0⤋
It happend ue to the higher rate of evaporation on your skin, when "wind" is blowing, as it does, when you wave paper of switch on a fan. We will feel the same temperature always "colder" when wind is blowing. You can feel that very good in winter. If there are minus 10 degrees outside, go out on a day with no wind and yu will ike playing in the snow, and then go out on another day with the very same temperature but very windy ... and you will start freezing like hell wherever the wind hits your face.
2006-12-10 00:42:17 · answer #6 · answered by jhstha 4 · 0⤊ 0⤋
Evaporation of skin moisture is increased by a draught of air, making the skin cooler. The same principle creates the temperature difference in a "wet and dry" thermometer
2006-12-13 10:17:39 · answer #7 · answered by peter c 2 · 0⤊ 0⤋
It takes off particles that is leaving your skin warm, it evaporates sweat, and it has a breeze that comes a bit colder... when cold air meets warm air it makes wind.
2006-12-10 00:45:17 · answer #8 · answered by Robbie F 2 · 0⤊ 0⤋
Most everyone has given the correct answer. It's the wind chill effect. I will only add that's why you reverse your ceiling fans in the winter to pull air up instead of blowing down on you.
2006-12-10 04:58:13 · answer #9 · answered by Dave 2 · 0⤊ 0⤋
Because moving air increases evaporation of sweat from your skin. This in turn increases the rate that heat is transferred from your skin to the evaporating sweat, and so you feel cooler.
2006-12-10 00:46:05 · answer #10 · answered by Otter 6 · 0⤊ 0⤋