how does moving air, as in from a fan, cool your body down?
2006-09-11 14:41:02 · 7 answers · asked by b-randon 2 in Science & Mathematics ➔ Biology
Evaporation
2006-09-11 14:49:20 · answer #1 · answered by yablomee 3 · 0⤊ 0⤋
The principal effect is the increase in rate of evaporation of perspiration from the skin. Evaporating sweat removes heat from the body (heat of evaporation). Sweat will evaporate in still air, but moving air speeds up the process, so more heat is removed in a given time. The reason moving air speeds up evaporation is that in still air, a layer of air next to the skin becomes saturated with moisture from the evaporating sweat, and can't hold any more, so evaporation is inhibited. Keeping the air moving, prevents this layer of saturated air from forming.
Another smaller effect is similar and occurs even if there is no sweat. The heat of the body will raise the temperature of air next to it. The higher air temperature will reduce the rate of heat loss from the body. Again, moving air keeps the air next to the body from becoming warmer, and keeps the rate of heat loss from decreasing.
2006-09-11 21:49:07 · answer #2 · answered by gp4rts 7 · 0⤊ 0⤋
Because the air is almost always cooler than the body temp of 98.6F, moving air moves heat away from your body faster than still air. The evaporative cooling mentioned in other answers is also true, but only if you're wet (including sweating).
2006-09-11 21:47:26 · answer #3 · answered by hslayer 3 · 0⤊ 0⤋
Two mechanisms- 1. increased airflow increases evaporation rate, so perspiration is more effective in cooling you. 2.Heat transfer to the air is more effective if the hot air is moved away and cooler air can get closer to the surface.
Note the first mechanism only is important if you are sweating.
2006-09-11 21:50:18 · answer #4 · answered by WildOtter 5 · 0⤊ 0⤋
It's called evaporational cooling. When water evaporates it takes heat away from whatever it is in contact with. So, when you sweat...and the sweat evaporates...it cools you down.
This is also why humidity makes such a huge difference. The higher the humidity, the less moisture can be evaporated into the air...the less effective the evaporational cooling process is.
2006-09-11 21:44:16 · answer #5 · answered by BadWX 3 · 0⤊ 0⤋
What the others said about evaopration.
Plus you can add convection to that. Convection carries the heat away faster than still air.
2006-09-11 21:46:29 · answer #6 · answered by Anonymous · 0⤊ 0⤋
it dries the sweat
2006-09-11 21:42:02 · answer #7 · answered by Anonymous · 0⤊ 0⤋