Have you ever seen a lady fanning herself? When she fans herself, she naturally feels refreshed. One might think that this occupation would be absolutely harmless for all others present that they must be only grateful to the lady for “cooling” the air. Well… before you agree on the statement we should really see whether this is really so.
Why do we feel cooler when we fan ourselves? This is the simple explanation: When air is fanned onto our faces the air in direct contact with our faces warms up (Yes it actually warms up instead of cooling off!! Remember that! It is contratry to what you expect, isn’t it?? 😉 ). It warms up because the molecules in the air collide with one another (and thus with our face too) more violently due to the fanning. These colliding molecules release energy in the form of heat. It is this warm invisible mask of air that “heats” the face, in other words, prevents it from shedding any more heat. When the air around is still, this “warm” mask is gradually pushed up by the cooler and heavier air from the surrounding space. When this “warm” mask is eventually fanned away, our face comes into contact with more and more new portions of non-warmed air, to which it sheds its warmth. That is how we cool ourselves. It is to some degree analogous to something like if we soak our hands in hot (not boiling though) water for a while then we immediately soak them in lukewarm water, our hands will feel cooler even if the temperature of the lukewarm water is higher than the temperature of the surrounding air. In short, the rotating contacts between our faces and the warmed and cooler air that give the fresh and cool sensation to our faces.
Now consequently when continously fanning herself, the lady whisk the warmed mask of air, replacing it with cooler air over and over. This portion of cooler air warms up when again is fanned by the lady before it is eventually whisked away and replaced by still another portion of cooler air. It is repeated over and over again. Fanning, thus accelerates air mixing and helps to quickly equalise the temperature throughout the room. In other words, it refreshes the possessor of the fan at the expense of the cooler air enveloping the other people present. Like the explanation in the previous paragraph, she feels cooler because she is first exposed to warm air before the cooler air replace the whisked warmed air. The whisked warmed air will proceed to the surrounding space and very very slightly raise the surrounding temperature. Of course this warmed air will not harm anyone let alone kill him or her, the persons next to the fanner will not even feel the temperature rise, but it might not be the case if there are so many ladies fanning themselves in an enclosed room with poor ventilation!! 😉
For your information, I am not a sexist. I know that it is not only a lady that fans herself, a gentleman can do the same on newspaper or something else in place of a fan.. 😛