How does a fan cool you down?

Question

A wind could be coming from Russia but a fan is just moving the warm air already in the room

Answer 1

Two answers:

1) Evaporative cooling.
2) The air in the room is usually cooler than body temperature (98.6 degrees)

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2) Second things first. Kinetic motion is to blame. Basically when an air molecule hits your body there is an exchange of energy. Nature generally wants things to equalize, so when cooler air hits your warmer body, the cooler air will be energized. According to conservation laws, you can't create or destry energy, only change its form. So, when the air molecules get energized, your body molecules lose energy, thus you become slightly cooler. Multiply this over millions or billions of body molecules and millions or billions of air molecules, and it adds up to a net loss of energy to your body, and a net gain of energy to the surrounding air. So, what happens when the surroundign air is warmer than your body?

1) First things second. One would think that when warmer air interacts with your colder body (say on a 100+ degree day) that your body would be on the receiving end of the net energy gain and the surrounding hotter air would be on the losing end of energy moving into your body. This is true, generally. However, the body has a number of homeostatic properties. Homeostasis is the process of a body trying to maintain a consistent state (temperature, fluid blaance, salt balance, and life).

So, what does the body do? It sweats. And what does that do? Well, the body trasfers heat energy to the sweat, and the sweat evaporates into water vapor in the air around you, thus taking the excess energy of the body and converting it into kinetic energy of the water vapor. Once the vapor leaves, it takes all that kinetic energy with it. Conservation of energy again says that since the energy isn't destroyed and the water takes all the energy necessary to achieve escape velocity with it, you lose the energy. Multiply with a few ounces of water, or a few pints over the course of a day and you get a net cooling effect on the body which keeps it in homeostasis, right arounf 98.6 degrees. Once you get back to that state, you'll basically stop sweating. Well, unless it's still hot out, in which case you'll release more sweat until your tempoerature drops, then stop sweating, then start again, etc. Woohoo! We are wonderfully complex beasts!

Answer 2

The moisture on your skin (sweat) evaporates more when the air from the fan goes by and causes cooling of the skin it was on. The blood circulating in the skin capillaries gets cooled by this process and takes the heat away from the rest of your body as it goes to other parts.
Dogs pant to cool themselves for the same reason - their tounge throat and lungs get cooler because of evaporation of moisture off those surfaces.

Answer 3

Your body has its own way of cooling down - sweating. But as you sweat, the air in your vicinity gets saturated with water vapour preventing further absorption of water. When the fan circulates air, it drives away the saturated air and replaces it with a fresh supply. Thus your biological AC continues. In this way a fan helps you cool down.

Answer 4

The same way it feels when you are lying on the beach and a warm breeze goes by. Having air move around you is a cooling effect.

Answer 5

2

Answer 6

1

Answer 7

Our bodies sweat to control our temperature. Sometimes it is very slight, so you may not realize it.

In order for the sweat to cool us, it must evaporate from our skin. In still air, the air in contact with our skin will gain humidity from the evaporating sweat, and become less effective. The fan moves more air in contact with our skin with lower humidity, and our sweat evaporates more easily, thus removing more energy (heat) from our bodies.

Answer 8

The fan forces lots of molecules against your skin. When connected with your body it picks up heat and bounces away taking with it the heat energy it took. With less heat energy repeated over 1,000,000's of molecules each second you quickly becomes very cool.

Answer 9

Bono gets them to stand next to him with a BIG FEATHER And wave it up and down.
Like the English did in the days of the RAJ, With there punka wallas fanning them.

Answer 10

The air from the fan, is made to prodcue cold air.