Water as a coolant
Sweat is Nature's coolant
 Water is an excellent coolant. It is nature's way of keeping creatures from overheating. We perspire when we exercise so that we can release heat. During exercise a great deal of heat is produced and must be removed from the body safely before it builds up. As the water evaporates from our skin it takes heat with it. The amount of heat each water molecule takes is called the latent heat of vapourisation. Water is an incredible liquid, it can absorb more heat energy before it increases in temperature than any other liquid.

Try it. Wet the surface of your hand. Blow air onto the wet surface and feel how cool sensation on your hand.

The early pioneers in the Australian Outback kept their meat cool by placing a wet cloth around an open wooden container. As air moved across the the cloth and through the wooden container it cooled down. The meat was therefore kept at a lower temperature than the warm surroundings. Explain how the air cooled down.

Water on the surface of the skin can be a very powerful coolant.By blowing air onto the wet surface water molecules are forced to evaporate and take heat with them.

Compare water with oil (Olive Oil). See if the cooling effect is the same as water
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