Thursday, April 16, 2009

Why Are Breezes Cool in Hot weather?


A person's body is quite warm. It's warm enough to heat the air around it so that the air also becomes warm. When a breeze blows, it pushes away the warm air, and cool air takes its place. That's one reason why a breeze feels cool when it blows on your skin. The temperature of the body is almost always higher than the temperature of the air surrounding it. Perspiration cools the body by taking heat with it as it evaporates. This increases the moisture in the surrounding air, which reduces the rate of evaporation. But when the wind blows the humid air away perspiration begins evaporating more quickly again. For the same reason laundry dries faster when it is hung in the wind. When we're hot we sweat. Sweat carries heat from the body into the air. It does this as it evaporates, or turns into vapour. That makes us feel cool. When a breeze blows, sweat evaporates more quickly. so that's another reason why we feel cool when a breeze blows.

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