What is the wind chill factor

A.� The wind chill factor is the term given to the measure of how much heat the body loses as wind passes over it. Specifically it represents the difference between how much heat loss someone experiences in still air compared to someone in wind.

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The speed that wind is travelling at can make things feel much colder than the actual temperature.

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Q.� How is it calculated

A.� How wind chill is calculated has been revised several times since it was first devised around 50 years ago, as equipment and understanding become more sophisticated.

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Q.� What was wrong with the original calculation

A.� The old method wasn't really related to people and how they experience wind chill. It was measured at 33 feet, much higher than most people spend their day.

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At around 5 feet, the average height of the human face, wind speeds are greatly reduced because of a greater incidence of friction.

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It was also based upon a person being naked, when most normal people only expose their face when it's cold.

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Finally it was calculated in open spaces when in fact most people spend their time in areas that are broken up by buildings and trees, which also slows down wind speed.

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The end result is a very complicated equation. Fortuntely there are numerous programmes that calculate wind chill for you on the web.

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Q.� How was wind chill discovered

A.� Early wind chill development arose as a result of human exploration into Antarctica. Frostbite was a serious and dangerous problem and its onset is greatly aided by wind speed.

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Even a relatively slow wind would greatly impede a persons chances of working safely in the Antarctic. Scientists realises they need a safe measure of wind chill.

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Q.� How is the heat lost

A.� In the same way that you cool hot food down when you blow on it. The movement of air over an object increases the rate at which it loses heat, by transferring it from the object, a process known as convection. The faster the air the quicker the object becomes cooler.

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Q.� So wind chill can affect inanimate objects too

A.� Yes, but only if they start out at a higher temperature than that of the surrounding air. This is why a car that has just been running and is turned off will get colder much quicker in strong winds than one that is left in calm air.

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Want to know how something is calculated Click here to ask The AnswerBank.

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by Lisa Cardy