Our skin temperature is normally about 33 Degrees Celsius, but it can vary from about 30 to 35 Degrees Celsius. In the winter when the air temperature is low, there is convective heat loss from our bodies. This is much increased when cool air moves across our skin, and increases as the speed of the air increases across our skin.
The cooling effect of cold air as it moves across our skin is called 'wind chill'. The wind chill temperature is the temperature of still cold air that would cause the same heat loss from our bodies as occurs when air is moving at a particular speed.
|
Wind Speed (m/s) |
|||||
|
Air Temperature, Degrees Celsius |
2 |
5 |
10 |
15 |
20 |
|
2 |
1 |
-6.6 |
-12 |
-16 |
-18 |
|
0 |
-1.3 |
-8.4 |
-15 |
-18 |
-20 |
|
-5 |
-7 |
-15 |
-22 |
-26 |
-29 |
|
-10 |
-12 |
-21 |
-29 |
-34 |
-36 |
|
-20 |
-23 |
-34 |
-44 |
-50 |
-52 |
Windchill is the same effect that causes hot drinks to cool quicker in a draught. It may be useful sometimes, as in motorcycle engines which are cooled by the air that passes over them, or in car engines, which use windchill to cool water in a radiator at the front of the engine. This water circulates around the engine, cooling it and preventing overheating and seizure. If the water pump which circulates the water fails, a car engine will typically seize up in ten minutes.