Losing your warm coat of air
Why Does Wind Make You Colder?
Your body heats a thin layer of air around it. Wind keeps stealing it.
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Step 1 of 5
Your skin heats the air touching it.
Body warmth passes into the nearest millimetres of air. In still conditions that layer stays put and acts like an invisible extra jumper.
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Step 2 of 5
Heat only escapes across a gap in temperature.
Once that layer is nearly as warm as you are, the escape slows right down. The warm layer is doing most of the insulating.
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Step 3 of 5
Wind removes the layer continuously.
Moving air sweeps the warmed millimetres away and replaces them with fresh cold air, so your skin is always facing the full temperature difference.
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Step 4 of 5
Damp skin makes it far worse.
Evaporating water carries away a lot of heat. Wet clothes plus wind can pull warmth out of you many times faster than dry cold air alone.
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Step 5 of 5
Which is what wind chill numbers mean.
The wind chill figure is not a real temperature. It is the still-air temperature that would cool your skin at the same rate the wind is doing now.
Wind chill only applies to bare skin. A thermometer, a car and a puddle do not feel it at all.
The short version
Wind strips away the warm layer of air your skin has built, so heat escapes far faster than the thermometer suggests.
Try it yourself
Wet the back of one hand and hold both in front of a fan. The wet one feels much colder within seconds.
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