Wind Chill

Understanding the concept of wind chill has been one of the most fascinating things I have ever learned in my life.

Wind chill is the apparent temperature felt on exposed skin because of the wind. That is, the temperature that our bodies might feel can be different from the actual air temperature.

The human body temperature is approximately 37ºC (98.6ºF). Since the air around is usually below that temperature, we are losing heat from anywhere not covered by clothing. When the air is still, we are mostly losing heat by convection.

However, when a breeze hits the face, the initial loss is from conduction: the wind cools the temperature of the skin almost to air temperature. Convection plays a part as well, helping to dissipate the warm air from the face. If the skin is wet, there will be additional cooling from the evaporation of moisture.

The stronger the wind, the faster the cooling. The lower the temperature, the more impact the wind has. Indeed, you can experience it yourself:

1. Blow the back of your hand: it will feel cooler.
2. Now, lick the back of your hand and blow: it will feel colder.
3. If you increase the speed of blowing, it will feel even colder.

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