Wind chill can best be described as a sensation that we feel as a result of the effects of wind and temperature. Wind chill is not something that can be measured using a device, so scientists have come up with a mathematical formula that relates wind speed and air temperature to the cooling sensation we feel on human skin.
Prior to 2001, wind chill was calculated based on the time it took for a cylinder of water to freeze in the wind based on experiments conducted in Antarctica in 1939. In 2001 a team of scientists from Canada and the US decided to develop a new wind chill index that is based instead on the loss of heat from people’s’ faces, the part of the body most likely to be affected by wind chill. Wind chill does not impact inanimate objects like automobiles or tents because they are objects that cannot cool below the actual air temperature.
Understanding wind chill is particularly important to the prevention of frostbite and hypothermia. As wind speed increases the body is cooled at a faster rate causing one’s skin temperature to drop. If your body is wet, wind can speed up the evaporation process and draws more heat away from your body. Studies show that when your body is wet, it loses heat much more rapidly than when it is dry.
The best way to protect yourself against wind chill is to find shelter and get out of the wind. If you are wet, change clothing, or remove clothes if you are sweating during strenuous activities such as hiking. When the wind chill is high, try to cover as much exposed skin as possible, particularly on your head where up to 40% of body heat is lost. Wear a wind-resistant outer layer like a shell and cover your hands with mittens that cover your wrists.