Breakdown: What is wind chill & why it can be dangerous

Published: Jan. 14, 2022 at 11:28 AM CST
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MEMPHIS, Tenn. (WMC) - Wind chill is how cold people and animals feel when outside. Wind chill is based on the rate of heat loss from exposed skin caused by wind and cold temperatures. As the wind increases, it draws heat away from the body, and can eventually draw the internal body temperature down. Thus, the wind chill temperature is the temperature that our bodies will feel when our skin is exposed to the cold temperatures and the winds especially in winter.

Wind chill isn’t measured but its a calculation. The calculation is dependent on both measured temperature and sustained wind speeds. Those are typically taken from weather stations. A forecast for wind chill can be produced by combining the forecast for temperature and sustained wind speed.

Extremely low wind chills, although dangerous, are not the actual air temperature reading. They are a measure of heat loss our body experiences when exposed to the wind. The colder the wind chills, the more dangerous.

A quick approximation of the wind-chill temperature can be found by multiplying the wind speed by 0.7 and then subtracting that value from the air temperature. For example, if the air temperature is 20 degrees and the wind speed is 25 mph, use the formula 20 - (25 x 0.7) to determine that the wind-chill temperature is 2.5 degrees.

Our body gives off a layer of heat that protects the skin from cold temperatures. A strong wind can blow this layer away from our skin, taking away our natural defenses from the cold away.

Wind chill is a great predictor of such dangers as frostbite and hypothermia. Being exposed to below zero wind chills can induce frostbite within five minutes. While wind chills below minus 20 degrees can result in frostbite within a minute of exposure.

If the temperature is 38°F and the wind chill is 32°F, that means you’d develop frostbite on exposed skin just as quickly as you would if the temperature was 32°F and with calm wind. This formula also assumes you’ll be walking directly into a steady wind continuously, with your face uncovered.

Wind chill was created in the late 1930`s scientists at the South Pole needed to find a measurement to give people an idea of when the weather conditions were too dangerous for prolonged exposure. They conducted an experiment with two buckets of 100-degree water. One bucket was left out in the wind, while the other was sheltered. Similar to our body`s skin, the bucket in the wind froze much faster as any heat it gave off was blown away from its surface.

The original formula was changed in 2001. Major changes were made to where the wind measurements were observed and the amount of skin a person might have exposed.

Originally the wind chill scale was based on winds measured from wind sensors 33 feet above the ground. Winds blow much faster with height than at the surface. The new wind chill calculation uses wind speeds at just 5 feet from the surface. Additionally, the new formula estimates for only a person`s hands and face being exposed to the elements rather than the whole body, which was used for the old scale.

Remember when going outside in dangerous wind chills, covering exposed skin should be your main concern. But even with your skin covered, wind chills can still be dangerous when exposed to them for long periods of time. The best course of action is to stay inside when wind chills are low. If you need to go outside remember to dress in layers, and minimize skin exposure.

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