Wind chill explained: stay warm and dry! - WVVA TV Bluefield Beckley WV News, Weather and Sports

Wind chill explained: stay warm and dry!

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What is wind chill?

The most common answer to first part of that question would sound something along the lines of…”It is what the temperature feels like to us when the wind is blowing, and when it is cold outside”.  To some degree, this statement is true.

But what is actually happening, in cold and windy weather, that makes us feel like it is colder than it actually is outside? And if it is just a “perception”  why do “Wind Chill Warnings” even need to be issued?

If our bodies begin to lose heat faster than we can naturally produce it, particularly on a cold, Winter’s day-we shiver- a way of our muscles generating heat. Since wind is just the movement of air, wind itself  is constantly affecting the temperature of the air that is contact with our skin!

  • When the wind blows across the exposed surface of our skin, it draws heat away from our bodies. When the wind picks up speed, it draws more heat away, so if your skin is exposed to the wind, your body will cool more quickly than it would have on a still day” (Ethan Trex, Mental Floss).
  •  Being cold is one thing- being cold and wet is another. Hypothermia, for instance, is much more likely to affect a cold and wet person more than a cold and dry one, most of the time.  These facts are precisely the reason why the National Weather Service will issue a “Wind Chill Warnings” at all: wind chill is more than “what we think the temperature feels like”- it is actually related to the rate of heat loss that humans experience! Think about this: It is often said that physical pain in general, is also a “perception”, but it is also our brain’s way of telling us that something is actually physically wrong. The same concept applies to the literal “chill” we get from the wind!

 Where does the   “wind chill” number actually come from? How is it calculated?

Believe it or not, there is actually a formula for it, recently revised in 2001 by the National Weather Service. For all of the math nerds out there here it is:

T(wc) = 35.74 + 0.6215T – 35.75(V0.16) + 0.4275T(V0.16)

The  “T” represents the actual air temperature, and the “W” represents the wind speed. Notice that the factors I discussed earlier have been put into this equation- to get the T(wc) the “Wind Chill Temperature”. Because heat loss is a primarily a concern in colder temperatures, Windchill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph.

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