Windchill Index: Useful Tool or Weathercaster Gimmick?

We didn’t have wind chill or school closings. We knew it was cold, we wore parkas and buckle galoshes and mittens until it wasn’t cool, and we walked to school. Yes, through drifts if the wind was blowing.

And at recess — yes, grade school included gym and recess to burn off energy outside of class — we played “King of the Hill,” where you kicked the other guys trying to climb up the icy slope. We threw snow balls that hurt. Not as bad as BB guns or threshing machines, but bad enough. We were not risk averse, and teachers wisely stayed inside.

Only the brain frozen had to be told when it was cold; that’s why you covered your head, fingers, ears and nose. It was why your eyes watered and you had a bright streak on the sleeve of your parka.

Later, walking to college classes from Mississippi River flats and over the gorge also encouraged proper dress. Cold was cold. It wasn’t colder because of the gale force winds whipping down from Lake Itasca through the Twin Cities to Nawlinz. We also learned that a Canadian Cold Air Mass was nothing to celebrate.

It was -26 F in the windless sun at the end of the first Winnipeg-St. Paul snowmobile race. I knew enough to leave my British sports car running and learned that ballpoint pens freeze unless you grip them in your bare hand while writing. And your hand freezes.

So when broadcasters began preaching that “we’re all going to die” because of wind chill, I suspected wind chill was invented to give them something new to say.

I sense a sadistic glow when TV weather people announce the wind chill is -29 and tell us to “bundle up.” Trust me, if this weather isn’t reason to dress warmly, viewers and listeners are candidates for a Darwin Award.

So this week, inspired by a three-hour ride from the airport to Clifton and another wonderful Borgman snow cartoon, I wondered again if wind chill really was invented by two bored guys in Alaska with a drum of water and a desire to frighten everyone in the Lower 48. At Weather Underground, Chief Meteorologist Dr. Jeff Masters confirmed my skepticism if not my history.

“Windchill is not a legitimate weather category, since it has some rather subjective elements that attempt to model how cold a human will feel when exposed to the wind,” he says. “Different humans will feel different windchill when exposed to the same conditions.”

It’s also more than something a broadcaster invented to fill time between traffic accidents and sports. Masters said windchill “uses the temperature and wind applied to a model of the human face using modern heat transfer theory. It assumes no sunshine. Windchill Temperature is only defined for temperatures at or below 50 degrees F and wind speeds above 3 mph. Bright sunshine may increase the windchill temperature by 10 to 18 degrees F.

“The index was developed in the 1940s by geographer Paul A. Siple and geologist Charles F. Passel during an Antarctic expedition. The two researchers hung plastic cylinders of water in the open air and measured the rate at which the water froze as temperature and wind speed changed. The National Weather Service adopted the wind chill index in 1973.”

And yes, Masters said, whether you feel it or not, “Skin will freeze faster with the wind blowing, since you are removing more heat from the body.”

The National Weather Service elaborates, saying it updated its Windchill Temperature (WCT) index in 2001 after relying on the 1945 Siple and Passel Index.

“The current formula uses advances in science, technology, and computer modeling to provide a more accurate, understandable, and useful formula for calculating the dangers from winter winds and freezing temperatures,” the Web site says. “Clinical trials were conducted at the Defence and Civil Institute of Environmental Medicine in Toronto, Canada, and the trial results were used to improve the accuracy of the new formula and determine frostbite threshold values.

“Standardization of the WCT Index among the meteorological community provides an accurate and consistent measure to ensure public safety. The new windchill formula is now being used in Canada and the United States. Specifically, the new WCT index:

• Calculates wind speed at an average height of 5 feet (typical height of an adult human face) based on readings from the national standard height of 33 feet (typical height of an anemometer)

• Is based on a human face model

• Incorporates modern heat transfer theory (heat loss from the body to its surroundings, during cold and breezy/windy days)

• Lowers the calm wind threshold to 3 mph

• Uses a consistent standard for skin tissue resistance

• And assumes no impact from the sun (i.e., clear night sky).

Now you know. Wind Chill is subjective, and cold weather — windy or not — is rough on noses and ears and badly protected toes and fingers.

But hell, we always knew that. It went with “don’t eat yellow snow” or “don’t let the big kids fool you into putting your tongue on the playground metal fence posts.”

— Ben L. Kaufman

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3 Comments on “Windchill Index: Useful Tool or Weathercaster Gimmick?”

  1. Ciesko Kid Says:

    Ah, another bogus mass-media myth exposed by the wisdom of Kaufman. Thanks for the diligent research in helping us see through the facade, and the men behind the curtains.

  2. WestEnder Says:

    The only gimmicky thing about the wind chill factor is that it provides an issue for an annual diatribe by somebody every winter.

    There is a reason scientists studied it and use it, and that reason is because it’s a real thing. Stop somewhere in Indiana on a cold winter day to pump gas and tell me you didn’t notice the wind.

    This is all you need to understand about wind chill: exposed skin (typically hands and face/head) feels it at low wind speeds and the whole body feels it at high wind speeds. So if it’s sort of windy, wear gloves and a good hat. If it’s very windy, layer your clothing.

  3. David Gallaher Says:

    If Ben comes in here more often, then CityBeat may be getting somewhere. Next thing you know, Fox may take this site to real time!
    aaaaeeeeeahh! wooowooowooo! Only in the Queen City would the thought be so frightening.
    Following up on Ben’s research, a key element would seem to be how much moisture is emitted from one’s skin? That seems to be a big variable.
    In general, I’m guessing children would have more moisture while geezers such as Ben and moi would have less.
    Does the sun cause more moisture to come to the surface of the skin? I would assume yes.
    As Ben knows, the latent heat of vaporization is the secret to refrigeration.


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