The180·The 180

The cold truth about wind chill

The wind chill is a fact of winter in most parts of Canada. But every year, the weather-conscious among us set out to set the record straight on wind chill: it's a value determined by a formula, and not a cold hard measurement. Weather student Scott Kehler joins us to explain.
Most Canadians know what it feels like to walk against the winter wind. But do they actually understand wind chill? (Charles Rex Arbogast/Associated Press)
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Wind chill.

It's a phrase we hear often in Canadian winters, but most weather nerds will tell you we don't understand it. 

Do you understand it? Here's a test: if you've ever said "it's –23 degrees with the wind chill," then you don't get it.

We asked Scott Kehler to help us sort out the truth about wind chill. He's a contributor at A Weather Moment, a blog about Manitoba weather, and is currently studying weather at the University of Manitoba. 

What is wind chill? 

Does windchill make you feel like this? (@fiestacrunchfun/Twitter)

It is a formula: "Wind chill is actually a formula which uses the air temperature and the current wind speed to try to quantify how it actually feels outside, when you're walking around." 

It tells us how the wind will affect us: "The wind chill is supposed to tell us now quickly our bodies will cool, as a result of the wind removing heat from the body." 

It is calculated for a particular circumstance: "You've got to be out in an open field, where that wind speed was measured, with full exposure to the elements."

This chart shows the wind chill formula. (Environment Canada)

What isn't wind chill?

It is not a temperature: "It's not a measured quantity the way that temperature or wind is, there's no wind chill sensor."

It does not necessarily reflect what you will feel: "Most of us are walking around within a city, where it's sheltered by buildings...so we're not really in that worst-case scenario of wind chill that's being reported in the news." 

So why do we use it? 

In this case, Scott Kehler is studying a different wind phenomenon: check out the tornado in the background. (submitted by Scott Kehler)

It's still valuable information, says Scott Kehler, because if you are actually outside in the wind for a sustained period of time, it will make you colder and give you frostbite faster.

But for the average city-dwelling, car-commuting Canadian, wind chill doesn't offer us much more than bragging rights.

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