Is Windchill Bunk?


Often in northern North American climates in the wintertime, not only is the forecast temperature reported, but alongside it is the "Windchill" - What it FEELS like to anyone who dare venture outside.

Recently (Friday,) a local school board in Southern Ontario closed all schools due to an "Extreme Windchill Factor" forecast. The actual temperature outside was -24C, but with the windchill, it "felt" like -37C. (It only ended up around -29 with windchill, but that's beside the point.) The board policy is with respect to windchill, not the actual temperature. Tomorrow looks to be much the same, and another cancellation looks likely. Parents left scrambling are not happy. This is Canada after all.

Slate reporter Daniel Engber wrote a good takedown of this weather concept. I truly wonder if a school board should be making policy decisions based on possibly bunk science - even if our national weather service promotes it as legit.

They also left out crucial variables that have an important effect on how we experience the weather, like solar radiation. Direct sunlight can make us feel 10 to 15 degrees warmer, even on a frigid winter day. The wind chill equivalent temperature, though, assumes that we're taking a stroll in the dead of night.
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No windchill is not bunk - its effects are well documented.

However it is not well understood. A windchill will not lower your temperature any further than ambient - eg in the example above a windchill of -37C will not reduce the temperature of anything to less than the -24C ambient.

what it does is make the body lose heat faster where exposed - it does this by removing the warm insulating layer of air that would normally lie next to the skin. The body's response to this is to try to produce more heat - so you are losing more heat from a finite resource (your reserves) - so you can certainly suffer hypothermia faster than without the windchill.

However if you are not actually exposed to the wind then there is no effect.

Direct sunshine can certainly make you feel warmer and does indeed increase your own temperature - but it also does not affect ambient temperature. Skiers know that direct sunshine does not automatically mean the temperature is any warmer.

what seems to be happening here is a mutual misunderstanding of the science - not that the science is bunk.
Personally, I like when people challenge concepts like this.

Going for the sensationalistic headline, however, probably makes Engber over-reach.

Because the concept has the word "feel" in it, I think that the overwhelming majority of people
accept it as a real phenomenon, but a somewhat subjective and imprecise one.
If Engber had stopped with "Let's not overstate the 'precision' of an inherently subjective concept"
I'd be more on board. Pretending that "wind chill" is so worthless that it should be 86'd, is silly.
It's a fun number that helps us quantify the bitter effect of wind...and which most take with a grain of salt.

Anecdotally: last month, I hopped out of my truck to get a look at a wolf in northern Wyoming,
around 10:45a.m. It was about 38-40 deg.F, but a surprise wicked wind rose up and blasted my face
so viciously that I just couldn't bear it, and was back in the truck in less than 60 seconds.
Even with a nice balaclava I did not want to get back out!
Many other 15-20 deg. F times--when there was no wind blowing--were perfectly pleasant.
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The measurement of windchill may be a moving target and/or an imprecise measure but the effects of wind combined with cold temps is very real.

You will die of exposure significantly faster at -15f and 30mph winds then you will at -15f and no wind.

As a kid growing up in MN, I learned the hard way. My frost bit ears can confirm the danger of wind when its cold is real.

...and just because its only a "feeling" and not a scientific exact doesn't invalidate the feeling....or so my wife says :)
I went to Iceland a few years ago and while I was there spent a day in the town of Hafnarfjörður, a major port town 10 clicks south of Reykjavík. (We went mainly to see the Cod War vessel Thor) Anyway it was mid September and a very sunny day without a cloud in the sky, but with a wind straight off the Arctic Ocean. In the shelter of buildings it was warm enough to feel a bit uncomfortable in the sunlight under a thick jumper, but step into the wind and it so cold it was hard to breathe and felt aleast 15C colder. Oh yes wind chill exists alright.
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Growing up in Iowa, at 0 degrees and sunny we still went sledding, add a -20 windchill and cloudy, we stayed in the house.
From wikipedia:
Now, the current model:
In November 2001 Canada, U.S. and U.K. implemented a new wind chill index developed by scientists and medical experts on the Joint Action Group for Temperature Indices (JAG/TI).[5][6][7] It is determined by iterating a model of skin temperature under various wind speeds and temperatures using standard engineering correlations of wind speed and heat transfer rate. Heat transfer was calculated for a bare face in wind, facing the wind, while walking into it at 1.4 metres per second (3.1 mph). The model corrects the officially measured wind speed to the wind speed at face height, assuming the person is in an open field.[8] The results of this model may be approximated, to within one degree, from the following formula:
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Surface heat transfer to a moving fluid is an incredibly well documented physical phenomena. It's the principle behind a number of technologies, from those palm frond fans in movies about ancient civilizations to the pressurized liquid cooling system that keeps your car from melting on the drive to work. Wind on faces is well understood enough that a scientist can even set an egg timer and tell you when you'll get frostbite to an accuracy of about +/- 5 minutes. The grid usually used for wind chill isn't quite that accurate, because it's an average and doesn't control for hair coverage or skin color, but controlling for those things is possible.

And not controlling for unknowns is pretty much the whole point.

The wind chill index and heat index (those "feels like" temperatures TV meteorologists like) don't control for a handful of values, because it's really hard to print a four dimensional chart on a two dimensional piece of paper. Strictly speaking, when applying them to local measurements, you're supposed to control for those things, but since few meteorologists provide street-by-street grids (and at that resolution wind itself is a bigger variable) unless you're walking around with a set of weather instruments and a graphing calculator, you're not going to be improving on the fuzzy numbers the weather man gives you.

After all, this is no more fuzzy than any of the other numbers meteorologists provide the public - on the scale that wind chill varies from the forecast, so does temperature and precipitation, and I can't for the life of me find any pseudointellectuals saying inches and degrees are bunk measurements.

Now, specifically to the OP's link: He repeatedly does THIS:
The gaudy negative numbers do more than describe the weather; they try to tell us how we experience it. The reporting of wind chill carries with it a paternalistic impulse to explain not just how cold it is, but how cold we'll feel. Well, I've been out in the cold every day this week, and I know exactly what it's like. If wind chill can tell me only what I've already experienced—my cell phone hand too numb to dial a number, my moustache freezing on my face—then we should just get rid of it altogether.
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This is just five different kinds of stupid at once. Not only does it acknowledge that wind chill is a very real and meaningful thing, but it reduces the reasons for getting rid of it two two equally stupid ones:

1. That meteorologists are supposed to clinically and scientifically describe the weather and not provide context for people who don't have a copy of Introduction to Mid-Latitude Dynamic Meteorology, Fourth Edition handy.
2. "I already know how cold it feels, stop telling me and making me feel bad."

Reason 1 is suggesting meteorologists stop doing their *job*, because they exist to provide context and planning assistance for people about to face the weather, and reason 2 is just... I'm not even sure what that is, but it's really stupid. He knows how cold it is and doesn't want to be told? Now, he clearly went out unprepared and unknowing since he already knew how cold it was before the news report. However, had he watched the morning news, he could worn touch screen gloves with a windproof layer to them. He COULD have known that BEFORE he went out. Because he didn't, he assumes nobody did, and everybody found out after the fact how cold they already felt.

This is a common fallacy, assuming everyone else acts exactly like you. And when you're not acting with rational diligence regarding your own health, that's a dangerous assumption to make.

Also, he should know it's pretty easy to keep your mustache from freezing - in through the nose, out through the mouth. You're losing body heat every time you breathe, but you can put it to use on its way out. If it does get a little frosty, a deep, slow breath, with your mouth just open a slit and your lower jaw pushed out so the hair touches your lower lip. Note all this can be a bad idea in a cold weather survival situation, but I'm assuming from his list of grievances the worst survival situation the author has faced was not being able to get the Grubhub app to recognize his location.

The recalibration he mentions (based on the extent of the change) wasn't the 2001 recalibration (which was based on the actual heat transfer rate between skin to moving air, rather than water to moving air like the original index) but a change made in the 60's. For a few years in the 60's, they used something called the Wind Chill Equivalent Temperature, which gave the equivalent air temperature of completely stationary air. This gave pretty absurdly exaggerated numbers because stationary air doesn't happen, and didn't last long before they recalibrated it around a low wind speed, causing dramatic changes in reported equivalent temperature. The change in 2001 was far less dramatic. His link is broken, of course).

a below-32 wind chill can't freeze our pipes or car radiators by itself, either.
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No, because neither one is standing out on the sidewalk exposed. Your pipes are inside your house completely sheltered from wind, and your radiator is inside the engine compartment not completely sheltered, but with no direct path for the wind to hit it full speed. It's also not full of water, unless you're just horrendously misinformed on automobile maintenance. Broken link, again. The actual link, however (see below) shows that the highest temperature where you'll get a -35 wind chill with a reasonable wind speed is -5F, where it requires over 35 mph (at 0F it takes over 60!). Your pipes can and will freeze at that temperature. Your radiator will not because it's full of antifreeze. If you have the cheap stuff or diluted too much you're still probably good to -15 at least, and if you live somewhere this cold you probably shouldn't be using the cheap stuff anyway.
If it were 35 degrees outside with a wind chill of 25, you might think you're in danger of getting frostbite.
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His link is broken, but the correct one:
when the thermometer says it is above freezing so you will not get frostbite; however, you might get hypothermia from exposure to cold.
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The link also includes the frostbite chart that clearly shows the wind's influence on time-to-frostbite.

I'm puzzled by the article. The author put a lot of effort together collecting links that actually refute him, and then using out of context phrases from it to hang his whole argument on the argument that, "I know it's cold, stop telling me."
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I'm puzzled by the article. The author put a lot of effort together collecting links that actually refute him, and then using out of context phrases from it to hang his whole argument on the argument that, "I know it's cold, stop telling me."

I fear in part it's creeping trolling. Sites like Slate and HuffPo increasingly post article that are little more than annoying grumpy opinions, as they inevitably get shared, and invoke angry discussion. Like this article that seems place the burden to date-rape avoidance largely on women drinking too much:

The wind chill article is from 2007, seven years ago. I wonder if the author would write the same article today.
I wonder if the author would write the same article today.
He probably would. He seems to have a built-in problem with understanding science. For example, just a few weeks ago during the Deflategate scandal, he suggested that using the fumbles/plays ratio instead of plays/fumbles made quantitative difference in analyzing the effect of deflated footballs. His argument was that if you calculate car efficiency by gallons per 10,000 miles driven you get different ratings than if you calculate miles per gallon. To prove that he linked to an article that said the two figures came out to the same result, but it was easier for consumers to predict their annual fuel costs from gallons/10k than miles/gallon, but the article had an ambiguous title and didn't get to that point for a while.

Edit: going through his post history, he has a lot of issues with talking about things that don't mean what he thinks they mean. Right after the Arawan earthquake, he misused PAGER casualty estimates to predict almost ten times more casualties than PAGER actually predicted, and when talking about the NFL concussion settlement, he called $10 million "just over 1%" of $100 million.

So I don't think he's trolling, I just think he doesn't read his sources carefully and makes a lot of assumptions about what he thinks he'll read if he finished the article.
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So I don't think he's trolling, I just think he doesn't read his sources carefully and makes a lot of assumptions about what he thinks he'll read if he finished the article.

Interesting. Perhaps his articles are so popular because they are invariably wrong, and people enjoy shouting them down. Kind of a natural selection in favor of bad science. Rather a sad state for journalism, when the more inaccurate an article is, the better it does.
They don't really seem that popular, either. His Pakistan article has one comment, and his NFL one (a hot topic when he posted it) has none at all. Another one theorizing that mice with human cartilage represent the next civil rights movement also managed to have none despite using tags to make it show up as related articles to gay marriage and police-related shootings. None of them have over 100 likes on Facebook, and only the last one has over 300 tweets. As far as I can tell, his windchill article was the most popular, with no comments but about 700 facebook clicks.

Compare to a softball article on the same site from Phil Plait: His recent article about light refraction in low resolution pictures of Pluto has more likes, tweets, and comments than most of Engber's articles on controversial current events topics.

Which is where I was so puzzled. He's been on Slate for years, but his stuff doesn't seem popular at all, and seems at odds with their attempt to "clean up" the anti-science noise when they stopped giving voice to intelligent deisgn and anti-vaxx writers.