Why the wind chill temperature deserves our cold shoulder

 

(This post first appeared on NewsCut on January 3, 2014)

If you’re one of the few remaining Minnesotans who actually likes winter, you’re going to have to grin and bear it for the next few days as weatherpeople struggle to describe an awful temperature in more awful terms.

It’ll be sickeningly cold; everyone understands that. So why do weatherpeople work so hard to make it sound even worse by citing the wind chill factor,which is rooted in (some say, “lame”) science, not human understanding, and serves no real purpose for understanding unless you intend to go outside naked next week?

windchill

For most people, the windchill factor serves one purpose: To provide people with ammunition to use when an out-of-state friend — in this case the East Coast — complains about the two feet of snow that just fell, or the house that fell into the ocean because of the strong winds. “Oh yeah,” we’ll say, “the windchill here is -70.” It requires us to disrespect the awesome awfulness of 25-below-zero weather in calm winds.

In terms of bravado, which of these charts is more valuable?

actchill_600x405

acttemp_600x405

What most weatherpeople don’t tell you is the wind chill factor “assumes that your exposed face is roughly five feet off the ground, it’s night, and you’re walking directly into the wind in an open field at a clip of about 3 mph,” according to Mental Floss.

“It’s a meaningless number,” Slate columnist Daniel Engber wrote four years ago, at a time when winter did what it’s supposed to do.

But no amount of tweaking will make wind chill more comprehensible. The language of “equivalent temperatures” creates a fundamental misconception about what wind chill really means. It doesn’t tell you how cold your skin will get; that’s determined by air temperature alone. Wind chill just tells you the rate at which your skin will reach the air temperature. If it were 35 degrees outside with a wind chill of 25, you might think you’re in danger of getting frostbite. But your skin can freeze only if the air temperature is below freezing. At a real temperature of 35 degrees, you’ll never get frostbite no matter how long you stand outside. And despite a popular misconception, a below-32 wind chill can’t freeze our pipes or car radiators by itself, either.

The recent fiddling with wind chill has only made the numbers less useful. The old system might have overstated the numbers when it said that 5 degrees could feel like minus 40. But after three decades of practice, we all got pretty good at translating from the outrageous numbers in the weather reports to our own experience. When the weather service recalibrated the system in 2001, we had to start all over and rebuild our frame of reference from scratch.

Rather than trying to patch up wind chill’s inconsistencies, we should just dump it altogether. The best algorithm we’ll ever have for determining how cold it feels comes from our own experience. A look out the window gives us most of the variables we need to compute our own, personal weather index. The sight of a few leafy trees will tell us how windy it is on our corner and whether the breeze is swirling or gusting. We’ll see if the sun is shining or if the sky is overcast. We’ll also know how we’re dressed, how tall we are, how much we weigh, and how quickly we walk down the street. We can even stick our hand outside for a moment, to get a sample of the ambient air temperature.

If you’ve been out in -20 weather before, you know what it feels like. The brain, Engber notes, has been tallying up all these variables for you, for years. It feels like -20. Period. Maybe the wind was blowing, maybe it wasn’t. But your body and brain don’t differentiate. It was cold. Your nasal mucus froze. You made the mistake of blinking and your eyes froze shut. The dog peed in the living room instead of going outside. That’s useful data.

The wind chill is irrelevant to almost everything else. It doesn’t affect your car in any way. It doesn’t affect your feet or any other body part — that is to say: almost all of your body — if you have the kind of clothing that people put on when it’s -20 anyway.

If you leave it outside Sunday night, your car probably isn’t going to start on Monday morning. Why? Because it’s -20, the temperature that we disrespect so much we don’t trust it to adequately convey our misery, except last week when it was zero with a wind speed of 15 mph and we exclaimed, “wow, that feels like minus 20” to our friends, who were — you’ll recall — pretty impressed with you for still living here.

Still, the National Weather Service has posted a wind chill warning for our area, predicting -35 to -60 wind chills, and warning exposed flesh will freeze in 10 minutes at that level, or about 4 minutes earlier than -20 with no wind. The Weather Service offers this guideline for dealing with the situation: Consider staying indoors.

Temperature, we can safely say, is all relative anyway, as proven by this famous Canada-U.S. temperature conversion chart:

50 Fahrenheit (10 C)
Californians shiver uncontrollably.
Canadians plant gardens.

35 Fahrenheit (1.6 C)
Italian Cars won’t start
Canadians drive with the windows down

32 Fahrenheit (0 C)
American water freezes
Canadian water gets thicker.

0 Fahrenheit (-17..9 C)
New York City landlords finally turn on the heat.
Canadians have the last cookout of the season.

-60 Fahrenheit (-51 C)
Santa Claus abandons the North Pole.
Canadian Girl Guides sell cookies door-to-door.

-109.9 Fahrenheit (-78.5 C)
Carbon dioxide freezes makes dry ice.
Canadians pull down their earflaps.

-173 Fahrenheit (-114 C)
Ethyl alcohol freezes.
Canadians get frustrated when they can’t thaw the keg

-459.67 Fahrenheit (-273.15 C)
Absolute zero; all atomic motion stops.
Canadians start saying “cold, eh?”

-500 Fahrenheit (-295 C)
Hell freezes over.
The Toronto Maple Leafs win the Stanley Cup.

So if the wind chill hits -35 on Monday morning, run outside naked for nine minutes and 59 seconds, and call your East Coast pals. Tell them the actual temperature and what you just did and see if they can top it with their little snowstorm.

If it doesn’t impress them, just tell them it’s colder here than the surface of Mars.

  • Jerry

    Sometimes a man just has to tilt at windmills

  • “Italian Cars won’t start” – Haha, I used to have a Vega. It is nice to at least have something marginally worse – Italian cars – to look down one’s nose at when you own a losermobile.

  • Jack

    Love the conversion chart. Must have missed it the first time it was posted.

    Best wishes for 2018 to Bob and all the Newscut commenters and readers.

    Dang – it’s cold out. 😉

  • Matt Todd

    I absolutely agree with this. People so often incorrectly use the windchill like it’s a real value. And they often use it make things sound much worse than it actually it.

    • Exactly. As if -13 needs to be embellished.

  • Gary F

    I was in Winnipeg a month ago. I’m not sure how they make it. They got it both actual temperature and being on the prairie, wind chill. Most parking lots have individual electrical outlets, and in certain downtown areas it’s illegal to walk across the intersection, you must take the underground tunnel system.

    Wind chill in Manitoba means life and death.

  • Brewer_ME

    I use windchill in my decision making process for winter recreation. Snowshoeing at -20 is fine if I can retain my body heat.. I also know that fuel delivery companies take it into consideration when calculating usage, and emergency responders consider windchill a serious issue for public health.
    Sure, I like my bragging rights for winter misery, too, but rate of heat loss is no joke.

  • KTN

    The writer from Slate has obviously never been outside in the winter, cause if he has any experience outdoors in winter, he would not have written that blather.
    Like the recent claim that toques don’t keep you warmer in the cold than a bald head, denying that windchill is real, is like saying we have a smart president. The wind makes it colder (to living things), like humans, and horses, and cats. Cars, not so much.
    Perpetuating the myth windchill is not a significant factor is dangerous and disingenuous to those who do actually spend a great deal of time outside in winter.

    • Why would you go out with no hat when it’s -13? Do people really say, “well it’s -13 but the wind chill is -20 so I guess I’ll wear a hat”?

      • KTN

        I don’t know about going out without a toque at those temps, but beyond the arms race with numbers, wind chill is very real, and ought to be part of the lexicon of weather forecasting.

        The other day I had my athletes out for a training session. It was cold, maybe zero, but no wind, and clear skies. It wasn’t long before I shed my toque, gloves and parka and stood on the hill in a sweater, and was very comfortable on that south facing slope. Skiing down to our training area, creating a wind chill, I had to have a face mask on so I wouldn’t frostbite my face – it was cold because of the wind, not the temps (well, it helped that the sun was shining at 6000ft).

        The tv news creates the hyperbole about wind chill, and that’s too bad, but in the end, below 32, the wind makes it colder for flesh, and dismissing that fact is lazy. .

        • It was cold because it was cold. It was the same temperature at the top of the hill and when you were skiing down the hill. So you dress for the temperature because you already have knowledge of what that temperature feels like in the environment in which you live. The citation of the wind chill is theater. It was plenty cold without embellishment.

          • KTN

            It was cold when I was moving, but when I was standing in zero in the sun, I wasn’t cold (granted, I have a skewed sense of cold to begin with). Skiing down hill isn’t embellishment, it’s real, and that reality is that wind matters.

            We have a group of young kids in our program (6-11 years old), and we plan our training days using temps, and wind chill to determine whether we cancel or not. Getting stuck on a chair lift for 20 minutes at zero is uncomfortable, but that same wait can be very dangerous when you factor wind.Again, no embellishment, just reality.

          • But the wind chill number you’re given was completely invalid because it was daytime and you were going faster than a walk. What wasn’t invalid was the actual temperature because you know what the temperature feels like in your various ways of experiencing it.

            There were probably 20 different “wind chill temperatures” from the top of the hill to the bottom and you likely didn’t know any of them. What you did know is that it was a particular temperature which feels like that particular temperature feels like when you’re skiing down a hill, or turning a corner, facing the wind, back to the wind, wearing this clothing or that clothing etc.

            The issue isn’t that the wind makes you feel colder; it’s that the ability to measure is incredibly flawed and so much less accurate in people’s experiences than the actual stated temperature. Unless, of course, in their lives they’ve only experienced that temperature standing still in the dark with absolutely no wind and no clothes. And that’s unlikely.

    • kevins

      I agree with you..Saturday we were at -26 but no wind. Had there been a breeze, I would not have even fed the birds.

      • Of course wind matters. But the numbers being quoted as wind chill are mostly fiction.

  • shaun

    “Time until frostbite” is a critical measurement for anyone using public transit or riding a school bus. My kids have waited 20-30 minutes for a bus after walking half a mile to the stop. Many people with heads 5 feet off the ground do this before sunrise and after sunset for school or work. I get that the Florida wind chill reading is a little silly. I never get the motive behind the yearly “too smart for wind chill” pieces. Other people don’t need the info because you’re a Master of Winter?

    • -13 is really cold. Do people dress differently at -13 than -26. Do people EVER experience -13 without a wind chill. I doubt it. So relaying the actual temperature is plenty sufficient.

  • Curmudge

    Ridiculous. If you don’t know the difference between cold with wind and cold at dead calm……I don’t think you can learn anything. Anyone who has parked a car outside can tell you it’s far worse starting up in the morning after a night with both wind and cold. Are you really a Minnesotan or did you sneak in from California?

    • Your car doesn’t get any colder than ambient temperature overnight. The wind accelerates the cooling, but that’s irrelevant in your scenario. Your car is difficult to start because of ambient temperature. It can never cool more than that.

      • Curmudge

        LOL! You’ve obviously never started cars sitting outside in winter. I’ve done it all my life and I’m 71 years old. It clearly DOES make a huge difference. I can see that you made your mind up based on what you’ve read and not on real live experience–and you don’t want to be confused by the facts.

        • So you’re saying an engine block — or oil for that matter — cools to a wind chill temperature and not ambient temperature?

          • Curmudge

            I’ve never put a thermometer on that engine block. Have you? What I’m saying is that there’s a huge difference starting a car after it’s exposed to cold AND wind as opposed to just cold without wind…..and I’ve experienced it many times. And, of course, the same holds true for the human body or ANY body. That’s why animals seek out shelter from the wind. I thought everybody knew this. Go figure.

          • In your life, what was the average wind when you’ve experienced -13 temperature? That’s your frame of reference for -13. I’d wager that standard already includes wind chill since it’s rare that it’s -13 without wind.

            So from an informational standpoint, -13 already provides sufficient information for survival. Any other number is more theater than fact, especially considering the wind chill chart is only valid in the conditions — darkness and walking into the wind — and not during the day.

            -13 doesn’t need theater.

          • Curmudge

            I’ve experienced wind chills of about -75 and ambient of about -50. You obviously haven’t a clue and yet you’re telling people to disregard wind chill. That’s criminally irresponsible. Do you have any idea what damage you might do? I doubt it.

          • Tell me how different you dressed from -50 ambient and -75 wind chill ( which would have had to have been at night)

          • Curmudge

            I dressed warm for both. Do you think I was staying out in that? Do some research and retract your dangerous article before you get sued.

          • I can’t be sued over readers’ comprehension. Dress for -13, you’ll be fine for the mythical but dramatic -26.

          • Curmudge

            Go back to California…..you’ll survive better there.

          • Sorry, not from California.

          • Curmudge

            So you say. I note that you keep talking about going out naked and not going out in thin cotton pajamas. Think about this: if wind chill were not real and dangerous, thin clothing would protect you just as well as thick layers. Yes, wind chill IS a thing–like it or not–and your silly article only confuses mothers who may be naive as yourself in dressing their kids to walk to school. Their harm is your doing.

          • Wind chill is a thing. The wind chill number is not.

            Mothers are smarter than you think they are. When they hear it’s going to be -13, they dress their kids just fine. Why? Because they know what -13 feels like in the real world and don’t need some phoney theatrical number to make it sound even more dire. They know it’s damned cold.

            -13 in the wind feels just like -13 felt with the wind last time. It’s colder when you walk into the wind…. not so bad when you don’t. But claiming it feels like -26 is simply inaccurate. It doesn’t . It feels like how people think -13 feels. Dress for your experience with -13 weather and you’ll be fine.

            This post was written four years ago. No one has ever died because they read NewsCut.

          • Curmudge

            You should have let the article die four years ago. But the whole point is to post ridiculous crap so you get lots of attention, right? 🙂

          • Nice talking to you. Stay warm.

          • emersonpie

            If the message here is that wind chill is not precisely useful, OK. Thirteen below is to be respected, but I can tramp the 200 steps to my barn with a hood but no face scarf when there’s no wind. The same temp with any wind and I have to cover up. These past several mornings of 15 and 17 below have had little to no wind. (It has picked up later in the day.) BTW my stock tank heater can’t keep up with the cold, and I have to hammer an opening in the inch or two of ice every morning. Heaven forbid the hammer should slip into the tank…

          • The only way to cool something to lower than ambient temperature is to transfer the heat (or coolness in this case) from another object. Assuming no frontal passage, the temperature of the wind is the ambient temperature.

            Now your oil can get gummier because the wind removes heat faster, but it never gets lower than ambient temperature.

            Ambient temperature is always going to be ambient temperature. Wind chill is going to change by wearing clothes, sticking your hands in your pocket, walking with the wind, walking in daylight etc.

            So it makes a lousy frame of reference because of the variables that ambient air temperature doesn’t have. To the degree wind chill exists, it doesn’t exist to the extremes the dramatists want you to think it does because the temperature it quotes is only for bare skin.

            So don’t start your car naked.

          • RBHolb

            “So don’t start your car naked.”

            That’s an early contender for “best advice I will receive in 2018.”

  • Trevor Henry

    Temperature + Wind Speed is plenty sufficient.

    Wind Chill is exactly the same as how ESPN measures pitch speed in the Little League World Series. Meaningless. ESPN says, “According to our formula that pitch was equal to a ninety MPH pitch in MLB.” No! It is not! The pitch was the speed it was, from a little league mound. There is no comparison to an MLB pitch. Wind Chill is the same way. Stupid formula.

    I also appreciate the wind direction. Wind direction matters. Strong wind from the north makes getting up the hill a different experience. Those days I tell myself, “I need gears man.” I guess that’s like my retirement plan. I will get gears. For now I can pedal straight uphill into the wind fixie or single speed.

    Wind direction matters. Wind speed matters. Temperature matters. The wind chill is like saying little Timmy just hit a home run off Scherzer.

    • And our sense of what -13 feels like from experience already includes a wind chill since we almost never experience winter in Minnesota without some wind.

      Plus, as was pointed out, the wind chill chart doesn’t account for daylight. So, by definition it’s an invalid number in the daylight.

  • Gordon near Two Harbors

    I live and play in the North. I’ve also been a cooperative weather observer for the National Weather Service for 20 years. Our coldest air temperatures always occur on clear, calm nights over a deep snow pack. The problem with windchill is that it is an arbitrary formula–and not a true measurement of cold. The formula was changed a few years ago; those -80 degree windchill of my youth would now be in the -50s.

    Does wind, combined with low air temperature matter? Of course it does. Ski into a strong wind at zero F and it will feel pretty darned cold. But I know as an absolute fact that a -40 F air temp is not the same as -40 F windchill. You car will likely easily start on a -10 F day with a -40 F windchill. It very likely will NOT start on a morning with a -40 F air temp.

    And that’s the problem.

    On a 40-above zero day with a strong wind the windchill might be in the 20s, but water will obviously stay liquid. But with an air temp in the 20s it will freeze.

    The weather media uses idiotic and confusing terms like “real-feel”, heat index and windchill like they are a true measured value, when in fact, they are not. It also gives the illusion that some dude down south or on the East Coast is enduring the same cold as folks in the North, when in fact there is no comparison.

  • KTFoley

    In the unofficial NewsCut weather bingo, this is the free center square, yes?

  • PeterPotamus

    Bob, you are spot on with your comments. I’m older than Curmudge and grew up on Minnesota’s Iron Range where living there demanded a general sense of insanity, winter weather notwithstanding. It boggles my mind how someone can think that any temperature can be something other than what it is due to air movement or without air movement. While a teenager, Ma told me to put a scarf on one morning and of course, I resisted. She said, “It’s cold!” “Aw, Ma, it’s not that cold. How cold is it?” She said, “Peter! It’s fifty four degrees below zero!” (This was in either 1961 or ’62). I let her put the scarf around my neck (she made sure it was tight!) and sent me on my way to school. My spit (because that’s what we Range boys did – spit) froze well before reaching the ground. Thanks for the scarf, Ma. It needs to be noted that the science behind the windchill factor hadn’t been created.

  • D.Robot

    The assumptions behind the windchill calculation seem reasonable. 5 feet off the ground, the average height of frequently exposed skin (the face), night time (no solar heat gain), walking at a decent clip of 3mph into the wind (worst case scenario, but something that definately happens).

    Things are a bit more complex than the air only being able to cool objects to the actual temperature. I’d say that there’s something to be said for the effect of a 10mph wind with air saturated with water vapor at 33F compared to the same speed wind with temps in the teens with the kind of dry air we usually have here in the winter. The former can’t give you frostbite and the temp difference to the human body is smaller, but it can pull a heck of a lot of heat from your body because of the higher density and heat absorbtion capacity of it (per unit volume).

    Human skin may be approaching the temp of the air, but it loses heat to the air faster with air flowing over it. At the same time, the body works to maintain internal and maybe even near surface temps by burning more or less calories to offset the heat loss.