Stories tagged wind chill

Jan
07
2014

Dude, what's the wind chill?: The first wind chill calculations were made in Antarctica, but not by penguins.
Dude, what's the wind chill?: The first wind chill calculations were made in Antarctica, but not by penguins.Courtesy Frank Hurley
As we're nearing the end of this polar vortex-driven, bone-chilling weather, it's a good time to review exactly what is wind chill and how the wind chill index is calculated.

Q: What is wind chill?
A:
It's the term used to describe the rate of heat loss on the human body resulting from the combined effect of low temperature and wind. As winds increase, heat is carried away from the body at a faster rate, driving down both the skin temperature and eventually the internal body temperature. Wind does not change the temperature of the air. If a thermometer is placed outside, it will read the same temperature regardless of whether it's a windy day or a calm day. It simply "feels" colder because the heat that we give off is immediately blown away.

Q: Has this always been calculated the same way?
A:
No. And it's good to keep that in mind as we've gone through some record-breaking cold temps. Old records for wind chills might not be the records we once thought they were.

Q: Why is that?
A:
In 2001, the National Weather Service implemented a new wind chill Temperature Index. The new index will usually be warmer than what you would have expected with the old index. The new wind chill temperature Index uses updated science and technology and new forms of computer modeling to provide a more accurate indication of the impact of wind on how it feels outside.

Q: Can I figure conversions between the new and old wind chill formulas?
A:
Yes you can. Click here to get to an online wind chill calculator. You'll need to know the air temperature and wind speed of the place you want to figure the wind chill for. This web link also has
charts that show the differences between the old and new calculations.

Q: How can I protect myself when there are high wind chills?
A:
Here are some good tips courtesy of the Weather Chennal
• Wear layers of loose-fitting, lightweight, warm clothing. Trapped air between the layers will insulate you. Outer garments should be tightly woven, water repellent, and hooded.
• Wear a hat, because 40 percent of your body heat can be lost from your head.
• Cover your mouth to protect your lungs from extreme cold.
• Mittens, snug at the wrist, are better than gloves.
• Try to stay dry and out of the wind.

Jan
13
2009

On January 17, 2007, I wrote this post. The weather outside must have been pretty darn similar to today's, and the information seems as relevant today as it did then.

Staying warm: When the wind chill reaches -40 or so, exposed skin will freeze in about 10 minutes. So stay inside or cover up! It's cold out there...
Staying warm: When the wind chill reaches -40 or so, exposed skin will freeze in about 10 minutes. So stay inside or cover up! It's cold out there...Courtesy Liza Pryor

Then I started searching for other stories we've posted on hypothermia and frostbite. Most Buzzers live in Minnesota, so there are quite a few. ;)

Check those out, and pay attention to severe weather alerts. Here's last night's:

"A WIND CHILL ADVISORY REMAINS IN EFFECT FROM MIDNIGHT
TONIGHT TO 12 PM CST TUESDAY. WIND CHILL READINGS OF 25 BELOW TO
35 BELOW ZERO WILL OCCUR OVERNIGHT AND TUESDAY MORNING.

A WIND CHILL ADVISORY MEANS THAT VERY COLD AIR AND STRONG WINDS
WILL COMBINE TO GENERATE LOW WIND CHILLS. THIS WILL RESULT IN
FROST BITE AND LEAD TO HYPOTHERMIA IF PRECAUTIONS ARE NOT TAKEN.

Jan
16
2007

It's cold this morning. Maybe the coldest morning of the season so far? Luckily, there's also a lot of sunshine, and almost no wind.

If it were windy, you'd hear the weather forecasters talking a lot not only about the air temperature (-6 degrees when I left the house), but also about the "wind chill." Wind chill is a way to describe how quickly heat is transferred from your body to the atmosphere when it's both cold and windy outside. As wind increases, more heat is drawn from your body, decreasing your skin temperature and eventually your internal body temperature. Wind chill makes it feel much colder than it actually is.

Last year, I overheard a woman in the Science Museum parking garage elevator talking about how she parks her car in a sheltered area to protect it from wind chill. She was worried that, if she left it in a more exposed area, it wouldn't start. I can't say anything about the state of her car battery, or condensation on her distributor, but I can say that wind chill has very little impact on cars or any other inanimate objects: wind will shorten the time it takes for an object to cool to the temperature of the surrounding air, but it won't get any colder than that no matter how much wind there is.

For humans and animals, though, wind chill affects how quickly hypothermia and frostbite can occur. Hypothermia is a condition in which core body temperature has fallen to the point where normal muscle and brain functions are interrupted. (Thor did a post about hypothermia a few weeks ago.) Frostnip/frostbite are conditions in which body tissues freeze. Knowing the wind chill helps us make decisions to avoid these and other cold weather dangers.

She's got the right idea: Bundle up! (Photo by Yann Richie)
She's got the right idea: Bundle up! (Photo by Yann Richie)

The best thing to do when there's a significant wind chill is to stay inside. But you can't stay at home on the sofa all winter. So what can you do? Dress right when you go outside. That means wearing several layers of loose-fitting, lightweight, warm clothing. (Trapped air between the layers will insulate you and keep you warm.) Stay dry. (Remove layers if need be to avoid sweating and later being wet and cold.) Wear a tightly woven, water repellent, hooded top layer. Cover your mouth to protect your lungs from the cold. Mittens, which allow your fingers to share warmth, are better than gloves. And your mom was right: wear a hat! Half your body heat can be lost from your head.