What’s Up With the Wind Chill Factor?
When I turned on the news Tuesday morning, I was pretty excited to see that it was already 29 degrees outside — pretty balmy for a pre-sunrise winter morning in Missoula.
Then I heard the meteorologist say something like, “You still might want to bundle up because it feels like 17 degrees with the wind chill.”
Feels like — two of the most dreaded words for cold-climate dwellers. In Missoula, the “feels like” factor is particularly strong near the UM campus, thanks to the famously frigid Hellgate Canyon winds. As a student, there were a few times I was seriously convinced that I was in the early stages of both frostbite and hypothermia after crossing the Oval.
But what, exactly, does the term “wind chill” mean, and how is it calculated? I have always wondered about this, so today I decided to do a little research. Here’s what I came up with:
A wind-chill-adjusted temperature reflects the increased rate of heat loss the human body endures in cold, windy conditions. For example, if the outside temperature is 30 degrees and the wind is blowing at 40 miles per hour, the 98.6-degree human body loses heat as though it is actually 13 degrees, according to the National Weather Service.
The air movement increases heat loss by convection, so we cool off more quickly. Scientists have compiled a chart that approximates what a temperature actually “feels like” at a given wind speed.
The same concept applies to inanimate objects, and even though they cool off faster in the wind, their temperature will never drop below the actual air temperature, regardless of how hard the wind is blowing. For example, if you put one warm cup of cocoa in a 35-degree refrigerator and another outside in 35-degree air with a 25-mile-an-hour wind, the temperature of the cocoa outside would reach 35 degrees more quickly. It would not, however, drop below 35 degrees despite the fact that would “feel like” 23 degrees outside.
Now if you’ll excuse me, all this talk about cold wind makes me “feel like” curling up on the couch with a warm cup of cocoa.
Brooke is a 2010 graduate of The University of Montana, where she ran track and cross country for the Grizzlies. She is currently working as a writer and editor in Missoula.