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I Don't Like The Wind Chill

Paul Siple and Charles Passel and another explorer on an an Antarctic exploration.

Some people hate the wind chill index, and I get that. They think it is something television prognosticators invented to make the weather sound even worse. For others, it’s a bit of a “duh, of course it feels colder when it’s windy”!

First some facts:

1. The wind does not change the air temperature.

2. Water does not freeze just because the wind chill is below 32° F.

3. The wind on a cold day affects people differently.

4. The wind chill is a calculation, not a temperature measurement.

When I was a meteorology student at OU, I recall (and sadly re-told) this bit of false information a professor told us. He said the early experiments for the wind chill were made by Admiral Byrd on his polar expeditions. He said the wind chill was based on the cooling effects the wind had on a naked person. Supposedly they calculated the surface area on a naked 160 lb. man and used that to help come up with his initial formula. I was 160 lbs. at the time, (but I wasn’t naked), and I believed this. Years later I looked around and could find no references to his story.

Here’s the real history: Credit Paul Siple and Charles Passel, who were not television meteorologists, but polar explorers for the concept. In the 1940s, during Antarctic explorations, they conducted experiments to see the wind’s impact on heat loss.

They put jugs of water outside their base station and measured how long it took the water to freeze under various temperatures and various wind conditions. After taking hundreds of these readings, they began to get an idea of how rapidly heat was lost at different wind speeds.

Ultimately, Siple was credited with coining the words “wind chill” in his doctoral thesis research on the freezing rate on windy days.

The original formula to calculate wind chill was modified in 2001. It was tweaked based on experiments that tested how fast the faces of volunteers cooled in a wind tunnel.

The current formula is:

Wind Chill = 35.74 + 0.6215T – 35.75(V0.16) + 0.4275T(V0.16).

T: is the air temperature in Fahrenheit
V: is velocity or wind speed in miles per hour

So you won’t have to wear out your calculator, there are wind chill charts designed to look up the current wind chill.

The misleading thing about the wind chill is that when we are covered, there is less heat loss from the wind. Some are more acclimated to the cold, so a person in Minnesota will feel differently than a Tulsan when the temperature drops. Someone sitting still in the cold will feel much worse than someone taking a brisk walk. Water doesn’t freeze when the wind chill is below 32°, though many believe this is true.

Like it or hate it, the wind chill is here to stay. It impacts everyone, but even more so if you happen to be a naked 160 lbs. man walking outside!

To learn more about the research and Siple and Passel:

http://www.wemjournal.org/article/S1080-6032(99)70867-7/pdf

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