Wx Savvy |

Why So Much Ado About The Wind Chill?

Why do meteorologists talk so much about the wind chill temperature in winter?

Well let's start by mentioning that the air temperature and the wind chill temperature are very different.

The air temperature at 30°F may feel somewhat cool one evening and yet bone chilling cold on another. The difference is how fast the winds are pumping, because the wind can create a cooler "feel like" temperature. And here's why.

It's all about the wind

During a cold winter day the reason we wear coats, sweaters, long sleeves etc... is because we are trying to trap our own body heat. Your body is like a furnace producing heat to keep your average body temperature at 98.6°F.

When the wind blows past your body it blows away a thin layer of warm air heated by your body. This thin layer of warm air surrounding your body will quickly be replaced as your body is constantly generating heat. However, the faster the winds blow, the more quickly the warm air is blown away. So it starts to "feel" colder because of the strong winds drawing warm air away from you.

So this is why meteorologists mention the wind chill temperature along with the air temperature during the wintertime; it better represents the temperature you are "feeling", and that is practical to most people.

Is The Wind Chill Temperature Accurate?

It's impossible to measure accuracy for such a subjective "feel like" temperature. The formula was designed during World War II to better measure battlefield conditions. In November of 2001 a new wind chill formula was put into use by the National Weather Service. It now has less exaggerated results and the biggest change in the formula is that it takes into account the average winds at 5 feet above the ground instead of 33 feet. The higher in the air you are, the faster the winds. So the old formula using winds at 33 ft. was not a good indication of what we humans were really experiencing. Why 33 ft.? Because that's the height of many of the anemometers or wind speed & direction measuring devices.

Also...

The wind chill temperature is based on the air temperature and the wind speed assuming you were naked. That's right naked! It's too subjective to create a formula based on clothing since everyone wears different types and amounts of clothing during the winter.

So this means that the wind chill represents the feel like temperature to exposed skin. The key being, Don't expose your skin!

Picture and Chart Courtesy of NOAA Photo Library