We say: "It's not the temperature, it's the humidity" in summer. In winter, it's not the temperature, it's the wind chill.
Some people might think it's just a made-up number just to make it seem colder, but there really is an effect on our bodies when you add wind.
Take today for example. It's 26 degrees in Philadelphia this Wednesday morning; Northwest winds are at 16mph.Gusts will be up to 35 mph in Tom's River and 30 mph in Delaware. Wind chills will be in the teens this afternoon. Because of the wind, it actually feels 14 degrees in Philadelphia, 10 degrees in Wilmington, and 9 degrees in Trenton.
You've felt it yourself; it's just that you can't calculate it.
The principle of wind chill is simple enough: it explains how it feels to exposed skin when you combine temperature with wind.
But you don't just subtract the wind speed from the temperature. Below is the actual formula:
Note: In the formula, V is in the wind speed in statute miles per hour, and T is the temperature in degrees Fahrenheit, ** means the following term is an exponent (i.e. 10**(0.5 ) means 10 to the 0.5 power, or the square root of V), - means to subtract, + means to add. A letter next to a number means to multiply that quantity represented by the letter by the number. The standard rules of algebra apply.
That's why we don't use the formula, we use a chart based on the formula.
The wind chill is NOT based on wind gusts-just the average wind speed. The chart also shows the physical danger zone: around -15 degrees or lower where frostbite is likely with just 30 minutes of the skin's exposure to the cold.
The National Weather Service also issues Wind Chill Advisories when dangerous wind chills are expected.