Answer to "wind chill" question

WIND CHILL-- William Moore of Irving, TX and a few of his friends have had a ongoing debate about whether or not the wind chill factor affects the freezing of water. They have had many long discussions on this matter and are looking for clarification. -- 12/15/01

By definition, Wind Chill Temperature is the temperature that it feels like. It is based on the rate of heat loss from exposed skin caused by combined effects of wind and cold. Without wind, the air next to skin warms by contact (conduction) and provides an invisible blanket around the skin. As the wind speed increases, this protective layer of heated air is carried away from the body at an accelerated rate. With heat loss from the skin, the body must either generate more heat or itself cool down.

According to the new NWS Wind Chill Chart, if the temperature is 0 degrees Fahrenheit and the wind is blowing at 15 mph, the wind chill is -19 degrees Fahrenheit. This means that without any wind (actually a 3 mph wind or a 3 mph walking rate), the rate of heat loss would equal that of outside air at -19 degrees Fahrenheit. At this wind chill temperature, exposed skin can freeze in 30 minutes. For other conditions of wind and temperature, check out the new NWS Wind Chill Chart and Calculator.

So much for the chilling effects of wind and cold temperatures on human skin. What about the effect of wind chill on things like car radiators or exposed water pipes?

Because wind chill is based on removing heat from the human body, there is no wind chill for inanimate objects, such as car radiators and water pipes. However, there is a faster heat loss with increasing winds, so the amount of time for an object to cool to the actual air temperature is less. Regardless, the inanimate object cannot not cool below the actual air temperature. Thus, if the temperature outside is -5 degrees Fahrenheit and the wind chill temperature is -31 degrees Fahrenheit, then your car's radiator will not drop lower than -5 degrees Fahrenheit.

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