wind chill

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Related to wind chill: Wind chill factor

wind chill,

the cooling effect of wind and temperature combined, expressed in terms of the effect produced by a lower, windless temperature, also called wind chill factor, wind chill temperature, wind chill equivalent temperature, wind chill index, wind chill equivalent index, and wind chill temperature index. Wind chill is based on the rate of heat loss from exposed skin. Under windless conditions air provides an invisible blanket around the skin. As wind speed increases, this layer of heated air is carried away from the body at an accelerated rate, forcing the body either to work harder to generate more heat or cool down. If the actual air temperature is −5°F;(−21°C;) with a 20 mph (32 km/hr) wind, the wind chill temperature is −29°F;(−34°C;). Because wind chill is based the removal of heat from the human body, it does not reflect the increased rate of heat loss for inanimate objects such as automobile radiators under the same conditions but they also experience a faster heat loss with increasing winds.

The term wind chill was coined by the American geographer Paul A. Siple in his dissertation, Adaptation of the Explorer to the Climate of Antarctica, (1939). Subsequently, on the third Byrd Antarctic expedition, Siple and American geologist Charles Passel determined how quickly extreme conditions could produce frostbite on exposed skin. By 1945, Siple and Passel had published a set of numbers expressing heat loss as a function of temperature and wind speed.

A wind chill advisory is issued when the forecast projects a wind velocity of at least 10 mph (16 km/hr) producing a wind chill temperature of −15°F; or lower for 3 hours or more. At these values wind chill is more of a nuisance than it is life threatening. A wind chill warning is issued when the forecasted wind chill temperature is −25°F; or lower, which can be life threatening if the individual is not suitably dressed. Persons who go outside under such conditions may experience frostbite and other cold-related symptoms in a matter of minutes, even if properly clothed for normal winter conditions, and longer exposures may prove fatal.

wind chill

[′win ‚chil]
That part of the total cooling of a body caused by air motion.
References in periodicals archive ?
In theory, skiers and others who spend a lot of time outdoors in the cold can use wind chill forecasts to help decide how much clothing they need to wear.
There's no reason why wind chill should not be taken into account.
Wind chills up to 30 below zero came with temperatures either in the single digits or slightly below zero, causing frozen pipes, water main breaks and hampered the ability of firefighters across the region to put out structure fires.
It could progress to -35C overnight Monday into Tuesday morning because of the wind chills.
Parts of upstate New York were under either a wind chill warning or advisory into Saturday morning.
Southern England and eastern parts of the country will be worst hit with the high wind chill factor pushing temperatures down to minus 5C in London.
The National Weather Service has issued a wind chill warning or advisory for northern and central Illinois and southern Wisconsin until noon Tuesday.
The high for the day will be 24 degrees, with wind chill values between -5 degrees and 5.
However the wind chill - how it actually feels in the wind when you are out and about - will be marked.