wind chill

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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 ?
The wind-chill factor is potent and in our environment often leads to small stock mortalities.
Looking ahead at the forecast, we are due -3C tonight, -4/5C Christmas Eve into Christmas Day and Christmas evening into Boxing Day is forecast to be -6C, with an estimated wind-chill factor of -9C.
The Met Office tell uswe are due an estimated wind-chill factor of minus 9C.
And the Met Office said today that the severe wind-chill factor will make the freezing temperatures feel even colder.
Our tie against Motherwell was played in terrible conditions, with a wind-chill factor of minus two, yet we were asking people to sit in that with their kids for two hours.
Day-time temperatures are expected to dip as low as 1C (34F), with the wind-chill factor making it feel even colder.
The temperature is a relatively balmy minus 21, but when you account for the wind-chill factor, it feels about minus 40.
Scotland's Louise Scott and American Tom Ferrel provide the biggest threat to the Scandinavian over a course where temperatures can fall to the equivalent of -50infinityC with the wind-chill factor.
Vertical International, based in Ruthin, Denbighshire, has designed a thermometer device which takes account of the wind-chill factor and is small enough to be fixed to equipment such as skis or ice axes.
We're speaking, of course, of the wind-chill factor, and the perverse thrill to be had upon hearing it announced over the airwaves.
My skin wasn't freezing in 15 seconds," like the meteorologists had warned when advising of the super-low wind-chill factor.