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.

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wind chill

[′win ‚chil]
That part of the total cooling of a body caused by air motion.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
soldiers (n = 273) are first- and second degree frostbite and 71% of them happened at equivalent wind chill temperatures of <-29[degrees]C (22).
During this period the personnel is exposed to wind speed up to 160 km/h (and sometimes even more) resulting in extreme equivalent wind chill temperatures and an extreme risk of frostbite.
According to Table 3, if wind chill temperature is considered in different areas, there will be some problems for human that are illustrated in Table 4 [7].
Type of Loss Price of Loss Earthquake $248,624,900,000 Flood $206,639,800,000 Tropical Cyclones $80,077,700,000 Windstorm $43,890,000,000 Fire $20,212,800,000 Drought $16,800,000,000 Cold Wave $9,555,000,000 Heat Wave $5,450,000,000 Sum total $631,250,200,000 Table 2: b and c values based on chosen units of wind speed b c Unit 0.453843 -0.0453843 m/s 0.239196 -0.0126067 Km/h 0.325518 -0.0233477 kt 0.303444 -0.0202886 Mi/h Table 3: wind chill temperature based on the formula No.
In certain conditions, the recent changes have significantly changed wind chill temperature computations.
For example, assuming an ambient air temperature of 5 degrees Fahrenheit as depicted on the top chart, and a wind speed of 30 miles per hour, the old wind chill temperature measurement was 40 degrees Fahrenheit.
I'm sure that revised local guidance will follow as the new index of wind chill temperatures becomes more widely understood.
One result of the new wind chill temperature recommendations is that frostbite clearly should be less of a concern at temperatures above zero degrees Fahrenheit.
As a result, wind chill temperatures all across the continent soared the very next day.
Wind chill temperatures have been published by the National Weather Service since 1973.
The original "wind chill temperatures" chart was based on the "Siple and Passel Index," named after Antarctic explorers James Siple and Charles Passel, who in 1945 conducted research on "connective heat loss" in the Antarctic.
Tom and his father Tim had wandered lost for six hours, battling driving snow, five-foot drifts and wind chill temperatures down to minus 8C.