Most of Canada has been dealing with a bitter winter this year. Heavy snowfall, ice storms, and Arctic temperatures made worse by wind have gripped most of the country relentlessly so far this winter. Add that wind to the already frigid temperature and you get something much colder..wind chill.
Dave Philips explains exactly what wind chill is. He is the senior climatologist with Environment Canada.
ListenIt should be noted that wind chill is a “perception” of the cold felt by humans. Although the actual temperature never changes, the fact that added wind robs exposed areas of a person’s body of heat faster makes it feel even colder to humans.
David Phillips, Senior Climatologist with Environment Canada
In other words if you are bundled up and standing beside a mailbox at -20C and the forecast says the wind chill is -30, your exposed face or hands will lose their heat at the same rate as if it was -30 with no wind. The mailbox which has no heat to lose, feels only the actual temperature of -20.
The idea of mentioning wind chill is to provide a guide to the risk of frostbite to exposed skin.
The idea of wind chill occurred to two American scientists (Paul Siple, Charles Passel) working in the Antarctic in the 1940’s. Their mathematical model involved the time required for a plastic cup of water froze outside their station. They determined that the rate of freezing depended on initial temperature of the water, temperature outside, and wind speed.
A modified wind chill formula was developed by Environment Canada and US agencies in 2001 to create a North American standard. The math was put to the test in the research labs of the Department of Defence in Toronto. A group of 12 volunteers, six men and six women, went through clinical trials in a refrigerated wind tunnel to see how the model held up in a real-world situation, e.g. at about face height, and walking into the wind at a typical speed of 1.4metres/sec
Britain has adopted the North American standard for calculating wind chill, while Australia factors in humidity making their calculations slightly more accurate.
Wind chill is calculated only for temperatures at 10-degree Celsius and less, and for wind speeds greater than 4.8 km/h.
Did you know?
The coldest wind chill recorded in Canada was at Pelly Bay, Nunavut, on January 13, 1975, when 56 km/h winds (a wind chill factor of 3,357 watts/m²) made the temperature of -51 C feel more like -92 C
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