Mike W. Bryant
Northern News Services

Yellowknife (Oct 03/01) - This winter's windchill ratings probably won't be as dramatic as usual, but don't think global warming has anything to do with it.

The real cause is Environment Canada's new windchill rating system, which will feature toned-down numeric values that reflect what the temperature actually feels like on skin.

Under the old system, a temperature of -30 C with 50 km/h winds would produce a windchill temperature equivalent of -65 C under shelter. Similar weather conditions under the new system would produce a seemingly balmy -49 degrees.

While this doesn't mean the actual windchill will be any less severe than in previous years, the psychological ramifications of the new numbers are quite clear.

"The media won't have as much to talk about because the numbers won't be as extreme," laughs Yvonne Bilan-Wallace, an Environment Canada climatologist based in Edmonton.

"At the high end (temperature-wise), it's a lot flatter of a curve."

Environment Canada starts using the new system today.

Previously, windchill factors were based on the heat energy, measured in watts, lost per square metre of exposed surface area.

According to Bilan-Wallace, that method is considered crude today because it doesn't take into account the body's natural ability to warm itself.

Moreover, Bilan-Wallace says, after 20 years in use, most people still don't understand how the watts-per-square-metre system works.

"The old windchill was developed by scientists in Antarctica during the 1940s," says Bilan-Wallace. "One of the scientists was watching how long it took before a plastic tube of water would freeze."

Last summer, at the National Defence Research Institute in Toronto, researchers conducted a series of new windchill formula tests using actual humans as subjects.

"They stuck people in a wind tunnel and squirted water on their faces and lowered the temperature," says Bilan-Wallace.

"Plastic bottles of water do not produce their own heat, but people do."

This winter, Environment Canada will begin posting windchill ratings in the NWT once it reaches -25 C. Frostbite warnings will be issued when ever the wind chill reaches -50 C.

Leo Reedyk, manager of operations and maintenance at the Yellowknife Airport, says the change to the windchill rating is news to him, but his work crews are always mindful of the weather.

"The colder it is outside, the more time you spend inside warming up," says Reedyk.

On extremely cold days, he adds, airport crews will spend 10 minutes outside followed by 10 minutes inside -- and that's in full Helly Hansen gear.

Fortunately, most of the snow in Yellowknife falls during the more milder months of winter.

"Our biggest task is removing snow from the airfield," says Reedyk. "But you don't get a lot of snow come January, February."