Chilly winds blow through cyberspace

MONTREAL — This week, a cold chill descended over the World Wide Web, as Environment Canada held its first-ever Internet workshop on the wind-chill factor.

As most northern residents know well, wind-chill is a potentially lethal combination of wind speed and cold temperatures. Exposure to wind-chill can cause frostnip, chilblains, frostbite, or even hypothermia and death.

Canada’s national weather service organized the five-day, online conference to see whether scientists, meteorologists and the media can better calculate windchill and communicate wind-chill levels to the public.

“We all know what it is to be cold- but how to describe it?” was the challenge presented by Danish scientist Leif Vanggaard to the Internet workshop participants.

With increased weather coverage, the demand for accurate and easy-to-understand information about wind-chill has been growing, but there’s little agreement on how to rate it or how to talk about windchill.

In Canada, when it’s -20 C° outside with a wind speed of 30 km/hr., people are just as likely to hear that the “windchill factor” is 1900 or very high, as they are that, due to the wind, the “equivalent temperature” is -38 C°.

The public and media prefers the system that says what the temperature feels like when a cold wind is blowing, while meteorologists and other weather scientists favor the more accurate numbers that express heat loss.

Yet both these systems fall short of being perfect.

The equivalent temperature model is usually off by three to five degrees, while the “watts per square metre” units used in the windchill factor system baffles most people.

“I strongly believe that you should use whatever works,” television broadcaster Claire Martin noted at the Internet workshop.

With only four to five seconds to deliver the weather, Martin said her message must be clearly understood.

“Take these two examples.

One: “Wind southeast, 30 km/hr…low minus 15. High windchill 1600, risk of frostbite.

Two: “Overnight lows down to minus 15. And it’s going to stay breezy, southeasterly winds of 30 km/hr., and, with cold temperatures and a brisk wind, you know the windchill effect will be significant, as will the risk of frostbite. In fact, when you factor in the effect of the wind, it’ll feel closer to temperatures of around minus 30 deg. C°.”

Which example gives you the clearer idea of the risk of windchill?,” Martin asked the workshop.

She also said she’s against Canada trying to force “blanket policies” on the public.

“Give them the information they want in any way they like,” Martin said. “And if it is not in a necessarily scientific form, well, then, so be it.”

In fact, Environment Canada’s own 1999 survey showed a large majority of Canadians prefer the equivalent temperature system of reporting windchill.

The survey asked more than 1100 Northerners in Yukon, Northwest Territories, Nunavut and Nunavik what they would do if the predicted windchill were 2400 watts per square metre.

A windchill level of 2400 is extremely dangerous, and exposed skin can freeze in 30 seconds.

But, according to the survey’s interviews, “63 per cent did not know what a windchill of 2400 means or would not know what to do if they heard this figure in a weather forecast.”

That’s why the Meteorological Service of Canada wants to find a more “accurate and meaningful” way to communicate windchill.

Some participants in the Internet workshop proposed new ways of calculating heat loss from humans in cold and wind. One researcher recommended that “any new index of windchill be based on the recent model of facial cooling in the wind.”

Another said Canadian and US practices on windchill reporting also need to be harmonized because Americans favor the equivalent temperature system.

The Internet workshop ended on Friday, but its web site windchill can still be consulted at http://windchill.ec.gc.ca.