December 24 2000 BRITAIN


Weathermen to chill out with 'comfort index'


John Harlow and Tom Robbins


WEATHERMEN are to do away with the bitter cold of winter winds. The United Nations wants to replace the wind-chill factor used by weathermen with a new German-designed scale called the thermal comfort index (TCI).

The chill factor measures how wind causes the human body to lose heat. For decades, however, the flaws of the system have been an open secret among meteorologists.

The measure was originally designed by explorers in the Arctic in 1940, but it typically overestimates how cold the weather is by up to 9C, which can confuse skiers, builders and generals, who depend on such predictions when plotting their next moves.

Scientists at the World Meteorological Organisation, a UN agency, now plan to adopt a method of measuring exposure outdoors designed by scientists at Munich University. The new scale, which it hopes to introduce before the end of next year, takes into consideration the effect of humidity on temperature.

It also allows for the fact that women start with warmer faces than men and give off more "radiant heat", while darker skins are more prone to chilling than lighter complexions.

It ranges from -10 - bitterly cold - through zero, as felt by an averagely built man sitting in his front room, to +10 - for a man facing a hot Saharan wind.

Today television meteorologists announce average air temperatures and then often subtract extra degrees depending on the speed of the wind. Under the new system, weather forecasters will announce the air temperature and a separate figure for the TCI index from -10 to +10.

It will be the most significant change in weather news since the introduction of ultra-violet sunburn and air quality readings in the 1980s.

The Royal Meteorological Society welcomed the demise of the wind-chill factor, but gave warning that extra figures tended to confuse the public.

"I've long argued against using wind-chill temperatures in forecasts," said a spokesman. "Weathermen give a temperature figure, and then another figure which sounds like a temperature but is not a real measurement.

"It is confusing to people who are in the know, let alone the general public. I always cringe when I see wind-chill factors on television."

Edwin Kessler, a former director of the National Severe Storms Laboratory in Oklahoma, said that wind chill was "just a load of hype used by TV weathermen to scare people".

"But crying wolf with exaggerated wind-chill factors can cause people not to take the real threat of cold seriously," he said. "Its demise is long overdue."

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