19 Feb Hey forecasters: nix “wind chill.” Give us real temperatures

In a letter to CBC Nova Scotia’s Information Morning, West Dublin listener Peter made a plea dear to Contrarian’s heart:

The formulas for calculating “wind chill” have the appearance of real science. In reality, they have little to do with science, and no useful meaning—other than to dramatize weather forecasting.

Various wind chill formulas, including the one used in Canada, attempt to predict the way a human perceives the effect of wind on a cool day. Wind chill is completely subjective and cannot be measured objectively.

Lets say the temperature, measured scientifically on a thermometer, is -20 and the wind speed is 5 km/h. The wind chill or “feels like temperature” is -24.

To understand how meaningless “wind chill” is, imagine a man riding a bicycle at the same speed as the wind (5 km/hr) in the same direction the wind is blowing. He won’t feel the wind at all. No wind chill! But when he turns around and heads home, peddling at the same rate, the “wind” is in effect doubled—his bike speed plus the speed of the true wind. Now the windchill for this man is -30.

Or take those those hardy souls who gain perverse pleasure in a Polar Bear Dip. Emerging from the icy water, they will perceive the effect of a blustery wind much differently than their fans sitting in the bleachers, snug in down jackets.

Same real temperature, same wind, very different subjective perceptions of the same weather conditions.

Real temperature can be measured. How an individual perceives the combination of the real temperature and the wind cannot be quantified.

So give us the real temperature and, if there’s a wind, suggest that your listeners “bundle up.” Nix the wind chill numbers. They don’t mean anything.

Peter Barss