If you think you understand wind chill, think again

As a kid growing up in the central Alps of Switzerland I knew three winter temperature conditions: not too bad, cold, and bloody cold. When I experienced my first 40 below in Fort Nelson, where Fahrenheit meets Celsius, I convinced myself that once the temperature hits 40 below it doesn’t make any difference anymore. I abandoned that assumption long before I experienced my all-time low, -54 C in Dawson City. All these experiences were before the invention of the wind chill factor.

We have standard definitions and measurements for temperature and wind speed; why not leave it at that in our weather reports? I was curious to find out how, using the two measurements of wind and temperature, a wind chill factor is determined.

The explanation is quite simple: the wind chill factor is the rate of heat transfer a person experiences when walking bare-faced in an open field, facing a wind speed of 1.4 metres per second at face height. Anyone who finds this explanation to be too vague may apply the standard wind chill formula used by Environment Canada: Twc = 13.12 + 0.6215Ta – 11.37v+0.16 + 0.3965Tav+0.16. Does that help?

Temperature reports given in wind chill measurements are problematic. The face height used in the formula is not specified. Do people who are more than six feet or less than 5 feet tall experience different wind chills?

What adjustments should people make when they are walking on a downtown sidewalk, not in an open field? What if the wind is not blowing at a steady rate into your face, but swirling and gusting? The most useful piece of information I found in my wind chill research was that “wind chill has no universally agreed upon standard definition or measurement.”

That explanation inevitably leads to the question why. Why report wind chills when the official formula has meaning only for a person who is 1.78m tall and who is walking into the wind in an open field? Would a weather report announcing a temperature of -15 C with strong, occasionally gusting north-northwest winds leave people puzzling, unsure as to what to wear? Light jacket or parka? Sandals or lined boots?

I assumed that people in Australia are spared such problems; then I discovered that Australia too has invented a temperature indicator unique to its climate. Australia has developed an apparent temperature (AT) index. AT is a mathematical model using temperature and humidity. The official formula is AT = Ta + 0.33e – 0.7v – 4.00. The measurement reveals the amount of discomfort an adult person experiences when walking outdoors, in the shade.

As a kid I had to learn to anticipate comfort (or discomfort) based on degrees Celsius and kilometer per hour wind speeds. On landing in Canada I had to adjust my preparations for what I would experience on stepping outside to degrees Fahrenheit and miles per hour. By the time I felt comfortable with Fahrenheit and miles reports I had to relearn Celsius and kilometers.

When I reached the age of retirement, instead of life becoming easier and simpler, along came wind chill. I give up. Time for me to revert to my original winter temperature assessments: it is not too bad, cold, or bloody cold. Remembering my Yukon days, early February days in Terrace were not too bad; still a long away from bloody cold.

Get local stories you won't find anywhere else right to your inbox.
Sign up here

Just Posted

COLUMN | Creating a “community of practice” inspires

Art Matters by columnist Sarah Zimmerman

Hockey puck with nails found at Terrace Sportsplex Arena

City believes it has already caused $4,000 of damage

Kitselas First Nation receives $1.2M boost for apprenticeship development program

Melanie Mark, Minister of Advanced Education announces $7.5M for six Indigenous training programs

Terrace Skating Club takes home 24 medals from regional championships

Skaters claim top spot for fifth year in a row

Women take centre stage at NHL all-star skills competition

Canada beat the United States 2-1 in a spirited 3-on-3 game between female players Friday night

BCLC opens novelty bet on Harry and Meghan moving to the west coast

Meanwhile, real estate agency points to four possible homes for the family

Coastal GasLink work camp in Vanderhoof gets approved by the ALC

The work camp behind the Vanderhoof airport was first rejected by the commission in October last year

Canada slips in global corruption ranking in aftermath of SNC-Lavalin scandal

The country obtained a score of 77, which places it at the top in the Americas

Wuhan bans cars, Hong Kong closes schools as coronavirus spreads

Hong Kong leader Carrie Lam said her government will raise its response level to emergency, highest one

B.C.’s oldest practising lawyer celebrates 100th birthday, shares advice

Firefighters bring Constance Isherwood a cake with 100 birthday candles

Vernon woman suing McDonald’s for spilled coffee

Woman seeking nearly $10K, says employee failed to put lid on properly

Diners’ health tax not catching on in B.C., restaurant group says

Small businesses look for options to cover employer health tax

Most Read