Wind Chill

A key to surviving the Canadian winter is understanding how we are affected by the wind chill.   The following information is from Environment Canada’s  Weather Office a great source for current weather listings, weather FAQ and much more!

What is Wind Chill?
Anyone who has ever waited at a bus stop or taken a walk on a blustery winter day knows that you feel colder when the wind blows. This cooling sensation that is caused by the combined effect of temperature and wind, is what is known as wind chill.

On a calm day, our bodies insulate us somewhat from the outside temperature by warming up a thin layer of air close to our skin, known as the boundary layer. When the wind blows, it takes this protective layer away, exposing our skin to the outside air. It takes energy for our bodies to warm up a new layer and, if each layer keeps getting blown away, our skin temperature will drop and we will feel colder.

Wind also makes you feel colder by evaporating any moisture on your skin, a process that draws more heat away from the body. Studies show that when skin is wet, it loses heat much faster than when it is dry.

How does Wind Chill affect you?
Living in a cold country can be hazardous to your health. Each year in Canada, more than 80 people die from over-exposure to the cold, and many more suffer injuries resulting from hypothermia and frostbite. Wind chill can play a major role in such health hazards because it speeds up the rate at which your body loses heat.

How much heat you lose depends not only on the cooling effects of the cold and the wind chill, but on other factors. Good quality clothing with high insulating properties traps air, creating a thicker boundary layer around the body which keeps in the heat. Wet clothing and footwear lose their insulating properties, resulting in body-heat loss nearly equal to that of exposed skin. Your body type also determines how quickly you lose heat; people with a tall, slim build become cold much faster than those that are shorter and heavier.

We can also gain heat by increasing our metabolism or soaking up the sun. Physical activity, such as walking or skiing, increases our metabolism – which generates more body heat. Age and physical condition also play a part. Elderly people and children have less muscle mass and as a result, generate less body heat. Sunshine, even on a cold winter day, can also make a difference. Bright sunshine can make you feel as much as 10 degrees warmer. Over time, our bodies can also adapt to the cold. People who live in a cold climate are often able to withstand cold better than those from warmer climates.

Beating the chill
The best way to avoid the hazards of wind chill is to check the weather forecast before going outside, and to be prepared by dressing warmly. As a guideline, keep in mind that the risk of frostbite increases rapidly when wind chill values go below -27.

A simple way to avoid wind chill is to get out of the wind. Environment Canada’s wind chill forecasts are based on the wind you would experience on open ground; taking shelter from the wind can therefore reduce or even eliminate the wind chill factor.

A recent survey indicated that 82 per cent of Canadians use wind chill information to decide how to dress before going outside in the winter. Many groups and organizations also use the wind chill index to regulate their outdoor activities.

Schools use wind chill information to decide whether it is safe for children to go outdoors at recess; hockey clubs cancel outdoor practices when the wind chill is too cold; people who work outside for a living, such as construction workers and ski-lift operators, are required to take indoor breaks to warm up when the wind chill is very cold.

The Wind Chill Index
The index is expressed in temperature-like units, the format preferred by most Canadians. By equating the current outdoor conditions to an equivalent temperature with no wind, the index represents the degree of “chill” that your skin senses. For example, if the wind chill is -20 while the outside temperature is only -10°C, it means that your face will feel as cold as if it was a calm day (no wind) with a temperature of -20° C. See the numerical chart on wind chill values estimate for more information.   The Weather Office also has an accompanying chart that lists wind chill hazards and what to do.  Follow the above link to view the chart.

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