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John Wheeler, Published January 14 2013

Weather Talk: F-M’s recent cold air came from north of Arctic Circle

The air the past several days has been of Arctic origin. That is to say, the air came from north of the Arctic Circle, where it tends to be extremely cold in midwinter.

When Canada is snow-covered, air from the Arctic is able to move into our region without being significantly modified. The snow is important because a snow-covered surface reflects most of the sunlight that strikes it, keeping the air from being warmed much at all. So when our weather is 10 or 20 or 30 below and the air has come from the Arctic, is it correct to call it Arctic air.

But farther south, places such as Texas and Atlanta sometimes get this same air from Arctic origins. However, the sunlight at these southern latitudes is much stronger and the air has usually crossed a couple of states’ worth of ground without snow cover, causing it to warm into the 20s or 10s. Southern television meteorologists and reporters are quick to talk about this as being Arctic air, but this is not precise. A more precise term would be modified Arctic air.

Have a weather question you’d like answered? Email weather@wday.com, or write to WDAY Stormtracker, WDAY-TV, Box 2466, Fargo, ND 58108

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