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Earth Sense: Polar vortex is nothing new

POSTED: January 18, 2014 9:24 p.m.

During the frigid spell of early January, news media were filled with articles about the “polar vortex.” Some sounded like this is some new, dangerous phenomenon, apparently just discovered, and it’s coming to get all of us.

If you got that impression, you may rest easy. The circumpolar vortex has existed for thousands of years. It defines air circulation at high altitude, caused by the temperature differences between a vast area surrounding the North Pole, and the continental regions to the south of there: Alaska, much of Canada, northern Europe and northern Russia, including Siberia.

Air moving slowly northward into the 24-hour darkness north of the Arctic Circle runs into a barrier of very cold, heavy air. Because the earth is a sphere, not a flat surface, there’s less space available for air to spread out. The result is that it rotates in the direction of the globe, but faster. In the animations that have been presented on TV, you see this as a circle rotating around the North Pole in a counterclockwise direction (from west to east). That’s the circumpolar vortex, or “whirl around the pole.”

At times, the frigid air to the north makes a dent in the circle, and this indentation travels from west to east like the bow wave of a ship. That’s the cold outbreak we saw in the Midwest, extending a huge finger of very cold air southward all the way into our subtropical latitude. No new phenomenon is at work here, just the bouncy nature of air masses. Global warming could be partly responsible for it because these outbreaks depend on temperature differences.

Push a balloon with your finger, and another part of it will jut out to compensate. Push warm air northward and cold air will poke south somewhere else. We’ll see more weather extremes in years to come, but it’s good to remember that we had them before.

On Feb. 5, 1996, the low in Gainesville was 8 degrees. On Jan. 11, 1982, it was 3 below. The morning of Jan. 21, 1985, brought us a frigid 8 degrees below zero. Blairsville reported minus 16 degrees that day.

In a nutshell, the current situation can be summarized like this: Will there be more extreme weather? Yes, both hot and cold, and we’ve seen it before.

Is there some strange new phenomenon, requiring us to go into survival mode? Highly unlikely.

Rudi Kiefer, Ph.D., is a professor of physical science and director of sustainability at Brenau University. His column appears Sundays and at gainesvilletimes.com.


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