What is the polar vortex and how did we get into it?

Compiled by Copy Editor Susan Johnson

National Public Radio recently discussed the topic of the polar vortex as it is affecting us. Science writer Andrew Freedman told David Greene on Morning Edition that it is “a low-pressure system that’s usually [at] the North Pole but has weakened and come south.” But the question keeps coming up, what is it, and why is so much of it in the U.S.?

Washington Post weather editor Jason Samenow described it as “a huge sprawling area of circulating cold air originating from the North Pole. It’s a low-pressure center, and typically during the winter months, it resides up there. At times, some tentacles of it will slip southward and bring cold air outbreaks into the U.S., but this year, we’re seeing a huge chunk of it, most of it descending into the U.S.”

Samenow explained that high-pressure systems over Alaska and Greenland allow the jet stream to dive south over the U.S., and along with it comes the polar vortex.

Freedman compared it to a figure skater who extends his arms, then trips. When a figure skater pulls his arms in, he spins tighter and tighter, faster and faster. But by putting his arms out, he becomes slower and more wobbly and is more prone to fall or stop skating at the end of a routine. In effect, a piece of this vortex system on the other side of the globe became lopsided and came down on top of us.

But now, why has the vortex weakened as it descended on us?

Besides the effects of high-pressure systems over Alaska and Greenland, Freedman suggests the possibility of climate change. The more arctic ice that melts during the summer months, the more the Arctic Ocean warms. “The ocean radiates much of that excess heat back to the atmosphere in winter, which disrupts the polar vortex,” he said. “Data taken over the past decade indicate that when a lot of arctic sea ice disappears in the summer, the vortex has a tendency to weaken over the subsequent winter.”

The Rock River Times’ Staff Writer Jim Hagerty noted that Rockford was among the nation’s coldest cities during a recent polar vortex shift. In an online article posted Jan. 8, 2014, he said, “Between Dec. 30 and Jan. 4, the stateline saw several inches of [snow] accumulation, followed by sub-zero temperatures and wind chills well past minus 40 degrees by Monday, Jan. 6.”

From the Feb. 19-25, 2014, issue

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