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Sundog appears over Kane Co. as polar vortex causes Arctic-like temps

This rainbow-like sundog caused by ice crystals atmosphere could be spotted over Hampshire late Monday afternoon. | Denise Moran for

This rainbow-like sundog, caused by ice crystals in the atmosphere, could be spotted over Hampshire late Monday afternoon. | Denise Moran for Sun-Times Media

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Updated: February 9, 2014 6:21AM



Area residents who might have thought they were looking at a rainbow in the sky over Kane County late Monday afternoon were actually viewing a “sundog.”

According to Jim Angel, Illinois state climatologist, “the scientific name for sundog is parhelion. They are bright spots of light on either side of the sun and caused by ice crystals, acting as tiny prisms bending (refracting) light from the sun. Because they act like prisms, most of the time you can see several colors in the bright spots. It is fairly common to see one or both spots on either side of the sun.”

Angel’s website, www.isws.illinois.edu/atmos/state, notes that the record low for Illinois — minus 36 degrees — was set in Congerville on Jan. 5, 1999. The website states that low temperatures in both Elgin and Aurora on Monday were minus 17 degrees.

According to the Christian Bible, God put a rainbow in the sky after the Great Flood as a sign that a flood would never again destroy the Earth.

It would be comforting if the sundog was a sign that the weather will eventually warm up.

Polar vortex

That is supposed to happen this week as the area shakes itself out of the polar vortex that has caused the coldest air in 20 years to descend on northern Illinois.

A release from Accuweather.com describes a polar vortex as a large pocket of very cold air, typically the coldest air in the Northern hemisphere, that sits over the polar region during the winter season.

The frigid air found its way into the United States when the polar vortex was pushed south, reaching southern Canada and the northern Plains, Midwest and northeastern portions of the United States, the website said.

“This is why we’ve had such extreme cold,” meteorologist Brett Anderson said in the release.

“The polar vortex moves around at times during the course of the winter, but rarely do you see it get pushed this far south.”

A large, powerful high-pressure system originating in the Eastern Pacific is stretching to the North Pole, shoving the vortex farther south than is typical, allowing it to settle in Canada and the U.S., according to Accuweather.com.

“These high-pressure systems can reach Alaska, but it is not typical to stretch all the way to the North Pole,” Anderson said.

“The high-pressure system, paired with the extensive snow cover over southern Canada and the northern United States, is allowing the air to stay very cold.”

According to the National Weather Service, the Upper Midwest — where some of the lowest temperatures are occurring — is currently more than 98 percent snow-covered.

The Upper Great Lakes region is 100 percent snow-covered, and the Midwest is more than 76 percent covered, the release noted.

It said that when the strong air from the Eastern Pacific weakens and falls apart, the polar vortex will retreat and go back into place near the North Pole.

Until then, temperatures across the northern Plains and Midwest will continue to be life-threateningly cold, shattering some all-time low record highs, Accuweather said.



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