The easy answer is a deep southward dip in the polar jet stream that typically rings the globe at higher latitudes but is ...

The polar vortex's icy grip on much of America has Arctic Greenland seeming like a toasty vacation spot by comparison.

"An Arctic air mass is expected to plunge into the Central U.S. this week, with high confidence for widespread, ...

Miles above the Earth, two bands of fast-moving air – the polar jet stream and the stratospheric polar vortex – sometimes tango together to influence weather in the northern hemisphere.