Polar vortex is 'spinning backwards' above Arctic after major reversal event

A satellite image of Earth taken from above the arctic, with green swirls moving counterclockwise representing the movement of cold air patterns.

The polar vortex circling the Arctic is swirling in the wrong direction after surprise warming in Earth's atmosphere triggered a major reversal event earlier this month. It is one of the most extreme atmospheric U-turns seen in recent memory.

In the past, disruptions to the polar vortex — a rotating mass of cold air that circles the Arctic — have triggered extremely cold weather and storms across large parts of the U.S..