Climate change has hit the Arctic worse than ever over the past few years, but that doesn't mean the Northern Hemisphere is going to be experiencing a mild winter this year. In fact, a new study shows that the polar vortex is shifting, and it's going to make winters on the east coast of the US and parts of Europe even longer, with exceptionally cold temperatures expected during March. The polar vortex is that lovely zone of cold air that swirls around the Arctic during winter. When parts of the vortex break apart and splinter off, it can cause unseasonably cold conditions in late-winter and early-spring in the Northern Hemisphere. This happened in early 2014 - as you can see in the satellite image above - and caused an extreme weather event in the northern US and Canada. But not many people realise there are actually two polar vortices: the stratospheric polar vortex, which is about 19,800 metres (65,000 feet) above the surface of the Earth; and the tropospheric polar vortex around 5