Is the polar vortex to blame for this winter's cold? Maybe not! While the stratospheric vortex has been wobbling and stretching, our experts say there's little evidence that it's the main driver of extreme winter weather in parts of the US so far. In fact, the stratosphere and troposphere have been largely uncoupled, doing their own thing for much of the season. So, what's really going on? And could the shape of the vortex, rather than its strength, be playing a role? Read more to find out: http