Climate Central: An unusual event playing out high in the atmosphere above the Arctic Circle is setting the stage for what could be weeks upon weeks of frigid cold across wide swaths of the U.S., having already helped to bring cold and snowy weather to parts of Europe.
This phenomenon, known as a "sudden stratospheric warming event,' started on Jan. 6, but is something that is just beginning to have an effect on weather patterns across North America and Europe.
While the physics behind sudden stratospheric...