New Scientist: Winter has come early to the US this year, with temperatures plunging below freezing across much of the continental US this week. Intense snowstorms dumped almost 2 metres of snow in a few places such as Buffalo in New York state (above), trapping people in cars and buses. So what has caused this unseasonal weather?
Cold air is usually trapped in the Arctic by the winds that circle the pole - the polar vortex. The strongest winds found high up in the atmosphere are called the polar jet stream....