The Polar Vortex, Explained

When most people think about the jet stream, if they think about it at all, it’s usually in the context of the high-altitude, fast moving wind currents of the northern hemisphere that enable speedy west-to-east long-haul flights. But the polar jet stream also plays a major role in our daily lives: the weaker it gets, the wackier our weather is, from the Texan deep freeze of 2021 to the snow bombs that have pummelled the West Coast over the past two weeks, and the winter storms now heading for the East Coast and Europe. It’s not just cold weather—an unstable jet stream can also lead to severe heat waves, droughts, or excessive amounts of rain. And the polar jet stream appears to be weakening, according to scientists, as a result of Arctic warming caused by climate change.