The Polar Vortex - Explained

In a winter of seemingly permanent extreme weather, the very cold weather in North America looks like it is going to take the prize for extreme weather of 2014.Temperatures across the United States have plunged to their lowest levels for 20 years, as almost half of the population (around 115 million people or so) have found themselves trapped under what is known as a "polar vortex".The life-threatening polar vortex is a persistent, large-scale cyclone. They are usually found around either the north or south poles – it is rare for them to swing as far as to affect densely-inhabited areas.In many parts of the US, it has not been this cold for almost two decades. Because of that, medical experts are reminding people that frostbite and hypothermia can set in quickly at -15 to -30F (-26 to -34.4C), and that it is vital to be dressed properly for the temperatures.This short video from Channel 4 explains what a polar vortex is.