This week, Hell literally froze over, as the small Michigan town of Hell experienced temperatures of minus 17 degrees Celsius. And Hell wasn't alone temperatures across the United States have plummeted to record lows as cold air from the Arctic has reached much lower latitudes than is usual. To explain how this has come about, here's your Quick Fire Science about the polar vortices with Kate Lamble and Dominic Ford Like this podcast? Please help us by supporting the Naked Scientists