11 January 2019
Vice-Chancellor’s Fellow Dr William Seviour comments on the impact and effect of the splitting of the polar vortex, in an article featured in Popular Science Magazine.
Though we might associate the polar vortex with anomalous cold weather and Nor’easters, it’s not unusual at all. “Sometimes you see headlines like the polar vortex is coming,” says William Seviour, an atmospheric scientist at the University of Bristol. “In fact, the polar vortex is always there.”
If left alone, the vortex hangs out through winter and dissipates in late spring. But, roughly every other year on average, waves of warm air intrude on the vortex in what’s called sudden stratospheric warming. It really is sudden—temperatures in this part of the atmosphere warm by as much as 50ºC (or 90º F) in just a few days.
When this happens, the vortex either moves south or is split apart. Then, sometimes—but not always—this disruption of the vortex leads to cold weather in the midlatitudes, including the northeastern U.S., western Europe, and northern Asia. “These are quite dramatic events,” says Seviour. “Even though they happen in the stratosphere … we see an impact that propagates down to the surface.”
Read the full article