The polar vortex is essentially a fast-moving wind high in the atmosphere that holds very cold air above the North Pole.
However, the polar vortex is a very common feature of winters in the northern hemisphere, alteration in its behavior can affect our local weather.
If the polar vertex immediately weakens or changes position, this can lead to sudden stratospheric warning (SSW) which in turn can be associated with cold, wintry weather in the UK although the link is not straightforward.
The polar vertex consists of a ring of strong western winds surrounding the North Pole every winter, around 10-30 miles above the Earth’s surface in the stratosphere.
It forms because as the North Pole tilts away from the Sun, the upper atmosphere becomes intensely frigid and compact. A strong polar vortex tends to foster a strong polar jet stream which brings us mild and unsettled weather as Atlantic low-pressure systems are forced. SSW do not inevitably manifest as surface weather anomalies, but the outlook is heavily skewed toward cold weather.
Furthermore, periods of planetary waves and cold winter weather often persist under a stable polar vertex.
