Weatherwatch: Sudden stratospheric warming has reset usual winter pattern

http://www.guardian.co.uk/news/2013/jan/27/weatherwatch-stratosphere-warm-winter

Version 0 of 1.

It is shocking to be plunged into freezing winter weather but it can all be blamed on the stratosphere, some 30km high. Around New Year something strange happened in the stratosphere over the Arctic where the usually frigid air suddenly warmed up by around 50C. That warming sent the usual freezing stratospheric air streaming down over Europe which then gradually trickled down into our weather pattern in the lower atmosphere, with biting easterly winds sweeping across from northern Europe.

One spectacle to watch out for in these episodes is a glow in the evening sky just after sunset. We saw this in December 2010 when the stratosphere turned so cold over Britain it created fabulous tangerine, pink and yellow afterglows blazing in the twilight sky. These colours came from unusual clouds in the stratosphere that form when temperatures drop to about –80C. That cold stratosphere also led to a great freeze and big snowfalls, when the country was reduced to chaos with Heathrow Airport and Eurostar services shut down.

This current sudden stratospheric warming is a major event and left the lower stratosphere badly disturbed as a swathe of cold weather settled across Europe for several weeks. For the UK at least, this cold weather is now over, thanks to a depression of noteworthy proportions which developed in the Atlantic this past weekend. This has reset the usual winter stratospheric pattern which is far more likely to bring mild and very wet weather for the next fortnight.