Jet Stream

[gerkin]

Apparently very cold air from the jet stream over Carlisle was sucked down during last fridays/saturdays storms and caused local rapid freezing.  Is this true / possible ??.

[Ewood27]

A jet stream is a very strong wind in the upper atmosphere (30,000 feet or so) which occurs where there are very active weather fronts.  I haven't seen any charts for the period you mention, but I'd say it's quite possible for a jet stream to drag cold air down from the Arctic, which could well hit suddenly and cause rapid temperature change.

[Ewood27]

This article appears in today's Daily Telegraph.

http://www.telegraph.co.uk/news/main.jhtml?xml=/news/200 5/01/13/nflood113.xml

[Ewood27]

Hmmm ... The link doesn't work.  Here's the article.  As printed in the paper it had diagrams which made things a bit clearer.  Hope you can follow it.

 

'Sting jet' blamed for winds
By Roger Highfield, Science Editor
(Filed: 13/01/2005)

The high winds that battered the north of Britain were blamed on a "sting jet" yesterday.

A sting jet "almost certainly" formed on Saturday morning, said Martin Young, a chief forecaster at the Met Office, Exeter. The wind gusted to more than 100mph across some parts of northern England, with speeds of almost 130mph on the Pennine peaks.

Research by the Met Office and Prof Keith Browning, of the University of Reading, discovered the phenomenon and coined the phrase.

Sting jets occur in cyclones when there is a dramatic fall in the barometric pressure. "The ones we have seen have shown a similar drop in as few as six hours," said Mr Young.

The sting jet is born at an altitude of three miles, within layers of ascending moist air. As the jet descends, it passes through ice crystals that cool it, increase its density and cause it to accelerate to more than 100mph at ground level.

Dr Robert Muir-Wood, of Risk Management Solutions, estimated that sting jets cause �600 million of damage in Europe each year. Sting jet formation could increase as more heat energy enters the atmosphere through global warming.