regarding cold/hot air masse why jetstream always breaks up over uk?

[chrcoluk]

Looking at pics of the jetstream the gap between hot and cold air, it always seems to go straight until it approaches western europe and then in that area breaks up or goes wavy.  If it were straight the uk would always be above the jetstream and be its natural colder state, but this wavyness seems to artifically shift hot air above the uk and nearly all radars seem to be like that, to show what I mean is 3 images I made, the black circle been the uk, the blue been cold air and red been hot air.  The third image is what they all seem to always look like, the 2nd image is what it should like that but never is and first I wonder why is never like the first.

Edited October 4, 2013 by chrcoluk

[cheeky_monkey]

it is often like your first image...the summers of 2007-2012 are a testimant to that..as are the the often cold spells in the last few winters..so i would wager there has been a lot more of image number 1 in the last 6 years..where as in the period 1988-2006 there were a lot more of image number 3.

[virtualsphere]

Here's an example of image 1:

 

Archive of jet stream maps: http://squall.sfsu.edu/crws/archive/jet_nh_arch.html

Edited October 4, 2013 by virtualsphere

[bobbydog]

because Mr Tumble painted it....

[Evening thunder]

It's not that it should be like number 3, the jet stream is a naturally varied/wavy and changing thing.

I believe all locations at this latitude can be and often are on the warm side of the jet stream, as is shown happening on the other side of the Atlantic (and looping right over Greenland!) on virtualsphere's image.

 

The jet stream can tend to get stuck in general patterns within it's variability though. At the moment we just seem to be getting warm patterns more, some time down the line we will probably get cool/cold patterns dominate more again (like later last winter and spring, or many recent summers)

 

Anyway things would be more boring if the jet stream was just a straight line :-)

[Isolated Frost]

It's all due to Rossby waves- it's very much hit and miss, and often subject to stratospheric blocking penetrating lower levels: though as CM says, recently it's been a lot more like image 1.

[chrcoluk]

all fair comments, I have only been into this since july this year so I based on what I have seen since then and you guys have been doing this for years.

[Interitus]

As mentioned above, the jet stream does have 'preferred' positions though, for example in winter it has been shown to be trimodal, where it averages towards three different tracks which are then reflected in the NAO index. This varies within the season, but also over periods of years.

 

Here is a bit of light reading -

Variability of the North Atlantic eddy-driven jet stream

http://centaur.reading.ac.uk/8175/1/jetlat.pdf

 

Twentieth century North Atlantic jet variability

http://www.met.reading.ac.uk/~swr01tjw/pubs/20Cjet.final.pdf

[chrcoluk]

those jetstream archives are interesting, they show that on the other side of the world the jetstream is usually much more powerful and also further south, but between america and western europe it moves north and breaks up a lot. eastern europe it is south again which might explain why russia gets so cold.

Edited October 8, 2013 by chrcoluk