BOAC what I mean is that they meander around for various complex reasons, I did not necessarily write that for your benefit, I'm not doubting your observations I'm just afraid that this thread may turn into yet another 'global whining' 'climate change' thread...with the wording in some posts...I can see the writing on the wall...for that discussion
just for completeness sake
Jet stream - Wikipedia, the free encyclopedia
They do a good job with it here
