"Jeremy Handscomb" wrote in message
...

PS Alternatively you could find a map that shows the lines of
thickness!
They are around somewhere but I'm afraid I don't know where to find
them.



http://www.westwind.ch/?page=gfsg

there are others: but don't get 'hung-up' on thickness (500-1000hPa) ..
it's useful, but for tracing low-level airmasses, use ThetaE or similar.

Martin.

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