"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.
--
FAQ & Glossary for uk.sci.weather at:-
http://homepage.ntlworld.com/booty.weather/uswfaqfr.htm