In article ,
Mike Tullett writes:
On Tue, 4 Jan 2005 17:14:52 -0000, Stuart wrote in


What do the coloured lines reresent?

http://129.13.102.67/wz/pics/Rtavn1683.gif

Assuming you mean the green and blue lines - they indicate the thickness of
the 1000hPa to 500 hPa layer in decametres. The greater the value the
warmer the air is. Get some way below the 528 line and snow is
increasingly likely and at 510 is virtually certain.

In case Stuart is a beginner, I feel that I should add the caveat: this
is assuming that you actually get some precipitation rather than it
remaining dry!
--
John Hall

"I don't even butter my bread; I consider that cooking."
Katherine Cebrian