The thickness is measured in decameters between 1000mb and 500mb.
Cold air decreases the thickness layer because it is more dense. Warm
air increases the thickness layer because of less density.

On Tue, 19 Aug 2008 15:58:34 -0700 (PDT), Weatherlawyer
wrote:

On Aug 19, 8:11*am, A1C Watkins wrote:
On Aug 16, 3:41*pm, wrote:

Why is the 540 isopleth significant on a 1000-500 thickness chart?

Thickness below 540 generally indicates a zero percent chance of
frozen precipitation (i.e. snow) so that is pretty significant.

The dartboard shown in such charts indicate heights I take it. Thus
the dots joined are for pressures on one plane and heights on the
other so (not counting my own) what does thickness mean?