On Mon, 22 Apr 2013 11:25:52 +0100
"Bertie Doe" wrote:

Is there a rule of thumb for wind veering or backing with height?
Reason I ask: I often see actual wind say, bonfire smoke to differ by
60 degrees, with cloud-over-ground movement? TIA.


Rather depends on the height of the cloud as to what caused the
difference. Over land, the surface wind is generally backed by about
thirty degrees from the wind at about 2,000ft due to frictional forces.
See http://weatherfaqs.org.uk/node/75 for more complete info.

Wind velocity also changes with height depending on the temperature
distribution. This can be used to do your own forecasting when you see
clouds at two levels moving in different directions. If the wind is
backing with height, then cold air advection is occurring between the
two levels; conversely, if the wind is veering, warm advection is
occurring.

--
Graham P Davis, Bracknell, Berks.
Free office softwa http://www.libreoffice.org/
Carlos Seixas, Sonata nº 1 - best version of this I've found:
http://www.youtube.com/watch?v=YXox7vonfEg