"George Booth" wrote in message
...
On 22/04/2013 11:25, 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.



In general wind veers and increases with height. Memories of fretting over
this on airfield layout for glider winching.

UKMO F214 spot wind forecast E.Anglia pm today gives 1000' 230/25knots,
2000' 240/30knots all the way up to 18000' 310/45knots.

Another useful source
http://rasp.inn.leedsmet.ac.uk/RASPt...SPtableGM.html where you'll
have to select 'soundings' from LH window, select the one you want and see
the wind speed and directions displayed on right of graph.

--
George in Epping, west Essex, 350'asl
www.eppingweather.co.uk
www.winter1947.co.uk

Not quite the whole story George.

Your statement is only true in the boundary layer, below about 1km altitude.
This veering and increasing with height is caused by the frictional drag of
the surface. The degree of coupling between the surface air and that at 1 km
is an essential ingredient in maintaining the surface wind. If the coupling
is reduced, for example due to the establishment of a strong surface
temperature inversion (radiational night-time cooling), the surface wind
soon decreases to near calm, due to frictional drag. During the daytime,
coupling is at a maximum in an unstable boundary layer temperature profile,
and the surface wind speed and direction will be closest to that at 1 km
altitude.
As has been pointed out elsewhere, wind in the free atmosphere, that is,
above the surface boundary layer, veers with height in the presence of warm
advection, and backs in the presence of cold advection. The magnitude of the
vector change with height is directly related to the magnitude of the
thermal gradient. It is this type of effect you are seeing in the F214 winds
you quote.

--
Bernard Burton

Wokingham Berkshire.

Weather data and satellite images at:
http://www.woksat.info/wwp.html