"Bernard Burton" wrote in message
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"George Booth" wrote in message
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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

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.

And of course it is all specific to the hemisphere that you are observing
in. In the southern hemisphere, frictional retardation causes backing of
the flow with height in the lower boundary layer; and in the southern
hemisphere winds veering with height indicate cold advection, and winds
backing with height indicate warm advection.

I bet it's as clear as mud now! ;-)
--
Freddie
Bayston Hill
Shropshire
102m AMSL
http://www.hosiene.co.uk/weather/
https://twitter.com/#!/BaystonHillWx for hourly reports

Yes, thanks Freddie. I didn't include that aspect for clarity, but you are
of course correct.

Behind a warm front, in the 'text book' case, there would be a region of no
thermal advection, = no change in wind direction with height. But truely
'tect book' cases are rare.

--
Bernard Burton

Wokingham Berkshire.

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

"Freddie" wrote in message
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