On Wed, 30 Jul 2003 08:04:49 +0100, "Ken Cook"
<kencook@copleydurham.freeserve.co.uk> wrote:

>"Dave Ludlow" <daveludlow@~SPAMTRAP~clara.co.uk> wrote in message
>
><snip>
>
>> As I've said before, I'd love to see if there's any correlation
>> between (low) wind speed and apparently anomalous temperature readings
>> in clear conditions. I am quite a trusting person :)
>
sveeral snips

>I have been reading the posts about erroneous wooden screen readings
>with great interest. The large discrepancies must put many of our urban
>and valley readings into question. Should readings show whether a wooden
>or plastic screen is in use?
>
>I once read, probably Manley - it usually is with me, that exposed
>airfields are the safest bet for comparable readings,

>In many cases, the MO can not pick and choose. 

>All sites, even well-established official MO ones, need careful local
>interpretation. Not easy for Quality Control!

Yes Ken, I'd hate to be the one to try and solve the screen "exposure"
problem and paradoxically, if the supposedly "better" plastic screens
are introduced more widely, it will make comparisons between sites
more difficult unless there is, as you suggest, a screen type
indicator.

One particular problem with site comparisons would be the siting of
the anemometer at 10metres, almost 9m above the thermometer screen.
I'd bet half my beer money that at urban and valley floor sites, the
difference in mean wind speed between these two heights is greater
than at exposed airfield sites. Obtaining meaningful comparisons of
wind speed with temperature might not be as easy as I first thought.

-- 
Dave