In article ,
says...



I am pleased to announce that the Davis Vantage Pro AWS at Haytor
meteorological
office is now online at
http://www.lyneside.demon.co.uk/Hayt...antage_Pro.htm.


Very nice


Wind information is still at 3m height and mean
speeds will have to be tripled to get an idea of open exposed moorland
conditions.


Is that correct? Mine is at about 4m, and I sometime record a mean (not
gust) of ~50mph. I would not think it's ~150mph on the moors!

Please explain if I have misunderstood.


TIA.
--
Nick Webster


Hi Nick,

The extra 1m height will make a bit of difference but the main point is that I
am very sheltered in the sector 200 degrees through 270 degrees to 020 degrees
as the land rises up to the open moor. Tripling the mean speed is a good
*estimate* in those wind directions. Admittedly in an easterly it would be an
over-estimate but that is not necessarily a bad thing as strong easterlies in
winter can give surprisingly severe conditions on Hay Tor. Many a day I have
recorded a 12 knot westerly at 3m agl at my site only to walk the 100 metres up
the hill onto the moor to be assaulted by a full blown gale difficult to walk
against. I have done some theoretical calculations and I calculate that a good
estimate of the 10m wind at my site is 2.2 times the 3m mean, but it depends on
atmospheric stability. If I can aquire more land I'll erect a proper 10m mast.
Mounting the anemometer on the roof is a poor idea in my location as the wind
rushes up the slates as if on a cliff edge. All my roof damage in the past year
has occurred when the 3m wind gust has exceeded 30 knots.

Will.

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