How do they do that?

[Twister_Ken]

Reports from coastal stations give visibility. I can understand how they might have done it in the dear, dead days of lightshipmen and lighthouse keepers ("You'm tell them boyahs at the met office that we can jist zee the Hen's Tit Rock and that's 13miles and 2 cables from 'ere"). But now that most stations are automated how's it done?

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[Evadne]

I think they have an device similar to a transmissometer that measures optical clarity by shining a light over a short path and comparing its intensity with the source. More absorption, more mist, less visibility. Gets confused whenever a big motorboat goes past upwind with the barbeque going full blast, though.

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[squidge]

Hi you might find this site interesting.
<A target="_blank" HREF=http://www.ndbc.noaa.gov/maps/united_kingdom.shtml>http://www.ndbc.noaa.gov/maps/united_kingdom.shtml</A>

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[Twister_Ken]

Site gone walkabout

" The page that you requested is not found

The page you requested cannot be found. The page may have been removed, may have been renamed, or may be temporarily unavailable. "


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[squidge]

When the page comes up just klick on the sites "home" and all will be revealed.

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[qsiv]

Re: Site gone walkabout

.. and how on earth do the bouys measure vis ...?

I cant find it on the NDBC site, but I can only guess they do it b measruring the ligh reflected back from a pulse emitted by the bouy itself, and then have some clever algorithm that imputes distance from % light returned. If they can measure surface windspeed from an orbiting settelite by estimating the height of wind generated wavelets, then I suppose the visibilty question id probably easy!

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[squidge]

look here
<A target="_blank" HREF=http://www.belfortinstrument.com/products/visibility/m6000.html>http://www.belfortinstrument.com/products/visibility/m6000.html</A>

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[graham]

It annoys me when vis is given in kilometers. I know its easy enough to work out but long live the nautical mile.

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[Cornishman]

Have you noticed that the automatic stations do not report precipitation either.
The remaining few manned (oops, that's not very PC) e.g. Jersey still do, though. I once asked the Met Office why and was told that the machinery to do this was not yet invented.

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