Hello David,
I agree that fog is more a cloud than a visibility, and I like you
description.
Best regards,
Heiko
On 2013-08-09 16:48, David Hassell wrote:
Hello Heiko,
OK with me, but I think I'd rather turn it around:
Fog means water droplets or minute ice crystals close to the surface
which reduce visibility in air to less than 1000m.
"X_area_fraction" means the fraction of horizontal area occupied by
X.
This is because I think of fog as 'a type of cloud' rather than 'an
amount of visibility'.
What do you think?
All the best,
David
---- Original message from Heiko Klein (09AM 07 Aug 13)
Date: Wed, 7 Aug 2013 09:22:22 +0200
From: Heiko Klein <[email protected]>
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623
Thunderbird/17.0.7
To: David Hassell <[email protected]>
CC: Jonathan Gregory <[email protected]>, [email protected]
Subject: Re: [CF-metadata] Standard name for fog as area fraction
Hello David,
I think we agree on the important parts about fog:
* visibility in air < 1000m
* caused by water (i.e. not by dust, which would be haze)
* near-surface (~ human eyes height)
Coming to the exact wording is more difficult. The term 'cloud'
might include dust (Saharan dust clouds) and exclude radiation fog,
so I wouldn't like to use it. 'humidity' is invisible as you note,
so I will drop that. water droplets might exclude ice-fog. What
about:
fog means visibility in air < 1000m due to water
droplets or minute ice crystals close to the surface.
"X_area_fraction" means the fraction of horizontal area occupied by X.
--
David Hassell
National Centre for Atmospheric Science (NCAS)
Department of Meteorology, University of Reading,
Earley Gate, PO Box 243,
Reading RG6 6BB, U.K.
Tel : +44 118 3785613
E-mail: [email protected]
--
Dr. Heiko Klein Tel. + 47 22 96 32 58
Development Section / IT Department Fax. + 47 22 69 63 55
Norwegian Meteorological Institute http://www.met.no
P.O. Box 43 Blindern 0313 Oslo NORWAY
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