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 <heiko.kl...@met.no> > User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:17.0) Gecko/20130623 > Thunderbird/17.0.7 > To: David Hassell <d.c.hass...@reading.ac.uk> > CC: Jonathan Gregory <j.m.greg...@reading.ac.uk>, cf-metadata@cgd.ucar.edu > 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: d.c.hass...@reading.ac.uk _______________________________________________ CF-metadata mailing list CF-metadata@cgd.ucar.edu http://mailman.cgd.ucar.edu/mailman/listinfo/cf-metadata
