"Will Hand" wrote in message
...

"Joe Egginton" wrote in message
...
Why is it that when the temperature is at 0c, it says fog instead
of freezing fog?

Just because the temperature falls below the melting point of water
it does not mean that fog magically turns into freezing fog.
Freezing fog is *NOT* fog with a temperature below zero, despite
what some say. For fog to be freezing fog it has to be depositing
rime. I have had this argument before, as a professional observer
many years ago in still air we had a fog with a temperature just
below zero, I was told off for not calling it freezing fog, but I
stood my ground as all surfaces were wet despite the temperature, in
no way was it rime icing.


.... I agree with you Will, but unfortunately, according to ICAO, if
the air temperature is *below* 0.0°C, then it *has* to be coded (in
the METAR) as FZFG. I believe that for the SYNOP, then the 'old' rules
still apply, i.e., 'fog depositing rime' etc. However, with more AWS
coming on stream, I suspect the ICAO definition will win out.

Martin.


--
Martin Rowley
West Moors, East Dorset (UK): 17m (56ft) amsl
Lat: 50.82N Long: 01.88W
NGR: SU 082 023