Just a reminder that in a METAR, freezing fog does not necessarily mean
'fog depositing rime' .. as in the SYNOP. As long as the temperature is
sub-zero, then the fog must be coded as 'freezing'; just because the air
temperature is below 0degC, doesn't mean that ice is being deposited - a
lot depends upon how long the temperature has been below zero, what the
thermal capacity of the particular surfaces under consideration are etc.

Martin.


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