"David Mitchell" wrote in message
...
A new one on me, but Radio Sheffield presenters were having a debate as
to
whether the situation in Sheffield this morning should be described as
mist
or fog. Enter BBC forecaster Lisa Gallagher, and although she
described fog
as being 1000m visibility or less, as far as the "public" are
concerned, fog
is of 200m or less, and out came the phrase "public service fog"!
Do they really descibe it as this internally at the dear old beeb?

.... not only there, but within the met. community forecasting for the
general public. The definition of fog (WMO) as being visibility less
than 1000m is a long-standing one: perhaps owing to the heavy aviation
bias of early forecasting work. This 'fog' has long been recognised as
being of little relevance to motorists and those on foot, cycle etc.,
hence 'public-service' fog.

Martin.