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What is frozen fog?

Posted: Sat Dec 09, 2006 1:51 pm
by JonathanBelles
i keep hearing TWC talking about it

Posted: Sat Dec 09, 2006 3:15 pm
by CajunMama
TWC's definition of freezing fog is "FREEZING FOG
Used to describe the phenomena when fog is present and the air temperature is below 0°C. It is reported as "FZFG" in an observation and on the METAR"

AMS defines freezing fog as "freezing fog—A fog the droplets of which freeze upon contact with exposed objects and form a coating of rime and/or glaze." http://amsglossary.allenpress.com/gloss ... ezing-fog1


Image

Posted: Fri Dec 22, 2006 12:59 am
by senorpepr
I meant to piggyback on this a few days ago.

From an operational standpoint, the observer will encode freezing fog (FZFG) when two conditions are met:

1) The prevailing visibility is less than 5/8mi (1km) and...
2) The temperature is less than 32°F (0°C)

If condition one is met, but not condition two, then the observer will encode fog (FG).
If the prevailing visibility is fog reducing visibility to between 6mi and 5/8mi, regardless of temperature, the observer will encode mist (BR), without a FZ descriptor.


...and now you know.