Winter fog

General Discussions: ASK John: Winter fog

By tequilamonsta on Wednesday, January 14, 2009 - 07:26 pm: Edit Post

The last two mornings up here have been fairly cold and there has been a 'fog' hanging before the sun comes up. Is this fog, or is there a more appropriate meteorological term used to describe it.

May be difficult to see in this picture:
winter fog?

If looks like fog, burns off like fog, just curious if it is indeed fog? The temperature was -47F and the RH was 55% at the time the picture was taken

By frnash on Wednesday, January 14, 2009 - 08:13 pm: Edit Post

Ice fog?


Ice fog is any kind of fog where the droplets have frozen into extremely tiny crystals of ice in midair. Generally this requires temperatures at or below -35 C (-30 F), making it common only in and near the Arctic and Antarctic regions. It is most often seen in urban areas where it is created by the freezing of water vapor present in automobile exhaust and combustion products from heating and power generation. Urban ice fog can become extremely dense and will persist day and night until the temperature rises. Extremely small amounts of ice fog falling from the sky form a type of precipitation called ice crystals, often reported in Barrow, Alaska. Ice fog often leads to the visual phenomenon of light pillars.

By tequilamonsta on Wednesday, January 14, 2009 - 08:37 pm: Edit Post

Temperature requirement: check.
Urban area: no check; middle of no where minnesota.
Light pillars: has happened here too in the past, but not right now:
ice pillars?

This picture dated 12-2-2005 up here as well. Being remote as we are, pillars are hard to come by in the plural sense, as there's only two in the picture - if they are indeed ice pillars.


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