# Cloud/Fog nomenclature

**URL:** <https://boards.straightdope.com/t/cloud-fog-nomenclature/605108>\
**Category:** Factual Questions\
**Created:** [December 5, 2011, 6:01am UTC](https://boards.straightdope.com/t/cloud-fog-nomenclature/605108 "2011-12-05T06:01:26Z")\
**Posts on this page:** 4\
**Page:** 1

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**Author:** ![Enola\_Straight](https://avatars.discourse-cdn.com/v4/letter/e/dec6dc/32.png) [@Enola\_Straight](https://boards.straightdope.com/u/Enola_Straight)\
**Post date:** [December 5, 2011, 6:01am UTC](https://boards.straightdope.com/t/cloud-fog-nomenclature/605108/1 "2011-12-05T06:01:26Z")

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Tonight @12:30 a.m. in Longport, NJ ( a Downbeach suburb of Atlantic City) I noticed an EXTREMELY low cloud covering the town…about level with the streetlights.

Thick cloud cover above, clear air below.

How low does a cloud have to be until it is considered fog?

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**Author:** ![Nametag](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/nametag/32/406_2.png) [@Nametag](https://boards.straightdope.com/u/Nametag)\
**Post date:** [December 5, 2011, 9:10am UTC](https://boards.straightdope.com/t/cloud-fog-nomenclature/605108/2 "2011-12-05T09:10:48Z")

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Fog is often distinguished from clouds by the means of generation; fog is usually generated at or near the surface. If a stratus cloud actually got low enough to affect visibility for activities at ground level, I’d call it fog anyway.

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**Author:** ![johnpost](https://avatars.discourse-cdn.com/v4/letter/j/f17d59/32.png) [@johnpost](https://boards.straightdope.com/u/johnpost)\
**Post date:** [December 5, 2011, 3:43pm UTC](https://boards.straightdope.com/t/cloud-fog-nomenclature/605108/3 "2011-12-05T15:43:20Z")

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fog has the moisture creating it coming from the earth surface.

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**Author:** ![MikeF](https://avatars.discourse-cdn.com/v4/letter/m/45deac/32.png) [@MikeF](https://boards.straightdope.com/u/MikeF)\
**Post date:** [December 5, 2011, 6:30pm UTC](https://boards.straightdope.com/t/cloud-fog-nomenclature/605108/4 "2011-12-05T18:30:59Z")

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[https://www.meted.ucar.edu/training\_module.php?id=795](https://www.meted.ucar.edu/training_module.php?id=795)

Requires registration to access the module but you will be an expert on fog when you are finished.