Meteorology · Fog — Advection
Advection fog at sea forms when:
- ACold air flows over much warmer water
- BWarm, moist air flows over a colder sea surface and is cooled to its dewpoint✓ Correct
- CAir subsides and warms aloft
- DRain falls through a dry layer
Explanation
Advection (sea) fog is the dominant marine fog: warm moist air moving over a cooler sea (e.g., over a cold current) is chilled to saturation. Because wind keeps it going, it can persist day and night and extend over large areas.
Authority: Bowditch (Pub. No. 9), fog types; WMO
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