Are there different types of fog?

Dateline article| David Murphy|

Yes! The usual fog we get around here is morning fog, officially called Radiation Fog (see the Weather Class topic: How does fog form?). Other types include Advection Fog, the kind that often makes San Francisco so murky. Warm moist air moving over the Pacific Ocean toward shore crosses cool currents near the coast, and the water vapor condenses into thick fog---which winds up covering San Francisco Bay like a blanket! Upslope Fog occurs when humid air moves up the slope of a hill or mountain and cools, smothering the mountainside with fog. Steam Fog develops when cool air moves over warm water. This type of fog is common around lakes and ponds. Frontal Fog occurs along a warm front occasionally. Warm air behind the front is lifted over the surface cold air, rain develops, and some of that rain evaporates and then condenses as fog.

---D.M.

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