Advection fog is formed as a result of what process?

Advection fog forms primarily when moist air moves horizontally over a colder surface, such as water or land. As this warmer, humid air comes into contact with the colder surface, it cools down, leading to condensation of water vapor in the air. This process results in the formation of tiny water droplets that create fog.

The uniqueness of advection fog lies in its formation due to the movement of air rather than a localized cooling or evaporation process. It is often seen along coastlines where warm, moist air from the sea encounters colder air from the land or cooler seawater. The cooling of the air to its dew point, caused by its movement over a colder surface, is the key factor in creating this type of fog.

Other processes, such as rapid rising of cool air or evaporation from warm water bodies, may lead to different types of fog but are not specific to advection fog. Ground cooling at sunset generally produces radiation fog, which forms when the surface cools and subsequently cools the air right above it, rather than involving movement of moist air over colder surfaces. Therefore, the process most closely associated with the formation of advection fog is the movement of moist air over a colder surface.