Fog
Advection Fog Explained: When Moist Air Moves Over a Cooler Surface
How advection fog forms when moist air moves over cooler land or water, and why it can affect coasts, lakes, airports, and roads.
Quick answer: Advection fog forms when moist air moves horizontally over a cooler surface and cools to saturation.
Moving air
Unlike radiation fog, advection fog needs air movement.
Warm moist air over cold water, snow, or land can cool from below and form fog.
Coastal examples
Sea fog can roll inland when moist marine air crosses colder water or land.
It may persist if the wind keeps supplying moist air.
Impacts
Advection fog can affect airports, bridges, coastal roads, and boating.
Visibility may stay poor even after sunrise.