As the air is forced to rise upward where the atmospheric pressure is less, it is cooled by expansion and produces fog on the windward slopes of hills or mountains. Advection fog may be generated by winds that contrast in temperature with the Earth's surface. Warm air advection can produce fog through contact cooling with a cold surface. This type of fog is sometimes called steam fog or sea smoke . Evaportation fog forming over a lake as cool air flows over the warm water.
Frontal fog is produced as weather fronts, especially warm fronts , pass through an area.
Precipitation falling into the colder air ahead of the warm front may evaporate enough water to cause the formation of small droplets as fog near the ground.