April 16, 2003
The above picture, taken in Iceland, is a great example of evaporation fog. This is a type of advection fog, which forms when cool air lies over a warm body of water. The water molecules evaporate from the surface of the water into the colder air above, rapidly humidifying it. When this overlying layer of air finally becomes saturated, condensation occurs, and since the air is adjacent to the ground, the cloud that results is referred to as fog. Evaporation fog frequently forms over lakes and ponds, but it can even form over a heated swimming pool. While it may occur anytime of the year, in general, it's most often observed in fall and winter.