How is fog formed?
Fog often forms after sunset, on days with clear skies and no wind. At night when the surface of earth cools off, it cools the air in contact with it. Since cool air is heavier, it tends to collect near the ground and if the air contains a large number of dirt and dust, fog will be formed. Fog is also formed when warm air passes over cold surfaces like off the coast of Newfoundland, warm air from the Gulf Stream passes over the cold Labrador current resulting in fog.
