Fog is thick mist. It may appear on land or sea and it usually lowers visibility (makes it hard to see very far). When fog forms at high levels it creates a cloud called stratus. When the air chills, moisture will turn to fog.
Fog is made up of tiny water droplets or, in very cold conditions, ice crystals. When seen on a high speed camera, (a special camera that takes many frames and can view videos at very low speed) it looks like hundreds of small water droplets moving through the air. These water droplets make up the fog or mist.
There are many types of fog, classified according to what makes the condensation. They include evaporation fog, advection fog, radiation fog, and upslope fog. The thickness of fog varies depending on the atmosphere, temperature, weather and location.
Ground fog in East Frisia (Moordorf)
Media related to Fog at Wikimedia Commons
- "Map of the United States showing days of heavy fog in each location". geography.hunter.cuny.edu. Retrieved 22 April 2010.