Fog

Fog near a tree.

Fog is mist when it is very thick. It may appear on land or sea. 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, such as evaporation fog, advection fog, radiation fog, and upslope fog. The thickness of fog varies depending on the atmosphere, temperature, weather and location.