Fog

Fog is produced from the air's humidity when the dew point is reached and microdroplets of water or ice are suspended in the air, like in a cloud.

Difference between mist and fog

Fog is distinguished from mist because it is denser: under foggy conditions, visibility is reduced to less than one kilometre. Fog episodes are therefore particularly dangerous for road travel. Audio devices (fog horn) or radars are then used.