WHAT IS FOG?

Fog is a stratus cloud which touches the ground. It forms in much the same way as dew. Dew and fog form when the air temperature is equal to or lower than the dew point temperature (the temperature to which air must be cooled for condensation to occur). When dew forms, air is cooled to the dew point temperature in a relatively shallow layer just above the surface of good radiators. When fog forms, air is cooled to the dew point temperature through a much deeper layer of the atmosphere.