Heavy mists are a type of weather phenomenon that is characterized by thick, low-lying clouds that can reduce visibility and create a damp atmosphere. Fogs are a type of heavy mist that is composed of tiny water droplets suspended in the air. Fogs can be caused by a variety of factors, including temperature inversions, evaporation from bodies of water, and condensation of moisture in the air. Fogs can also be created artificially, such as when smoke or dust particles are released into the atmosphere.