Sangeetha Pulapaka

Fog and mist are both created by water droplets, differing only in their overall locations and density. Fog is a cloud that reaches ground level, even if that "ground" is a hill or mountaintop. Mist forms wherever water droplets are suspended in the air by temperature inversion, volcanic activity, or changes in humidity. Fog is denser than mist and tends to last longer. In terms of visibility, fog reduces it to less than one kilometer (0.6 miles), while mist can reduce visibility to between 1 and 2 kilometers (0.6 - 1.2 miles).

.A distinction is made in terms of development between radiation fogm advection fog, evaporative fog, orographic fog (or rising fog) and mixed fog. Sometimes, these forms appear in combinations


Evaporation fog forms when the relative humidity is increased by the evaporation from soil, plants or water surfaces, while the air temperature remains constant.Evaporation fog forms above very humid and warm surfaces. It will predominantly form over waters which are warm relative to the air temperature. In this case, the evaporation fog is also called steam fog (sea smoke).

Special cases of evaporation fog are the thaw fog and precipitation fog. Thaw fog appears when moderate warm air passes over frozen ground or snow, heats this surface layer and increases evaporation. The evaporating humidity may partly condensate again. Precipitation fog is formed when rainfall fall through warmer air layers and thereby evaporate.

Radiation fog usually forms when the air is cooled to such an extent that the relative humidity reaches 100%, the saturation point. It usually forms during the night due to the heat irradiation from the surface of the Earth and the associated cooling of the lower air layer. It dissolves very quickly again in most of the mornings, thanks to the ground warming.

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