What Is The Difference Between Fog And Mist?

Reduced visibility on a path through the autumn forest due to mist.
Reduced visibility on a path through the autumn forest due to mist.

Fog and mist are weather phenomena that are similar, and more often than not people refer to one when they are talking about the other. While both are formed under similar conditions, they do have many key differences which are based on visibility, density, and altitude. These are the main differences between fog and mist.


Mist is a form of dispersion that occurs as a result of droplets of water being suspended in the air. It is seen when warm air is suddenly cooled, and this means that mist can be created artificially if the conditions are favorable. One way of creating mist is when one breathes on a glass surface on a cold morning, the warm air we exhale is subjected to cooler conditions and therefore mist is formed.

Fog is considered a type of cloud since it bears the characteristics of clouds such as the influence of weather in the formation of fog. Fog is formed when water vapor in the atmosphere condenses to form water droplets that are suspended in the air.


Both fog and mist obscure visibility and this is where their first difference is and the level of visibility differs. Fog is significantly denser than mist, and therefore, it affects visibility to a greater degree than mist. In mist, it is possible to see out to at least 1.2 miles, while fog reduces this distance to around 0.6 miles. In some cases, fog resulting from changes in humidity or merged with smoke is even denser which has been reported to reduce visibility to just below 60 yards. Some scientists describe fog as obscurity in the surface of the atmosphere. If visibility is less than 0.6 miles it is referred to as fog; if visibility is above 0.6 miles, it is called mist.


The conditions that influence the formation of mist are subject to warm air encountering a cooling effect and as such mist is not divided into categories.

On the other hand, the conditions that cause the formation of fog are varied, and this leads to the further classification of fog. Types of fog include upslope fog formed when air ascends the slope of a mountain. Freezing fog is comprised of supercooled droplets of water which freezes on contact with surfaces. Hail fog forms near places that have experienced hail which may cause an increase in moisture and lower temperature.


Fog can be classified as a cloud, however, sometimes cloud cover can also be called mist. Cloud cover is known as mist when it forms above mountain regions. In the same way, fog is moisture or water droplets suspended above a water body or wet region such as a marsh. Fog cover tends to dissipate as the sun gets stronger at around midday since fog is primarily composed of moisture suspended low above the atmosphere. The heat from the sun causes the water droplets to evaporate, and this is why fog is usually seen early in the morning or late in the evening. Some places in the world are more prone to fog than others. 


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