Mist is a phenomenon caused by small droplets of water suspended in the cold air, usually by

condensation Condensation is the change of the state of matter from the gas phase into the liquid phase, and is the reverse of vaporization. The word most often refers to the water cycle. It can also be defined as the change in the state of water vapor ...

. Physically, it is an example of a dispersion. It is most commonly seen where water vapor in warm, moist air meets sudden cooling, such as in exhaled air in the winter, or when throwing water onto the hot stove of a

sauna A sauna (, ) is a room or building designed as a place to experience dry or wet heat sessions or an establishment with one or more of these facilities. The steam and high heat make the bathers perspire. A thermometer in a sauna is used to meas ...

. It can be created artificially with aerosol canisters if the

humidity Humidity is the concentration of water vapor present in the air. Water vapor, the gaseous state of water, is generally invisible to the human eye. Humidity indicates the likelihood for precipitation (meteorology), precipitation, dew, or fog t ...

and temperature conditions are right. It can also occur as part of natural weather, when humid air cools rapidly, notably when the air comes into contact with surfaces that are much cooler than the air (e.g. mountains). The formation of mist, as of other suspensions, is greatly aided by the presence of nucleation sites on which the suspended water phase can congeal. Thus even such unusual sources of nucleation as small particulates from

volcanic eruption A volcanic eruption occurs when material is expelled from a volcanic vent or fissure. Several types of volcanic eruptions have been distinguished by volcanologists. These are often named after famous volcanoes where that type of behavior h ...

s, releases of strongly polar gases, and even the magnetospheric ions associated with polar lights can in right conditions trigger condensation and the formation of mist. Mist is commonly confused with fog, which resembles a

stratus cloud Stratus clouds are low-level clouds characterized by horizontal layering with a uniform base, as opposed to convective or cumuliform clouds formed by rising thermals. The term ''stratus'' describes flat, hazy, featureless clouds at low altit ...

lying at ground level. These two phenomena differ, but share some commonalities; similar processes form both fog and mist. Fog is denser, more opaque, and generally lasts a longer time, while mist is thinner and more transparent.

Description

Cloud cover is often referred to as "mist" when encountered on surfaces of mountains, whereas moisture suspended above a body of water, cleared or marsh area is usually called "fog". One main difference between mist and fog is

visibility In meteorology, visibility is the measure of the distance at which an object or light can be clearly discerned. It depends on the Transparency and translucency, transparency of the surrounding air and as such, it is unchanging no matter the amb ...

. The phenomenon is called fog if the visibility is or less. In the United Kingdom, the definition of fog is visibility less than on the surface for driving purposes, while for pilots the distance is 1 km at cruising height. Otherwise, it is known as mist. American Falls and Rainbow

Mist makes a light beam visible from the side via

refraction In physics, refraction is the redirection of a wave as it passes from one transmission medium, medium to another. The redirection can be caused by the wave's change in speed or by a change in the medium. Refraction of light is the most commo ...

and

scattering In physics, scattering is a wide range of physical processes where moving particles or radiation of some form, such as light or sound, are forced to deviate from a straight trajectory by localized non-uniformities (including particles and radiat ...

on the suspended water droplets, and

rainbow A rainbow is an optical phenomenon caused by refraction, internal reflection and dispersion of light in water droplets resulting in a continuous spectrum of light appearing in the sky. The rainbow takes the form of a multicoloured circular ...

s can be possibly created. "Scotch mist" is a light steady drizzle that appears like mist. Mist usually occurs near the shores and is often associated with fog. Mist can be as high as mountain tops when extreme temperatures are low and strong condensation occurs. Freezing mist is similar to freezing fog, only the density is less and the visibility greater. When fog falls below 0°C, it is known as freezing fog, however it still stays suspended.

References

External links

{{Aerosol terminology, state=expanded Air pollution Fog Psychrometrics

Description

See also

References

External links