How vapor mist is formed. How is fog formed? Where does it come from? Gradual formation of fog in the atmosphere What is fog definition for children

Fog is essentially a cloud that exists low above the surface. It appears when the contact of warm, humid air with colder.

The level of concentration of water vapor in the air is determined by temperature: the colder the air, the less vapor it can contain. If the vapor exceeds the amount possible at a given temperature (a point called the saturated vapor level), it condenses into fog.

If the temperature is low enough, fog can form even in relatively dry air. The presence of fog is most likely in air containing a large number of dust or other particles to which water droplets can attach. In the polar regions, where the temperature can drop below -15 °C, sometimes there is a frozen fog, consisting of ice crystals.

Condensation - Everywhere

The same condensation process that creates fog accompanies some of the usual Everyday life phenomena. For example, cold air outside a window cools warm air in a room (1, top). As the inside air cools, the water vapor condenses to form water particles that cause the window to fog up. When warm moist air is exhaled from the mouth (2), it cools rapidly and the water vapor condenses, causing the exhaled air to resemble fog. The cold juice in the glass (3) radiates cold around it, causing the water vapor in the air to condense and droplets form on the glass. Water vapor escaping from the kettle (4) is cooled by air and condenses into a misty cloud.

How is radiant fog formed?

At night, when the soil begins to release the heat absorbed during the day, the temperature of the air above it begins to drop. When it is sufficiently cooled, the water vapor condenses into a radiant mist. This kind of fog often appears in low-lying places on clear and relatively calm nights. (pictured at the top of the article)

Formation of advective fog

Advective fog, typical of places close to the oceans, occurs when a mass of moist, warm air suddenly rises above a cold surface. The lower layer of air cools, causing condensation and the formation of fog particles.

How fog is formed

As warm, moist air rises up a mountainside, it expands and cools, causing the water vapor in the air to condense into fog. Such fog, which can resemble uneven patches, is very often encountered by climbers. If the air currents continue to rise, eventually the creeping fog turns into clouds.

How steam fog is formed

Sometimes cold air circulates over places that retain heat at night, such as over rivers or ponds. Steam from warm water condenses in cold air, forming steam mist. The greater the temperature amplitude between water and air, the thicker the fog will be.

Fogs occur at any time of the year, but most often they occur in late summer or autumn, when the air cools faster than the ground cools. As a result, cool air sinks to the ground or water, which still retains heat, condensation occurs, and many water droplets hang in the air. It turns out that a huge cloud hangs directly above the ground or a pond. In the place where the fog has formed, the air humidity is 100%. Fogs are different in their structure. If the air temperature is not very cold, above 10 degrees below zero, then the foggy cloud consists of water droplets. At a temperature of 10-15 degrees below zero, the cloud consists of a mixture of water droplets with ice crystals. If the temperature drops below 15 degrees below zero, then an ice fog is formed, when the entire cloud consists of ice crystals. In cities and towns, fogs are denser due to the fact that condensate mixes with exhaust gases and dust.

What are fogs?

Fogs are different. It depends on how good the visibility is at the location of the fog.

Haze is the weakest form of fog.

Ground fog is fog that spreads over the ground or a body of water in a thin layer. This fog does not render great influence for visibility.

Translucent fog, visibility in which ranges from several tens to several hundred meters. Through such fog, the sun and clouds are visible.

Solid fog, when a whitish cloud envelops the earth, through which it is impossible to see literally anything at a distance of several meters, and sometimes even within an outstretched arm. With such fog, traffic becomes impossible. If the driver is caught in a cloud of solid fog, it is better for him to wait until the fog clears.

There are not only natural fogs, but also artificial ones. Artificial fogs are caused by human industrial activity. Artificial fog consists of dust, smoke, exhaust gases, chemical substances, other combustion products. Otherwise it is called smog. Smog-one of critical issues modern cities, as it causes irreparable harm to human health and pollutes the environment.

Natural phenomena are often more admired than man-made ones. No matter what a person does, everyone will look with admiration at the mountains, hurricanes and tsunamis. Admiration, horror and awe. All this is natural, in relation to such majestic and hazards. Interest can also be caused by more ordinary moments, many would not refuse to know how fog is formed and whether it is worth fearing this. natural phenomenon.

Fight with nature

Man fights with nature throughout his existence. Civilization opposes itself to chaotic primordial power:

• People tend to love orderliness and constancy.
• Since primitive times, it was nature, in all its manifestations, that most of all “spoiled life” for a person.
• Fighting with environment, the first settlers colonized new lands and asserted their power.
• Every year, farmers entered into a deadly race with nature. Its meaning was to get as much harvest as possible in a short time and feed everyone who needs it.
• Physicians in ancient times faced the problems of mass epidemics. Their sources were microorganisms, the same elements of wildlife.

Today, although people have moved far enough away from nature, having conquered it in many areas of their activity, humanity still depends on it in many ways. And yet it cannot be said that no “sudden turn” in the performance of Mother Nature will be able to erase our civilization and any memories of it.

Where does fog come from?

Fog, oddly enough, mist is taken from the air. To do this, depending on the area, you will need:

• The presence of a large number of industrial enterprises and road transport.
• Special weather conditions.
• Reservoirs, preferably - rivers and lakes.

Fog caused by exposure to exhaust gases and emissions from factories is called smog, and it is typical for industrial centers. If 150 years ago he most often met in England, today the "palm tree" has moved to South America and China. It just so happened that Europe and the United States are trying to move their production as far as possible so as not to “enjoy” the smog and other possible consequences.

Weather changes and the presence of water bodies affect the amount of evaporated moisture, which leads to the formation of fog. This variety is less dangerous for people, it practically does not cause exacerbation chronic bronchitis and new asthma attacks. But the visibility is still reduced.

Such a fog spreads over the surface, disappears within a few hours. But there are exceptions, strict rules nature doesn't have much.

How does fog appear?

To deal with the formation of fog, it is necessary to remember about movement of air masses:

1. Air moves not only horizontally, but also vertically.
2. There are two types of masses - cold and heated air.
3. Obeying the laws of physics, warm air rises higher, while cold air, on the contrary, descends closer to the surface.
4. During such a movement, condensation occurs - evaporation and fixation of microscopic water droplets in the air.
5. Best of all, they are fixed on dust particles, so even ordinary fog occurs earlier in industrial areas. What can we say about the smog.

Colossal volumes of air are constantly moving, the laws of physics also operate without change. But fog is a rare phenomenon, sometimes people forget about it for months. And the secret is simple for maximum effect maximum humidity level is also required. In a dry climate, such phenomena occur only at very low temperatures, extremely low.

So that fog is based on the movement of warm and cold air , contact and a kind of "conflict" of these two environments, ending with the evaporation of moisture into the environment.

How to make fog at home?

Fog can also be created artificially. The only question is the scale and purpose:

At home you will need:

• An empty bottle, preferably a liter. One third filled with hot water.
• A drop of vodka to be added to water.
• Ice tongs and, in fact, a piece of ice. It will need to be kept at the very neck.

That's the whole simple scheme. Of course, it will not be possible to achieve a thick and long fog, but even such a result will surprise the guests. For the same purposes, it is possible to acquire a special machine that, based on the same principles, will produce fog on an industrial scale. But this is an expensive option and bulky equipment. For those who are not looking for easy ways.

Fog formation by stages

There is nothing secret about the formation of fog; physicists uncovered the secret of this natural phenomenon centuries ago. How does fog form in the atmosphere?:

1. There is a constant circulation of air in the atmosphere.
2. Warm and cold masses move, replacing each other.
3. During movement, condensation and evaporation of moisture occurs.
4. Water can also evaporate from the surface of water sources if the ambient temperature is slightly lower than the water temperature.
5. Droplets are fixed on any surface and linger in the air for a while.
6. The delay is observed for several hours, as a rule. At this time, the surface is covered with a light haze and visibility is significantly reduced.

The fog can be a challenge for those suffering from chronic lung diseases. Most often, problems arise with smog. Reduced visibility increases the risk of accidents, so motorists need to either be extremely careful or limit their driving for a couple of hours.

FOG

FOG, a mass of small drops of water that hangs directly above the earth's surface and is the cause of poor visibility. Light fog is called haze. According to the standard definition, visibility in haze is 1-2 km. Haze turns to fog at visibility below 1 km. Fog is formed as a result of condensation of water vapor after cooling the air. Vapors condense around dust particles. The main types of fog are: advection, formed due to the difference in temperature of the air and the surface over which it passes (an example is the fog formed as a result of the passage of cold air over warm water), frontal fog that forms when warm rain falls through a layer of cold air close to earth, radiation fog formed as a result of air cooling in a clear good night(most characteristic of the valleys), and lifting, formed when air cools as it rises up a slope. see alsoSMOG.

Scientific and technical encyclopedic dictionary.

See what "FOG" is in other dictionaries:

Husband. (darkness, darkness) dense steam, water vapor in the lower layers of the air, on the surface of the earth; steamy air. Fog falls on the bottoms and along the valleys. The fog spreads like a veil. Fog in my eyes, I see everything in a fog, muddy, dark, unclear, as in ... ... Dictionary Dalia

Explanatory Dictionary of Ushakov

1. FOG1, fog, husband. (Turk. fog). 1. The opaque state of air in the lower layers of the atmosphere due to the accumulation of water vapor in it. "Fog rises at the bottom of the rapids." A.K. Tolstoy. "Fog smokes over the swamp." Lermontov. “Through the wavy…… Explanatory Dictionary of Ushakov

Haze, steam, cloud, cloud. See cloud... Dictionary of Russian synonyms and expressions similar in meaning. under. ed. N. Abramova, M .: Russian dictionaries, 1999. mist haze, mga; couples, cloud, cloud; mist, mist, haze, toman, gloom, smoke, smog, gauze, ... ... Synonym dictionary

fog- Fog: Accumulation of condensation products in the form of droplets or crystals suspended in the air just above the ground, accompanied by a significant reduction in visibility. [GOST 22.0.03 97, article 3.4.18] Source ... Dictionary-reference book of terms of normative and technical documentation

- (Fog) an accumulation of microscopic water droplets (or ice needles) suspended in the lower layer of the atmosphere (clouds are the same T., but at a greater or lesser height above the earth's surface). Formed when moist air is cooled ... ... Marine Dictionary

1. FOG, a (y); m. [Turk. fog] 1. The accumulation of small water droplets or ice crystals in the surface layers of air, making it opaque. Strong, rare, thick m. Gray-haired m. Shroud, haze, haze of fog. T. over the lake, over the river. Go to… … encyclopedic Dictionary

The monetary unit of Iran. Tuman Iranian gold and silver coin, contains 10 rials. See also: Silver coins Gold coins Counting monetary units Finam Financial Dictionary ... Financial vocabulary

Fog. It was given to boys born in foggy weather. Preserved at baptized Tatars in the surnames Tumanov, Tumanin. Tatar, Turkic, Muslim male names. Glossary of terms ... Dictionary of personal names

fog- crazy (White); pale white (White); whitish (Gumilyov, Chirikov); whitish (Artsybashev); white (Korolenko); wet (Balmont, Chyumina); wavy (Pushkin, Fet); blue (Bashkin, Bunin, Lermontov); stuffy (Censor); yellow (Chulkov); ... ... Dictionary of epithets

Books

• Fog, A. Rodionov. It can happen to anyone: a shocking letter, a high-speed mountain serpentine ride, an accident. It can happen to anyone, but not everyone will be able to open their eyes after the experience. Angelmo...

Fog - atmospheric phenomenon, the accumulation of water in the air, when the smallest condensation products of water vapor are formed (at air temperatures above -10 ° these are the smallest droplets of water, at -10 ... -15 ° - a mixture of water droplets and ice crystals, at temperatures below -15 ° - ice crystals , sparkling in the sun or in the light of the moon and lanterns).

Relative humidity during fogs is usually close to 100% (at least exceeds 85-90%). However, in severe frosts (-30 ° and below) in settlements, at railway stations and airfields, fogs can be observed at any relative humidity air (even less than 50%) - due to the condensation of water vapor formed during the combustion of fuel (in engines, furnaces, etc.) and emitted into the atmosphere through exhaust pipes and chimneys.

The continuous duration of fogs usually ranges from several hours (and sometimes half an hour or an hour) to several days, especially during the cold period of the year.

The following types of fog are noted at weather stations:

• Ground fog - fog that creeps low over the earth's surface (or body of water) in a continuous thin layer or in the form of separate tufts, so that in the fog layer the horizontal visibility is less than 1000 m, and at a level of 2 m it exceeds 1000 m (usually it is, as with haze, from 1 to 9 km, and sometimes 10 km or more). It is observed, as a rule, in the evening, night and morning hours. Separately, ground ice fog is noted - observed at air temperatures below -10 ... -15 ° and consisting of ice crystals sparkling in the sun or in the light of the moon and lanterns.

• Translucent fog - fog with horizontal visibility at a level of 2 m less than 1000 m (usually it is several hundred meters, and in some cases even drops to several tens of meters), poorly developed vertically, so that it is possible to determine the state of the sky (the number and shape of clouds ). It is more often observed in the evening, at night and in the morning, but it can also be observed during the day, especially in the cold half of the year when the air temperature rises. A translucent ice fog is noted separately - observed at air temperatures below -10 ... -15 ° and consisting of ice crystals sparkling in the sun or in the light of the moon and lanterns.

• Fog - continuous fog with horizontal visibility at a level of 2 m less than 1000 m (usually it is several hundred meters, and in some cases even drops to several tens of meters), developed vertically enough so that it is impossible to determine the state of the sky (the number and shape of clouds ). It is more often observed in the evening, at night and in the morning, but it can also be observed during the day, especially in the cold half of the year when the air temperature rises. Separately, ice fog is noted - observed at air temperatures below -10 ... -15 ° and consisting of ice crystals sparkling in the sun or in the light of the moon and lanterns.

The largest number of foggy days at sea level - an average of more than 120 per year - is observed on the Canadian island of Newfoundland in the Atlantic Ocean.

The average annual number of days with fog in some Russian cities:

Pier in the fog. Vancouver Island, City of Sydney

Mountain road in fog (highway D81 in Corsica)

Fogs impede the normal operation of all types of transport (especially aviation), so fog forecasts are of great national economic importance.

Artificial fogging is used in scientific research, in chemical industry, heat engineering and other areas.

Classification

Sea fog in the Øresund Strait

Country road in the fog (Moscow region, Naro-Fominsk)

Fog in San Francisco (Golden Gate)

Fog on the Volga near Nizhny Novgorod

According to the method of occurrence, fogs are divided into two types:

• Cooling fogs - formed due to the condensation of water vapor when the air is cooled below the dew point.
• Evaporation fogs are evaporation from a warmer evaporating surface into cold air over bodies of water and wet land.

In addition, fogs differ in synoptic conditions of formation:

• Intramass - formed in homogeneous air masses.
• Frontal - formed at the borders atmospheric fronts.

Haze is a very faint mist. With haze, the visibility range is several kilometers. In the practice of meteorological forecasting, it is considered: haze - visibility is more than / equal to 1000 m, but less than 10 km, and fog - visibility is less than 1000 m. Heavy fog is considered when visibility is less than or equal to 500 m.

Intramass fogs

Intramass fogs predominate in nature, as a rule they are cooling fogs. They are also usually divided into several types:

• Radiative fogs - fogs that appear as a result of radiative cooling earth's surface and the mass of moist surface air up to the dew point. Radiation fog usually occurs at night in anticyclone conditions with cloudless weather and a light breeze. Radiation fog often occurs under the conditions of a temperature inversion that prevents the rise air mass. Radiation fogs usually dissipate quickly after sunrise. However, in the cold season, in stable anticyclones, they can persist during the day, sometimes for many days in a row. In industrial areas, an extreme form of radiation fog, smog, can occur.

• Advective fog - formed due to the cooling of warm, moist air as it moves over a colder surface of land or water. Their intensity depends on the temperature difference between the air and the underlying surface and on the moisture content of the air. These fogs can develop both over the sea and over land and cover vast areas, in some cases up to hundreds of thousands of km². Advective fogs are usually cloudy weather and most often in the warm sectors of cyclones. Advective fogs are more stable than radiative fogs and often do not dissipate during the day.

Sea fog is an advective fog that has arisen over the sea during the transfer of cold air to warm water. This fog is an evaporative fog. Fogs of this type are frequent, for example, in the Arctic, when air enters from the ice cover onto the open sea surface.

Frontal fogs

Frontal fogs form near atmospheric fronts and move with them. Saturation of air with water vapor occurs due to the evaporation of precipitation falling in the front zone. A certain role in the strengthening of fogs in front of the fronts is played by the observed drop atmospheric pressure, which creates a slight pdiabatic decrease in air temperature.

Dry fogs

To the mists colloquial speech and in fiction sometimes include the so-called dry fogs (haze, haze) - a significant deterioration in visibility due to the smoke of forest, peat or steppe fires, or due to loess dust or part of the sand, sometimes raised and carried by the wind over considerable distances, as well as due to emissions from industrial enterprises .

A transitional step between dry and wet fogs is also not uncommon - such fogs consist of water particles together with rather large masses of dust, smoke and soot. These are the so-called dirty, urban fogs, which are the result of the presence in the air big cities masses of solid particles emitted during combustion by flue, and to an even greater extent - factory chimneys.

Mist Characteristics

View of Bragino (Yaroslavl)

Fog in the Izborsk Valley (Pskov region)

The water content of fog is used to characterize fogs, it indicates the total mass of water droplets per unit volume of fog. The water content of fogs usually does not exceed 0.05-0.1 g/m³, but in some dense fogs it can reach 1-1.5 g/m³.

In addition to water content, the transparency of the fog is affected by the size of the particles forming it. The radius of fog droplets usually ranges from 1 to 60 µm. Most of the drops have a radius of 5-15 microns at a positive air temperature and 2-5 microns at a negative temperature.