FOG

FOG, a mass of small drops of water hovering directly above earth's surface and causing poor visibility. Light fog is called haze. By standard definition, visibility in haze is 1-2 km. Haze turns into fog when visibility is below 1 km. Fog is formed as a result of condensation of water vapor after cooling the air. The fumes condense around the dust particles. The main types of fog are: advection, formed due to the difference in temperature between the air and the surface over which it passes (an example is 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 clear conditions good night(most typical for valleys), and lifting, formed when air cools as it rises up a slope. see alsoSMOG.

Scientific and technical encyclopedic dictionary.

Synonyms:

See what "FOG" is in other dictionaries:

Husband. (darkness, darkness) thick steam, water vapor in the lower layers of the air, on the surface of the earth; air clouded with vapors. Fog falls along the bottoms and valleys. The fog spreads like a veil. There is fog in my eyes, I see everything in a fog, dull, dark, unclear, like in... ... Dictionary Dahl

Ushakov's Explanatory Dictionary

1. TUMAN1, fog, male. (Turkic: fog). 1. The opaque state of air in the lower layers of the atmosphere due to the accumulation of water vapor in it. “The fog rises at the bottom of the rapids.” A.K. Tolstoy. "The fog smokes over the swamp." Lermontov. "Through the wavy... ... Ushakov's Explanatory Dictionary

Haze, vapor, cloud, cloud. See cloud... Dictionary of Russian synonyms and similar expressions. under. ed. N. Abramova, M.: Russian Dictionaries, 1999. fog haze, mga; vapors, cloud, cloud; fog, fog, haze, toman, gloom, smoke, smog, gauze,... ... Synonym dictionary

fog- fog: An accumulation of condensation products in the form of drops or crystals suspended in the air directly above the surface of the earth, accompanied by a significant decrease in visibility. [GOST 22.0.03 97, article 3.4.18] Source... Dictionary-reference book of terms of normative and technical documentation

- (Fog) a collection of microscopic droplets of water (or ice needles) suspended in bottom layer atmosphere (clouds are the same clouds, but at a greater or lesser height above the earth’s surface). Formed when moist air cools... ...Marine Dictionary

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

The counting monetary unit of Iran. Fog Iranian gold and silver coin, contains 10 rials. See also: Silver coins Gold coins Countable monetary units Financial dictionary Finam ... Financial Dictionary

Fog. Given to boys born in foggy weather. Preserved among 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 (Gumilev, Chirikov); whitish (Artsybashev); white (Korolenko); wet (Balmont, Chyumina); wavy (Pushkin, Fet); blue (Bashkin, Bunin, Lermontov); stuffy (Censor); yellow (Chulkov);… … Dictionary of epithets

Books

• The Fog, Stephen King. The fog came in small provincial town- out of nowhere. The fog thickened over the narrow streets and crawled into the windows of the houses. And out of the fog came death. Death has many faces, forever...

Anyuta rubbed her eyes and stretched sweetly - the alarm clock rang, which meant she had to get up. She looked around, very surprised - it was dark. The girl went to the window and looked out. It seemed as if the street was flooded with milk diluted in water.

- Mother! – the girl screamed joyfully. - There's fog there!

Mom sighed sadly in the bedroom, and for some reason dad groaned with annoyance...

Surely, each of us, no, no, has wondered where this whitish haze comes from, which envelops the city, bringing so much joy to children, and adding trouble to adults.

In fact, fog, like clouds, is nothing more than water vapor, which, in turn, consists of tiny droplets of water. So if there are romantics among the readers who have always dreamed of touching a cloud, they just have to wait for the fog, or go to Newfoundland, which is located in Canada. This city is considered the most “foggy” place on the planet.

In fact, the clouds of steam that we exhale in the cold are also fog, like a boiling kettle - the principle of the appearance of all these smokes is the same, with only one difference - the fog lasts a little longer. Although, over time, of course, it also condenses into droplets of water and settles on the ground.

But, in order not to go into details ahead of time, let's find out - is there only one type of fog? It turns out not.

Meteorologists distinguish two types of fog.

The first, and the one we are most familiar with, is cooling mist, where cold air mixes with warm water vapor. This occurs either on cold nights near wet soil, but such fogs disperse by morning, or above the surface of the water. It is because of this that fogs are so frequent in St. Petersburg and London - a large amount of water and cool night air create a dense whitish curtain. Moreover, it should be noted that in cities the fog is usually denser than near villages or in areas remote from people. This does not happen because there is a lot of water near a large crowd of people, but rather because the fog - tiny droplets of water - is mixed with city smog and exhaust, which colors the water an opaque, dirty color and makes the fog denser. From the outside, such subtleties, of course, are not visible, but the dirtier the city and the more water there is next to it, the denser the fogs will be.

Most often, fogs can be found in autumn, when the water and soil are warmed by the warm sun, and the air is already starting to get colder.

The second type of fog, evaporation fog, is more unusual. If in the first case visible water vapor appears from contact warm surface with cold, then the opposite is true. This is the name for fog that was supposed to condense into dew, but based on thermal indicators - cooling the air below the required point - it did not do this.

Also, outside of species, there is the so-called “dry” fog - fog consisting of particles of dust, soot, ash and the like. In essence, this is not fog at all, since it does not contain moisture, but it bears this name because of similar properties in reducing the clarity of vision of the population.

Despite the fact that most ships are equipped with radar installations, fogs still present great danger for navigation. Therefore, predicting the appearance and disappearance (evaporation) of fogs is very important great importance for navigation.

Fogs usually form when the surface layer of air cools to the dew point or below., i.e., to a temperature at which the water vapor contained in the air reaches complete saturation and condensation of water vapor occurs.

On the seas and oceans, fogs most often form as a result of advection(horizontal movement) of warm and moist air over a relatively cold water surface, which is why such fogs are called advective (Fig. 26).
These fogs are distinguished by significant vertical power, long duration of existence (from one to several days in a row), large coverage areas, mobility, and suddenness of appearance.
Advective fogs usually dissipate in the event of a sharp change in wind direction, during which warmer or colder and relatively less humid air masses spread into a given area.

On the seas and oceans, fogs usually form in temperate and polar latitudes, where frequent significant fluctuations in air temperature occur and where there are pronounced cold sea currents, closely bordering on warm ones. In tropical latitudes, fogs are observed very rarely.

If you compare the diagram of surface sea currents with maps of the distribution of fogs on the seas and oceans, you can immediately find that the greatest frequency of fogs occurs precisely in areas of cold currents.

Rice. 26 Advective fog over the sea

The air over the sea always contains a lot of moisture and is often close to saturation, so a relatively small cooling is enough for it to become completely saturated. This can happen if air passes over the surface of cold waters. Therefore, areas of cold currents, areas of surface cold waters in general are characterized by very frequent fogs.

IN Atlantic Ocean a very large "foggy" area is the area near Newfoundland, where air masses, heated and moistened above the Gulf Stream, with southeastern and southern winds then move to the surface of the hungry Labrador Current.

In a similar way, fogs are formed in the Pacific Ocean in areas of cold currents (Oya Sio, Primorsky, North Korean, etc.) On our seas, fogs form especially often during the summer monsoon from April to August (especially in June and July) with southeastern and southern winds. warm currents There are almost no fogs observed.

Fog is common in Antarctic waters (occurs when warm air masses penetrate here from the north). The influx of this air occurs here with the winds of the northwestern quarter and other northern directions.

Having appeared above the surface of the cold current, the fog then spreads to neighboring areas. For example, if the fog arose under the influence of southeastern and southern winds, then areas lying to the north and west of the cold current may be subject to frequent fogs. Fog here appears with steady winds blowing from the area of ​​its formation, and persists as long as the winds of a given direction remain.

The intensity of the fog brought in depends on the temperature of the underlying surface of the area. The higher it is (compared to the temperature of the cold current), the more the brought fog will weaken. Usually in such cases the fogs have diurnal cycle: They are most dense at night and in the morning; during the day they weaken or temporarily dissipate.
If the conditions of the underlying surface are heterogeneous, for example, there are areas of cold rising to the surface deep waters and shallow-water areas with large local heating of the water surface, then the fog will be located in patches. These phenomena are more pronounced in weak winds and less pronounced in strong winds.

When the wind stops, the flow of fog also stops, and the existing fog dissipates with increasing temperature, as well as with a significant change in the direction of a given wind, especially when the wind changes to the points of the northern half of the horizon in the northern hemisphere, and to the southern points in the southern hemisphere.

Disappearance of sea fog can be sudden - immediately after the passage of a cold front or gradual - as fog turns into haze; visibility gradually improves.

On sea coasts, fogs are formed when humid and warm air on the cold surface of the land, which usually occurs in autumn, winter and spring.
On flat terrain, for example, along river valleys, fog spreads unhindered and can penetrate over 100 km inland. But this usually happens at night and in the morning when the soil surface is cool. During the day, the fog, falling on the shore, quickly dissipates.

Mountain ranges serve as an obstacle to the spread of fog. On the windward side the fog intensifies. Sometimes high banks are covered with fog, while there is no fog at the surface of the water. This is explained as follows.
The cooling experienced by the air above the surface may not be sufficient to cause fog to form. Rising along the slopes of the coastal mountains, the air cools further and reaches a state of saturation.
But going down the leeward slopes of the mountains, it quickly heats up, and the fog usually disappears before reaching the surface of the earth. For this reason, the spread of fog from the sea on the mountainous coast is very uneven.
In some bays and bays closed from the sea high mountains, fog is very rare. At the same time, in areas relatively far from the sea, but not separated from it by mountains, fogs are frequent.

On the seas and oceans, except for advective fogs, in winter, during negative temperature air, often form fogs of evaporation, or the so-called “sea soaring” phenomena.
They usually form when the air temperature is 10 - 12° or more below the sea surface temperature. With such a large temperature difference, intense evaporation of water from the sea surface occurs.
Water vapor entering large quantities into very cold air, it quickly saturates, condenses and forms fog. The height of evaporation fogs usually does not exceed 3 - 5 m above the water surface.

Frontal fogs(precipitation fogs) are formed if the cold air under a layer of nimbostratus clouds is sufficiently humid, and falling raindrops, evaporating, increase the degree of saturation of the air with water vapor. Frontal fogs are observed in the area of ​​occlusion or in front warm front, in a strip several tens of kilometers wide.

Radiation mists, Formed on the coast and on land with strong night cooling of the underlying surface, as a rule, they are not formed at sea, since the cooling of water and air above the sea during the night is small.

Signs of the appearance or disappearance of fogs in the seas and oceans are as follows:

1. Fogs should be expected if, after more or less prolonged cold weather warming is coming. They can last quite a long time. Fogs are especially likely to appear if warming began in the evening or at night with weak winds.
2. Significant growth in relative and absolute humidity air favors the formation of fog.
3. If there are clear skies and signs of an approaching warm front, expect fog.

In mid-latitudes, the appearance of fogs over areas of cold currents in the western parts of the seas and oceans in the northern hemisphere is more likely with winds from the southeastern and southern directions, in southern hemisphere- northeastern and northern directions; V eastern parts: in the northern hemisphere with winds of southwestern and southern directions, in the southern hemisphere - northwestern and northern. At the same time, it is thicker and spreads over a larger area:

1. In mid-latitudes, the appearance of fog is unlikely in the northern hemisphere with winds of northern directions, and in the southern hemisphere - with winds of southern directions; the previously formed fog soon disappears when the wind moves to these points.
2. If during the fog there is torrential or heavy rain, the fog will intensify even more, but with the end of the rain it will soon disappear or weaken significantly, even with the same wind.

During the day in coastal zone the sea (in bays, bays, etc.) and on the shore, the fog sometimes dissipates due to warming up of the air, but if a strip of fog remains above the sea at the horizon, and the wind from the sea remains the same (i.e., the one in which the fog arose) , then in the evening or at night fog will appear both in the coastal zone of the sea and on the shore:

1. With overcast skies, fog is less likely than with clear skies, especially along the coast.
2. The high fog is long-lasting, and the thin fog dissipates soon after sunrise.

On the shore, if in evening hours the air temperature is close to the dew point (no more than 3 - 4° above it), then on a clear night, by morning you can expect the appearance of radiation fog, which will dissipate at sunrise.

Under these conditions, fog formation will be facilitated by the presence of a weak wind of 0.5 to 5 m/sec:

1. After daytime or evening thunderstorms that cause cooling, fog can be expected at night and in the morning, and sometimes during the day with light winds.
2. Before a night thunderstorm, fog does not appear in the evening: if it does appear, it quickly dissipates.

Being at sea and having data on the distribution of surface water temperature, you need to choose, if possible, the most high temperatures- there is less chance of fog.

If there is dew or frost in the morning, there will be no fog in the next 12 hours.

Physics at every step Perelman Yakov Isidorovich

Can you see steam?

Can you see steam?

You are sure, of course, that you have seen water vapor many times already, you see it every day. Meanwhile, it is absolutely impossible to see water vapor, just as it is impossible to see air. The point is that steam real steam, transparent and invisible. That white smoke that escapes from the spout of the kettle, or those white puffs that the locomotive produces, is not steam in the strict sense of the word, although it is called that in everyday life. It's fog, not steam. What is the difference between fog and steam? Steam is a transparent and invisible gas; fog is a gas condensed into tiny water droplets, which, like specks of dust, float in the air and, like dust, make it opaque. Fog white for the same reason that snow is white: every small, crushed transparent substance (in snow - ice, in fog - water) has a white color.

So, the steam that we use in technology as a source of energy is completely invisible - it doesn’t matter whether it is “saturated” steam (i.e., which at its temperature cannot contain more moisture in the space allotted to it) or “superheated” " If you want to verify this, look in the firebox at the water gauge glass - a tube showing the water level in the steam boiler. You will see water in the tube, but you will not notice anything above the water. Meanwhile, all top part The tubes above the water level are occupied by steam - the same steam, hot and compressed, that is formed in the boiler and works in the steam cylinder. If you could look into a steam cylinder, you would see a strange, unexpected picture: the piston quickly moves back and forth, but the steam that pushes it and is the source of the work of the entire machine is completely invisible.

From the book of Revelations by Nikola Tesla by Tesla Nikola

From the book Secrets of Space and Time author Komarov Victor

From the book Interplanetary Travel [Flights into outer space and achievement celestial bodies] author Perelman Yakov Isidorovich

From the book What is the theory of relativity author Landau Lev Davidovich

From the book Universe. Instruction Manual [How to Survive Black Holes, Time Paradoxes and Quantum Uncertainty] by Goldberg Dave

IV Is it possible to hide from gravity? We are too accustomed to the fact that all things, everything physical bodies chained by their weight to the ground; Therefore, it is difficult for us even to mentally detach ourselves from the force of gravity and imagine a picture of what would happen if we had the ability

From the book Where the River of Time Flows author Novikov Igor Dmitrievich

V Is it possible to weaken the earth's heaviness? If hopes of sheltering from gravity are unrealistic, then perhaps there are ways to at least ease the gravity on earth

From the book Tweets about the Universe by Chaun Marcus

Is it possible to throw a cannonball to the Moon The first question that we have to discuss is, of course, the question of how permissible is the very idea of ​​​​throwing a cannonball to the Moon. To many, the idea of ​​being able to throw a body at such a speed seems completely ridiculous.

From the book Perpetual Motion Machine - before and now. From utopia to science, from science to utopia author Brodyansky Viktor Mikhailovich

Is it possible to change the speed of light? By her own enormous speed the propagation of light is not particularly surprising. The amazing thing is that this speed is characterized by strict constancy. The movement of any body can always be artificially slowed down or accelerated.

From the book How to Understand the Complex Laws of Physics. 100 simple and fun experiments for children and their parents author Dmitriev Alexander Stanislavovich

I. Is it possible to build a perpetual motion machine? Consider the good old classic perpetual motion machine. This invention of crazy science is a device that doesn't waste energy, doesn't wear out, and lasts forever. The best of them take the next step and

From the book The Atomic Problem by Ran Philip

TIME CAN BE SLOWED OUT! Here we begin the story about the great achievements of science related to our 20th century. Perhaps, amazing discovery was done at the very beginning by A. Einstein, who created the so-called theory of relativity. He showed that there was no

From the book The Beginning of Infinity [Explanations that Change the World] by David Deutsch

12. How many stars can I see? It depends on the circumstances. On a crystal clear moonless night, far from city lights, you can see several thousand stars with the naked eye. In a big city, you can only see the most bright stars. Those that are weaker turn out to be

From the book Ideal Theory [Battle for general theory relativity] by Ferreira Pedro

2.5. Discussion about laws and whether they can be broken. The history of ppm shows that inventors perpetual motion machine I have had and still have to face a wide variety of difficulties. There is a lack of funds and materials, and the distrust of others, and difficulties

From the author's book

56 Is it possible to cover a star with a match? For the experiment we need: a match. Since we're talking about stars, let's remember a rather old, but very interesting experience. IN dark night, when the sky is clear and the stars are clearly visible, go out onto the balcony or street and look at one of the brightest

From the author's book

II. What can be produced in a nuclear reactor? A nuclear reactor allows you to: - produce plutonium; - generate thermal energy; - produce radioactive isotopes. Reactors, called primary, are used to produce plutonium, so heat is only a by-product in them

From the author's book

Further reading John Barrow, Frank Tipler, The Anthropic Cosmological Principle (Clarendon Press, 1986). Susan Blackmore, The Meme Machine (Oxford University Press, 1999). Nick Bostrom, 'Are You Living in a Computer Simulation?', Philosophical Quarterly 53 (2003). David Deutsch, 'Apart from Universes', in S. Saunders, J. Barrett, A. Kent and D. Wallace, eds., Many Worlds?: Everett, Quantum Theory, and Reality (Oxford University Press ,

From the author's book

Chapter 10: Seeing Gravity It was once announced that the first person to observe gravitational waves was Joseph Weber. He experimented in this area almost alone. In the late 1960s and early 1970s, his results were celebrated as

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 tiny 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).

A stronger wind will mix a more powerful layer of air, and therefore it can hardly be assumed that its entire mass will cool to the dew point. Therefore, strong wind prevents fog from forming.

By international convention, the appearance of fog is said to occur if daytime horizontal visibility due to water droplets becomes less than 1 km. If there is cloudiness in the air, but the visibility range due to water droplets slightly exceeds 1 km, this phenomenon is called haze. If poor visibility is caused by the presence of particulate dust particles in the air, the phenomenon is called haze. Smoke particles and particulate dust particles emitted industrial enterprises, reduce visibility both directly and indirectly due to the fact that they are hygroscopic nuclei that promote condensation. This thick mixed fog is called smog.

In accordance with the reason why the underlying surface turned out to be colder than the air in contact with it, two main types of fogs are distinguished.

• 1. Radiation fog is formed over the earth's surface as a result of its cooling by long-wave radiation of heat into space at night. The nighttime cooling of the sea surface is very small compared to the cooling of the land surface. Favorable conditions for the appearance of radiation fog is the absence of cloud cover and low wind speed. Thus, such fog is formed over the earth's surface at low wind speeds during clear nights and most often when the surface layers of air have high relative humidity, and the land surface is cold and wet, such as marshy areas in winter time. Since the air containing the fog is cold and therefore relatively dense, it will tend to settle in depressions or will move towards the sea, especially over estuaries. Usually early in the morning Sun rays penetrate through such radiation fog and, heating, dissipate it. But if a thick layer of such fog forms over the cold surface of the sea in winter, when the amount of solar heat is very small, the radiation fog can last all day.
• 2. Advection fog is formed as a result of the horizontal movement of a relatively warm air mass over a colder land or sea surface. Such fog is most stable over the sea, the surface of which is more difficult to heat up with a layer of air or solar heat. Most sea fogs are advective. At strong wind and a significant difference between the air temperature and the temperature of the underlying water surface, this fog is very stable and extends to a height of about 200 m above sea level. It can be assumed that such fogs can form over any cold sea surface if there is a surface current or upwelling of cold waters, most often in spring or summer, when the air temperature is highest and it is saturated with water vapor. Over land, advective fogs most often occur in winter, when moist sea air enters a cooled surface. But since the earth's surface can heat up quite quickly, advective fog will soon dissipate, unless this is prevented by processes that contribute to the formation of radiation fog.

In addition to these two main types, there are several less common varieties of fogs. Steam mist, or “smoking the sea,” occurs when a mass of cold air moves over the sea and constant rapid evaporation of water vapor occurs. The air in contact with the surface of the sea receives heat and at the same time is saturated with water vapor in relation to the temperature surface waters. It then rises and mixes with the cooler layers, which can become saturated to a very small extent with water vapor, so that a supersaturated mixture is formed and condensation begins. Such fogs usually lie very low, and since their formation requires a temperature difference between water and air to be of the order of 10 ° C, they usually form at the edge of the pack ice field when the wind is directed from the direction of the ice field.

Frontal fog, or mixing fog, forms at the boundary between two air masses With different temperatures and humidity, each of which is close to saturation.