Earth's atmospheres in order. Layers of the atmosphere, the structure of the atmospheric layers
Atmospheric air consists of nitrogen (77.99%), oxygen (21%), inert gases (1%) and carbon dioxide (0.01%). The share of carbon dioxide increases over time due to the fact that the products of combustion of fuel are released into the atmosphere, and, in addition, the area of \u200b\u200bforests that absorb carbon dioxide and release oxygen decreases.
The atmosphere also contains a small amount of ozone, which is concentrated at an altitude of about 25-30 km and forms the so-called ozone layer. This layer creates a barrier to solar ultraviolet radiation, which is dangerous for the living organisms of the Earth.
In addition, the atmosphere contains water vapor and various impurities - dust particles, volcanic ash, soot, and so on. The concentration of impurities is higher near the surface of the earth and in certain areas: over large cities, deserts.
Troposphere- lower, it contains most of the air and. The height of this layer is not the same: from 8-10 km near the tropics to 16-18 km near the equator. in the troposphere it decreases with elevation: by 6°C per kilometer. Weather is formed in the troposphere, winds, precipitation, clouds, cyclones and anticyclones are formed.
The next layer of the atmosphere is stratosphere. The air in it is much more rarefied, it has much less water vapor. The temperature in the lower part of the stratosphere is -60 - -80°C and falls with increasing altitude. The ozone layer is in the stratosphere. The stratosphere is characterized by high wind speeds (up to 80-100 m/s).
Mesosphere- the middle layer of the atmosphere lying above the stratosphere at altitudes from 50 to S0-S5 km. The mesosphere is characterized by a decrease in the average temperature with height from 0°C at the lower boundary to -90°C at the upper boundary. Near the upper boundary of the mesosphere, noctilucent clouds are observed, illuminated by the sun at night. The air pressure at the upper boundary of the mesosphere is 200 times less than at the earth's surface.
Thermosphere- located above the mesosphere, at altitudes from SO to 400-500 km, in it the temperature at first slowly, and then quickly begins to rise again. The reason is the absorption of ultraviolet radiation from the Sun at altitudes of 150-300 km. In the thermosphere, the temperature rises continuously up to a height of about 400 km, where it reaches 700-1500°C (depending on solar activity). Under the action of ultraviolet and X-ray and cosmic radiation, air ionization also occurs (“polar lights”). The main regions of the ionosphere lie within the thermosphere.
Exosphere- the outer, most rarefied layer of the atmosphere, it begins at altitudes of 450-000 km, and its upper boundary is located at a distance of several thousand km from the earth's surface, where the concentration of particles becomes the same as in interplanetary space. The exosphere consists of ionized gas (plasma); the lower and middle parts of the exosphere are mainly composed of oxygen and nitrogen; with an increase in altitude, the relative concentration of light gases, especially ionized hydrogen, rapidly increases. The temperature in the exosphere is 1300-3000°C; it grows slowly with height. The exosphere contains the Earth's radiation belts.
The world around us is formed from three very different parts: earth, water and air. Each of them is unique and interesting in its own way. Now we will talk only about the last of them. What is atmosphere? How did it come about? What is it made of and what parts is it divided into? All these questions are extremely interesting.
The very name "atmosphere" is formed from two words of Greek origin, translated into Russian they mean "steam" and "ball". And if you look at the exact definition, you can read the following: "The atmosphere is the air shell of the planet Earth, which rushes along with it in outer space." It developed in parallel with the geological and geochemical processes that took place on the planet. And today all the processes occurring in living organisms depend on it. Without an atmosphere, the planet would become a lifeless desert like the moon.
What does it consist of?
The question of what is the atmosphere and what elements are included in it has interested people for a long time. The main components of this shell were already known in 1774. They were installed by Antoine Lavoisier. He found that the composition of the atmosphere is mostly formed from nitrogen and oxygen. Over time, its components have been refined. And now we know that it contains many more gases, as well as water and dust.
Let us consider in more detail what the Earth's atmosphere near its surface consists of. The most common gas is nitrogen. It contains a little more than 78 percent. But, despite such a large amount, nitrogen in the air is practically not active.
The next largest and most important element is oxygen. This gas contains almost 21%, and it just shows very high activity. Its specific function is to oxidize dead organic matter, which decomposes as a result of this reaction.
Low but important gases
The third gas that is part of the atmosphere is argon. Its slightly less than one percent. It is followed by carbon dioxide with neon, helium with methane, krypton with hydrogen, xenon, ozone and even ammonia. But they are contained so little that the percentage of such components is equal to hundredths, thousandths and millionths. Of these, only carbon dioxide plays a significant role, since it is the building material that plants need for photosynthesis. Its other important function is to keep out radiation and absorb part of the sun's heat.
Another rare but important gas, ozone, exists to trap ultraviolet radiation coming from the sun. Thanks to this property, all life on the planet is reliably protected. On the other hand, ozone affects the temperature of the stratosphere. Due to the fact that it absorbs this radiation, the air is heated.
The constancy of the quantitative composition of the atmosphere is maintained by non-stop mixing. Its layers move both horizontally and vertically. Therefore, anywhere in the world there is enough oxygen and there is no excess of carbon dioxide.
What else is in the air?
It should be noted that steam and dust can be detected in the airspace. The latter consists of pollen and soil particles, in the city they are joined by impurities of particulate emissions from exhaust gases.
But there is a lot of water in the atmosphere. Under certain conditions, it condenses, and clouds and fog appear. In fact, this is the same thing, only the first ones appear high above the surface of the Earth, and the last one spreads along it. Clouds take on a variety of shapes. This process depends on the height above the Earth.
If they formed 2 km above land, then they are called layered. It is from them that rain falls on the ground or snow falls. Cumulus clouds form above them up to a height of 8 km. They are always the most beautiful and picturesque. It is they who are examined and wondered what they look like. If such formations appear in the next 10 km, they will be very light and airy. Their name is cirrus.
What are the layers of the atmosphere?
Although they have very different temperatures from each other, it is very difficult to say at what particular height one layer begins and another ends. This division is very conditional and is approximate. However, the layers of the atmosphere still exist and perform their functions.
The lowest part of the air shell is called the troposphere. Its thickness increases when moving from the poles to the equator from 8 to 18 km. This is the warmest part of the atmosphere, since the air in it is heated from the earth's surface. Most of the water vapor is concentrated in the troposphere, so clouds form in it, precipitation falls, thunderstorms rumble and winds blow.
The next layer is about 40 km thick and is called the stratosphere. If the observer moves to this part of the air, he will find that the sky has become purple. This is due to the low density of the substance, which practically does not scatter the sun's rays. It is in this layer that jet planes fly. For them, all open spaces are open there, since there are practically no clouds. Inside the stratosphere there is a layer consisting of a large amount of ozone.
It is followed by the stratopause and the mesosphere. The latter has a thickness of about 30 km. It is characterized by a sharp decrease in air density and temperature. The sky appears black to the observer. Here you can even watch the stars during the day.
Layers with little to no air
The structure of the atmosphere continues with a layer called the thermosphere - the longest of all the others, its thickness reaches 400 km. This layer is characterized by a huge temperature, which can reach 1700 ° C.
The last two spheres are often combined into one and called it the ionosphere. This is due to the fact that reactions occur in them with the release of ions. It is these layers that allow you to observe such a natural phenomenon as the northern lights.
The next 50 km from the Earth are reserved for the exosphere. This is the outer shell of the atmosphere. In it, air particles are scattered into space. Weather satellites usually move in this layer.
The Earth's atmosphere ends with a magnetosphere. It was she who sheltered most of the artificial satellites of the planet.
After all that has been said, there should be no question about what the atmosphere is. If there are doubts about its necessity, then it is easy to dispel them.
The value of the atmosphere
The main function of the atmosphere is to protect the surface of the planet from overheating during the day and excessive cooling at night. The next importance of this shell, which no one will dispute, is to supply oxygen to all living beings. Without it, they would suffocate.
Most meteorites burn up in the upper layers, never reaching the Earth's surface. And people can admire the flying lights, mistaking them for shooting stars. Without an atmosphere, the entire Earth would be littered with craters. And about protection from solar radiation has already been mentioned above.
How does a person affect the atmosphere?
Very negative. This is due to the growing activity of people. The main share of all the negative aspects falls on industry and transport. By the way, it is cars that emit almost 60% of all pollutants that penetrate the atmosphere. The remaining forty are divided between energy and industry, as well as industries for the destruction of waste.
The list of harmful substances that replenish the composition of the air every day is very long. Because of the transport in the atmosphere are: nitrogen and sulfur, carbon, blue and soot, as well as a strong carcinogen that causes skin cancer - benzopyrene.
The industry accounts for the following chemical elements: sulfur dioxide, hydrocarbons and hydrogen sulfide, ammonia and phenol, chlorine and fluorine. If the process continues, then soon the answers to the questions: “What is the atmosphere? What does it consist of? will be completely different.
The composition of the atmosphere. The air shell of our planet - atmosphere protects the earth's surface from the harmful effects on living organisms of ultraviolet radiation from the Sun. It also protects the Earth from cosmic particles - dust and meteorites.
The atmosphere consists of a mechanical mixture of gases: 78% of its volume is nitrogen, 21% is oxygen, and less than 1% is helium, argon, krypton and other inert gases. The amount of oxygen and nitrogen in the air is practically unchanged, because nitrogen almost does not enter into compounds with other substances, and oxygen, which, although very active and is spent on respiration, oxidation and combustion, is constantly replenished by plants.
Up to a height of about 100 km, the percentage of these gases remains practically unchanged. This is due to the fact that the air is constantly mixed.
In addition to these gases, the atmosphere contains about 0.03% carbon dioxide, which is usually concentrated near the earth's surface and is distributed unevenly: in cities, industrial centers and areas of volcanic activity, its amount increases.
There is always a certain amount of impurities in the atmosphere - water vapor and dust. The content of water vapor depends on the temperature of the air: the higher the temperature, the more vapor the air holds. Due to the presence of vaporous water in the air, atmospheric phenomena such as rainbows, refraction of sunlight, etc. are possible.
Dust enters the atmosphere during volcanic eruptions, sand and dust storms, with incomplete combustion of fuel at thermal power plants, etc.
The structure of the atmosphere. The density of the atmosphere changes with height: it is highest at the Earth's surface, and decreases as it rises. So, at an altitude of 5.5 km, the density of the atmosphere is 2 times, and at an altitude of 11 km - 4 times less than in the surface layer.
Depending on the density, composition and properties of gases, the atmosphere is divided into five concentric layers (Fig. 34).
Rice. 34. Vertical section of the atmosphere (atmospheric stratification)
1. The bottom layer is called troposphere. Its upper boundary runs at an altitude of 8-10 km at the poles and 16-18 km at the equator. The troposphere contains up to 80% of the total mass of the atmosphere and almost all of the water vapor.
The air temperature in the troposphere decreases with height by 0.6 °C every 100 m and at its upper boundary it is -45-55 °C.
The air in the troposphere is constantly mixed, moving in different directions. Only here fogs, rains, snowfalls, thunderstorms, storms and other weather phenomena are observed.
2. Above is located stratosphere, which extends to a height of 50-55 km. Air density and pressure in the stratosphere are negligible. The rarefied air consists of the same gases as in the troposphere, but it contains more ozone. The highest concentration of ozone is observed at an altitude of 15-30 km. The temperature in the stratosphere rises with height and reaches 0 °C or more at its upper boundary. This is due to the fact that ozone absorbs the short-wavelength part of solar energy, as a result of which the air heats up.
3. Above the stratosphere lies mesosphere, extending to a height of 80 km. In it, the temperature drops again and reaches -90 ° C. The air density there is 200 times less than at the surface of the Earth.
4. Above the mesosphere is thermosphere(from 80 to 800 km). The temperature in this layer rises: at an altitude of 150 km to 220 °C; at an altitude of 600 km to 1500 °C. The atmospheric gases (nitrogen and oxygen) are in an ionized state. Under the action of short-wave solar radiation, individual electrons are detached from the shells of atoms. As a result, in this layer - ionosphere layers of charged particles appear. Their densest layer is at an altitude of 300-400 km. Due to the low density, the sun's rays do not scatter there, so the sky is black, stars and planets shine brightly on it.
In the ionosphere there are polar lights, powerful electric currents are generated that cause disturbances in the Earth's magnetic field.
5. Above 800 km, the outer shell is located - exosphere. The speed of movement of individual particles in the exosphere approaches the critical one - 11.2 mm/s, so individual particles can overcome the Earth's gravity and escape into the world space.
The value of the atmosphere. The role of the atmosphere in the life of our planet is exceptionally great. Without it, the Earth would be dead. The atmosphere protects the Earth's surface from intense heating and cooling. Its influence can be likened to the role of glass in greenhouses: to let in the sun's rays and prevent heat from escaping.
The atmosphere protects living organisms from the shortwave and corpuscular radiation of the Sun. The atmosphere is the environment where weather phenomena occur, with which all human activity is associated. The study of this shell is carried out at meteorological stations. Day and night, in any weather, meteorologists monitor the state of the lower atmosphere. Four times a day, and at many stations every hour they measure temperature, pressure, air humidity, note cloudiness, wind direction and speed, precipitation, electrical and sound phenomena in the atmosphere. Meteorological stations are located everywhere: in Antarctica and in tropical rainforests, on high mountains and in the vast expanses of the tundra. Observations are also being made on the oceans from specially built ships.
From the 30s. 20th century observations began in the free atmosphere. They began to launch radiosondes, which rise to a height of 25-35 km, and with the help of radio equipment transmit to Earth information about temperature, pressure, air humidity and wind speed. Nowadays, meteorological rockets and satellites are also widely used. The latter have television installations that transmit images of the earth's surface and clouds.
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5. Air shell of the earth§ 31. Heating of the atmosphere
The stratosphere is one of the upper layers of the air shell of our planet. It starts at an altitude of about 11 km above the ground. Passenger aircraft no longer fly here and clouds rarely form. Ozone is located in the stratosphere - a thin shell that protects the planet from the penetration of harmful ultraviolet radiation.
Air shell of the planet
The atmosphere is the gaseous shell of the Earth, adjacent to the inner surface of the hydrosphere and the earth's crust. Its outer boundary gradually passes into outer space. The composition of the atmosphere includes gases: nitrogen, oxygen, argon, carbon dioxide, and so on, as well as impurities in the form of dust, water drops, ice crystals, combustion products. The ratio of the main elements of the air shell is kept constant. The exceptions are carbon dioxide and water - their amount in the atmosphere often changes.
Layers of the gaseous envelope
The atmosphere is divided into several layers, located one above the other and having features in the composition:
boundary layer - directly adjacent to the surface of the planet, extending to a height of 1-2 km;
troposphere - the second layer, the outer boundary is located on average at an altitude of 11 km, almost all the water vapor of the atmosphere is concentrated here, clouds form, cyclones and anticyclones arise, as the height increases, the temperature rises;
tropopause - transitional layer, characterized by the cessation of temperature decrease;
the stratosphere is a layer that extends up to a height of 50 km and is divided into three zones: from 11 to 25 km the temperature changes slightly, from 25 to 40 - the temperature rises, from 40 to 50 - the temperature remains constant (stratopause);
the mesosphere extends to a height of up to 80-90 km;
the thermosphere reaches 700-800 km above sea level, here at an altitude of 100 km there is the Karman line, which is taken as the boundary between the Earth's atmosphere and space;
The exosphere is also called the scatter zone, here it loses particles of matter a lot, and they fly away into space.
Temperature changes in the stratosphere
So, the stratosphere is the part of the gaseous shell of the planet that follows the troposphere. Here, the air temperature, which is constant throughout the tropopause, begins to change. The height of the stratosphere is approximately 40 km. The lower limit is 11 km above sea level. Starting from this mark, the temperature undergoes slight changes. At an altitude of 25 km, the heating index begins to slowly increase. By the mark of 40 km above sea level, the temperature rises from -56.5º to +0.8ºС. Further, it remains close to zero degrees up to an altitude of 50-55 km. The zone between 40 and 55 kilometers is called the stratopause, since the temperature here does not change. It is a transition zone from the stratosphere to the mesosphere.
Features of the stratosphere
The Earth's stratosphere contains about 20% of the mass of the entire atmosphere. The air here is so rarefied that it is impossible for a person to stay without a special space suit. This fact is one of the reasons why flights into the stratosphere began to be carried out only relatively recently.
Another feature of the planet's gas envelope at an altitude of 11-50 km is a very small amount of water vapor. For this reason, clouds almost never form in the stratosphere. For them, there is simply no building material. However, it is rarely possible to observe the so-called mother-of-pearl clouds, which “decorate” the stratosphere (the photo is presented below) at an altitude of 20-30 km above sea level. Thin, as if luminous formations from the inside can be observed after sunset or before sunrise. The shape of mother-of-pearl clouds is similar to cirrus or cirrocumulus.
Earth's ozone layer
The main distinguishing feature of the stratosphere is the maximum concentration of ozone in the entire atmosphere. It is formed under the influence of sunlight and protects all life on the planet from their destructive radiation. The ozone layer of the Earth is located at an altitude of 20-25 km above sea level. O 3 molecules are distributed throughout the stratosphere and even exist near the surface of the planet, but their highest concentration is observed at this level.
It should be noted that the ozone layer of the Earth is only 3-4 mm. This will be its thickness if particles of this gas are placed under conditions of normal pressure, for example, near the surface of the planet. Ozone is formed as a result of the breakdown of an oxygen molecule under the action of ultraviolet radiation into two atoms. One of them combines with a "full-fledged" molecule and ozone is formed - O 3.
Dangerous Defender
Thus, today the stratosphere is a more explored layer of the atmosphere than at the beginning of the last century. However, the future of the ozone layer, without which life on Earth would not have arisen, is still not very clear. While countries are reducing the production of freon, some scientists say that this will not bring much benefit, at least at such a pace, while others say that this is not necessary at all, since most of the harmful substances are formed naturally. Who is right, time will tell.
ATMOSPHERE
gaseous envelope surrounding a celestial body. Its characteristics depend on the size, mass, temperature, rotation speed and chemical composition of a given celestial body, and are also determined by the history of its formation from the moment of its birth. Earth's atmosphere is made up of a mixture of gases called air. Its main constituents are nitrogen and oxygen in a ratio of approximately 4:1. A person is affected mainly by the state of the lower 15-25 km of the atmosphere, since it is in this lower layer that the bulk of the air is concentrated. The science that studies the atmosphere is called meteorology, although the subject of this science is also the weather and its effect on humans. The state of the upper layers of the atmosphere, located at altitudes from 60 to 300 and even 1000 km from the Earth's surface, is also changing. Strong winds, storms develop here, and such amazing electrical phenomena as auroras appear. Many of these phenomena are associated with fluxes of solar radiation, cosmic radiation, and the Earth's magnetic field. The high layers of the atmosphere are also a chemical laboratory, since there, under conditions close to vacuum, some atmospheric gases, under the influence of a powerful flow of solar energy, enter into chemical reactions. The science that studies these interrelated phenomena and processes is called the physics of the high layers of the atmosphere.
GENERAL CHARACTERISTICS OF THE EARTH'S ATMOSPHERE
Dimensions. Until sounding rockets and artificial satellites explored the outer layers of the atmosphere at distances several times greater than the radius of the Earth, it was believed that as you move away from the earth's surface, the atmosphere gradually becomes more rarefied and smoothly passes into interplanetary space. It has now been established that energy flows from the deep layers of the Sun penetrate into outer space far beyond the Earth's orbit, up to the outer limits of the Solar System. This so-called. The solar wind flows around the Earth's magnetic field, forming an elongated "cavity" within which the Earth's atmosphere is concentrated. The Earth's magnetic field is noticeably narrowed on the day side facing the Sun and forms a long tongue, probably extending beyond the orbit of the Moon, on the opposite, night side. The boundary of the Earth's magnetic field is called the magnetopause. On the day side, this boundary passes at a distance of about seven Earth radii from the surface, but during periods of increased solar activity it is even closer to the Earth's surface. The magnetopause is at the same time the boundary of the earth's atmosphere, the outer shell of which is also called the magnetosphere, since it contains charged particles (ions), the movement of which is due to the earth's magnetic field. The total weight of atmospheric gases is approximately 4.5*1015 tons. Thus, the "weight" of the atmosphere per unit area, or atmospheric pressure, is approximately 11 tons/m2 at sea level.
Significance for life. It follows from the above that the Earth is separated from interplanetary space by a powerful protective layer. Outer space is permeated with powerful ultraviolet and X-ray radiation from the Sun and even harder cosmic radiation, and these types of radiation are detrimental to all living things. At the outer edge of the atmosphere, the radiation intensity is lethal, but a significant part of it is retained by the atmosphere far from the Earth's surface. The absorption of this radiation explains many properties of the high layers of the atmosphere, and especially the electrical phenomena that occur there. The lowest, surface layer of the atmosphere is especially important for a person who lives at the point of contact of the solid, liquid and gaseous shells of the Earth. The upper shell of the "solid" Earth is called the lithosphere. About 72% of the Earth's surface is covered by the waters of the oceans, which make up most of the hydrosphere. The atmosphere borders both the lithosphere and the hydrosphere. Man lives at the bottom of the air ocean and near or above the level of the water ocean. The interaction of these oceans is one of the important factors that determine the state of the atmosphere.
Compound. The lower layers of the atmosphere consist of a mixture of gases (see table). In addition to those listed in the table, other gases are also present in the form of small impurities in the air: ozone, methane, substances such as carbon monoxide (CO), nitrogen and sulfur oxides, ammonia.
COMPOSITION OF THE ATMOSPHERE
In the high layers of the atmosphere, the composition of the air changes under the influence of hard radiation from the Sun, which leads to the breakdown of oxygen molecules into atoms. Atomic oxygen is the main component of the high layers of the atmosphere. Finally, in the most distant layers of the atmosphere from the surface of the Earth, the lightest gases, hydrogen and helium, become the main components. Since the bulk of matter is concentrated in the lower 30 km, changes in air composition at altitudes above 100 km do not have a noticeable effect on the overall composition of the atmosphere.
Energy exchange. The sun is the main source of energy coming to the Earth. Being at a distance of approx. 150 million km from the Sun, the Earth receives about one two billionth of the energy it radiates, mainly in the visible part of the spectrum, which man calls "light". Most of this energy is absorbed by the atmosphere and lithosphere. The earth also radiates energy, mostly in the form of far infrared radiation. Thus, a balance is established between the energy received from the Sun, the heating of the Earth and the atmosphere, and the reverse flow of thermal energy radiated into space. The mechanism of this balance is extremely complex. Dust and gas molecules scatter light, partially reflecting it into the world space. Clouds reflect even more of the incoming radiation. Part of the energy is absorbed directly by gas molecules, but mostly by rocks, vegetation and surface waters. Water vapor and carbon dioxide present in the atmosphere transmit visible radiation but absorb infrared radiation. Thermal energy accumulates mainly in the lower layers of the atmosphere. A similar effect occurs in a greenhouse when the glass lets light in and the soil heats up. Since glass is relatively opaque to infrared radiation, heat accumulates in the greenhouse. The heating of the lower atmosphere due to the presence of water vapor and carbon dioxide is often referred to as the greenhouse effect. Cloudiness plays a significant role in the conservation of heat in the lower layers of the atmosphere. If the clouds dissipate or the transparency of the air masses increases, the temperature will inevitably decrease as the surface of the Earth freely radiates thermal energy into the surrounding space. Water on the surface of the Earth absorbs solar energy and evaporates, turning into a gas - water vapor, which carries a huge amount of energy into the lower atmosphere. When water vapor condenses and forms clouds or fog, this energy is released in the form of heat. About half of the solar energy reaching the earth's surface is spent on the evaporation of water and enters the lower atmosphere. Thus, due to the greenhouse effect and the evaporation of water, the atmosphere warms up from below. This partly explains the high activity of its circulation in comparison with the circulation of the World Ocean, which warms up only from above and is therefore much more stable than the atmosphere.
See also METEOROLOGY AND CLIMATOLOGY. In addition to the general heating of the atmosphere by solar "light", significant heating of some of its layers occurs due to ultraviolet and X-ray radiation from the Sun. Structure. Compared to liquids and solids, in gaseous substances, the force of attraction between molecules is minimal. As the distance between molecules increases, gases are able to expand indefinitely if nothing prevents them. The lower boundary of the atmosphere is the surface of the Earth. Strictly speaking, this barrier is impenetrable, since gas exchange occurs between air and water and even between air and rocks, but in this case these factors can be neglected. Since the atmosphere is a spherical shell, it has no side boundaries, but only a lower boundary and an upper (outer) boundary open from the side of interplanetary space. Through the outer boundary, some neutral gases leak out, as well as the flow of matter from the surrounding outer space. Most of the charged particles, with the exception of high-energy cosmic rays, are either captured by the magnetosphere or repelled by it. The atmosphere is also affected by the force of gravity, which keeps the air shell at the surface of the Earth. Atmospheric gases are compressed by their own weight. This compression is maximum at the lower boundary of the atmosphere, and therefore the air density is the highest here. At any height above the earth's surface, the degree of air compression depends on the mass of the overlying air column, so the air density decreases with height. The pressure, equal to the mass of the overlying air column per unit area, is directly related to the density and, therefore, also decreases with height. If the atmosphere were an "ideal gas" with a constant composition independent of height, a constant temperature, and a constant force of gravity acting on it, then the pressure would decrease by a factor of 10 for every 20 km of altitude. The real atmosphere slightly differs from the ideal gas up to about 100 km, and then the pressure decreases more slowly with height, as the composition of the air changes. Small changes in the described model are also introduced by a decrease in the force of gravity with distance from the center of the Earth, amounting to approx. 3% for every 100 km of altitude. Unlike atmospheric pressure, temperature does not decrease continuously with altitude. As shown in fig. 1, it decreases to approximately 10 km and then begins to rise again. This occurs when oxygen absorbs ultraviolet solar radiation. In this case, ozone gas is formed, the molecules of which consist of three oxygen atoms (O3). It also absorbs ultraviolet radiation, and therefore this layer of the atmosphere, called the ozonosphere, heats up. Higher, the temperature drops again, since there are much fewer gas molecules, and the energy absorption is correspondingly reduced. In even higher layers, the temperature rises again due to the absorption of the shortest wavelength ultraviolet and X-ray radiation from the Sun by the atmosphere. Under the influence of this powerful radiation, the atmosphere is ionized, i.e. A gas molecule loses an electron and acquires a positive electric charge. Such molecules become positively charged ions. Due to the presence of free electrons and ions, this layer of the atmosphere acquires the properties of an electrical conductor. It is believed that the temperature continues to rise to heights where the rarefied atmosphere passes into interplanetary space. At a distance of several thousand kilometers from the surface of the Earth, temperatures from 5000 ° to 10,000 ° C probably prevail. Although molecules and atoms have very high speeds of movement, and therefore a high temperature, this rarefied gas is not "hot" in the usual sense. . Due to the meager number of molecules at high altitudes, their total thermal energy is very small. Thus, the atmosphere consists of separate layers (i.e., a series of concentric shells, or spheres), the selection of which depends on which property is of greatest interest. Based on the average temperature distribution, meteorologists have developed a scheme for the structure of an ideal "middle atmosphere" (see Fig. 1).
Troposphere - the lower layer of the atmosphere, extending to the first thermal minimum (the so-called tropopause). The upper limit of the troposphere depends on the geographical latitude (in the tropics - 18-20 km, in temperate latitudes - about 10 km) and the time of year. The US National Weather Service conducted soundings near the South Pole and revealed seasonal changes in the height of the tropopause. In March, the tropopause is at an altitude of approx. 7.5 km. From March to August or September there is a steady cooling of the troposphere, and its boundary rises for a short period in August or September to a height of approximately 11.5 km. Then from September to December it drops rapidly and reaches its lowest position - 7.5 km, where it remains until March, fluctuating within only 0.5 km. It is in the troposphere that the weather is mainly formed, which determines the conditions for human existence. Most of the atmospheric water vapor is concentrated in the troposphere, and therefore clouds form mainly here, although some of them, consisting of ice crystals, are also found in the higher layers. The troposphere is characterized by turbulence and powerful air currents (winds) and storms. In the upper troposphere, there are strong air currents of a strictly defined direction. Turbulent eddies, like small whirlpools, are formed under the influence of friction and dynamic interaction between slow and fast moving air masses. Since there is usually no cloud cover in these high layers, this turbulence is referred to as "clear air turbulence".
Stratosphere. The upper layer of the atmosphere is often erroneously described as a layer with relatively constant temperatures, where the winds blow more or less steadily and where the meteorological elements change little. The upper layers of the stratosphere heat up as oxygen and ozone absorb solar ultraviolet radiation. The upper boundary of the stratosphere (stratopause) is drawn where the temperature rises slightly, reaching an intermediate maximum, which is often comparable to the temperature of the surface air layer. Based on observations made with airplanes and balloons adapted to fly at a constant altitude, turbulent disturbances and strong winds blowing in different directions have been established in the stratosphere. As in the troposphere, powerful air vortices are noted, which are especially dangerous for high-speed aircraft. Strong winds, called jet streams, blow in narrow zones along the borders of temperate latitudes facing the poles. However, these zones can shift, disappear and reappear. Jet streams usually penetrate the tropopause and appear in the upper troposphere, but their speed decreases rapidly with decreasing altitude. It is possible that part of the energy entering the stratosphere (mainly spent on the formation of ozone) affects the processes in the troposphere. Particularly active mixing is associated with atmospheric fronts, where extensive flows of stratospheric air were recorded significantly below the tropopause, and tropospheric air was drawn into the lower layers of the stratosphere. Significant progress has been made in the study of the vertical structure of the lower layers of the atmosphere in connection with the improvement of the technique of launching radiosondes to altitudes of 25-30 km. The mesosphere, located above the stratosphere, is a shell in which, up to a height of 80-85 km, the temperature drops to the minimum for the atmosphere as a whole. Record low temperatures down to -110°C were recorded by meteorological rockets launched from the US-Canadian installation at Fort Churchill (Canada). The upper limit of the mesosphere (mesopause) approximately coincides with the lower limit of the region of active absorption of the X-ray and the shortest wavelength ultraviolet radiation of the Sun, which is accompanied by heating and ionization of the gas. In the polar regions in summer, cloud systems often appear in the mesopause, which occupy a large area, but have little vertical development. Such clouds glowing at night often make it possible to detect large-scale undulating air movements in the mesosphere. The composition of these clouds, sources of moisture and condensation nuclei, dynamics and relationship with meteorological factors are still insufficiently studied. The thermosphere is a layer of the atmosphere in which the temperature rises continuously. Its power can reach 600 km. The pressure and, consequently, the density of a gas constantly decrease with height. Near the earth's surface, 1 m3 of air contains approx. 2.5x1025 molecules, at a height of approx. 100 km, in the lower layers of the thermosphere - approximately 1019, at an altitude of 200 km, in the ionosphere - 5 * 10 15 and, according to calculations, at an altitude of approx. 850 km - approximately 1012 molecules. In interplanetary space, the concentration of molecules is 10 8-10 9 per 1 m3. At a height of approx. 100 km, the number of molecules is small, and they rarely collide with each other. The average distance traveled by a randomly moving molecule before colliding with another similar molecule is called its mean free path. The layer in which this value increases so much that the probability of intermolecular or interatomic collisions can be neglected is located on the boundary between the thermosphere and the overlying shell (exosphere) and is called the thermal pause. The thermopause is located approximately 650 km from the earth's surface. At a certain temperature, the speed of a molecule's movement depends on its mass: lighter molecules move faster than heavier ones. In the lower atmosphere, where the free path is very short, there is no noticeable separation of gases according to their molecular weight, but it is expressed above 100 km. In addition, under the influence of ultraviolet and X-ray radiation from the Sun, oxygen molecules break up into atoms, the mass of which is half the mass of the molecule. Therefore, as we move away from the Earth's surface, atomic oxygen becomes increasingly important in the composition of the atmosphere and at an altitude of approx. 200 km becomes its main component. Higher, at a distance of about 1200 km from the Earth's surface, light gases - helium and hydrogen - predominate. They are the outer layer of the atmosphere. This separation by weight, called diffuse separation, resembles the separation of mixtures using a centrifuge. The exosphere is the outer layer of the atmosphere, which is isolated on the basis of changes in temperature and the properties of neutral gas. Molecules and atoms in the exosphere revolve around the Earth in ballistic orbits under the influence of gravity. Some of these orbits are parabolic and similar to the trajectories of projectiles. Molecules can revolve around the Earth and in elliptical orbits, like satellites. Some molecules, mainly hydrogen and helium, have open trajectories and escape into outer space (Fig. 2).
SOLAR-TERRESTRIAL RELATIONSHIPS AND THEIR INFLUENCE ON THE ATMOSPHERE
atmospheric tides. The attraction of the Sun and the Moon causes tides in the atmosphere, similar to the terrestrial and sea tides. But atmospheric tides have a significant difference: the atmosphere reacts most strongly to the attraction of the Sun, while the earth's crust and ocean - to the attraction of the Moon. This is explained by the fact that the atmosphere is heated by the Sun and, in addition to the gravitational tide, a powerful thermal tide arises. In general, the mechanisms of formation of atmospheric and sea tides are similar, except that in order to predict the reaction of air to gravitational and thermal influences, it is necessary to take into account its compressibility and temperature distribution. It is not entirely clear why semidiurnal (12-hour) solar tides in the atmosphere predominate over diurnal solar and semidiurnal lunar tides, although the driving forces of the latter two processes are much more powerful. Previously, it was believed that a resonance occurs in the atmosphere, which amplifies precisely the oscillations with a 12-hour period. However, observations carried out with the help of geophysical rockets indicate that there are no temperature reasons for such a resonance. In solving this problem, one should probably take into account all the hydrodynamic and thermal features of the atmosphere. At the earth's surface near the equator, where the influence of tidal fluctuations is maximum, it provides a change in atmospheric pressure by 0.1%. The speed of the tidal winds is approx. 0.3 km/h. Due to the complex thermal structure of the atmosphere (especially the presence of a temperature minimum in the mesopause), tidal air currents intensify, and, for example, at an altitude of 70 km, their speed is about 160 times higher than at the earth's surface, which has important geophysical consequences. It is believed that in the lower part of the ionosphere (layer E) tidal oscillations move the ionized gas vertically in the Earth's magnetic field, and therefore, electric currents arise here. These constantly emerging systems of currents on the surface of the Earth are established by perturbations of the magnetic field. The diurnal variations of the magnetic field are in good agreement with the calculated values, which convincingly testifies in favor of the theory of tidal mechanisms of the "atmospheric dynamo". Electric currents arising in the lower part of the ionosphere (layer E) must move somewhere, and, therefore, the circuit must be closed. The analogy with the dynamo becomes complete if we consider the oncoming movement as the work of the engine. It is assumed that the reverse circulation of the electric current is carried out in a higher layer of the ionosphere (F), and this counter flow can explain some of the peculiar features of this layer. Finally, the tidal effect must also generate horizontal currents in the E layer and, consequently, in the F layer.
Ionosphere. Trying to explain the mechanism of the occurrence of auroras, scientists of the 19th century. suggested that in the atmosphere there is a zone with electrically charged particles. In the 20th century convincing evidence was obtained experimentally for the existence of a layer reflecting radio waves at altitudes from 85 to 400 km. It is now known that its electrical properties are the result of atmospheric gas ionization. Therefore, this layer is usually called the ionosphere. The impact on radio waves is mainly due to the presence of free electrons in the ionosphere, although the propagation mechanism of radio waves is associated with the presence of large ions. The latter are also of interest in the study of the chemical properties of the atmosphere, since they are more active than neutral atoms and molecules. Chemical reactions occurring in the ionosphere play an important role in its energy and electrical balance.
normal ionosphere. Observations carried out with the help of geophysical rockets and satellites have given a lot of new information, indicating that the ionization of the atmosphere occurs under the influence of broad-spectrum solar radiation. Its main part (more than 90%) is concentrated in the visible part of the spectrum. Ultraviolet radiation with a shorter wavelength and more energy than violet light rays is emitted by the hydrogen of the inner part of the Sun's atmosphere (chromosphere), and X-ray radiation, which has even higher energy, is emitted by the gases of the Sun's outer shell (corona). The normal (average) state of the ionosphere is due to constant powerful radiation. Regular changes occur in the normal ionosphere under the influence of the daily rotation of the Earth and seasonal differences in the angle of incidence of the sun's rays at noon, but unpredictable and abrupt changes in the state of the ionosphere also occur.
Disturbances in the ionosphere. As is known, powerful cyclically repeating perturbations arise on the Sun, which reach a maximum every 11 years. Observations under the program of the International Geophysical Year (IGY) coincided with the period of the highest solar activity for the entire period of systematic meteorological observations, i.e. from the beginning of the 18th century During periods of high activity, some areas on the Sun increase in brightness several times, and they send out powerful pulses of ultraviolet and X-ray radiation. Such phenomena are called solar flares. They last from several minutes to one or two hours. During a flare, solar gas (mostly protons and electrons) erupts, and elementary particles rush into outer space. The electromagnetic and corpuscular radiation of the Sun at the moments of such flares has a strong effect on the Earth's atmosphere. The initial reaction is observed 8 minutes after the flash, when intense ultraviolet and X-ray radiation reaches the Earth. As a result, ionization sharply increases; x-rays penetrate the atmosphere to the lower boundary of the ionosphere; the number of electrons in these layers increases so much that the radio signals are almost completely absorbed ("extinguished"). Additional absorption of radiation causes heating of the gas, which contributes to the development of winds. Ionized gas is an electrical conductor, and when it moves in the Earth's magnetic field, a dynamo effect appears and an electric current occurs. Such currents can, in turn, cause noticeable perturbations of the magnetic field and manifest themselves in the form of magnetic storms. This initial phase takes only a short time, corresponding to the duration of a solar flare. During powerful flares on the Sun, a stream of accelerated particles rushes into outer space. When it is directed towards the Earth, the second phase begins, which has a great influence on the state of the atmosphere. Many natural phenomena, among which the auroras are best known, indicate that a significant number of charged particles reach the Earth (see also POLAR LIGHTS). Nevertheless, the processes of detachment of these particles from the Sun, their trajectories in interplanetary space, and the mechanisms of interaction with the Earth's magnetic field and the magnetosphere are still insufficiently studied. The problem became more complicated after the discovery in 1958 by James Van Allen of shells held by the geomagnetic field, consisting of charged particles. These particles move from one hemisphere to another, rotating in spirals around the magnetic field lines. Near the Earth, at a height depending on the shape of the lines of force and on the energy of the particles, there are "points of reflection", in which the particles change their direction of motion to the opposite (Fig. 3). Since the strength of the magnetic field decreases with distance from the Earth, the orbits along which these particles move are somewhat distorted: electrons deviate to the east, and protons to the west. Therefore, they are distributed in the form of belts around the globe.
Some consequences of the heating of the atmosphere by the Sun. Solar energy affects the entire atmosphere. We have already mentioned the belts formed by charged particles in the Earth's magnetic field and revolving around it. These belts are closest to the earth's surface in the circumpolar regions (see Fig. 3), where auroras are observed. Figure 1 shows that the aurora regions in Canada have significantly higher thermospheric temperatures than those in the US Southwest. It is likely that the captured particles give up some of their energy to the atmosphere, especially when colliding with gas molecules near the reflection points, and leave their former orbits. This is how the high layers of the atmosphere are heated in the aurora zone. Another important discovery was made while studying the orbits of artificial satellites. Luigi Iacchia, an astronomer at the Smithsonian Astrophysical Observatory, believes that the small deviations of these orbits are due to changes in the density of the atmosphere as it is heated by the Sun. He suggested the existence of a maximum electron density in the ionosphere at an altitude of more than 200 km, which does not correspond to solar noon, but under the influence of friction forces lags with respect to it by about two hours. At this time, the values of the atmospheric density, typical for an altitude of 600 km, are observed at a level of approx. 950 km. In addition, the maximum electron concentration experiences irregular fluctuations due to short-term flashes of ultraviolet and X-ray radiation from the Sun. L. Yakkia also discovered short-term fluctuations in air density, corresponding to solar flares and magnetic field disturbances. These phenomena are explained by the intrusion of particles of solar origin into the Earth's atmosphere and the heating of those layers where satellites orbit.
ATMOSPHERIC ELECTRICITY
In the surface layer of the atmosphere, a small part of the molecules undergo ionization under the influence of cosmic rays, radiation from radioactive rocks and decay products of radium (mainly radon) in the air itself. In the process of ionization, an atom loses an electron and acquires a positive charge. A free electron quickly combines with another atom, forming a negatively charged ion. Such paired positive and negative ions have molecular dimensions. Molecules in the atmosphere tend to cluster around these ions. Several molecules combined with an ion form a complex commonly referred to as a "light ion". The atmosphere also contains complexes of molecules, known in meteorology as condensation nuclei, around which, when the air is saturated with moisture, the condensation process begins. These nuclei are particles of salt and dust, as well as pollutants released into the air from industrial and other sources. Light ions often attach to such nuclei to form "heavy ions". Under the influence of an electric field, light and heavy ions move from one area of the atmosphere to another, transferring electric charges. Although the atmosphere is not generally considered to be an electrically conductive medium, it does have a small amount of conductivity. Therefore, a charged body left in the air slowly loses its charge. Atmospheric conductivity increases with height due to increased cosmic ray intensity, reduced ion loss under lower pressure conditions (and hence longer mean free path), and due to fewer heavy nuclei. The conductivity of the atmosphere reaches its maximum value at a height of approx. 50 km, so-called. "compensation level". It is known that between the Earth's surface and the "compensation level" there is always a potential difference of several hundred kilovolts, i.e. constant electric field. It turned out that the potential difference between a certain point in the air at a height of several meters and the Earth's surface is very large - more than 100 V. The atmosphere has a positive charge, and the earth's surface is negatively charged. Since the electric field is an area, at each point of which there is a certain potential value, we can talk about a potential gradient. In clear weather, within the lower few meters, the electric field strength of the atmosphere is almost constant. Due to differences in the electrical conductivity of air in the surface layer, the potential gradient is subject to diurnal fluctuations, the course of which varies significantly from place to place. In the absence of local sources of air pollution - over the oceans, high in the mountains or in the polar regions - the daily course of the potential gradient in clear weather is the same. The magnitude of the gradient depends on the universal, or Greenwich Mean Time (UT) and reaches a maximum at 19:00 E. Appleton suggested that this maximum electrical conductivity probably coincides with the greatest thunderstorm activity on a planetary scale. Lightning discharges during thunderstorms carry a negative charge to the Earth's surface, since the bases of the most active cumulonimbus thunderclouds have a significant negative charge. The tops of thunderclouds have a positive charge, which, according to the calculations of Holzer and Saxon, flows from their tops during thunderstorms. Without constant replenishment, the charge of the earth's surface would be neutralized due to the conductivity of the atmosphere. The assumption that the potential difference between the earth's surface and the "compensation level" is maintained due to thunderstorms is supported by statistical data. For example, the maximum number of thunderstorms is observed in the valley of the river. Amazons. Most often, thunderstorms occur there at the end of the day, i.e. OK. 19:00 Greenwich Mean Time, when the potential gradient is at its maximum anywhere in the world. Moreover, the seasonal variations in the shape of the curves of the diurnal variation of the potential gradient are also in full agreement with the data on the global distribution of thunderstorms. Some researchers argue that the source of the Earth's electric field may be of external origin, since electric fields are believed to exist in the ionosphere and magnetosphere. This circumstance probably explains the appearance of very narrow elongated forms of auroras, similar to backstage and arches.
(see also POLAR LIGHTS). Due to the potential gradient and conductivity of the atmosphere between the "compensation level" and the Earth's surface, charged particles begin to move: positively charged ions - towards the earth's surface, and negatively charged - upwards from it. This current is approx. 1800 A. Although this value seems large, it must be remembered that it is distributed over the entire surface of the Earth. The current strength in an air column with a base area of 1 m2 is only 4 * 10 -12 A. On the other hand, the current strength during a lightning discharge can reach several amperes, although, of course, such a discharge has a short duration - from fractions of a second to a whole second or a little more with repeated discharges. Lightning is of great interest not only as a peculiar phenomenon of nature. It makes it possible to observe an electric discharge in a gaseous medium at a voltage of several hundred million volts and a distance between the electrodes of several kilometers. In 1750, B. Franklin proposed to the Royal Society of London that they experiment with an iron rod fixed on an insulating base and mounted on a high tower. He expected that when a thundercloud approaches the tower, a charge of the opposite sign will be concentrated at the upper end of the initially neutral rod, and a charge of the same sign as at the base of the cloud will be concentrated at the lower end. If the electric field strength during a lightning discharge increases sufficiently, the charge from the upper end of the rod will partially drain into the air, and the rod will acquire a charge of the same sign as the base of the cloud. The experiment proposed by Franklin was not carried out in England, but it was set up in 1752 in Marly near Paris by the French physicist Jean d'Alembert. He used an iron rod 12 m long inserted into a glass bottle (which served as an insulator), but did not place it on the tower. May 10 his assistant reported that when a thundercloud was over a rod, sparks were produced when a grounded wire was brought to it.Franklin himself, unaware of the successful experience realized in France, in June of that year conducted his famous experiment with a kite and observed electric sparks at the end of a wire tied to it.The following year, while studying the charges collected from a rod, Franklin found that the bases of thunderclouds are usually negatively charged.More detailed studies of lightning became possible in the late 19th century due to improvements in photographic methods, especially after the invention of the apparatus with rotating lenses, which made it possible to fix rapidly developing processes. Such a camera was widely used in the study of spark discharges. It was found that there are several types of lightning, with the most common being linear, flat (intra-cloud) and globular (air discharges). Linear lightning is a spark discharge between a cloud and the earth's surface, following a channel with downward branches. Flat lightning occurs inside a thundercloud and looks like flashes of scattered light. Air discharges of ball lightning, starting from a thundercloud, are often directed horizontally and do not reach the earth's surface.
A lightning discharge usually consists of three or more repeated discharges - impulses following the same path. The intervals between successive pulses are very short, from 1/100 to 1/10 s (this is what causes lightning to flicker). In general, the flash lasts about a second or less. A typical lightning development process can be described as follows. First, a weakly luminous discharge-leader rushes from above to the earth's surface. When he reaches it, a brightly glowing reverse, or main, discharge passes from the earth up the channel laid by the leader. The discharge-leader, as a rule, moves in a zigzag manner. The speed of its propagation ranges from one hundred to several hundred kilometers per second. On its way, it ionizes air molecules, creating a channel with increased conductivity, through which the reverse discharge moves upward at a speed of about a hundred times greater than that of the leader discharge. It is difficult to determine the size of the channel, but the diameter of the leader discharge is estimated at 1–10 m, and that of the reverse discharge, several centimeters. Lightning discharges create radio interference by emitting radio waves in a wide range - from 30 kHz to ultra-low frequencies. The greatest radiation of radio waves is probably in the range from 5 to 10 kHz. Such low-frequency radio interference is "concentrated" in the space between the lower boundary of the ionosphere and the earth's surface and is capable of propagating to distances of thousands of kilometers from the source.
CHANGES IN THE ATMOSPHERE
Impact of meteors and meteorites. Although sometimes meteor showers make a deep impression with their lighting effects, individual meteors are rarely seen. Far more numerous are invisible meteors, too small to be seen at the moment they are swallowed up by the atmosphere. Some of the smallest meteors probably do not heat up at all, but are only captured by the atmosphere. These small particles ranging in size from a few millimeters to ten-thousandths of a millimeter are called micrometeorites. The amount of meteoric matter entering the atmosphere every day is from 100 to 10,000 tons, with most of this matter being micrometeorites. Since meteoric matter partially burns up in the atmosphere, its gas composition is replenished with traces of various chemical elements. For example, stone meteors bring lithium into the atmosphere. The combustion of metallic meteors leads to the formation of tiny spherical iron, iron-nickel and other droplets that pass through the atmosphere and are deposited on the earth's surface. They can be found in Greenland and Antarctica, where ice sheets remain almost unchanged for years. Oceanologists find them in bottom ocean sediments. Most of the meteor particles entering the atmosphere are deposited within approximately 30 days. Some scientists believe that this cosmic dust plays an important role in the formation of atmospheric phenomena such as rain, as it serves as the nuclei of water vapor condensation. Therefore, it is assumed that precipitation is statistically associated with large meteor showers. However, some experts believe that since the total input of meteoric matter is many tens of times greater than even with the largest meteor shower, the change in the total amount of this material that occurs as a result of one such shower can be neglected. However, there is no doubt that the largest micrometeorites and, of course, visible meteorites leave long traces of ionization in the high layers of the atmosphere, mainly in the ionosphere. Such traces can be used for long-distance radio communications, as they reflect high-frequency radio waves. The energy of meteors entering the atmosphere is spent mainly, and perhaps completely, on its heating. This is one of the minor components of the heat balance of the atmosphere.
Carbon dioxide of industrial origin. In the Carboniferous period, woody vegetation was widespread on Earth. Most of the carbon dioxide absorbed by plants at that time was accumulated in coal deposits and in oil-bearing deposits. People have learned to use the huge reserves of these minerals as a source of energy and are now rapidly returning carbon dioxide to the circulation of substances. The fossil is probably ca. 4*10 13 tons of carbon. Over the past century, mankind has burned so much fossil fuel that approximately 4 * 10 11 tons of carbon has again entered the atmosphere. There are currently approx. 2 * 10 12 tons of carbon, and in the next hundred years this figure may double due to the burning of fossil fuels. However, not all carbon will remain in the atmosphere: some of it will dissolve in the waters of the ocean, some will be absorbed by plants, and some will be bound in the process of weathering of rocks. It is not yet possible to predict how much carbon dioxide will be in the atmosphere or what effect it will have on the world's climate. Nevertheless, it is believed that any increase in its content will cause warming, although it is not at all necessary that any warming will significantly affect the climate. The concentration of carbon dioxide in the atmosphere, according to the results of measurements, is noticeably increasing, albeit at a slow pace. Climate data for Svalbard and Little America station on the Ross Ice Shelf in Antarctica indicate an increase in average annual temperatures over a period of approximately 50 years by 5° and 2.5°C, respectively.
The impact of cosmic radiation. When high-energy cosmic rays interact with individual components of the atmosphere, radioactive isotopes are formed. Among them, the 14C carbon isotope, which accumulates in plant and animal tissues, stands out. By measuring the radioactivity of organic substances that have not exchanged carbon with the environment for a long time, their age can be determined. The radiocarbon method has established itself as the most reliable method for dating fossil organisms and objects of material culture, the age of which does not exceed 50 thousand years. Other radioactive isotopes with long half-lives could be used to date materials that are hundreds of thousands of years old if the fundamental problem of measuring extremely low levels of radioactivity is solved.
(see also RADIOCARBON DATING).
ORIGIN OF THE EARTH'S ATMOSPHERE
The history of the formation of the atmosphere has not yet been restored absolutely reliably. Nevertheless, some probable changes in its composition have been identified. The formation of the atmosphere began immediately after the formation of the Earth. There are quite good reasons to believe that in the process of the evolution of the Pra-Earth and its acquisition of close to modern dimensions and mass, it almost completely lost its original atmosphere. It is believed that at an early stage the Earth was in a molten state and ca. 4.5 billion years ago, it took shape in a solid body. This milestone is taken as the beginning of the geological chronology. Since that time there has been a slow evolution of the atmosphere. Some geological processes, such as eruptions of lava during volcanic eruptions, were accompanied by the release of gases from the bowels of the Earth. They probably included nitrogen, ammonia, methane, water vapor, carbon monoxide and carbon dioxide. Under the influence of solar ultraviolet radiation, water vapor decomposed into hydrogen and oxygen, but the released oxygen reacted with carbon monoxide to form carbon dioxide. Ammonia decomposed into nitrogen and hydrogen. Hydrogen in the process of diffusion rose up and left the atmosphere, while heavier nitrogen could not escape and gradually accumulated, becoming its main component, although some of it was bound during chemical reactions. Under the influence of ultraviolet rays and electrical discharges, a mixture of gases, probably present in the original atmosphere of the Earth, entered into chemical reactions, as a result of which organic substances, in particular amino acids, were formed. Consequently, life could originate in an atmosphere fundamentally different from the modern one. With the advent of primitive plants, the process of photosynthesis began (see also PHOTOSYNTHESIS), accompanied by the release of free oxygen. This gas, especially after diffusion into the upper atmosphere, began to protect its lower layers and the Earth's surface from life-threatening ultraviolet and X-ray radiation. It is estimated that as little as 0.00004 of today's volume of oxygen could lead to the formation of a layer with half the current ozone concentration, which nevertheless provided very significant protection from ultraviolet rays. It is also likely that the primary atmosphere contained a lot of carbon dioxide. It was consumed during photosynthesis, and its concentration must have decreased as the plant world evolved, and also due to absorption during some geological processes. Since the greenhouse effect is associated with the presence of carbon dioxide in the atmosphere, some scientists believe that fluctuations in its concentration are one of the important causes of large-scale climatic changes in the history of the Earth, such as ice ages. The helium present in the modern atmosphere is probably mostly a product of the radioactive decay of uranium, thorium, and radium. These radioactive elements emit alpha particles, which are the nuclei of helium atoms. Since no electrical charge is created or destroyed during radioactive decay, there are two electrons for every alpha particle. As a result, it combines with them, forming neutral helium atoms. Radioactive elements are contained in minerals dispersed in the thickness of rocks, so a significant part of the helium formed as a result of radioactive decay is stored in them, volatilizing very slowly into the atmosphere. A certain amount of helium rises up into the exosphere due to diffusion, but due to the constant influx from the earth's surface, the volume of this gas in the atmosphere is unchanged. Based on the spectral analysis of starlight and the study of meteorites, it is possible to estimate the relative abundance of various chemical elements in the Universe. The concentration of neon in space is about ten billion times higher than on Earth, krypton - ten million times, and xenon - a million times. It follows that the concentration of these inert gases, which were originally present in the Earth's atmosphere and were not replenished in the course of chemical reactions, greatly decreased, probably even at the stage of the Earth's loss of its primary atmosphere. An exception is the inert gas argon, since it is still formed in the form of the 40Ar isotope in the process of radioactive decay of the potassium isotope.
OPTICAL PHENOMENA
The variety of optical phenomena in the atmosphere is due to various reasons. The most common phenomena include lightning (see above) and the very picturesque aurora borealis and aurora borealis (see also POLAR LIGHTS). In addition, the rainbow, gal, parhelion (false sun) and arcs, crown, halos and ghosts of Brocken, mirages, St. Elmo's fires, luminous clouds, green and twilight rays are of particular interest. Rainbow is the most beautiful atmospheric phenomenon. Usually this is a huge arch, consisting of multi-colored stripes, observed when the Sun illuminates only part of the sky, and the air is saturated with water droplets, for example, during rain. The multi-colored arcs are arranged in a spectrum sequence (red, orange, yellow, green, cyan, indigo, violet), but the colors are almost never pure because the bands overlap. As a rule, the physical characteristics of rainbows vary significantly, and therefore they are very diverse in appearance. Their common feature is that the center of the arc is always located on a straight line drawn from the Sun to the observer. The main rainbow is an arc consisting of the brightest colors - red on the outside and purple on the inside. Sometimes only one arc is visible, but often a secondary one appears on the outside of the main rainbow. It has not as bright colors as the first one, and the red and purple stripes in it change places: red is located on the inside. The formation of the main rainbow is explained by double refraction (see also OPTICS) and single internal reflection of sunlight rays (see Fig. 5). Penetrating inside a drop of water (A), a ray of light is refracted and decomposed, as when passing through a prism. Then it reaches the opposite surface of the drop (B), is reflected from it and exits the drop to the outside (C). In this case, the beam of light, before reaching the observer, is refracted a second time. The initial white beam is decomposed into rays of different colors with a divergence angle of 2°. When a secondary rainbow is formed, double refraction and double reflection of the sun's rays occur (see Fig. 6). In this case, the light is refracted, penetrating inside the drop through its lower part (A), and reflected from the inner surface of the drop, first at point B, then at point C. At point D, the light is refracted, leaving the drop towards the observer.
At sunrise and sunset, the observer sees the rainbow in the form of an arc equal to half a circle, since the axis of the rainbow is parallel to the horizon. If the Sun is higher above the horizon, the arc of the rainbow is less than half a circle. When the Sun rises above 42° above the horizon, the rainbow disappears. Everywhere, except at high latitudes, a rainbow cannot appear at noon when the Sun is too high. It is interesting to estimate the distance to the rainbow. Although it seems that the multi-colored arc is located in the same plane, this is an illusion. In fact, the rainbow has great depth, and it can be represented as the surface of a hollow cone, at the top of which is the observer. The axis of the cone connects the Sun, the observer and the center of the rainbow. The observer looks, as it were, along the surface of this cone. Two people can never see exactly the same rainbow. Of course, one can observe the same effect in general, but the two rainbows are in different positions and are formed by different water droplets. When rain or mist forms a rainbow, the full optical effect is achieved by the combined effect of all the water droplets crossing the surface of the rainbow's cone with the observer at the apex. The role of each drop is fleeting. The surface of the rainbow cone consists of several layers. Quickly crossing them and passing through a series of critical points, each drop instantly decomposes the sun's ray into the entire spectrum in a strictly defined sequence - from red to purple. Many drops cross the surface of the cone in the same way, so that the rainbow appears to the observer as continuous both along and across its arc. Halo - white or iridescent light arcs and circles around the disk of the Sun or Moon. They are caused by the refraction or reflection of light by ice or snow crystals in the atmosphere. The crystals that form the halo are located on the surface of an imaginary cone with the axis directed from the observer (from the top of the cone) to the Sun. Under certain conditions, the atmosphere is saturated with small crystals, many of whose faces form a right angle with the plane passing through the Sun, the observer, and these crystals. Such facets reflect the incoming light rays with a deviation of 22 °, forming a halo that is reddish on the inside, but it can also consist of all colors of the spectrum. Less common is a halo with an angular radius of 46°, located concentrically around a 22-degree halo. Its inner side also has a reddish tint. The reason for this is also the refraction of light, which occurs in this case on the crystal faces that form right angles. The ring width of such a halo exceeds 2.5°. Both 46-degree and 22-degree halos tend to be brightest at the top and bottom of the ring. The rare 90-degree halo is a faintly luminous, almost colorless ring that has a common center with the other two halos. If it is colored, it has a red color on the outside of the ring. The mechanism of the appearance of this type of halo has not been fully elucidated (Fig. 7).
Parhelia and arcs. Parhelic circle (or circle of false suns) - a white ring centered at the zenith point, passing through the Sun parallel to the horizon. The reason for its formation is the reflection of sunlight from the edges of the surfaces of ice crystals. If the crystals are sufficiently evenly distributed in the air, a full circle becomes visible. Parhelia, or false suns, are brightly luminous spots resembling the Sun, which form at the points of intersection of the parhelic circle with the halo, having angular radii of 22°, 46° and 90°. The most frequently formed and brightest parhelion forms at the intersection with a 22-degree halo, usually colored in almost all colors of the rainbow. False suns at intersections with 46- and 90-degree halos are observed much less frequently. Parhelia that occur at intersections with 90-degree halos are called paranthelia, or false countersuns. Sometimes an antelium (counter-sun) is also visible - a bright spot located on the parhelion ring exactly opposite the Sun. It is assumed that the cause of this phenomenon is the double internal reflection of sunlight. The reflected beam follows the same path as the incident beam, but in the opposite direction. The circumzenithal arc, sometimes incorrectly referred to as the upper tangent arc of the 46-degree halo, is an arc of 90° or less centered on the zenith point and approximately 46° above the Sun. It is rarely visible and only for a few minutes, has bright colors, and the red color is confined to the outer side of the arc. The circumzenithal arc is notable for its coloration, brightness, and clear outlines. Another curious and very rare optical effect of the halo type is the Lovitz arc. They arise as a continuation of parhelia at the intersection with the 22-degree halo, pass from the outer side of the halo and are slightly concave towards the Sun. Pillars of whitish light, as well as various crosses, are sometimes visible at dawn or dusk, especially in the polar regions, and can accompany both the Sun and the Moon. At times, lunar halos and other effects similar to those described above are observed, with the most common lunar halo (ring around the Moon) having an angular radius of 22°. Like false suns, false moons can arise. Crowns, or crowns, are small concentric colored rings around the Sun, Moon or other bright objects that are observed from time to time when the light source is behind translucent clouds. The corona radius is smaller than the halo radius and is approx. 1-5°, the blue or violet ring is closest to the Sun. A corona occurs when light is scattered by small water droplets of water that form a cloud. Sometimes the crown looks like a luminous spot (or halo) surrounding the Sun (or Moon), which ends with a reddish ring. In other cases, at least two concentric rings of larger diameter, very weakly colored, are visible outside the halo. This phenomenon is accompanied by iridescent clouds. Sometimes the edges of very high clouds are painted in bright colors.
Gloria (halos). Under special conditions, unusual atmospheric phenomena occur. If the Sun is behind the observer, and its shadow is projected onto nearby clouds or a curtain of fog, under a certain state of the atmosphere around the shadow of a person's head, you can see a colored luminous circle - a halo. Usually such a halo is formed due to the reflection of light by dew drops on a grassy lawn. Glorias are also quite common to be found around the shadow that the plane casts on the underlying clouds.
Ghosts of the Brocken. In some regions of the globe, when the shadow of an observer on a hill, at sunrise or sunset, falls behind him on clouds located at a short distance, a striking effect is revealed: the shadow acquires colossal dimensions. This is due to the reflection and refraction of light by the smallest water droplets in the fog. The described phenomenon is called the "ghost of the Brocken" after the peak in the Harz mountains in Germany.
Mirages- an optical effect caused by the refraction of light when passing through layers of air of different densities and is expressed in the appearance of a virtual image. In this case, distant objects may turn out to be raised or lowered relative to their actual position, and may also be distorted and acquire irregular, fantastic shapes. Mirages are often observed in hot climates, such as over sandy plains. Inferior mirages are common, when the distant, almost flat desert surface takes on the appearance of open water, especially when viewed from a slight elevation or simply above a layer of heated air. A similar illusion usually occurs on a heated paved road that looks like a water surface far ahead. In reality, this surface is a reflection of the sky. Below eye level, objects, usually upside down, may appear in this "water". An "air layer cake" is formed above the heated land surface, and the layer closest to the earth is the most heated and so rarefied that light waves passing through it are distorted, since their propagation speed varies depending on the density of the medium. Superior mirages are less common and more scenic than inferior mirages. Distant objects (often below the sea horizon) appear upside down in the sky, and sometimes a direct image of the same object also appears above. This phenomenon is typical for cold regions, especially when there is a significant temperature inversion, when a warmer layer of air is above the colder layer. This optical effect is manifested as a result of complex patterns of propagation of the front of light waves in air layers with a non-uniform density. Very unusual mirages occur from time to time, especially in the polar regions. When mirages occur on land, trees and other landscape components are upside down. In all cases, objects in the upper mirages are more clearly visible than in the lower ones. When the boundary of two air masses is a vertical plane, side mirages are sometimes observed.
Saint Elmo's fire. Some optical phenomena in the atmosphere (for example, glow and the most common meteorological phenomenon - lightning) are electrical in nature. Much less common are the fires of St. Elmo - luminous pale blue or purple brushes from 30 cm to 1 m or more in length, usually on the tops of masts or the ends of the yards of ships at sea. Sometimes it seems that the entire rigging of the ship is covered with phosphorus and glows. Elmo's fires sometimes appear on mountain peaks, as well as on spiers and sharp corners of tall buildings. This phenomenon is brush electric discharges at the ends of electrical conductors, when the electric field strength is greatly increased in the atmosphere around them. Will-o'-the-wisps are a faint bluish or greenish glow that is sometimes seen in swamps, cemeteries, and crypts. They often appear as a calmly burning, non-heating, candle flame raised about 30 cm above the ground, hovering over the object for a moment. The light seems to be completely elusive and, as the observer approaches, it seems to move to another place. The reason for this phenomenon is the decomposition of organic residues and the spontaneous combustion of swamp gas methane (CH4) or phosphine (PH3). Wandering lights have a different shape, sometimes even spherical. Green beam - a flash of emerald green sunlight at the moment when the last ray of the Sun disappears below the horizon. The red component of sunlight disappears first, all the others follow in order, and the emerald green remains last. This phenomenon occurs only when only the very edge of the solar disk remains above the horizon, otherwise there is a mixture of colors. Crepuscular rays are diverging beams of sunlight that become visible when they illuminate dust in the high atmosphere. Shadows from the clouds form dark bands, and rays propagate between them. This effect occurs when the Sun is low on the horizon before dawn or after sunset.
Staging sounds in children
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Synopsis of a speech therapy lesson in the senior group “Sounds (P - Pb), letter P