The uppermost part of the atmosphere. The main layers of the earth's atmosphere in ascending order

Troposphere

Its upper limit is at an altitude of 8-10 km in polar, 10-12 km in temperate and 16-18 km in tropical latitudes; lower in winter than in summer. The lower, main layer of the atmosphere contains more than 80% of the total mass of atmospheric air and about 90% of all water vapor present in the atmosphere. In the troposphere, turbulence and convection are highly developed, clouds appear, cyclones and anticyclones develop. Temperature decreases with altitude with an average vertical gradient of 0.65°/100 m

tropopause

The transitional layer from the troposphere to the stratosphere, the layer of the atmosphere in which the decrease in temperature with height stops.

Stratosphere

The layer of the atmosphere located at an altitude of 11 to 50 km. A slight change in temperature in the 11-25 km layer (the lower layer of the stratosphere) and its increase in the 25-40 km layer from −56.5 to 0.8 °C (upper stratosphere layer or inversion region) are typical. Having reached a value of about 273 K (almost 0 °C) at an altitude of about 40 km, the temperature remains constant up to an altitude of about 55 km. This region of constant temperature is called the stratopause and is the boundary between the stratosphere and the mesosphere.

Stratopause

The boundary layer of the atmosphere between the stratosphere and the mesosphere. There is a maximum in the vertical temperature distribution (about 0 °C).

Mesosphere

The mesosphere begins at an altitude of 50 km and extends up to 80-90 km. The temperature decreases with height with an average vertical gradient of (0.25-0.3)°/100 m. The main energy process is radiant heat transfer. Complex photochemical processes involving free radicals, vibrationally excited molecules, etc., cause atmospheric luminescence.

mesopause

Transitional layer between mesosphere and thermosphere. There is a minimum in the vertical temperature distribution (about -90 °C).

Karman Line

Altitude above sea level, which is conventionally accepted as the boundary between the Earth's atmosphere and space. The Karmana line is located at an altitude of 100 km above sea level.

Earth's atmosphere boundary

Thermosphere

The upper limit is about 800 km. The temperature rises to altitudes of 200-300 km, where it reaches values ​​of the order of 1500 K, after which it remains almost constant up to high altitudes. Under the influence of ultraviolet and x-ray solar radiation and cosmic radiation, air is ionized (“polar lights”) - the main regions of the ionosphere lie inside the thermosphere. At altitudes above 300 km, atomic oxygen predominates. The upper limit of the thermosphere is largely determined by the current activity of the Sun. During periods of low activity, there is a noticeable decrease in the size of this layer.

Thermopause

The region of the atmosphere above the thermosphere. In this region, the absorption of solar radiation is insignificant and the temperature does not actually change with height.

Exosphere (scattering sphere)

Atmospheric layers up to a height of 120 km

Exosphere - scattering zone, the outer part of the thermosphere, located above 700 km. The gas in the exosphere is very rarefied, and hence its particles leak into interplanetary space (dissipation).

Up to a height of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases in height depends on their molecular weights, the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0 °C in the stratosphere to −110 °C in the mesosphere. but kinetic energy individual particles at altitudes of 200–250 km corresponds to a temperature of ~150 °C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.

At an altitude of about 2000-3500 km, the exosphere gradually passes into the so-called near space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas is only part of the interplanetary matter. The other part is composed of dust-like particles of cometary and meteoric origin. In addition to extremely rarefied dust-like particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere accounts for about 20%; the mass of the mesosphere - no more than 0.3%, the thermosphere - less than 0.05% of total mass atmosphere. Based on the electrical properties in the atmosphere, the neutrosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.

Depending on the composition of the gas in the atmosphere, homosphere and heterosphere are distinguished. The heterosphere is an area where gravity has an effect on the separation of gases, since their mixing at such a height is negligible. Hence follows the variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere, called the homosphere. The boundary between these layers is called the turbopause and lies at an altitude of about 120 km.

The atmosphere is what makes life possible on Earth. We receive the very first information and facts about the atmosphere back in primary school. In high school, we are already more familiar with this concept in geography lessons.

The concept of the earth's atmosphere

The atmosphere is not only on the Earth, but also on other celestial bodies. This is the name of the gaseous shell surrounding the planets. The composition of this gas layer of different planets is significantly different. Let's look at the basic information and facts about otherwise called air.

Its most important component is oxygen. Some mistakenly think that the earth's atmosphere is made entirely of oxygen, but air is actually a mixture of gases. It contains 78% nitrogen and 21% oxygen. The remaining one percent includes ozone, argon, carbon dioxide, water vapor. Let the percentage of these gases be small, but they perform an important function - they absorb a significant part of the solar radiant energy, thereby preventing the luminary from turning all life on our planet into ashes. The properties of the atmosphere change with altitude. For example, at an altitude of 65 km, nitrogen is 86% and oxygen is 19%.

The composition of the Earth's atmosphere

• Carbon dioxide essential for plant nutrition. In the atmosphere, it appears as a result of the process of respiration of living organisms, rotting, burning. The absence of it in the composition of the atmosphere would make it impossible for any plants to exist.
• Oxygen is a vital component of the atmosphere for humans. Its presence is a condition for the existence of all living organisms. It makes up about 20% of the total volume of atmospheric gases.
• Ozone It is a natural absorber of solar ultraviolet radiation, which adversely affects living organisms. Most of it forms a separate layer of the atmosphere - the ozone screen. Recently, human activity has led to the fact that it begins to gradually collapse, but since it is of great importance, it is being active work for its conservation and restoration.
• water vapor determines the humidity of the air. Its content may vary depending on various factors: air temperature, geographical location, season. At low temperatures, there is very little water vapor in the air, maybe less than one percent, and at high temperatures, its amount reaches 4%.
• In addition to all of the above, the earth's atmosphere there is always a certain percentage solid and liquid impurities. These are soot, ash, sea salt, dust, water drops, microorganisms. They can get into the air both naturally and by anthropogenic means.

Layers of the atmosphere

And the temperature, and density, and the qualitative composition of the air is not the same at different heights. Because of this, it is customary to distinguish different layers of the atmosphere. Each of them has its own characteristic. Let's find out which layers of the atmosphere are distinguished:

• The troposphere is the layer of the atmosphere closest to the Earth's surface. Its height is 8-10 km above the poles and 16-18 km in the tropics. Here is 90% of all water vapor that is available in the atmosphere, so there is an active formation of clouds. Also in this layer there are such processes as the movement of air (wind), turbulence, convection. The temperature ranges from +45 degrees at noon in the warm season in the tropics to -65 degrees at the poles.
• The stratosphere is the second furthest layer from the atmosphere. It is located at an altitude of 11 to 50 km. In the lower layer of the stratosphere, the temperature is approximately -55, towards the distance from the Earth it rises to +1˚С. This region is called the inversion and is the boundary between the stratosphere and the mesosphere.
• The mesosphere is located at an altitude of 50 to 90 km. The temperature at its lower boundary is about 0, at the upper it reaches -80...-90 ˚С. Meteorites entering the Earth's atmosphere burn out completely in the mesosphere, which causes airglows to occur here.
• The thermosphere is about 700 km thick. The northern lights appear in this layer of the atmosphere. They appear due to the action of cosmic radiation and radiation emanating from the Sun.
• The exosphere is a zone of air dispersion. Here, the concentration of gases is small and their gradual escape into interplanetary space takes place.

boundary between the earth's atmosphere and outer space considered to be a milestone of 100 km. This line is called the Karman line.

atmospheric pressure

Listening to the weather forecast, we often hear barometric pressure readings. But what does atmospheric pressure mean, and how might it affect us?

We figured out that air consists of gases and impurities. Each of these components has its own weight, which means that the atmosphere is not weightless, as was believed until the 17th century. Atmospheric pressure is the force with which all layers of the atmosphere press on the surface of the Earth and on all objects.

Scientists have carried out complex calculations and proved that for one square meter area, the atmosphere presses with a force of 10,333 kg. This means that the human body is subject to air pressure, the weight of which is 12-15 tons. Why don't we feel it? It saves us its internal pressure, which balances the external one. You can feel the pressure of the atmosphere while in an airplane or high in the mountains, since the atmospheric pressure at altitude is much less. In this case, physical discomfort, stuffy ears, dizziness are possible.

A lot can be said about the atmosphere around. We know a lot of interesting facts about her, and some of them may seem surprising:

• The weight of the earth's atmosphere is 5,300,000,000,000,000 tons.
• It contributes to the transmission of sound. At an altitude of more than 100 km, this property disappears due to changes in the composition of the atmosphere.
• The movement of the atmosphere is provoked by uneven heating of the Earth's surface.
• A thermometer is used to measure air temperature, and a barometer is used to measure atmospheric pressure.
• The presence of an atmosphere saves our planet from 100 tons of meteorites daily.
• The composition of the air was fixed for several hundred million years, but began to change with the onset of rapid industrial activity.
• It is believed that the atmosphere extends upwards to an altitude of 3000 km.

The value of the atmosphere for humans

The physiological zone of the atmosphere is 5 km. At an altitude of 5000 m above sea level, a person begins to experience oxygen starvation, which is expressed in a decrease in his working capacity and a deterioration in well-being. This shows that a person cannot survive in a space where this amazing mixture of gases does not exist.

All information and facts about the atmosphere only confirm its importance for people. Thanks to its presence, the possibility of the development of life on Earth appeared. Already today, having assessed the extent of the harm that mankind is capable of inflicting with its actions on the life-giving air, we should think about further measures to preserve and restore the atmosphere.

At sea level 1013.25 hPa (about 760 mmHg). The average global air temperature at the Earth's surface is 15°C, while the temperature varies from about 57°C in subtropical deserts to -89°C in Antarctica. Air density and pressure decrease with height according to a law close to exponential.

The structure of the atmosphere. Vertically, the atmosphere has a layered structure, determined mainly by the features of the vertical temperature distribution (figure), which depends on the geographical location, season, time of day, and so on. The lower layer of the atmosphere - the troposphere - is characterized by a drop in temperature with height (by about 6 ° C per 1 km), its height is from 8-10 km in polar latitudes to 16-18 km in the tropics. Due to the rapid decrease in air density with height, about 80% of the total mass of the atmosphere is in the troposphere. Above the troposphere is the stratosphere - a layer that is characterized in general by an increase in temperature with height. The transition layer between the troposphere and stratosphere is called the tropopause. In the lower stratosphere, up to a level of about 20 km, the temperature changes little with height (the so-called isothermal region) and often even slightly decreases. Above, the temperature rises due to the absorption of UV radiation from the Sun by ozone, slowly at first, and faster from a level of 34-36 km. The upper boundary of the stratosphere - the stratopause - is located at an altitude of 50-55 km, corresponding to the maximum temperature (260-270 K). The layer of the atmosphere, located at an altitude of 55-85 km, where the temperature drops again with height, is called the mesosphere, at its upper boundary - the mesopause - the temperature reaches 150-160 K in summer, and 200-230 K in winter. The thermosphere begins above the mesopause - a layer, characterized by a rapid increase in temperature, reaching values ​​of 800-1200 K at an altitude of 250 km. The corpuscular and X-ray radiation of the Sun is absorbed in the thermosphere, meteors are slowed down and burned out, so it performs the function of the Earth's protective layer. Even higher is the exosphere, from where atmospheric gases are dissipated into world space due to dissipation and where a gradual transition from the atmosphere to interplanetary space takes place.

Composition of the atmosphere. Up to a height of about 100 km, the atmosphere is practically homogeneous in chemical composition and the average molecular weight of air (about 29) is constant in it. Near the Earth's surface, the atmosphere consists of nitrogen (about 78.1% by volume) and oxygen (about 20.9%), and also contains small amounts of argon, carbon dioxide ( carbon dioxide), neon and other constant and variable components (see Air).

In addition, the atmosphere contains small amounts of ozone, nitrogen oxides, ammonia, radon, etc. The relative content of the main components of the air is constant over time and uniform in different geographical areas. The content of water vapor and ozone is variable in space and time; despite the low content, their role in atmospheric processes is very significant.

Above 100-110 km, the dissociation of oxygen, carbon dioxide and water vapor molecules occurs, so the molecular weight of air decreases. At an altitude of about 1000 km, light gases - helium and hydrogen - begin to predominate, and even higher, the Earth's atmosphere gradually turns into interplanetary gas.

The most important variable component of the atmosphere is water vapor, which enters the atmosphere through evaporation from the surface of water and moist soil, as well as through transpiration by plants. The relative content of water vapor varies near the earth's surface from 2.6% in the tropics to 0.2% in the polar latitudes. With height, it quickly falls, decreasing by half already at a height of 1.5-2 km. The vertical column of the atmosphere at temperate latitudes contains about 1.7 cm of the “precipitated water layer”. When water vapor condenses, clouds form, from which atmospheric precipitation falls in the form of rain, hail, and snow.

An important component of atmospheric air is ozone, 90% concentrated in the stratosphere (between 10 and 50 km), about 10% of it is in the troposphere. Ozone provides absorption of hard UV radiation (with a wavelength of less than 290 nm), and this is its protective role for the biosphere. The values ​​of the total ozone content vary depending on the latitude and season, ranging from 0.22 to 0.45 cm (the thickness of the ozone layer at a pressure of p= 1 atm and a temperature of T = 0°C). In the ozone holes observed in spring in Antarctica since the early 1980s, the ozone content can drop to 0.07 cm. grows at high latitudes. A significant variable component of the atmosphere is carbon dioxide, the content of which in the atmosphere has increased by 35% over the past 200 years, which is mainly explained by the anthropogenic factor. Its latitudinal and seasonal variability is observed, associated with plant photosynthesis and solubility in sea water (according to Henry's law, the solubility of gas in water decreases with increasing temperature).

Important role Atmospheric aerosol plays a role in the formation of the planet's climate - solid and liquid particles suspended in the air ranging in size from several nm to tens of microns. There are aerosols of natural and anthropogenic origin. Aerosol is formed in the process of gas-phase reactions from the products of plant vital activity and human economic activity, volcanic eruptions, as a result of dust being lifted by the wind from the surface of the planet, especially from its desert regions, and is also formed from cosmic dust entering the upper atmosphere. Most of the aerosol is concentrated in the troposphere; aerosol from volcanic eruptions forms the so-called Junge layer at an altitude of about 20 km. The largest amount of anthropogenic aerosol enters the atmosphere as a result of the operation of vehicles and thermal power plants, chemical industries, fuel combustion, etc. Therefore, in some areas the composition of the atmosphere differs markedly from ordinary air, which required the creation of a special service for monitoring and controlling the level of atmospheric air pollution.

Atmospheric evolution. The modern atmosphere is apparently of secondary origin: it was formed from the gases released by the solid shell of the Earth after the formation of the planet was completed about 4.5 billion years ago. During geological history The Earth's atmosphere underwent significant changes in its composition under the influence of a number of factors: dissipation (volatilization) of gases, mainly lighter ones, into outer space; release of gases from the lithosphere as a result of volcanic activity; chemical reactions between the components of the atmosphere and the rocks that make up the earth's crust; photochemical reactions in the atmosphere itself under the influence of solar UV radiation; accretion (capture) of the matter of the interplanetary medium (for example, meteoric matter). The development of the atmosphere is closely connected with geological and geochemical processes, and for the last 3-4 billion years also with the activity of the biosphere. A significant part of the gases that make up the modern atmosphere (nitrogen, carbon dioxide, water vapor) arose during volcanic activity and intrusion, which carried them out from the depths of the Earth. Oxygen appeared in appreciable quantities about 2 billion years ago as a result of the activity of photosynthetic organisms, which originally originated in surface waters ocean.

Based on the data on the chemical composition of carbonate deposits, estimates of the amount of carbon dioxide and oxygen in the atmosphere of the geological past were obtained. During the Phanerozoic (the last 570 million years of the Earth's history), the amount of carbon dioxide in the atmosphere varied widely in accordance with the level of volcanic activity, ocean temperature and photosynthesis. Most of this time, the concentration of carbon dioxide in the atmosphere was significantly higher than the current one (up to 10 times). The amount of oxygen in the atmosphere of the Phanerozoic changed significantly, and the tendency to increase it prevailed. In the Precambrian atmosphere, the mass of carbon dioxide was, as a rule, greater, and the mass of oxygen, less than in the atmosphere of the Phanerozoic. Fluctuations in the amount of carbon dioxide have had a significant impact on the climate in the past, increasing the greenhouse effect with an increase in the concentration of carbon dioxide, due to which the climate during the main part of the Phanerozoic was much warmer than in the modern era.

atmosphere and life. Without an atmosphere, Earth would be a dead planet. Organic life proceeds in close interaction with the atmosphere and its associated climate and weather. Insignificant in mass compared to the planet as a whole (about a millionth part), the atmosphere is a sine qua non for all life forms. Oxygen, nitrogen, water vapor, carbon dioxide, and ozone are the most important atmospheric gases for the life of organisms. When carbon dioxide is absorbed by photosynthetic plants, organic matter is created, which is used as an energy source by the vast majority of living beings, including humans. Oxygen is necessary for the existence of aerobic organisms, for which the energy supply is provided by oxidation reactions. organic matter. Nitrogen, assimilated by some microorganisms (nitrogen fixers), is necessary for the mineral nutrition of plants. Ozone, which absorbs the Sun's harsh UV radiation, significantly attenuates this life-threatening portion of the sun's radiation. Condensation of water vapor in the atmosphere, the formation of clouds and the subsequent precipitation of precipitation supply water to land, without which no form of life is possible. The vital activity of organisms in the hydrosphere is largely determined by the number and chemical composition atmospheric gases dissolved in water. Since the chemical composition of the atmosphere significantly depends on the activities of organisms, the biosphere and atmosphere can be considered as part of a single system, the maintenance and evolution of which (see Biogeochemical cycles) was of great importance for changing the composition of the atmosphere throughout the history of the Earth as a planet.

Radiation, heat and water balances of the atmosphere. Solar radiation is practically the only source of energy for all physical processes in the atmosphere. The main feature of the radiation regime of the atmosphere is the so-called greenhouse effect: the atmosphere transmits solar radiation to the earth's surface quite well, but actively absorbs the thermal long-wave radiation of the earth's surface, part of which returns to the surface in the form of counter radiation that compensates for the radiative heat loss of the earth's surface (see Atmospheric radiation ). In the absence of an atmosphere, the average temperature of the earth's surface would be -18°C, in reality it is 15°C. Incoming solar radiation is partially (about 20%) absorbed into the atmosphere (mainly by water vapor, water droplets, carbon dioxide, ozone and aerosols), and is also scattered (about 7%) by aerosol particles and density fluctuations (Rayleigh scattering). The total radiation, reaching the earth's surface, is partially (about 23%) reflected from it. The reflectance is determined by the reflectivity of the underlying surface, the so-called albedo. On average, the Earth's albedo for the integral solar radiation flux is close to 30%. It varies from a few percent (dry soil and black soil) to 70-90% for freshly fallen snow. The radiative heat exchange between the earth's surface and the atmosphere essentially depends on the albedo and is determined by the effective radiation of the earth's surface and the counter-radiation of the atmosphere absorbed by it. The algebraic sum of radiation fluxes entering the earth's atmosphere from outer space and leaving it back is called the radiation balance.

Transformations of solar radiation after its absorption by the atmosphere and the earth's surface determine the heat balance of the Earth as a planet. The main source of heat for the atmosphere is the earth's surface; heat from it is transferred not only in the form of long-wave radiation, but also by convection, and is also released during the condensation of water vapor. The shares of these heat inflows are on average 20%, 7% and 23%, respectively. About 20% of heat is also added here due to the absorption of direct solar radiation. The flux of solar radiation per unit of time through a single area perpendicular to the sun's rays and located outside the atmosphere at an average distance from the Earth to the Sun (the so-called solar constant) is 1367 W / m 2, the changes are 1-2 W / m 2 depending on cycle of solar activity. With a planetary albedo of about 30%, the time-average global influx of solar energy to the planet is 239 W/m 2 . Since the Earth as a planet emits the same amount of energy into space on average, then, according to the Stefan-Boltzmann law, the effective temperature of the outgoing thermal long-wave radiation is 255 K (-18°C). At the same time, the average temperature of the earth's surface is 15°C. The 33°C difference is due to the greenhouse effect.

The water balance of the atmosphere as a whole corresponds to the equality of the amount of moisture evaporated from the surface of the Earth, the amount of precipitation falling on the earth's surface. The atmosphere over the oceans receives more moisture from evaporation processes than over land, and loses 90% in the form of precipitation. Excess water vapor over the oceans is carried to the continents by air currents. The amount of water vapor transported into the atmosphere from the oceans to the continents is equal to the volume of river flow that flows into the oceans.

air movement. The Earth has a spherical shape, so much less solar radiation comes to its high latitudes than to the tropics. As a result, large temperature contrasts arise between latitudes. The relative position of the oceans and continents also significantly affects the distribution of temperature. Due to the large mass of ocean waters and the high heat capacity of water, seasonal fluctuations in ocean surface temperature are much less than those of land. In this regard, in the middle and high latitudes, the air temperature over the oceans is noticeably lower in summer than over the continents, and higher in winter.

The uneven heating of the atmosphere in different regions of the globe causes a distribution of atmospheric pressure that is not uniform in space. At sea level, the pressure distribution is characterized by relatively low values ​​near the equator, an increase in the subtropics (high-pressure zones) and a decrease in middle and high latitudes. At the same time, over the continents of extratropical latitudes, the pressure is usually increased in winter, and lowered in summer, which is associated with the temperature distribution. Under the action of a pressure gradient, the air experiences an acceleration directed from areas of high pressure to areas of low pressure, which leads to the movement of air masses. The moving air masses are also affected by the deflecting force of the Earth's rotation (the Coriolis force), the friction force, which decreases with height, and in the case of curvilinear trajectories, the centrifugal force. Of great importance is the turbulent mixing of air (see Turbulence in the atmosphere).

Associated with planetary pressure distribution a complex system air currents (general circulation of the atmosphere). In the meridional plane, on average, two or three meridional circulation cells are traced. Near the equator, heated air rises and falls in the subtropics, forming a Hadley cell. The air of the reverse Ferrell cell also descends there. At high latitudes, a direct polar cell is often traced. Meridional circulation velocities are on the order of 1 m/s or less. Due to the action of the Coriolis force, westerly winds are observed in most of the atmosphere with speeds in the middle troposphere of about 15 m/s. There are relatively stable wind systems. These include trade winds - winds blowing from high pressure belts in the subtropics to the equator with a noticeable eastern component (from east to west). Monsoons are quite stable - air currents that have a clearly pronounced seasonal character: they blow from the ocean to the mainland in summer and in the opposite direction in winter. The monsoons are especially regular indian ocean. In middle latitudes, the movement of air masses is mainly western (from west to east). This is a zone of atmospheric fronts, on which large eddies arise - cyclones and anticyclones, covering many hundreds and even thousands of kilometers. Cyclones also occur in the tropics; here they differ in smaller sizes, but very high wind speeds, reaching hurricane force (33 m/s or more), the so-called tropical cyclones. In the Atlantic and in the east Pacific Ocean they are called hurricanes, and in the western Pacific, typhoons. In the upper troposphere and lower stratosphere, in the areas separating the direct cell of the Hadley meridional circulation and the reverse Ferrell cell, relatively narrow, hundreds of kilometers wide, jet streams with sharply defined boundaries are often observed, within which the wind reaches 100-150 and even 200 m/ from.

Climate and weather. The difference in the amount of solar radiation coming at different latitudes to a variety of physical properties the earth's surface, determines the diversity of the Earth's climates. From the equator to tropical latitudes, the air temperature near the earth's surface averages 25-30 ° C and changes little during the year. In the equatorial zone, a lot of precipitation usually falls, which creates conditions for excessive moisture there. In tropical zones, the amount of precipitation decreases and in some areas becomes very small. Here are the vast deserts of the Earth.

In subtropical and middle latitudes, air temperature varies significantly throughout the year, and the difference between summer and winter temperatures is especially large in areas of the continents remote from the oceans. Thus, in some areas of Eastern Siberia, the annual amplitude of air temperature reaches 65°С. Humidification conditions in these latitudes are very diverse, depend mainly on the regime of the general circulation of the atmosphere, and vary significantly from year to year.

In the polar latitudes, the temperature remains low throughout the year, even if there is a noticeable seasonal variation. This contributes to the widespread distribution of ice cover on the oceans and land and permafrost, occupying over 65% of Russia's area, mainly in Siberia.

Over the past decades, changes in the global climate have become more and more noticeable. The temperature rises more at high latitudes than at low latitudes; more in winter than in summer; more at night than during the day. Over the 20th century, the average annual air temperature near the earth's surface in Russia increased by 1.5-2 ° C, and in some regions of Siberia an increase of several degrees is observed. This is associated with an increase in the greenhouse effect due to an increase in the concentration of small gaseous impurities.

The weather is determined by the conditions of atmospheric circulation and geographic location terrain, it is most stable in the tropics and most variable in middle and high latitudes. Most of all, the weather changes in the zones of change of air masses, due to the passage of atmospheric fronts, cyclones and anticyclones, carrying precipitation and increasing wind. Data for weather forecasting is collected from ground-based weather stations, ships and aircraft, and meteorological satellites. See also meteorology.

Optical, acoustic and electrical phenomena in the atmosphere. When electromagnetic radiation propagates in the atmosphere, as a result of refraction, absorption and scattering of light by air and various particles (aerosol, ice crystals, water drops), various optical phenomena: rainbow, crowns, halo, mirage, etc. Scattering of light determines the apparent height of the firmament and the blue color of the sky. The visibility range of objects is determined by the conditions of light propagation in the atmosphere (see Atmospheric visibility). The transparency of the atmosphere at different wavelengths determines the communication range and the possibility of detecting objects with instruments, including the possibility of astronomical observations from the Earth's surface. For studies of optical inhomogeneities in the stratosphere and mesosphere, the phenomenon of twilight plays an important role. For example, photographing twilight with spacecraft allows detection of aerosol layers. Features of the propagation of electromagnetic radiation in the atmosphere determine the accuracy of the methods remote sensing its parameters. All these questions, like many others, are studied by atmospheric optics. Refraction and scattering of radio waves determine the possibilities of radio reception (see Propagation of radio waves).

The propagation of sound in the atmosphere depends on the spatial distribution of temperature and wind speed (see Atmospheric acoustics). It is of interest for remote sensing of the atmosphere. Explosions of charges launched by rockets into the upper atmosphere provided a wealth of information about wind systems and the course of temperature in the stratosphere and mesosphere. In a stably stratified atmosphere, when the temperature falls with height more slowly than the adiabatic gradient (9.8 K/km), so-called internal waves arise. These waves can propagate upward into the stratosphere and even into the mesosphere, where they attenuate, contributing to increased wind and turbulence.

The negative charge of the Earth and the electric field caused by it, the atmosphere, together with the electrically charged ionosphere and magnetosphere, create a global electrical circuit. An important role is played by the formation of clouds and lightning electricity. The danger of lightning discharges necessitated the development of methods for lightning protection of buildings, structures, power lines and communications. This phenomenon is of particular danger to aviation. Lightning discharges cause atmospheric radio interference, called atmospherics (see Whistling atmospherics). During a sharp increase in tension electric field luminous discharges are observed that occur on the points and sharp corners of objects protruding above the earth's surface, on individual peaks in the mountains, etc. (Elma lights). The atmosphere always contains a number of light and heavy ions, which vary greatly depending on the specific conditions, which determine the electrical conductivity of the atmosphere. The main air ionizers near the earth's surface are the radiation of radioactive substances contained in the earth's crust and in the atmosphere, as well as cosmic rays. See also atmospheric electricity.

Human influence on the atmosphere. Over the past centuries, there has been an increase in the concentration of greenhouse gases in the atmosphere due to human activities. The percentage of carbon dioxide increased from 2.8-10 2 two hundred years ago to 3.8-10 2 in 2005, the content of methane - from 0.7-10 1 about 300-400 years ago to 1.8-10 -4 at the beginning of the 21st century; about 20% of the increase in the greenhouse effect over the past century was given by freons, which practically did not exist in the atmosphere until the middle of the 20th century. These substances are recognized as stratospheric ozone depleters and their production is prohibited by the 1987 Montreal Protocol. The increase in carbon dioxide concentration in the atmosphere is caused by the burning of ever-increasing amounts of coal, oil, gas and other carbon fuels, as well as the deforestation, which reduces the absorption of carbon dioxide through photosynthesis. The concentration of methane increases with the growth of oil and gas production (due to its losses), as well as with the expansion of rice crops and an increase in the number of cattle. All this contributes to climate warming.

To change the weather, methods of active influence on atmospheric processes have been developed. They are used to protect agricultural plants from hail damage by dispersing special reagents in thunderclouds. There are also methods for dispelling fog at airports, protecting plants from frost, influencing clouds to increase rainfall in the right places, or to disperse clouds at times of mass events.

Study of the atmosphere. Information about the physical processes in the atmosphere is obtained primarily from meteorological observations, which are carried out by a global network of permanent meteorological stations and posts located on all continents and on many islands. Daily observations provide information about air temperature and humidity, atmospheric pressure and precipitation, cloudiness, wind, etc. Observations of solar radiation and its transformations are carried out at actinometric stations. Of great importance for the study of the atmosphere are the networks of aerological stations, where meteorological measurements are made with the help of radiosondes up to a height of 30-35 km. At a number of stations, observations are made of atmospheric ozone, electrical phenomena in the atmosphere, and the chemical composition of the air.

Data from ground stations are supplemented by observations on the oceans, where "weather ships" operate, permanently located in certain areas of the World Ocean, as well as meteorological information received from research and other ships.

In recent decades, an increasing amount of information about the atmosphere has been obtained with the help of meteorological satellites, which are equipped with instruments for photographing clouds and measuring the fluxes of ultraviolet, infrared, and microwave radiation from the Sun. Satellites make it possible to obtain information about vertical temperature profiles, cloudiness and its water content, elements radiation balance atmosphere, the temperature of the ocean surface, etc. Using measurements of the refraction of radio signals from a system of navigation satellites, it is possible to determine the vertical profiles of density, pressure and temperature, as well as moisture content in the atmosphere. With the help of satellites, it became possible to clarify the value of the solar constant and the planetary albedo of the Earth, build maps of the radiation balance of the Earth-atmosphere system, measure the content and variability of small atmospheric impurities, and solve many other problems of atmospheric physics and environmental monitoring.

Lit .: Budyko M. I. Climate in the past and future. L., 1980; Matveev L. T. Course of general meteorology. Physics of the atmosphere. 2nd ed. L., 1984; Budyko M. I., Ronov A. B., Yanshin A. L. History of the atmosphere. L., 1985; Khrgian A.Kh. Atmospheric Physics. M., 1986; Atmosphere: A Handbook. L., 1991; Khromov S. P., Petrosyants M. A. Meteorology and climatology. 5th ed. M., 2001.

G. S. Golitsyn, N. A. Zaitseva.

The exact size of the atmosphere is unknown, since its upper boundary is not clearly visible. However, the structure of the atmosphere has been studied enough so that everyone can get an idea of ​​​​how the gaseous shell of our planet is arranged.

Atmospheric physics scientists define it as the area around the Earth that rotates with the planet. The FAI gives the following definition:

• The boundary between space and the atmosphere runs along the Karman line. This line, according to the definition of the same organization, is the height above sea level, located at an altitude of 100 km.

Everything above this line is outer space. The atmosphere gradually passes into interplanetary space, which is why there are different ideas about its size.

With the lower boundary of the atmosphere, everything is much simpler - it passes through the surface earth's crust and the water surface of the Earth - the hydrosphere. At the same time, the boundary, one might say, merges with the earth and water surfaces, since particles of air are also dissolved there.

What layers of the atmosphere are included in the size of the Earth

Interesting fact: in winter it is lower, in summer it is higher.

It is in this layer that turbulence, anticyclones and cyclones arise, clouds form. It is this sphere that is responsible for the formation of the weather; approximately 80% of all air masses are located in it.

The tropopause is the layer in which temperature does not decrease with height. Above the tropopause, at an altitude above 11 and up to 50 km, is the stratosphere. The stratosphere contains a layer of ozone, which is known to protect the planet from ultraviolet rays. The air in this layer is rarefied, which explains the characteristic purple hue of the sky. The speed of air currents here can reach 300 km/h. Between the stratosphere and the mesosphere is the stratopause - the boundary sphere, in which the temperature maximum takes place.

The next layer is the mesosphere. It extends to heights of 85-90 kilometers. The color of the sky in the mesosphere is black, so the stars can be observed even in the morning and afternoon. The most complex photochemical processes take place there, during which atmospheric glow occurs.

Between the mesosphere and the next layer, the thermosphere, is the mesopause. It is defined as a transition layer in which a temperature minimum is observed. Above, at an altitude of 100 kilometers above sea level, is the Karman line. Above this line are the thermosphere (altitude limit 800 km) and the exosphere, which is also called the "dispersion zone". At an altitude of about 2-3 thousand kilometers, it passes into the near space vacuum.

Given that the upper layer of the atmosphere is not clearly visible, its exact size cannot be calculated. Besides, in different countries there are organizations with different opinions on this matter. It should be noted that Karman line can be considered the boundary of the earth's atmosphere only conditionally, since different sources use different boundary marks. So, in some sources you can find information that the upper limit passes at an altitude of 2500-3000 km.

NASA uses the 122 kilometer mark for calculations. Not so long ago, experiments were carried out that clarified the border as located at around 118 km.

10.045×10 3 J/(kg*K) (in the temperature range from 0-100°C), C v 8.3710*10 3 J/(kg*K) (0-1500°C). The solubility of air in water at 0°C is 0.036%, at 25°C - 0.22%.

Composition of the atmosphere

History of the formation of the atmosphere

Early history

At present, science cannot trace all the stages of the formation of the Earth with 100% accuracy. According to the most common theory, the Earth's atmosphere has been in four different compositions over time. Initially, it consisted of light gases (hydrogen and helium) captured from interplanetary space. This so-called primary atmosphere. At the next stage, active volcanic activity led to the saturation of the atmosphere with gases other than hydrogen (hydrocarbons, ammonia, water vapor). This is how secondary atmosphere. This atmosphere was restorative. Further, the process of formation of the atmosphere was determined by the following factors:

• constant leakage of hydrogen into interplanetary space;
• chemical reactions occurring in the atmosphere under the influence of ultraviolet radiation, lightning discharges and some other factors.

Gradually, these factors led to the formation tertiary atmosphere, characterized by a much lower content of hydrogen and a much higher content of nitrogen and carbon dioxide (formed as a result of chemical reactions from ammonia and hydrocarbons).

The emergence of life and oxygen

With the advent of living organisms on Earth as a result of photosynthesis, accompanied by the release of oxygen and the absorption of carbon dioxide, the composition of the atmosphere began to change. However, there are data (an analysis of the isotopic composition of atmospheric oxygen and that released during photosynthesis) that testify in favor of the geological origin of atmospheric oxygen.

Initially, oxygen was spent on the oxidation of reduced compounds - hydrocarbons, the ferrous form of iron contained in the oceans, etc. At the end of this stage, the oxygen content in the atmosphere began to grow.

In the 1990s, experiments were carried out to create a closed ecological system (“Biosphere 2”), during which it was not possible to create a stable system with a single air composition. The influence of microorganisms led to a decrease in the level of oxygen and an increase in the amount of carbon dioxide.

Nitrogen

The formation of a large amount of N 2 is due to the oxidation of the primary ammonia-hydrogen atmosphere by molecular O 2, which began to come from the surface of the planet as a result of photosynthesis, as expected, about 3 billion years ago (according to another version, atmospheric oxygen is of geological origin). Nitrogen is oxidized to NO in the upper atmosphere, used in industry and bound by nitrogen-fixing bacteria, while N 2 is released into the atmosphere as a result of the denitrification of nitrates and other nitrogen-containing compounds.

Nitrogen N 2 is an inert gas and reacts only under specific conditions (for example, during a lightning discharge). It can be oxidized and converted into a biological form by cyanobacteria, some bacteria (for example, nodule bacteria that form rhizobial symbiosis with legumes).

Oxidation of molecular nitrogen by electric discharges is used in the industrial production of nitrogen fertilizers, and it also led to the formation of unique saltpeter deposits in the Chilean Atacama Desert.

noble gases

Fuel combustion is the main source of pollutant gases (CO , NO, SO 2). Sulfur dioxide is oxidized by air O 2 to SO 3 in the upper atmosphere, which interacts with H 2 O and NH 3 vapors, and the resulting H 2 SO 4 and (NH 4) 2 SO 4 return to the Earth's surface along with precipitation. The use of internal combustion engines leads to significant air pollution with nitrogen oxides, hydrocarbons and Pb compounds.

Aerosol pollution of the atmosphere is caused both by natural causes (volcanic eruption, dust storms, entrainment of sea water droplets and pollen particles, etc.) and by human economic activity (mining of ores and building materials, fuel combustion, cement production, etc.) . Intense large-scale removal of solid particles into the atmosphere is one of the possible causes of climate change on the planet.

The structure of the atmosphere and the characteristics of individual shells

The physical state of the atmosphere is determined by weather and climate. The main parameters of the atmosphere: air density, pressure, temperature and composition. As altitude increases, air density and atmospheric pressure decrease. The temperature also changes with the change in altitude. The vertical structure of the atmosphere is characterized by different temperature and electrical properties, different state air. Depending on the temperature in the atmosphere, the following main layers are distinguished: troposphere, stratosphere, mesosphere, thermosphere, exosphere (scattering sphere). The transitional regions of the atmosphere between adjacent shells are called the tropopause, stratopause, etc., respectively.

Troposphere

Stratosphere

In the stratosphere lingers most of short-wave part of ultraviolet radiation (180-200 nm) and the transformation of short-wave energy takes place. Under the influence of these rays, magnetic fields, molecules break up, ionization occurs, new formation of gases and other chemical compounds. These processes can be observed in the form of northern lights, lightning, and other glows.

In the stratosphere and higher layers, under the influence of solar radiation, gas molecules dissociate - into atoms (above 80 km, CO 2 and H 2 dissociate, above 150 km - O 2, above 300 km - H 2). At an altitude of 100–400 km, ionization of gases also occurs in the ionosphere; at an altitude of 320 km, the concentration of charged particles (O + 2, O − 2, N + 2) is ~ 1/300 of the concentration of neutral particles. In the upper layers of the atmosphere there are free radicals - OH, HO 2, etc.

There is almost no water vapor in the stratosphere.

Mesosphere

Up to a height of 100 km, the atmosphere is a homogeneous, well-mixed mixture of gases. In higher layers, the distribution of gases in height depends on their molecular masses, the concentration of heavier gases decreases faster with distance from the Earth's surface. Due to the decrease in gas density, the temperature drops from 0°С in the stratosphere to −110°С in the mesosphere. However, the kinetic energy of individual particles at altitudes of 200–250 km corresponds to a temperature of ~1500°C. Above 200 km, significant fluctuations in temperature and gas density are observed in time and space.

At an altitude of about 2000-3000 km, the exosphere gradually passes into the so-called near space vacuum, which is filled with highly rarefied particles of interplanetary gas, mainly hydrogen atoms. But this gas is only part of the interplanetary matter. The other part is composed of dust-like particles of cometary and meteoric origin. In addition to these extremely rarefied particles, electromagnetic and corpuscular radiation of solar and galactic origin penetrates into this space.

The troposphere accounts for about 80% of the mass of the atmosphere, the stratosphere for about 20%; the mass of the mesosphere is no more than 0.3%, the thermosphere is less than 0.05% of the total mass of the atmosphere. Based on the electrical properties in the atmosphere, the neutrosphere and ionosphere are distinguished. It is currently believed that the atmosphere extends to an altitude of 2000-3000 km.

Depending on the composition of the gas in the atmosphere, they emit homosphere And heterosphere. heterosphere- this is an area where gravity affects the separation of gases, since their mixing at such a height is negligible. Hence follows the variable composition of the heterosphere. Below it lies a well-mixed, homogeneous part of the atmosphere called the homosphere. The boundary between these layers is called turbopause, it lies at an altitude of about 120 km.

Atmospheric properties

Already at an altitude of 5 km above sea level, an untrained person develops oxygen starvation and, without adaptation, a person's performance is significantly reduced. This is where the physiological zone of the atmosphere ends. Human breathing becomes impossible at an altitude of 15 km, although up to about 115 km the atmosphere contains oxygen.

The atmosphere provides us with the oxygen we need to breathe. However, due to the decrease in the total pressure of the atmosphere, as one rises to a height, the partial pressure of oxygen also decreases accordingly.

The human lungs constantly contain about 3 liters of alveolar air. The partial pressure of oxygen in the alveolar air at normal atmospheric pressure is 110 mm Hg. Art., pressure of carbon dioxide - 40 mm Hg. Art., and water vapor −47 mm Hg. Art. With increasing altitude, the oxygen pressure drops, and the total pressure of water vapor and carbon dioxide in the lungs remains almost constant - about 87 mm Hg. Art. The flow of oxygen into the lungs will completely stop when the pressure of the surrounding air becomes equal to this value.

At an altitude of about 19-20 km, the atmospheric pressure drops to 47 mm Hg. Art. Therefore, at this height, water and interstitial fluid begin to boil in the human body. Outside the pressurized cabin at these altitudes, death occurs almost instantly. Thus, from the point of view of human physiology, "space" begins already at an altitude of 15-19 km.

Dense layers of air - the troposphere and stratosphere - protect us from the damaging effects of radiation. With sufficient rarefaction of air, at altitudes of more than 36 km, ionizing radiation, primary cosmic rays, has an intense effect on the body; at altitudes of more than 40 km, the ultraviolet part of the solar spectrum, which is dangerous for humans, operates.