What is the name of the air shell of the Earth? Atmosphere. air shell of the earth Interrelation of the shells of the Earth

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 fuel combustion products are released into the atmosphere, and, in addition, the area of ​​forests 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 to living organisms on Earth.

In addition, the atmosphere contains water vapor and various impurities - dust particles, volcanic ash, soot, etc. The concentration of impurities is higher near the surface of the earth and in certain areas: above large cities, deserts.

Troposphere- lower, it contains most of the air and. The height of this layer varies: from 8-10 km near the tropics to 16-18 near the equator. in the troposphere it decreases with rise: by 6°C for every kilometer. The 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, and there is much less water vapor in it. The temperature in the lower part of the stratosphere is -60 - -80°C and falls with increasing altitude. It is in the stratosphere that the ozone layer is located. The stratosphere is characterized by high wind speeds (up to 80-100 m/sec).

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 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 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 continuously increases to an altitude of about 400 km, where it reaches 700 - 1500 ° C (depending on solar activity). Under the influence of ultraviolet, X-ray and cosmic radiation, ionization of the air (“auroras”) also occurs. 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 mainly consist of oxygen and nitrogen; With increasing altitude, the relative concentration of light gases, especially ionized hydrogen, rapidly increases. The temperature in the exosphere is 1300-3000° C; it grows weakly with height. The Earth's radiation belts are mainly located in the exosphere.

It's no secret that air is an extremely important part of the biosphere. After all, it is its unique composition that ensures the possibility of life on the planet. But what is the name of the airborne one? What is it and why is it unique? What is its chemical composition and physical properties? These questions interest many.

What is the name of the air shell of the Earth?

It is known that life on Earth is possible largely due to the unique composition of the air. And the gas shell is called the atmosphere. This part of the biosphere completely surrounds the planet and is held around the celestial body by gravity.

Naturally, this shell has certain chemical and physical properties. As for the boundaries, it is impossible to draw them clearly. Closer to the earth's surface, the atmosphere is in contact with the lithosphere and hydrosphere. But it is extremely difficult to determine where the gas shell ends and open space begins. Today, the border is usually drawn at an altitude of 100 km, where the so-called Karman line is located - aeronautics is no longer possible in this area.

The atmosphere is the air envelope of the Earth, the importance of which is difficult to overestimate. After all, we should not forget that almost all celestial bodies are under the influence of ionizing and ultraviolet radiation, which are destructive to living organisms. It is in the gas shell that these rays are neutralized.

Theory of the formation of the atmosphere

In fact, many people wonder how the Earth's air envelope was formed. The answer to this question is unlikely to be accurate, since today there are several different theories about the origin of the atmosphere.

According to the most common hypothesis, the primary atmosphere formed four billion years ago from light gases, namely helium and hydrogen, which were captured from interplanetary space. Due to high volcanic activity, a secondary gas shell was subsequently created, which was saturated with carbon dioxide, water vapor and ammonia.

The tertiary atmosphere was formed through many processes—chemical reactions (such as lightning), ultraviolet exposure, and the leakage of helium and hydrogen back into interplanetary space.

Chemical composition of the atmosphere

Now that it has become clear what the Earth’s air envelope is called, it is worth considering its chemical composition, which is considered unique. It should immediately be noted that only the lower layers of the atmosphere are saturated with various gases. In particular, nitrogen predominates in the air we breathe (78.08%). The oxygen level is 20.95%. These are the two main gases.

In addition, the air envelope of the Earth includes other components - hydrogen, argon, helium, xenon, methane, sulfur and nitrogen oxides, ozone, ammonia.

The structure of the Earth's air shell

The atmosphere is usually divided into several main layers, each of which has different physical and chemical characteristics.

• The troposphere is the layer closest to the earth's surface. This is where 80% of all air is concentrated. And it is here that human life is possible. By the way, almost all atmospheric water (90%) is concentrated in this layer. Clouds and precipitation form here. The troposphere extends 18 km from the earth's surface. As you go up, the temperature here decreases.
• The stratosphere (12-50 km) is a layer that is considered the calmest part of the atmosphere. This is where the ozone protective layer is located.
• The thermosphere is part of the atmosphere, the upper boundary of which is approximately 700-800 km. Here the temperature begins to rise sharply as it rises, and in some areas it reaches about 1200 degrees Celsius. Within the boundaries of this layer is the so-called ionosphere, where the air is highly ionized under the influence of solar radiation.
• The exosphere is a dispersion zone that at an altitude of 3000 km passes into outer space. The air here is saturated with light gases, in particular hydrogen and helium.

Basic physical characteristics of the atmosphere

Of course, the physical properties of air are extremely important. For example, knowing them, you can determine how the atmosphere affects a human or any other living organism. In addition, the measurement of physical parameters is simply necessary to determine the optimal characteristics of aircraft, aircraft, etc. In particular, the following physical indicators are taken into account:

• Air temperature is measured using the following formula: t1 = t - 6.5H (here t is the air temperature at the earth's surface, and H is the height).
• Air density is the mass of air per cubic meter.
• Pressure, which can be measured in both Pascals and atmospheres.
• Air humidity shows the amount of water in a unit of air. It should be noted that zero humidity is only possible in laboratory conditions. The higher this indicator, the lower the air density, and vice versa.

By the way, the science that answers questions about what the Earth’s air envelope is called and what its properties and characteristics are is meteorology. Scientists not only study the atmosphere, but also monitor its constant changes, which affect weather and climate.

Atmosphere and its meaning

The importance of the gaseous shell of the Earth is very difficult to overestimate. After all, just a few minutes without air lead to loss of consciousness, hypoxia and irreversible brain damage. Only thanks to the amazing composition of the atmosphere can living organisms receive the oxygen they need.

In addition, the air shell protects the surface of the planet from harmful cosmic radiation. At the same time, a sufficient amount of ultraviolet rays pass through the atmosphere, which warm the Earth. Scientists say that reducing ultraviolet radiation will lead to lower overall temperatures and freezing. In addition, under the influence of sunlight (in a reasonable amount), vitamin D is formed in human skin tissues.

Ozone layer and its importance

The ozone layer is located in the stratosphere, at an altitude of 12-50 km from the earth's surface. This part of the atmosphere was discovered in 1912 by French scientists C. Fabry and A. Buisson.

Ozone is a colorless gas with a sharp, characteristic odor. It consists of three oxygen atoms. It is this part of the gas shell that protects the earth's surface from dangerous cosmic radiation.

Unfortunately, due to technical and industrial progress, the amount of harmful substances in the air shell of the Earth has increased, which gradually destroy the ozone layer. The so-called ozone holes are an extremely dangerous problem.

greenhouse effect and acid rain

Unfortunately, the constant, which is associated mainly with developed industry, leads to a lot of deterioration. Such dangerous changes include the so-called greenhouse effect. The fact is that terrestrial bodies emit waves predominantly in the infrared spectrum - they cannot always penetrate the atmosphere. An increase in the concentration of carbon dioxide, which absorbs infrared radiation, leads to an increase in the overall temperature in the lower layers of the atmosphere, which, accordingly, affects the climate.

Acid rain is another result of industrial pollution of the Earth's air. Sulfur and nitrogen oxides, which are emitted into the air by thermal power plants, cars, metallurgical plants and some other enterprises, can react with atmospheric water vapor - under the influence of solar radiation, acids are formed here, which fall together with other precipitation.

The air shell of our planet - the atmosphere - protects living organisms on the earth's surface from the harmful effects of ultraviolet radiation from the Sun and other hard cosmic radiation. It protects the Earth from meteorites and cosmic dust. The atmosphere also serves as a “clothing” that prevents the loss of heat radiated by the Earth into space. Atmospheric air is a source of respiration for humans, animals and vegetation, a raw material for the processes of combustion and decomposition, and the synthesis of chemicals. It is a material used for cooling various industrial and transport installations, as well as an environment into which human waste, higher and lower animals and plants, production and consumption waste are discharged.

The interaction of atmospheric air with water and soil entails certain changes in the biosphere both as a whole and in its individual components, enhancing and accelerating undesirable changes in the composition and structure of atmospheric air and the Earth's climate.

It is known that a person can live about 5 weeks without food, about 5 days without water, and cannot live even 5 minutes without air. The human need for clean air (by “clean” is meant air suitable for breathing and without negative consequences for the human body) ranges from 5 to 10 l/min or 12-15 kg/day. From this it is clear how great the importance of the atmosphere is in solving environmental problems.

Exosphere

Thermosphere

auroras in the lower ionosphere

Mesopause

noctilucent clouds

Stratosphere

Tropopause^

• 1,9-10 8
• 3.8-10 ^ 1.4-10 7 2.2-10" 7 3-10" 7
• 1-yu-6
• 2- 10 ^ 7-10*
• 4 10 5 0,0004

Sea level

120-90 -60 -30 0 30 60 90 120150180 210 240 270300 330 360 390 1°

Temperature, °С

Rice. 21. Vertical section of the atmosphere

Humanity lives at the bottom of the Great Ocean of Air, which is a continuous shell that completely surrounds the globe. The most studied region of the atmosphere extends from sea level to an altitude of 100 km. In general, the atmosphere is divided into several spheres: troposphere, stratosphere, mesosphere, ionosphere (thermosphere), exosphere. The boundaries between spheres are called pauses (Fig. 21). According to the chemical composition, the Earth's atmosphere is divided into the lower (up to 100 km) homosphere, which has a composition similar to surface air, and the upper hetosphere, which has a heterogeneous chemical composition. In addition to gases, the atmosphere contains various aerosols - dusty or water particles suspended in a gaseous environment. They have both natural and man-made origin.

The troposphere is the lower surface part of the atmosphere, i.e., the zone where most living organisms, including humans, live. More than 80% of the mass of the entire atmosphere is concentrated in this area. Its power (height on the earth's surface) is determined by the intensity of vertical (ascending and descending) air flows caused by heating of the earth's surface. As a result, at the equator it extends to an altitude of 16-18 km, in the middle (temperate) latitudes - up to 10-11 km, and at the poles - up to 8 km. There was a natural decrease in air temperature with height by an average of 0.6 degrees Celsius for every 100 m.

The troposphere contains most of the cosmic and anthropogenic dust, water vapor, nitrogen, oxygen and noble gases. It is almost transparent to short-wave solar radiation passing through it. At the same time, the water vapor, ozone and carbon dioxide contained in it quite strongly absorb the thermal (long-wave) radiation of our planet, as a result of which some heating of the troposphere occurs. This leads to vertical movement of air currents, condensation of water vapor, formation of clouds and precipitation.

The stratosphere is located above the troposphere to an altitude of 50-55 km. The temperature at its upper limit increases due to the presence of ozone.

Mesosphere - the upper boundary of this layer is fixed at altitudes of about 80 km. Its main feature is a sharp drop in temperature (-75° - 90 °C) at the upper limit. So-called noctilucent clouds, consisting of ice crystals, are observed here.

The ionosphere (thermosphere) is located up to an altitude of 800 km, and is characterized by a significant increase in temperature (more than 1000 °C). Under the influence of ultraviolet radiation from the Sun, atmospheric gases are in an ionized state. This condition is associated with the appearance of the aurora, like the glow of gases. The ionosphere has the ability to repeatedly reflect radio waves, which ensures long-distance radio communications on Earth.

The exosphere extends from an altitude of 800 km to altitudes of 2000-3000 km. In this altitude range, temperatures rise to 2000 "C. Very important is the fact that the speed of movement of gases approaches the critical value of 11.2 km/s. The composition is dominated by hydrogen and helium atoms, which form the so-called corona around our planet, extending up to altitudes of 20 thousand km.

As can be seen from the above, the temperature in the atmosphere changes in a very complex way (see Fig. 21) and has a maximum or minimum value during pauses. The greater the height of the rise above the earth's surface, the lower the atmospheric pressure. Due to the high compressibility of the atmosphere, its pressure decreases from an average value of 760 mm Hg. Art. (101,325 Pa) at sea level up to 2.3 -K)" mm Hg. Art. (0.305 Pa) at an altitude of 100 km and only up to 1 -10 6 mm Hg. Art. (1.3!0" 4 Pa ) at an altitude of 200 km.

The conditions of life on the surface of the Earth in terms of its atmospheric “support” differ sharply at high altitudes, i.e. at the heights of the stratosphere, most life forms of the Earth cannot exist without means of protection.

The composition of the atmosphere is not constant over altitude and varies over a fairly wide range. The main reasons for this are: the force of gravity, diffusion mixing, the action of cosmic and solar rays and the high-energy particles emitted by them (Table 8).

Spectrum of sunlight

Table 8

Under the influence of gravity, heavier atoms and molecules fall to the lower part of the atmosphere, and lighter ones remain in its upper part. In table Figure 9 shows the composition of dry air near sea level, and Fig. Figure 21 shows the change in the average molecular weight of the atmosphere depending on the height above the Earth's surface.

In general, the mechanical mixture of atmospheric gases is represented on average by nitrogen - 78% of its volume; oxygen - 21%; helium, argon, krypton and the above other components - 1% or less.

Composition of atmospheric air

Notes: I. Ozone O, sulfur dioxide 50; Nitrogen dioxide NO^amchiacMN^ and CO monoxide are present in the form of pollutants and, as a result, their content can vary within significant limits. 2. The mole fraction is understood as the ratio of the number of moles of a particular component in the air sample under consideration to the total number of moles of all components in this sample.

The average molecular weight of such air is 28.96 a. e. m and remains almost unchanged up to an altitude of 90 km. At high altitudes, the molecular mass decreases sharply and at altitudes of 500 km and above, helium becomes the most important component of the atmosphere, although its content in it at sea level is extremely small. The main components of air (at 99 % of the entire composition) are diatomic gases (oxygen 0 2 and nitrogen 2).

Oxygen is the most necessary atmospheric element for the functioning of the biosphere. If in the atmosphere it can be up to 23% by weight, then in water - about 89%, and in the human body - almost 65%. In total, in all geospheres - the atmosphere, hydrosphere and in the accessible part of the lithosphere, oxygen accounts for 50% of the total mass of air. But in a free state, oxygen is concentrated in the atmosphere, where its quantity is estimated at 1.5 10 15. In nature, processes of oxygen consumption and release constantly occur. Oxygen consumption occurs during the respiration of humans and animals, during various oxidative processes, such as combustion, corrosion of metals, and smoldering of organic residues. As a result, oxygen passes from a free state to a bound one. However, its quantity remains practically unchanged due to the vital activity of plants. It is believed that ocean phytoplakton and terrestrial plants play a major role in oxygen reduction. Align-

Oxygen exists in the atmosphere in the form of allotropic modifications - 0 2 and 0 3 (ozone). In all states (gaseous, liquid and solid) 0 2 is paramagnetic and has a very high dissociation energy - 496 kJ/mol. In the gaseous state 0 2 is colorless, in the liquid and solid state it has a light blue color. Chemically very active, forms compounds with all elements except helium and neon.

Ozone Oj is a gas formed from 0 2 in a quiet electrical discharge in a concentration of up to 10%, diamagnetic, toxic, has a dark blue (blue) color. Traces of O appear under the influence of ultraviolet (UV) radiation from 0 2 in the upper layers of the atmosphere. The maximum concentration of 0 3 in the upper layers of the atmosphere at altitudes of 25-45 km forms the now famous ozone screen (layer).

Another very important and constant component of air is nitrogen, the mass of which is 75.5% (4 -10 15 g). It is part of proteins and nitrogenous compounds, which are the basis of all life on our planet.

Nitrogen N 2 is a colorless, chemically inactive gas. The dissociation energy of N 2 - 2N is almost twice that of 0 2 and amounts to 944.7 kJ/mol. The high strength of the N and N bond determines its low reactivity. However, despite this, nitrogen forms many different compounds, including with oxygen. Thus, N,0 - dinitrogen oxide is relatively inert, but when heated it reacts with N 2 and 0 2. Nitrogen monoxide -NO instantly reacts with ozone according to the reaction:

2NO + O, = 2N0 3

The N0 molecule is paramagnetic. The electron of the l-orbital is easily split off to form the nitrosonium cation N0*, the bond in which is strengthened. Nitrogen dioxide N0, very toxic, when reacting with water it forms strong nitric acid

2NOj + H.0 - HN0 3 + HNOj

Under natural conditions, the formation of the nitrogen oxides discussed above occurs during lightning discharges and as a result of the activity of nitrogen-fixing and protein-decomposing bacteria.

The use of nitrogen fertilizers (nitrates, ammonia) leads to an increase in the amount of nitrogen oxides of bacterial origin in the atmosphere. The share of natural processes in the formation of nitrogen oxides is estimated at 50%.

The composition of the atmosphere, especially in the upper layers (above the troposphere), is greatly influenced by cosmic and solar radiation and emitted high-energy particles.

The sun emits radiant energy - a stream of photons - of a wide variety of wavelengths. Energy E each photon is determined by the relation

Where AND- Planck's constant; V - radiation frequency, V = 1D (X - wavelength).

In other words, the shorter the wavelength, the higher the frequency of the radiation and, accordingly, the greater the energy. When a photon collides with an atom or molecule of any substance, various chemical transformations are initiated, such as dissociation, ionization, etc. But for this, certain conditions must be met: first, the photon energy must be no less than that required to break a chemical bond, removing an electron, etc.; second, molecules (atoms) must absorb these photons.

One of the most important processes occurring in the upper atmosphere is the photodissociation of oxygen molecules as a result of photon absorption:

Knowing the bond dissociation energy in the oxygen molecule (495 kJ/mol), we can calculate the maximum wavelength of the photon that causes the formation of O. This length turns out to be equal to 242 nm, which means that all photons with this and shorter wavelengths will have an energy that sufficient for the above reaction to occur.

Oxygen molecules are also capable of absorbing a large range of high-energy short-wave radiation from the solar spectrum. The oxygen composition of the atmosphere (see Fig. 21) indicates how intensely photodissociation of oxygen occurs at high altitudes. At an altitude of 400 km, 99% of oxygen is dissociated, while O accounts for only 1%. At an altitude of 130 km, the content of O and O is approximately the same; at lower altitudes, the content of 0 2 significantly exceeds the O content.

Due to the high binding energy of the K molecule (944 kJ/mol), photons with only a very short wavelength have sufficient energy to cause the dissociation of this molecule. In addition, And does not absorb photons well, even if they have quite sufficient energy. As a result, photodissociation of N3 in the upper layers of the atmosphere occurs very little and very little atmospheric nitrogen is formed.

Vaporous water is found near the surface of the Earth and already at an altitude of 30 km its content is 3 million, and at even higher altitudes the content of water vapor is even less. This means that the amount of water moving into the upper atmosphere is very small. Once in the upper layers of the atmosphere, water vapor undergoes photodissociation:

N 2 0 + -> H + OH

OH + Au -> H + O

According to a number of experts, in the early stages of the Earth’s development, when the oxygen atmosphere had not yet been formed, it was photodissociation that largely contributed to its formation.

As a result of the influence of solar radiation on the molecules of matter in the atmosphere, free electrons and positive ions are formed. Such processes are called photoionization. For them to occur, the above conditions must also be met. In table Figure 10 shows some of the most important photoionization processes occurring in the upper atmosphere. As follows from the table, photons that cause photoionization belong to the short-wave (high-frequency) ultraviolet part of the spectrum. Radiation from this part of the spectrum does not reach the Earth's surface; it is absorbed by the upper layers of the atmosphere.

Table 10

Energy and wave parameters of photoionization processes

	Ionization energy, kJ/mop
O ) + yu -> O/ + e

The resulting molecular ions are very reactive. Without any additional energy, they react very quickly when colliding with a variety of charged particles and neutral molecules.

One of the most obvious reactions is the recombination of a molecular ion with an electron - the reverse reaction of photoionization. This releases an amount of energy equal to the ionization energy of a neutral molecule. And if there is no way to release this excess energy, for example, as a result of a collision with another molecule, then it causes the dissociation of the newly formed molecule. In the upper layers of the atmosphere, due to the very low density of matter, the probability of collisions between molecules and energy transfer is very low. Therefore, almost all acts of recombination of electrons with molecular ions lead to dissociation:

N5 +е-> N + N1, DN

SG! +s->o + o,dn

G^O"+c->N + O, DN

Atomic nitrogen contained in the upper atmosphere is formed mainly as a result of dissociative recombination.

When a molecular ion collides with a neutral molecule, electron transfer can occur between them, for example

N,+ 0,-» И 2 + 0‘,

This type of reaction is called charge transfer reaction.

In order for such a reaction to take place, the ionization energy of the molecule losing an electron must be less than the ionization energy of the molecule formed as a result of charge transfer. As can be seen from table. 10, the ionization energy of O is less than that of N2, the charge transfer reaction is exothermic, the excess energy is released in the form of kinetic energy of the resulting products. According to these data, the reactions below must also occur and be exothermic (i.e., DN

SG + 0,-> O + O2

O; + N0-» о,-+-ыо‘

N2 + N0 -» + N0*

Because the N2 molecule has the highest ionization energy of any particle in the upper atmosphere, the N2 ion is capable of undergoing transfer reactions with any molecule that encounters it. The rate of the charge transfer reaction is quite high, so although the photoionization process leads to intense formation of N3 ions, their concentration in the upper layers of the atmosphere is very low.

In addition to the above, reactions occur in the upper layers of the atmosphere during which interacting particles exchange atoms:

O + N5 -» N0 + S GM; +0->N0+N

These reactions are also exothermic and proceed very easily. Since the ionization energy of NO is lower than that of other particles (see Table 10), the resulting NO ions cannot be neutralized as a result of the charge transfer reaction, and the only reason for the death of this ion is the dissociative recombination reaction. This is the reason for the widest distribution of the NO ion in the upper layers of the atmosphere.

Although the upper layers of the atmosphere account for a fairly small part of its total mass, it is this zone of the atmosphere, due to the chemical reactions occurring in it, that plays a significant role in creating the conditions for the occurrence of life processes on our planet. It is the upper layers of the atmosphere that play the role of an advanced “bastion” that protects the Earth’s surface from the destructive effects of a stream of cosmic rays and a “hail” of high-energy particles for all living organisms. It should be noted that N5, 0 2 and N0 molecules cannot filter out the entire volume of short-wave radiation, the remnants of which are “neutralized” in the atmosphere as they approach the earth’s surface.

Ozone as a filter for short-wave radiation. The chemical processes occurring in the atmosphere, in layers located below 90 km, except for the photodissociation of O, differ significantly from those processes observed at high altitudes. In the meso- and stratosphere, in contrast to higher layers, the concentration of 0 2 increases, therefore the probability of a collision of 0 2 with O, which leads to the formation of 0 3, increases sharply.

This process is described by the following equations:

0 3 + AND-» 0 + 0

O; + m -> o, + mln

where M - 0 2, K.

An O molecule can give up energy when colliding with O and D molecules. However, most of the O,' molecules decay into 0 2 and O before they undergo a stabilizing collision, i.e., the equilibrium of the process 0 7 + O ^ 0 3 is strongly shifted to the left.

Penetration of ultraviolet beams

Rice. 22.

The rate of ozone formation depends on opposing factors. On the one hand, it increases with decreasing height of the atmospheric layers, since the concentration of atmospheric matter increases, and therefore the frequency of stabilizing collisions. On the other hand, with decreasing altitude the speed decreases, since the amount of atmospheric oxygen formed by the reaction decreases O g +Ау -> 20, due to reduced penetration of high-frequency radiation. Therefore, the maximum ozone concentration, about 10 5% by volume, is observed at an altitude of 40 to 25 km (Fig. 22).

The process of ozone formation is exothermic. Ultraviolet radiation from the Sun absorbed by oxygen - reaction 0 2 + 20,

are converted into thermal energy by the reaction

O; + M-> 0 3 + M‘,DN

which is most likely associated with an increase in temperature in the stratosphere, which reaches a maximum in the stratopause (see Fig. 22).

The resulting ozone molecules are not very durable; ozone itself is capable of absorbing solar radiation, as a result of which it decomposes:

0 3 + yu -» O, + O

To implement this process, only 105 kJ/mol is required. This energy can be supplied by photons in a wide range of wavelengths up to 1140 nm. Ozone molecules most often absorb photons with wavelengths from 200 to 310 nm, which is very important for living organisms on Earth. Radiation in this range is not absorbed by other particles as strongly as by ozone. It is the presence of the ozone layer in the stratosphere that prevents high-energy short-wave photons from penetrating through the atmosphere and reaching the earth's surface. As is known, plants and animals cannot exist in the presence of such radiation, therefore the “ozone shield” plays an important role in preserving life on Earth.

Naturally, the “ozone shield” is not an absolutely insurmountable obstacle to ultraviolet radiation; approximately one hundredth of it reaches the Earth's surface. With an increase in penetrating radiation, disturbances occur in the genetic mechanisms of some living organisms, and various skin diseases become more active in humans. Ozone is chemically very active and therefore interacts not only with ultraviolet radiation from the Sun. Nitrogen oxides play an important role in the ozone cycle, increasing the rate of ozone decomposition by acting as a catalyst:

0 3 + НО-> N0.4-0,

N02+ O -» N0 + 02 0 3 + 0-> 20 3

High temperatures, which arise, in particular, during the operation of certain types of aircraft, have a great influence on the destruction of ozone. In this case the reaction occurs:

O, + N2 PRN > 2N0, DN > O

The issue of the impact of chlorofluoromethanes (freons) on ozone is quite debatable, but in any case it is necessary to dwell on possible reactions involving these compounds, ozone, nitrogen, atomic oxygen and ultraviolet radiation in different layers of the atmosphere.

In the upper layers of the atmosphere, in the presence of short-wave ultraviolet radiation, a number of reactions involving chlorofluoromethanes occur, in particular, the action of photons with a wavelength from 190 to 225 nm leads to the photolysis of chlorofluoromethanes with the formation of several dozen different compounds and radicals, for example:

CFCL +Av-» CFC+C1

In principle, the reaction does not end there and further photochemical decomposition of CF x Cl 3 x is possible, again with the formation of free chlorine.

It has been established that chlorine is released at a maximum speed at an altitude of about 30 km, and this is precisely the zone of maximum ozone concentrations.

The free atomic chlorine that forms reacts very quickly with ozone:

C1 +0,-> SY + o,

C1 + 20C1 + O,

The last two reactions, as well as the reactions:

Oh, +NO->NO, +Oh,

generally lead to the disappearance of ozone and atomic oxygen and practically lead to a constant content of nitrogen monoxide and atomic chlorine.

Chlorine monoxide can react with nitrogen oxides:

SJ + N0 -> C1 + N0,

C10 + N0, -» CINO,

Chlorinated nitrate can decompose under the influence of ultraviolet radiation or in reaction with atomic oxygen:

CINO, -» O -> O, + SY + N0

Reactions involving chlorine monoxide are of particular importance because they effectively remove nitrogen and chlorine compounds from the ozone destruction cycle. Methane and hydrogen have a similar effect:

Rice. 23.

C1 + CH, -> HC1 + CH,

a + n g -> ns1 + n

Some of the hydrogen chloride reacts with the hydroxide, returning the chlorine to its atomic state:

NSN-OH -> H,0 +C1

but the main share of HC1 is transferred to the troposphere, where it mixes with water vapor or liquid water, turning into hydrochloric acid.

The reactions discussed above occur in the atmosphere due to the entry of reagents into it from natural and man-made sources, and this process with varying concentrations of reagents has accompanied the entire history of the formation and existence of the earth’s atmosphere. The fact is that chlorofluoromethanes can be formed even under natural conditions, so the main question is not about the presence of interaction reactions similar to those described above, but about the intensity and volume of the formed and destroyed components of the atmosphere entering into reactions and mainly those of them that provide optimal conditions for the passage of life processes on our planet.

Thermal regime of the atmosphere and surface zone of the Earth. The main source of thermal energy reaching the earth's surface and simultaneously heating the atmosphere is naturally the Sun. Sources such as the Moon, stars and other planets

put on a negligible amount of heat. A fairly noticeable, but also not very large source is the heated interior of the Earth (Fig. 23).

It is known that the Sun emits colossal energy into space in the form of heat, light, ultraviolet and other rays. The impact of certain types of radiation on chemical reactions occurring in the atmosphere and the formation of various compounds has already been discussed above.

In general, the entire totality of the radiant energy of the Sun is called solar radiation. The Earth receives a very small share of it - one two-billionth part, but this volume is enough to carry out all processes known on Earth, including life.

Solar radiation is divided into direct, diffuse and total.

The impact on the earth's surface and its heating in clear, cloudless weather is defined as straight radiation. Direct radiation directly, through ultraviolet radiation, affects, for example, the pigmentation of human and animal skin, and some other phenomena in living organisms.

When solar rays pass through the atmosphere, they encounter various molecules, dust, and water droplets in their haze and deviate from a straight path, resulting in the dispersion of solar radiation. Depending on the amount of cloudiness, the degree of air humidity, and its dust content, the degree of dispersion reaches 45%. Meaning absent-minded radiation is quite large - it generally determines the degree of illumination of various relief elements, as well as the color of the sky.

Total radiation accordingly consists of direct and diffuse radiation.

The angle of incidence of sunlight on the ground surface determines the intensity of radiation, which, in turn, affects the air temperature during the day.

The distribution of solar radiation over the Earth's surface and the heating of atmospheric air depend on the sphericity of the planet and the inclination of the earth's axis to the orbital plane. In equatorial and tropical latitudes, the Sun is high above the horizon throughout the year; in mid-latitudes, its height varies depending on the time of year, and in the Antarctic and Arctic regions the Sun never rises high above the horizon. This generally affects the degree of dissipation of solar energy in the atmosphere, as a result of which there is a greater amount of solar rays per unit area of ​​the Earth's surface in the tropics than in middle or high latitudes. For this reason, the amount of radiation depends on the latitude of the place: the further from the equator, the less it reaches the earth's surface.

Solar radiation 100%

/// /V /// /// /// /// /V /// /// /// />/ /LG //u /u/

Absorption

soil

Rice. 24. Balance of solar radiation on the earth's surface during the daytime

(T.K. Goryshina, 1979)

The urgent movement of the Earth also affects the amount of radiant energy received. In middle and high latitudes, its amount depends on the time of year. At the North Pole, as is known, the Sun does not set beyond the horizon for 6 months (more precisely, 186 days) and the amount of incoming radiant energy is greater than at the equator. However, the sun's rays have a small angle of incidence and therefore a significant part of solar radiation is scattered in the atmosphere. In this regard, both the surface of the Earth and the atmosphere itself heat up slightly. In winter, in Arctic and Antarctic latitudes, the Sun does not rise above the horizon and therefore solar radiation does not reach the earth's surface at all.

A significant influence on the amount of solar radiation “perceived” by the earth’s surface, including the surface of the oceans, as well as by the atmosphere, is exerted by the features of the relief, its ruggedness, absolute and relative heights of the surface, the “exposure” of the slopes (i.e., their “facing” to the Sun) , even the presence or absence of vegetation and its character, as well as the “color” of the earth’s surface. The latter is determined by the value apbedo, which generally refers to the amount of light reflected from a unit surface, and sometimes albedo is defined as the quantity

reflectivity of a body or system of bodies, usually considered as the fraction (in %) of the energy of incident light reflected back to the earth's surface.

The magnitude of the reflectivity of the earth's surface is affected, for example, by the presence of snow cover on it, its purity, etc.

The combination of all these factors shows that there are practically no places on the Earth’s surface where the magnitude and intensity of solar radiation would be the same and do not change over time (Fig. 24).

Heating of land and water occurs very differently due to differences in the heat capacity of the materials that “form” them. Land heats up and cools down quite quickly. Water masses in oceans and seas heat up slowly, but retain heat longer.

On land, solar radiation heats only the surface layer of soil and underlying rocks, but in clear water heat penetrates to significant depths, and the heating process proceeds more slowly. Evaporation has a significant impact, since its implementation consumes a large amount of incoming thermal energy. The cooling of water occurs slowly due to the fact that the volume of heated water is significantly greater than the volume of heated land. Water masses, due to temperature changes in the upper and lower layers, are in a state of continuous “mixing”. The cooled upper layers, being denser and heavier, sink down, and warmer water rises from below to meet them. The waters of the seas and oceans expend accumulated heat more “economically” and evenly than the land surface. As a result, the sea is always, on average, warmer than the land, and fluctuations in water temperature are never as sharp as fluctuations in land temperature.

Ambient air temperature. Air, like any transparent body, heats up very little when sunlight passes through it. Air heating is carried out due to the heat given off by the heated earth or water surface. Air with an increased temperature and, as a result, a decreased mass rises to higher cold layers of the atmosphere, where it transfers its heat to them.

As the air rises, it cools. The air temperature at an altitude of 10 km is almost always constant and amounts to -45 "C. The natural decrease in air temperature with height is sometimes disrupted by the so-called temperature inversion (temperature rearrangement). Inversions occur with sharp decreases or increases in the temperatures of the earth's surface and adjacent air, which sometimes represents is a rapid “flowing” of cold air along the mountain slopes into the valleys.

Atmospheric air is characterized by daily temperature changes. During the day, the Earth's surface heats up and transfers heat to the surrounding air; at night, the process is reversed.

The lowest temperatures are observed not at night, but before sunrise, when the earth's surface has already given up its heat. In the same way, the highest air temperatures are established in the afternoon with a delay of 2-4 hours.

In different geographical zones of the Earth, the daily variation of temperatures is different; at the equator, on the seas and near sea coasts, the amplitudes of air temperature fluctuations are very small, and in deserts, for example, during the day the Earth’s surface heats up to a temperature of about 60 ° C, and at night it drops to almost 0 ° C, i.e. the daily “change” of temperatures is 60 °C.

In mid-latitudes, the greatest amount of solar radiation reaches the Earth on the days of the solstice (June 22 in the northern hemisphere and December 21 in the southern). However, the hottest months are not June (December), but July (January) due to the fact that in June (December) the actual heating of the earth's surface occurs, which consumes a significant part of solar radiation, and in July (December) there is a loss in the incoming amount of solar radiation is not only compensated for, but also exceeds it in the form of heat from the heated earth's surface. In a similar way, we can explain why the coldest month is not December (June), but January (July). At sea, due to the fact that the water cools and warms up more slowly, the hottest month is August (February), the coldest month is February (August).

The geographic latitude of a place affects the annual amplitude of air temperatures. In the equatorial parts, the temperature is almost constant throughout the year and averages 23 °C. The highest annual amplitudes are characteristic of territories located in mid-latitudes in the depths of continents.

Each area is characterized by its own absolute and average air temperatures. Absolute temperatures are determined based on long-term observation data at weather stations. For example, the hottest place on Earth is located in the Libyan Desert (+58 °C), the coldest is in Antarctica (-89.2 °C). In our country, the lowest temperature of -70.2 C was recorded in Eastern Siberia (Oymyakon village).

The average temperature for a given area is calculated first by the day of the day according to thermometric determinations at 1:00, 7:00, 13:00 and 19:00, i.e. four times a day; Then, based on average daily data, average monthly and average annual temperatures are calculated.

For practical purposes, isotherm maps are made, among which the most indicative are the isotherms of January and July, i.e., the warmest and coldest months.

Water in the atmosphere. The gases that form the atmosphere include water vapor, which is formed due to the evaporation of water from the surface of the oceans and continents. The higher the temperature and the larger the capacity

steam, the stronger the evaporation. The rate of evaporation is affected by wind speed and terrain on land, as well as, naturally, temperature fluctuations.

The ability to release a certain amount of water vapor from any surface when exposed to temperature is called volatility. This conditional value of evaporation is influenced by the air temperature and the amount of water vapor in it. Minimum values ​​were recorded for polar countries and the equator, and maximum evaporation was recorded for tropical deserts.

Air can accept water vapor up to a certain point, when it becomes saturated. With further heating of the air, it becomes capable of accepting water vapor again, i.e., unsaturated. When unsaturated air cools, it becomes saturated. There is a relationship between temperature and the content of water vapor contained in the air at a given moment (in g per 1 m 5), which is called absolute humidity.

The ratio of the amount of water vapor contained in the air at a given moment to the amount that it can contain at a given temperature is called relative humidity (%).

The moment of transition of air from an unsaturated state to a saturated state is called dew point. The lower the air temperature, the less water vapor it can contain and the higher the relative humidity. This means that when the air is cold, the dew point reaches the dew point faster.

When the dew point occurs, i.e. when the air is completely saturated with water vapor, when the relative humidity approaches 100 %, condensation of water vapor occurs, the transition of water from a gaseous state to a liquid one.

So, the process of condensation of water vapor occurs either with strong evaporation of moisture and saturation of the air with water vapor, or with a decrease in air temperature and relative humidity. At subzero temperatures, water vapor, bypassing the liquid state, turns into ice and snow crystals, i.e., turns into a solid state. This process is called sublimation of water vapor.

Condensation and sublimation of water vapor are processes that are a source of precipitation. One of the most obvious manifestations of water vapor condensation in the atmosphere is the formation of clouds, which are usually located at altitudes from several tens and hundreds of meters to several kilometers. An upward flow of warm air with water vapor enters the layers of the atmosphere with conditions for the formation of clouds consisting of water droplets or ice and snow crystals, which is associated with the temperature of the cloud itself. Ice and snow crystals and water droplets have such a small mass that they can be kept suspended even by very weak rising air currents.

Clouds have a variety of shapes, which depend on many factors: height, wind speed, humidity, etc. The best known are cumulus, cirrus and stratus, as well as their varieties. Clouds that are supersaturated with water vapor and have a dark purple or almost black tint are called clouds. The sky is covered by clouds to varying degrees and this degree, expressed in points (from 1 to 10), is called cloudiness. High cloudiness creates conditions for precipitation.

Atmospheric precipitation is water in all types of solid and liquid phases, which the earth's surface receives in the form of rain, snow, fog, hail or dew condensed on the surface of various bodies. In general, precipitation is one of the most important abiotic factors that significantly influences the living conditions of living organisms. In addition, precipitation determines the migration and distribution of various substances, including pollutants, in the environment. In the general moisture cycle, it is precipitation that is most mobile, since the volume of moisture in the atmosphere rotates 40 times a year. Rain forms when tiny droplets of moisture contained in a cloud merge into larger ones and, overcoming the resistance of rising warm air currents, fall to the surface of the Earth under the influence of gravity. In air that contains dust particles, the condensation process occurs much faster, since these dust particles act as condensation nuclei. In deserts, where relative humidity is very low, condensation of water vapor is possible only at significant

altitudes, at low temperatures. However, rain on the desert

1 Temperature below O C

Temperature higher 0°С

does not fall out, since the snowflakes do not have time to fall to the surface, but evaporate. This phenomenon is called dry rains. When water vapor condenses, which occurs at subzero temperatures, precipitation forms in the form of snow. When snowflakes are mixed with snow droplets, spherical snowballs with a diameter of 2-3 mm are formed, which fall in the form of a blizzard. For hail to form, the cloud must be of considerable size and its lower part Fig. 25. The pattern of hail formation in the clouds was in the ZONE of POSITIVE themes - vertical development of psratures, and the upper one was negative -

tel. The resulting lumps of blizzard, rising upward, turn into spherical pieces of ice - hailstones. The size of hailstones gradually increases and falls onto the earth's surface, overcoming the forces of rising air currents under the influence of gravity. Hailstones come in different sizes: from a pea to a chicken egg (Fig. 25).

Precipitation such as dew, frost, fog, hoarfrost, and ice are formed not in the upper layers of the atmosphere, but in the ground layer. In conditions of decreasing temperature at the surface of the earth, the air cannot always retain water vapor, which precipitates on various objects in the form dew, and if these objects have a negative temperature, then in the form frost. When cold objects are exposed to warm air, frost - a coating of loose ice and snow crystals. At significant concentrations of water vapor in the surface layer of the atmosphere, fog. The formation of an ice crust on the surface of the earth from rainfall is called black ice, by the way under icy conditions understand liquid precipitation that falls and freezes as it falls.

The main conditions for the occurrence of various types of precipitation are air temperature, atmospheric circulation, sea currents, relief, etc. There is zonality in the distribution of precipitation over the earth's surface, the following zones are distinguished:

• humid equatorial (approximately between 20° N and 20" S): this includes the basins of the Amazon River, the Congo River, the coast of the Gulf of Guinea, the Indo-Malayan region; more than 2000 mm falls here, the greatest amount of precipitation falls on Kauan Island (Hawaiian Islands) - 11,684 mm and in Cherrapunja (southern slopes of the Himalayas) - 11,633 mm; in this zone there are moist equatorial forests - one of the richest types of vegetation on the globe (more than 50,000 species);
• dry zones of tropical zones (between 20°N and 40°S) - anticyclonic conditions with downward air flows dominate here. As a rule, the amount of precipitation is less than 200-250 mm. Therefore, the most extensive deserts on the globe are concentrated in these zones (Sahara, Libyan, deserts of the Arabian Peninsula, Australia, etc.). The world's lowest average annual precipitation (only 0.8 mm) was recorded in the Atacama Desert (South America);
• humid zones of temperate latitudes (between 40° N and 60° S) - a significant amount of precipitation (more than 500 mm) is due to the cyclonic activity of air masses. Thus, in the forest zone of Europe and North America, the annual precipitation ranges from 500 to 1000 mm, beyond the Urals it decreases to 500 mm, and then in the Far East due to monsoon activity it increases again to 1000 mm;
• the polar regions of both hemispheres are characterized by insignificant amounts of precipitation (on average up to 200-250 mm); These precipitation minimums are associated with low air temperatures, negligible evaporation and anticyclonic atmospheric circulation. There are arctic deserts with extremely poor vegetation (mainly mosses and lichens). In Russia, the greatest amount of precipitation falls on the southwestern slopes of the Greater Caucasus - about 4000 mm (Mount Achishko - 3682 mm), and the least in the tundras of the northeast (about 250 mm) and in the Caspian deserts (less than 300 mm).

Atmospheric pressure. The mass of 1 m 3 of air at sea level at a temperature of +4 ° C is on average 1.3 kg, which determines the existence of atmospheric pressure. A person, like other living organisms, does not feel the effects of this pressure, since he has a balancing internal pressure. Atmospheric pressure at a latitude of 45° at an altitude equal to sea level, at a temperature of +4 °C is considered normal, it corresponds to 1013 hPa or 760 mm Hg. Art. or 1 atm. Naturally, atmospheric pressure decreases with height, and on average this is 1 hPa for every 8 m of height. It should be said that pressure varies depending on air density, which, in turn, depends on temperature. On special

Rotation

Earth's North Pole

Rice. 26.

In alical maps, lines with identical pressure values ​​are depicted; these are the so-called isobar maps. The following two patterns have been identified:

• pressure varies from the equator to the poles zonally; at the equator it is low, in the tropics (especially over the oceans) it is high, in the temperate regions it varies from season to season; in the polar - increased;
• Over the continents, increased pressure is established in winter, and low pressure in summer - Fig. 27. Wind erosion (Fig. 26).

Wind. The movement of air caused by differences in atmospheric pressure is called by the wind. Wind speed determines its types, for example when calm wind speed is zero, and wind with a speed of more than 29 m/s is called hurricane. The highest wind speed of more than 100 m/s was recorded in Antarctica. For practical purposes, when solving various engineering, environmental and other problems, so-called compass roses(Fig. 27).

Some general patterns in the directions of the main air flows in the lower layers of the atmosphere have been identified:

• from tropical and subtropical areas of high pressure, the main flow of air moves towards the equator into an area of ​​constant low pressure; when the Earth rotates, these flows are oriented to the right in the northern hemisphere and to the left in the southern hemisphere; these currents of constant winds are called trade winds;
• a certain part of tropical air moves to temperate latitudes; This process is especially active in the summer, since in temperate latitudes in summer the pressure is usually low. This flow is also oriented due to the rotation of the Earth, but is slow and gradual; in general, westerly air transport predominates in the temperate latitudes of both hemispheres;
• from polar areas of high pressure, air moves to moderate latitudes, taking a northeasterly direction in the northern hemisphere and southeasterly in the southern hemisphere.

In addition to the so-called planetary winds described above, monsoons - winds that change their direction according to the seasons: in winter the winds blow from land to sea, and in summer - from sea to land. These winds also have deviations in their directions due to the rotation of the Earth. Monsoon winds are especially characteristic of the Far East and Eastern China.

In addition to planetary winds and monsoons, there are local or regional winds: breezes- onshore winds; hair dryers - warm dry winds of mountain slopes; hot winds- dry and very hot winds of deserts and semi-deserts; bora (sarma, chipuk, mistral) - dense cold winds from mountain barriers.

Wind is an important abiotic factor that significantly shapes the living conditions of organisms, as well as affecting the formation of weather and climate. In addition, wind is one of the very promising alternative energy sources.

Weather is the state of the lower layer of the atmosphere at a given time and place. The most characteristic feature of the weather is its variability, or rather its continuous change. This most often and most clearly manifests itself when air masses change. An air mass is a huge moving volume of air with a certain temperature, density, humidity, transparency, etc.

Depending on the place of formation, arctic, temperate, tropical and equatorial air masses are distinguished. The place of formation and its duration affect the properties of the air masses located above them. For example, the humidity and temperature of air masses are influenced by the fact of their formation over a continent or ocean, in winter or summer.

Russia is located in the temperate zone, therefore, in its west, maritime temperate air masses predominate, and over most of the rest of the territory - continental ones; Arctic air masses form beyond the Arctic Circle.

Meetings of various air masses in the troposphere create transition regions - atmospheric fronts - up to 1000 km long and several hundred meters thick. A warm front is formed when warm air moves over cold air, and a cold front forms when the air mass moves in the opposite direction (Fig. 28, 29).

At the fronts, under certain conditions, powerful vortices with diameters of up to 3 thousand km are formed. At low pressure in the center of such a vortex, it is called cyclone, with increased - anticyclone(Fig. 30). Cyclones usually move from west to east at speeds of up to 700 km/day. A type of cyclonic vortex are smaller, but very stormy tropical cyclones. The pressure in their center drops to 960 hPa, and the accompanying winds are hurricane-force (> 50 m/s) with a storm front width of up to 250 km.

Climate is a long-term weather pattern characteristic of a given area. Climate is one of the important long-term abiotic factors; it influences the regime of rivers, the formation of various types of soils, types of plant and animal communities

Rice. 28.

00 700 800 km Cold

Horizontal distance front

society In areas of the Earth where the surface receives heat and moisture in abundance, moist evergreen forests with enormous bioproductivity are widespread. Areas located near the tropics receive enough heat, but much less moisture, which leads to the formation of semi-desert forms of vegetation. Temperate latitudes have their own characteristics associated with the sustainable adaptation of vegetation to rather difficult climatic conditions. The formation of climate is mainly influenced by the geographical position of the area, in particular, over water

air

6 Warm air

thunder cloud

* Ice crystals

Warm Cirrus

air Peristo -layered

Icy-d. - --*

crystals . .

Mermen * ,

drops ^ ^

- ____; at Cold

Rice. 29.

Various weather regimes are formed on the surface and over land. With distance from the ocean, the average temperature of the warmest month increases and the coldest month decreases, i.e., the amplitude of annual temperatures increases. Thus, in Nerchinsk it reaches 53.2 °C, and in Ireland on the Atlantic coast - only 8.1 °C.

Mountains, hills, and basins are very often zones of special climate, and mountain ranges are climate divisions.

Sea currents influence the climate; it is enough to mention the influence of the Gulf Stream on the climate of Europe. Filed by B.P. Alisov, according to the prevailing climate, the following zones are distinguished.

1. The equatorial belt, covering the basins of the Congo and Amazon rivers, the coast of the Gulf of Guinea, the Sunda Islands; The average annual temperature ranges from 25 to 28 ° C, the maximum temperature does not exceed +30 C, but the relative humidity is 70-90%. The amount of precipitation exceeds 2000 mm, and in some areas up to 5000 mm. The distribution of precipitation throughout the year is uniform.

High

pressure

H Low pressure

Low

pressure

High

pressure

Rice. 30. Scheme of air movement in a cyclone (A) and anticyclone (b)

• 2. Subequatorial belt, occupying the Brazilian Highlands, Central America, most of Hindustan and Indochina, and the northern part of Australia. The most characteristic feature is the seasonal change of air masses: wet (summer) and dry (winter) seasons are distinguished. It is in this belt in the northeast of Hindustan and the Hawaiian Islands that the “wettest” places on Earth are located, where the most precipitation falls.
• 3. The tropical zone, located on both sides of the tropics both on the oceans and on the continents. The average temperature significantly exceeds +30 *C (even +55 °C was noted). There is little precipitation (less than 200 mm). The largest deserts in the world are located here - the Sahara, Western Australian, Arabian, but at the same time, a lot of precipitation falls in the trade wind zones - the Greater Antilles, the eastern coasts of Brazil and Africa.
• 4. Subtropical zone, occupying large areas between the 25th and 40th parallels of northern and southern latitude. This belt is characterized by seasonal changes in air masses: in summer the entire region is occupied by tropical air, in winter by air of temperate latitudes. Three climatic regions have been identified - western, central and eastern. The western climatic region includes the Mediterranean coast, California, the central Andes, and southwestern Australia - the climate here is called Mediterranean (the weather is dry and sunny in summer, and warm and humid in winter). In East Asia and the southeast of North America, the climate is established under the influence of monsoons; the temperature of the coldest month is always above 0 C. In Eastern Turkey, Iran, Afghanistan, and the Great Basin of North America, dry air prevails all year round: tropical in summer, tropical in winter. continental. The amount of precipitation does not exceed 400 mm. In winter, the temperature is below 0 ° C, but without snow cover, daily amplitudes of values ​​​​up to 30 "C; there is a large difference in temperatures throughout the year. Here, in the central regions of the continents, deserts are located.
• 5. Temperate zone, located north and south of the subtropics approximately to the polar circles. In the southern hemisphere, the oceanic climate predominates, and in the northern hemisphere there are three climatic regions: western, central and eastern. In western Europe and Canada, the southern Andes, humid sea air of temperate latitudes predominates (500-1000 mm of precipitation per year). Precipitation falls evenly, and annual temperature fluctuations are small. Summer is long and warm; winters are mild, sometimes with heavy snowfalls. In the east (Far East, northeast China) the climate is monsoonal: in summer, humidity and precipitation are significant due to the oceanic monsoon input; In winter, due to the influence of continental cold air masses, temperatures drop to more than -30 °C. In the center (middle

Rice. 31.

strip of Russia, Ukraine, northern Kazakhstan, southern Canada) a temperate climate is formed, although the name is quite arbitrary, since often in winter the Arctic air comes here with very low temperatures. Winter is long and frosty; snow cover lasts for more than three months, summers are rainy and warm; the amount of precipitation decreases as we move deeper into the continent (from 700 to 200 mm). The most characteristic feature of the climate of this area is sharp temperature changes throughout the year and uneven distribution of precipitation, which sometimes causes droughts (Fig. 31, 32).

• 6. Subarctic (subantarctic) belt; these transition zones are located north of the temperate zone in the northern hemisphere and south of it in the southern hemisphere. They are characterized by a change in air masses by season: in summer - air of temperate latitudes, in winter - Arctic (Antarctic). Summer is short, cool, with an average temperature of the warmest month from 12 to 0 ° C with little precipitation (an average of 200 mm). Winter is long, frosty with a lot of snow. In the northern hemisphere, at these latitudes there is a tundra zone.
• 7. The Arctic (Antarctic) belt is a source of formation of cold air masses under conditions of high pressure. This belt is characterized by long polar nights and polar

Arctic fronts in summer

Polar fronts in summer

in winter

Rice. 32. Atmospheric fronts over the territory of Russia

in winter

days; their duration at the poles reaches up to six months. The low temperature background maintains a constant ice cover, which lies in the form of a thick layer in Antarctica and Greenland, and ice mountains - icebergs and ice fields float in the polar seas. The absolute minimum temperatures and the strongest winds are recorded here (Fig. 33).

The richest variety of relief forms, rivers, seas and lakes create conditions for education microclimate terrain, which is also important for the formation of the living environment.

The Earth's atmosphere, its air shell as a living environment, has features arising from the general characteristics described above and guiding the main paths of evolution of the inhabitants of this environment. Thus, a sufficiently high oxygen content (up to 21% in atmospheric air and somewhat less in the respiratory system of animals) determines the possibility of forming a high level of energy metabolism. It was in these basic conditions of the atmospheric environment that homeothermic animals arose, characterized by a high level of body energy, a high degree of autonomy from external influences and high biological activity in ecosystems. On the other hand, atmospheric air has low and variable humidity. This circumstance

Wrong Tropic

KEkhny tropic

Western winds

Eastern winds

Rice. 33. Polar vortex in the Northern Hemisphere

largely limited the possibilities of mastering the air environment, and among its inhabitants it directed the evolution of the fundamental properties of the water-salt metabolism system and the structure of the respiratory organs.

One of the most important (I.A. Shilov, 2000) features of the atmosphere as an arena of life is the low density of the air environment. When talking about its inhabitants, we mean terrestrial forms of plants and animals. The fact is that the low density of the habitat closes the possibility of the existence of organisms that carry out their vital functions without connection with the substrate. That is why life in the air occurs near the surface of the earth, rising into the atmosphere no more than 50-70 m (tree crowns in tropical forests). Following the features of the relief, living organisms can also be found at high altitudes (up to 5-6 km above sea level, although there is a fact of the presence of birds on Mount Everest, and lichens, bacteria and insects are regularly recorded at altitudes of about 7 km). High mountain conditions limit physiological processes that are associated with the partial pressure of atmospheric

gases, for example, in the Himalayas at an altitude of more than 6.2 km the border of green vegetation passes, since the reduced partial pressure of carbon dioxide does not allow photosynthetic plants to develop; animals, as having the ability to move, rise to great heights. Thus, the temporary presence of living organisms in the atmosphere is recorded at altitudes of up to 10-11 km; the record holder is the griffon vulture, which collided with an airplane at an altitude of 12.5 km (I.A. Shilov, 2000); flying insects were found at the same altitudes, and bacteria, spores, and protozoa were found at an altitude of 15 km; bacteria were even described to be found at an altitude of 77 km, and in a viable state.

Life in the atmosphere does not differ in any vertical structure in accordance with the flows of matter and energy moving in the biological cycle. The diversity of life forms in the terrestrial environment is more related to zonal climatic and landscape factors. The spherical shape of the Earth, its rotation and orbital movement create seasonal and latitudinal dynamics of the intensity of solar energy supply to various parts of the earth's surface, where geographic spaces similar in living conditions are formed, within which the features of climate, relief, water, soil and vegetation cover form the so-called landscape-climatic zones: polar deserts, tundras, temperate forests (coniferous, deciduous), steppes, savannas, deserts, tropical forests.

A complex of physical-geographical and climatic factors forms the most fundamental living conditions in each zone and acts as a powerful factor in the evolutionary formation of morphophysiological adaptations of plants and animals to life in these conditions.

Landscape-climatic zones play a significant role in the biogenic cycle. In particular, the leading role of green plants is clearly expressed in the terrestrial environment. The transparency of the atmosphere determines the circumstance in which the flow of solar radiation reaches the surface of the planet. Almost half of it is photosynthetically active radiation with a wavelength of 380-710 nm.

It is this part of the light flux that forms the energy basis of photosynthesis - a process in which, on the one hand, organic matter is created from inorganic components, and on the other, it opens up the possibility of using the released oxygen for respiration of both the plants themselves and heterotrophic aerobic organisms. This reflects the very presence of a biological cycle of substances on Earth.

An asterisk (2) in the formulas means that this molecule contains excess energy, which it needs to get rid of as quickly as possible, otherwise a reverse reaction will occur.

Earth is the 3rd planet from the Sun, located between Venus and Mars. It is the densest planet in the solar system, the largest of the four, and the only astronomical object known to host life. According to radiometric dating and other research methods, our planet formed about 4.54 billion years ago. The Earth gravitationally interacts with other objects in space, especially the Sun and Moon.

The Earth consists of four main spheres or shells, which depend on each other and are the biological and physical components of our planet. They are scientifically called biophysical elements, namely the hydrosphere ("hydro" for water), the biosphere ("bio" for living things), the lithosphere ("litho" for land or earth's surface), and the atmosphere ("atmo" for air). These main spheres of our planet are further divided into various sub-spheres.

Let's look at all four shells of the Earth in more detail to understand their functions and meaning.

Lithosphere - the hard shell of the Earth

According to scientists, there are more than 1386 million km³ of water on our planet.

The oceans contain more than 97% of the Earth's water. The rest is fresh water, two-thirds of which is frozen in the planet's polar regions and on snowy mountain peaks. It is interesting to note that although water covers most of the planet's surface, it makes up only 0.023% of the Earth's total mass.

The biosphere is the living shell of the Earth

The biosphere is sometimes considered one big one - a complex community of living and nonliving components functioning as a single whole. However, most often the biosphere is described as a collection of many ecological systems.

Atmosphere - the air envelope of the Earth

The atmosphere is the collection of gases surrounding our planet, held in place by the Earth's gravity. Most of our atmosphere is located near the earth's surface, where it is densest. The Earth's air is 79% nitrogen and just under 21% oxygen, as well as argon, carbon dioxide and other gases. Water vapor and dust are also part of the Earth's atmosphere. Other planets and the Moon have very different atmospheres, and some have no atmosphere at all. There is no atmosphere in space.

The atmosphere is so widespread that it is almost invisible, but its weight is equal to the layer of water more than 10 meters deep that covers our entire planet. The lower 30 kilometers of the atmosphere contain about 98% of its total mass.

Scientists say many of the gases in our atmosphere were released into the air by early volcanoes. At that time there was little or no free oxygen around the Earth. Free oxygen consists of oxygen molecules not bonded to another element, such as carbon (to form carbon dioxide) or hydrogen (to form water).

Free oxygen may have been added to the atmosphere by primitive organisms, probably bacteria, during . Later, more complex forms added more oxygen to the atmosphere. The oxygen in today's atmosphere likely took millions of years to accumulate.

The atmosphere acts like a giant filter, absorbing most of the ultraviolet radiation and allowing the sun's rays to penetrate. Ultraviolet radiation is harmful to living things and can cause burns. However, solar energy is essential for all life on Earth.

The Earth's atmosphere has. The following layers extend from the surface of the planet to the sky: troposphere, stratosphere, mesosphere, thermosphere and exosphere. Another layer, called the ionosphere, extends from the mesosphere to the exosphere. Outside the exosphere is space. The boundaries between atmospheric layers are not clearly defined and vary depending on latitude and time of year.

Interrelation of the Earth's shells

All four spheres can be present in one place. For example, a piece of soil will contain minerals from the lithosphere. In addition, there will be elements of the hydrosphere, which is moisture in the soil, the biosphere, which is insects and plants, and even the atmosphere, which is soil air.

All spheres are interconnected and depend on each other, like a single organism. Changes in one area will lead to changes in another. Therefore, everything we do on our planet affects other processes within its boundaries (even if we cannot see it with our own eyes).

For people dealing with problems, it is very important to understand the interconnection of all the layers of the Earth.