>> Earth's atmosphere

Description Earth's atmosphere for children of all ages: what air is made of, the presence of gases, layers with photos, climate and weather of the third planet of the solar system.

For the little ones It is already known that the Earth is the only planet in our system that has a viable atmosphere. The gas blanket is not only rich in air, but also protects us from excessive heat and solar radiation. Important explain to the children that the system is designed incredibly well, because it allows the surface to warm up during the day and cool down at night, maintaining an acceptable balance.

Begin explanation for children It is possible from the fact that the globe of the earth's atmosphere extends over 480 km, but most of it is located 16 km from the surface. How more height, the lower the pressure. If we take sea level, then the pressure there is 1 kg per square centimeter. But at an altitude of 3 km, it will change - 0.7 kg per square centimeter. Of course, in such conditions it is more difficult to breathe ( children you could feel this if you ever went hiking in the mountains).

Composition of the Earth's air - explanation for children

Among the gases there are:

• Nitrogen – 78%.
• Oxygen – 21%.
• Argon – 0.93%.
• Carbon dioxide – 0.038%.
• There is also water vapor and other gas impurities in small quantities.

Atmospheric layers of the Earth - explanation for children

Parents or teachers At school We should remind you that the earth's atmosphere is divided into 5 levels: exosphere, thermosphere, mesosphere, stratosphere and troposphere. With each layer, the atmosphere dissolves more and more until the gases finally disperse into space.

The troposphere is closest to the surface. With a thickness of 7-20 km, it makes up half of the earth's atmosphere. The closer to Earth, the more the air warms up. Almost all water vapor and dust are collected here. Children may not be surprised that clouds float at this level.

The stratosphere starts from the troposphere and rises 50 km above the surface. There is a lot of ozone here, which heats the atmosphere and protects from harmful solar radiation. The air is 1000 times thinner than above sea level and unusually dry. That is why airplanes feel great here.

Mesosphere: 50 km to 85 km above the surface. The peak is called the mesopause and is the coolest place in the earth's atmosphere (-90°C). It is very difficult to explore because jet planes cannot get there, and the orbital altitude of the satellites is too high. Scientists only know that this is where meteors burn up.

Thermosphere: 90 km and between 500-1000 km. The temperature reaches 1500°C. It is considered part of the earth's atmosphere, but it is important explain to the children that the air density here is so low that most of it is already perceived as outer space. In fact, this is where the space shuttles and the International space station. In addition, auroras are formed here. Charged cosmic particles come into contact with atoms and molecules of the thermosphere, transferring them to a higher energy level. Thanks to this, we see these photons of light in the form of the aurora.

The exosphere is the highest layer. An incredibly thin line of merging the atmosphere with space. Consists of widely scattered hydrogen and helium particles.

Earth's climate and weather - explanation for children

For the little ones need to explain that the Earth manages to support many living species thanks to a regional climate that is represented by extreme cold at the poles and tropical warmth at the equator. Children should know that regional climate is the weather that in a particular area remains unchanged for 30 years. Of course, sometimes it can change for a few hours, but for the most part it remains stable.

In addition, the global earth climate is distinguished - the average of the regional one. It has changed throughout human history. Today there is rapid warming. Scientists are sounding the alarm as greenhouse gases caused by human activity are trapping heat in the atmosphere, risking turning our planet into Venus.

The atmosphere is the air envelope of the Earth. Extending up to 3000 km from the earth's surface. Its traces can be traced to altitudes of up to 10,000 km. A. has an uneven density 50 5 its masses are concentrated up to 5 km, 75% - up to 10 km, 90% - up to 16 km.

The atmosphere consists of air - a mechanical mixture of several gases.

Nitrogen(78%) in the atmosphere plays the role of an oxygen diluent, regulating the rate of oxidation, and, consequently, the speed and intensity of biological processes. Nitrogen – main element the earth's atmosphere, which continuously exchanges with the living matter of the biosphere, the constituent parts of the latter being nitrogen compounds (amino acids, purines, etc.). Nitrogen is extracted from the atmosphere by inorganic and biochemical routes, although they are closely interrelated. Inorganic extraction is associated with the formation of its compounds N 2 O, N 2 O 5, NO 2, NH 3. They are in precipitation and are formed in the atmosphere under the influence of electrical discharges during thunderstorms or photochemical reactions under the influence of solar radiation.

Biological fixation of nitrogen is carried out by some bacteria in symbiosis with higher plants in soils. Nitrogen is also fixed by some plankton microorganisms and algae in marine environment. In quantitative terms, the biological fixation of nitrogen exceeds its inorganic fixation. The exchange of all nitrogen in the atmosphere occurs within approximately 10 million years. Nitrogen is found in gases of volcanic origin and in igneous rocks. When various samples of crystalline rocks and meteorites are heated, nitrogen is released in the form of N 2 and NH 3 molecules. However, the main form of the presence of nitrogen, both on Earth and on the terrestrial planets, is molecular. Ammonia, entering the upper atmosphere, quickly oxidizes, releasing nitrogen. In sedimentary rocks it is buried together with organic matter and is found in increased quantities in bituminous deposits. During regional metamorphism of these rocks, nitrogen is released in various forms into the Earth's atmosphere.

Geochemical nitrogen cycle (

Oxygen(21%) is used by living organisms for respiration and is part of organic matter (proteins, fats, carbohydrates). Ozone O 3. delays life-destructive ultraviolet radiation from the Sun.

Oxygen is the second most widespread gas in the atmosphere, playing an extremely important role in many processes in the biosphere. The dominant form of its existence is O 2. IN upper layers In the atmosphere, under the influence of ultraviolet radiation, dissociation of oxygen molecules occurs, and at an altitude of approximately 200 km, the ratio of atomic oxygen to molecular (O:O2) becomes equal to 10. When these forms of oxygen interact in the atmosphere (at an altitude of 20-30 km), an ozone belt appears ( ozone screen). Ozone (O 3) is necessary for living organisms, blocking most of the ultraviolet radiation from the Sun, which is harmful to them.

In the early stages of the Earth's development, free oxygen appeared in very small quantities as a result of photodissociation of carbon dioxide and water molecules in the upper layers of the atmosphere. However, these small amounts were quickly consumed by the oxidation of other gases. With the appearance of autotrophic photosynthetic organisms in the ocean, the situation changed significantly. The amount of free oxygen in the atmosphere began to increase progressively, actively oxidizing many components of the biosphere. Thus, the first portions of free oxygen contributed primarily to the transition of ferrous forms of iron into oxide forms, and sulfides into sulfates.

Eventually, the amount of free oxygen in the Earth's atmosphere reached a certain mass and was balanced in such a way that the amount produced became equal to the amount absorbed. A relative constant content of free oxygen has been established in the atmosphere.

Geochemical oxygen cycle (V.A. Vronsky, G.V. Voitkevich)

Carbon dioxide, goes into the formation of living matter, and together with water vapor creates the so-called “greenhouse (greenhouse) effect.”

Carbon (carbon dioxide) - most of it in the atmosphere is in the form of CO 2 and much less in the form of CH 4. The significance of the geochemical history of carbon in the biosphere is extremely great, since it is part of all living organisms. Within living organisms, reduced forms of carbon predominate, and in environment biospheres are oxidized. Thus, a chemical exchange is established life cycle: CO 2 ↔ living matter.

The source of primary carbon dioxide in the biosphere is volcanic activity associated with secular degassing of the mantle and lower horizons of the earth's crust. Part of this carbon dioxide arises during the thermal decomposition of ancient limestones in various metamorphic zones. Migration of CO 2 in the biosphere occurs in two ways.

The first method is expressed in the absorption of CO 2 during photosynthesis with the formation of organic substances and subsequent burial in favorable reducing conditions in the lithosphere in the form of peat, coal, oil, and oil shale. According to the second method, carbon migration leads to the creation of a carbonate system in the hydrosphere, where CO 2 turns into H 2 CO 3, HCO 3 -1, CO 3 -2. Then, with the participation of calcium (less commonly magnesium and iron), carbonates are deposited via biogenic and abiogenic pathways. Thick layers of limestone and dolomite appear. According to A.B. Ronov, the ratio of organic carbon (Corg) to carbonate carbon (Ccarb) in the history of the biosphere was 1:4.

Along with the global carbon cycle, there are also a number of small carbon cycles. So, on land, green plants absorb CO 2 for the process of photosynthesis in daytime, and at night they release it into the atmosphere. With the death of living organisms on the earth's surface, oxidation of organic substances occurs (with the participation of microorganisms) with the release of CO 2 into the atmosphere. IN last decades A special place in the carbon cycle is occupied by the massive combustion of fossil fuels and the increase in its content in the modern atmosphere.

Carbon cycle in the geographic envelope (according to F. Ramad, 1981)

Argon- the third most widespread atmospheric gas, which sharply distinguishes it from the extremely sparsely distributed other inert gases. However, argon in its geological history shares the fate of these gases, which are characterized by two features:

1. the irreversibility of their accumulation in the atmosphere;
2. close connection with the radioactive decay of certain unstable isotopes.

Inert gases are outside the cycle of most cyclic elements in the Earth's biosphere.

All inert gases can be divided into primary and radiogenic. The primary ones include those that were captured by the Earth during the period of its formation. They are extremely rare. The primary part of argon is represented mainly by the isotopes 36 Ar and 38 Ar, while atmospheric argon consists entirely of the isotope 40 Ar (99.6%), which is undoubtedly radiogenic. In potassium-containing rocks, the accumulation of radiogenic argon occurred and continues to occur due to the decay of potassium-40 through electron capture: 40 K + e → 40 Ar.

Therefore, the argon content in rocks is determined by their age and the amount of potassium. To this extent, the helium concentration in rocks is a function of their age and thorium and uranium content. Argon and helium are released into the atmosphere from the bowels of the earth during volcanic eruptions, through cracks in the earth's crust in the form of gas jets, and also during weathering of rocks. According to calculations performed by P. Dimon and J. Culp, helium and argon in modern era accumulate in the earth's crust and enter the atmosphere in relatively small quantities. The rate of entry of these radiogenic gases is so low that during the geological history of the Earth it could not ensure their observed content in the modern atmosphere. Therefore, it remains to be assumed that most of the argon in the atmosphere came from the interior of the Earth at the earliest stages of its development, and much less was added subsequently during the process of volcanism and during the weathering of potassium-containing rocks.

Thus, over geological time, helium and argon have had different migration processes. There is very little helium in the atmosphere (about 5 * 10 -4%), and the “helium breathing” of the Earth was lighter, since it, as the lightest gas, evaporated into outer space. And “argon breathing” was heavy and argon remained within the boundaries of our planet. Most of the primordial noble gases, such as neon and xenon, were associated with primordial neon captured by the Earth during its formation, as well as with release during degassing of the mantle into the atmosphere. The entire body of data on the geochemistry of noble gases indicates that the primary atmosphere of the Earth arose at the earliest stages of its development.

The atmosphere contains water vapor And water in liquid and solid state. Water in the atmosphere is an important heat accumulator.

The lower layers of the atmosphere contain a large number of mineral and technogenic dust and aerosols, combustion products, salts, spores and pollen, etc.

Up to an altitude of 100-120 km, due to complete mixing of air, the composition of the atmosphere is homogeneous. The ratio between nitrogen and oxygen is constant. Above, inert gases, hydrogen, etc. predominate. In the lower layers of the atmosphere there is water vapor. With distance from the earth its content decreases. Higher the ratio of gases changes, for example, at an altitude of 200-800 km, oxygen predominates over nitrogen by 10-100 times.

Composition of the Earth. Air

Air is a mechanical mixture of various gases that make up the Earth's atmosphere. Air is necessary for the respiration of living organisms and is widely used in industry.

The fact that air is a mixture, and not a homogeneous substance, was proven during the experiments of the Scottish scientist Joseph Black. During one of them, the scientist discovered that when white magnesia (magnesium carbonate) is heated, “bound air” is released, that is, carbon dioxide, and burnt magnesia (magnesium oxide) is formed. When burning limestone, on the contrary, “bound air” is removed. Based on these experiments, the scientist concluded that the difference between carbon dioxide and caustic alkalis is that the former contains carbon dioxide, which is one of the constituents of air. Today we know that in addition to carbon dioxide, the composition of the earth’s air includes:

The ratio of gases in the earth's atmosphere indicated in the table is typical for its lower layers, up to an altitude of 120 km. In these areas lies a well-mixed, homogeneous region called the homosphere. Above the homosphere lies the heterosphere, which is characterized by the decomposition of gas molecules into atoms and ions. The regions are separated from each other by a turbo pause.

The chemical reaction in which molecules are decomposed into atoms under the influence of solar and cosmic radiation is called photodissociation. The decay of molecular oxygen produces atomic oxygen, which is the main gas of the atmosphere at altitudes above 200 km. At altitudes above 1200 km, hydrogen and helium, which are the lightest of the gases, begin to predominate.

Since the bulk of the air is concentrated in the 3 lower atmospheric layers, changes in air composition at altitudes above 100 km do not have a noticeable effect on general composition atmosphere.

Nitrogen is the most common gas, accounting for more than three-quarters of the Earth's air volume. Modern nitrogen was formed by the oxidation of the early ammonia-hydrogen atmosphere by molecular oxygen, which is formed during photosynthesis. Currently, small amounts of nitrogen enter the atmosphere as a result of denitrification - the process of reducing nitrates to nitrites, followed by the formation of gaseous oxides and molecular nitrogen, which is produced by anaerobic prokaryotes. Some nitrogen enters the atmosphere during volcanic eruptions.

In the upper layers of the atmosphere, when exposed to electrical discharges with the participation of ozone, molecular nitrogen is oxidized to nitrogen monoxide:

N 2 + O 2 → 2NO

Under normal conditions, the monoxide immediately reacts with oxygen to form nitrous oxide:

2NO + O 2 → 2N 2 O

Nitrogen is essential chemical element earth's atmosphere. Nitrogen is part of proteins and provides mineral nutrition to plants. It determines the rate of biochemical reactions and plays the role of an oxygen diluent.

The second most common gas in the Earth's atmosphere is oxygen. The formation of this gas is associated with the photosynthetic activity of plants and bacteria. And the more diverse and numerous photosynthetic organisms became, the more significant the process of oxygen content in the atmosphere became. A small amount of heavy oxygen is released during degassing of the mantle.

In the upper layers of the troposphere and stratosphere, under the influence of ultraviolet solar radiation (we denote it as hν), ozone is formed:

O 2 + hν → 2O

As a result of the same ultraviolet radiation, ozone decomposes:

O 3 + hν → O 2 + O

О 3 + O → 2О 2

As a result of the first reaction, atomic oxygen is formed, and as a result of the second, molecular oxygen is formed. All 4 reactions are called the “Chapman mechanism”, named after the British scientist Sidney Chapman who discovered them in 1930.

Oxygen is used for the respiration of living organisms. With its help, oxidation and combustion processes occur.

Ozone serves to protect living organisms from ultraviolet radiation, which causes irreversible mutations. The highest concentration of ozone is observed in the lower stratosphere within the so-called. ozone layer or ozone screen, lying at altitudes of 22-25 km. The ozone content is low: at normal pressure all the ozone in the earth's atmosphere would occupy a layer only 2.91 mm thick.

The formation of the third most common gas in the atmosphere, argon, as well as neon, helium, krypton and xenon, is associated with volcanic eruptions and the decay of radioactive elements.

In particular, helium is a product of the radioactive decay of uranium, thorium and radium: 238 U → 234 Th + α, 230 Th → 226 Ra + 4 He, 226 Ra → 222 Rn + α (in these reactions the α-particle is the helium nucleus, which in During the process of energy loss, it captures electrons and becomes 4 He).

Argon is formed during the decay of the radioactive isotope of potassium: 40 K → 40 Ar + γ.

Neon escapes from igneous rocks.

Krypton is formed as the end product of the decay of uranium (235 U and 238 U) and thorium Th.

The bulk of atmospheric krypton was formed in the early stages of the Earth's evolution as a result of the decay of transuranic elements with a phenomenally short half-life or came from space, where the krypton content is ten million times higher than on Earth.

Xenon is the result of the fission of uranium, but the bulk of this gas remains from the early stages of the formation of the Earth, from the primordial atmosphere.

Carbon dioxide enters the atmosphere as a result of volcanic eruptions and during the decomposition of organic matter. Its content in the atmosphere of the Earth's mid-latitudes varies greatly depending on the seasons of the year: in winter the amount of CO 2 increases, and in summer it decreases. This fluctuation is associated with the activity of plants that use carbon dioxide in the process of photosynthesis.

Hydrogen is formed as a result of the decomposition of water by solar radiation. But, being the lightest of the gases that make up the atmosphere, it constantly evaporates into outer space, and therefore its content in the atmosphere is very small.

Water vapor is the result of the evaporation of water from the surface of lakes, rivers, seas and land.

The concentration of the main gases in the lower layers of the atmosphere, with the exception of water vapor and carbon dioxide, is constant. In small quantities the atmosphere contains sulfur oxide SO 2, ammonia NH 3, carbon monoxide CO, ozone O 3, hydrogen chloride HCl, hydrogen fluoride HF, nitrogen monoxide NO, hydrocarbons, mercury vapor Hg, iodine I 2 and many others. In the bottom atmospheric layer The troposphere constantly contains a large number of suspended solid and liquid particles.

The sources of particulate matter in the Earth's atmosphere are volcanic eruptions, plant pollen, microorganisms, and Lately and human activities, such as the burning of fossil fuels during production. The smallest particles of dust, which are condensation nuclei, cause the formation of fogs and clouds. Without particulate matter constantly present in the atmosphere, precipitation would not fall on Earth.

The Earth's atmosphere is gas shell of our planet. Its lower boundary passes at the level of the earth's crust and hydrosphere, and its upper boundary passes into the near-Earth region of outer space. The atmosphere contains about 78% nitrogen, 20% oxygen, up to 1% argon, carbon dioxide, hydrogen, helium, neon and some other gases.

This earth's shell is characterized by clearly defined layering. The layers of the atmosphere are determined by the vertical distribution of temperature and the different densities of gases at different levels. The following layers of the Earth's atmosphere are distinguished: troposphere, stratosphere, mesosphere, thermosphere, exosphere. The ionosphere is separated separately.

Up to 80% of the total mass of the atmosphere is the troposphere - the lower ground layer atmosphere. The troposphere in the polar zones is located at a level of up to 8-10 km above earth's surface, V tropical zone- maximum up to 16-18 km. Between the troposphere and the overlying layer of the stratosphere there is a tropopause - a transition layer. In the troposphere, the temperature decreases as altitude increases; similarly, it decreases with altitude Atmosphere pressure. The average temperature gradient in the troposphere is 0.6°C per 100 m. Temperature at different levels of a given shell is determined by the characteristics of absorption of solar radiation and the efficiency of convection. Almost all human activity takes place in the troposphere. The most high mountains do not go beyond the troposphere, only air transport can cross the upper boundary of this shell at a low altitude and be in the stratosphere. A large proportion of water vapor is found in the troposphere, which is responsible for the formation of almost all clouds. Also, almost all aerosols (dust, smoke, etc.) formed on the earth’s surface are concentrated in the troposphere. In the boundary lower layer of the troposphere, daily fluctuations in temperature and air humidity are pronounced, and wind speed is usually reduced (it increases with increasing altitude). In the troposphere, there is a variable division of the air thickness into air masses in the horizontal direction, which differ in a number of characteristics depending on the zone and area of ​​their formation. On atmospheric fronts– boundaries between air masses – cyclones and anticyclones form, determining the weather on certain territory during a specific period of time.

The stratosphere is the layer of atmosphere between the troposphere and mesosphere. The limits of this layer range from 8-16 km to 50-55 km above the Earth's surface. In the stratosphere, the gas composition of the air is approximately the same as in the troposphere. Distinctive feature– decrease in water vapor concentration and increase in ozone content. The ozone layer of the atmosphere, which protects the biosphere from the aggressive effects of ultraviolet light, is located at a level of 20 to 30 km. In the stratosphere, temperature increases with altitude, and temperature values ​​​​are determined by solar radiation, and not by convection (movements). air masses), as in the troposphere. The heating of the air in the stratosphere is due to the absorption of ultraviolet radiation by ozone.

Above the stratosphere the mesosphere extends to a level of 80 km. This layer of the atmosphere is characterized by the fact that the temperature decreases as the altitude increases from 0 ° C to - 90 ° C. This is the coldest region of the atmosphere.

Above the mesosphere is the thermosphere up to a level of 500 km. From the border with the mesosphere to the exosphere, the temperature varies from approximately 200 K to 2000 K. Up to the level of 500 km, the air density decreases several hundred thousand times. The relative composition of the atmospheric components of the thermosphere is similar to the surface layer of the troposphere, but with increasing altitude, more oxygen becomes atomic. A certain proportion of molecules and atoms of the thermosphere are in an ionized state and are distributed in several layers; they are united by the concept of the ionosphere. The characteristics of the thermosphere vary over a wide range depending on geographic latitude, the amount of solar radiation, time of year and day.

The upper layer of the atmosphere is the exosphere. This is the thinnest layer of the atmosphere. In the exosphere, the mean free path of particles is so enormous that particles can freely escape into interplanetary space. The mass of the exosphere is one ten-millionth of the total mass of the atmosphere. The lower boundary of the exosphere is the level of 450-800 km, and the upper boundary is considered to be the region where the concentration of particles is the same as in outer space - several thousand kilometers from the Earth's surface. The exosphere consists of plasma - ionized gas. Also in the exosphere are the radiation belts of our planet.

Video presentation - layers of the Earth's atmosphere:

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The gaseous envelope surrounding our planet Earth, known as the atmosphere, consists of five main layers. These layers originate on the surface of the planet, from sea level (sometimes below) and rise to outer space in the following sequence:

• Troposphere;
• Stratosphere;
• Mesosphere;
• Thermosphere;
• Exosphere.

Diagram of the main layers of the Earth's atmosphere

In between each of these main five layers are transition zones called "pauses" where changes in air temperature, composition and density occur. Together with pauses, the Earth's atmosphere includes a total of 9 layers.

Troposphere: where weather occurs

Of all the layers of the atmosphere, the troposphere is the one with which we are most familiar (whether you realize it or not), since we live on its bottom - the surface of the planet. It envelops the surface of the Earth and extends upward for several kilometers. The word troposphere means "change of the globe." Very appropriate name, since this layer is where our everyday weather occurs.

Starting from the surface of the planet, the troposphere rises to a height of 6 to 20 km. The lower third of the layer, closest to us, contains 50% of all atmospheric gases. This is the only part of the entire atmosphere that breathes. Due to the fact that the air is heated from below by the earth's surface, absorbing thermal energy The sun, with increasing altitude, the temperature and pressure of the troposphere decrease.

At the top there is a thin layer called the tropopause, which is just a buffer between the troposphere and the stratosphere.

Stratosphere: home of the ozone

The stratosphere is the next layer of the atmosphere. It extends from 6-20 km to 50 km above the Earth's surface. This is the layer in which most commercial airliners fly and hot air balloons travel.

Here the air does not flow up and down, but moves parallel to the surface in very fast air currents. As you rise, the temperature increases, thanks to the abundance of naturally occurring ozone (O3), a byproduct of solar radiation and oxygen, which has the ability to absorb the sun's harmful ultraviolet rays (any increase in temperature with altitude in meteorology is known as an "inversion") .

Since the stratosphere has more warm temperatures below and cooler above, convection (vertical movement of air masses) is rare in this part of the atmosphere. In fact, you can view a storm raging in the troposphere from the stratosphere because the layer acts as a convection cap that prevents storm clouds from penetrating.

After the stratosphere there is again a buffer layer, this time called the stratopause.

Mesosphere: middle atmosphere

The mesosphere is located approximately 50-80 km from the Earth's surface. The upper mesosphere is the coldest natural place on Earth, where temperatures can drop below -143°C.

Thermosphere: upper atmosphere

After the mesosphere and mesopause comes the thermosphere, located between 80 and 700 km above the surface of the planet, and contains less than 0.01% of the total air in the atmospheric envelope. Temperatures here reach up to +2000° C, but due to the strong rarefaction of the air and the lack of gas molecules to transfer heat, these high temperatures are perceived as very cold.

Exosphere: the boundary between the atmosphere and space

At an altitude of about 700-10,000 km above the earth's surface is the exosphere - the outer edge of the atmosphere, bordering space. Here weather satellites orbit the Earth.

What about the ionosphere?

The ionosphere is not a separate layer, but in fact the term is used to refer to the atmosphere between 60 and 1000 km altitude. It includes the uppermost parts of the mesosphere, the entire thermosphere and part of the exosphere. The ionosphere gets its name because in this part of the atmosphere the radiation from the Sun is ionized when it passes through the Earth's magnetic fields at and. This phenomenon is observed from the ground as the northern lights.