Layers of planet earth in order. Internal structure of the Earth (core, mantle, crust). Layers of the earth for children in pictures

In the twentieth century, through numerous studies, humanity revealed the secret of the earth's interior; the structure of the earth in cross-section became known to every schoolchild. For those who do not yet know what the earth is made of, what its main layers are, their composition, what the thinnest part of the planet is called, we will list a number of significant facts.

Shape and size of planet Earth

Contrary to general delusion our planet is not round. Its shape is called a geoid and is a slightly flattened ball. The places where the globe is compressed are called poles. The axis of the earth's rotation passes through the poles; our planet makes one revolution around it in 24 hours - an earthly day.

The planet is encircled in the middle - an imaginary circle dividing the geoid into the Northern and Southern Hemispheres.

Besides the equator, there are meridians - circles, perpendicular to the equator and passing through both poles. One of them, passing through the Greenwich Observatory, is called zero - it serves as the reference point for geographic longitude and time zones.

To the main characteristics globe can be attributed:

• diameter (km): equatorial – 12,756, polar (at the poles) – 12,713;
• length (km) of the equator – 40,057, meridian – 40,008.

So, our planet is a kind of ellipse - a geoid, rotating around its axis passing through two poles - North and South.

The central part of the geoid is surrounded by the equator - a circle dividing our planet into two hemispheres. In order to determine what the radius of the earth is, half the values ​​of its diameter at the poles and the equator are used.

And now about that what the earth is made of, what shells is it covered with and what is the sectional structure of the earth.

Earth shells

Basic shells of the earth allocated depending on their contents. Since our planet is spherical in shape, its shells, held by gravity, are called spheres. If you look at tripling of the earth in cross-section, then three spheres can be seen:

In order(starting from the surface of the planet) they are located as follows:

1. Lithosphere - the hard shell of the planet, including minerals layers of the earth.
2. Hydrosphere - contains water resources - rivers, lakes, seas and oceans.
3. Atmosphere – is a shell of air surrounding the planet.

In addition, the biosphere is also distinguished, which includes all living organisms that inhabit other shells.

Important! Many scientists classify the planet's population as belonging to a separate vast shell called the anthroposphere.

The earth's shells - lithosphere, hydrosphere and atmosphere - are identified according to the principle of combining a homogeneous component. In the lithosphere - these are solid rocks, soil, the internal contents of the planet, in the hydrosphere - all of it, in the atmosphere - all the air and other gases.

Atmosphere

The atmosphere is a gaseous shell, in its composition includes: nitrogen, carbon dioxide, gas, dust.

1. The troposphere is the upper layer of the earth, containing most of the earth's air and extending from the surface to a height of 8-10 (at the poles) to 16-18 km (at the equator). Clouds and various air masses form in the troposphere.
2. The stratosphere is a layer in which the air content is much lower than in the troposphere. His average thickness is 39-40 km. This layer begins from the upper boundary of the troposphere and ends at an altitude of about 50 km.
3. The mesosphere is a layer of the atmosphere extending from 50-60 to 80-90 km above the earth's surface. Characterized by a steady decrease in temperature.
4. Thermosphere - located 200-300 km from the surface of the planet, differs from the mesosphere by the increase in temperature as altitude increases.
5. Exosphere - starts from the upper boundary, lying below the thermosphere, and gradually moves into open space, it is characterized by low air content and high solar radiation.

Attention! In the stratosphere, at an altitude of about 20-25 km, there is a thin layer of ozone that protects all life on the planet from harmful ultraviolet rays. Without it, all living things would die very soon.

The atmosphere is the earth's shell, without which life on the planet would be impossible.

It contains the air necessary for living organisms to breathe, determines suitable weather conditions, and protects the planet from negative influence solar radiation.

The atmosphere consists of air, in turn, the air consists of approximately 70% nitrogen, 21% oxygen, 0.4% carbon dioxide and the rest of the rare gases.

In addition, there is an important ozone layer in the atmosphere, at an altitude of approximately 50 km.

Hydrosphere

The hydrosphere is all the liquids on the planet.

This shell by location water resources and the degree of their salinity includes:

• the world ocean - a huge space occupied by salt water and including four and 63 seas;
• The surface waters of the continents are freshwater, as well as occasionally brackish waters. They are divided according to the degree of fluidity into bodies of water with flow - rivers and reservoirs with standing water - lakes, ponds, swamps;
• groundwater is fresh water located below the earth's surface. Depth their occurrence ranges from 1-2 to 100-200 or more meters.

Important! Huge number fresh water is currently in the form of ice - today in permafrost zones in the form of glaciers, huge icebergs, permanent non-melting snow, there are about 34 million km3 of fresh water reserves.

The hydrosphere is, first of all,, fresh source drinking water, one of the main climate-forming factors. Water resources are used as communication routes and tourism and recreation (leisure) facilities.

Lithosphere

The lithosphere is solid ( mineral) layers of the earth. The thickness of this shell ranges from 100 (under the seas) to 200 km (under the continents). The lithosphere includes the earth's crust and upper mantle.

What is located below the lithosphere is the immediate internal structure of our planet.

The lithosphere plates are predominantly composed of basalt, sand and clay, stone, and the soil layer.

Earth structure diagram together with the lithosphere, it is represented by the following layers:

• earth's crust - upper, consisting of sedimentary, basaltic, metamorphic rocks and fertile soil. Depending on the location, continental and oceanic crust are distinguished;
• mantle - located under the earth's crust. Weighs about 67% of the total mass of the planet. The thickness of this layer is about 3000 km. The upper layer of the mantle is viscous and lies at a depth of 50-80 km (under the oceans) and 200-300 km (under the continents). The lower layers are harder and denser. The mantle contains heavy iron and nickel materials. Processes occurring in the mantle are responsible for many phenomena on the surface of the planet (seismic processes, volcanic eruptions, formation of deposits);
• The central part of the earth is occupied core consisting of an inner solid and an outer liquid part. The thickness of the outer part is about 2200 km, the inner part is 1300 km. Distance from surface d about the core of the earth is about 3000-6000 km. The temperature in the center of the planet is about 5000 Cº. According to many scientists, the nucleus land by composition is a heavy iron-nickel melt with an admixture of other elements similar in properties to iron.

Important! Among a narrow circle of scientists, in addition to the classical model with a semi-molten heavy core, there is also a theory that in the center of the planet there is an inner star, surrounded on all sides by an impressive layer of water. This theory, except for a small circle of adherents in the scientific community, has found widespread use in science fiction literature. An example is the novel by V.A. Obruchev "Plutonia", which tells about the expedition of Russian scientists to the cavity inside the planet with its own small star and a world of animals and plants extinct on the surface.

Such a generally accepted diagram of the structure of the earth, including the earth's crust, mantle and core, is becoming more and more improved and refined every year.

Many parameters of the model will be updated more than once with the improvement of research methods and the advent of new equipment.

So, for example, in order to find out exactly how many kilometers to the outer part of the core, more years of scientific research will be needed.

On at the moment The deepest mine in the earth's crust dug by man is about 8 kilometers, so studying the mantle, and even more so the planet's core, is possible only in a theoretical context.

Layer-by-layer structure of the Earth

We study what layers the Earth consists of inside

Conclusion

Having considered sectional structure of the earth, we have seen how interesting and complex our planet is. Studying its structure in the future will help humanity understand the mysteries natural phenomena, will make it possible to more accurately predict destructive natural disasters, discover new, not yet developed deposits minerals.

A characteristic feature of the evolution of the Earth is the differentiation of matter, the expression of which is the shell structure of our planet. The lithosphere, hydrosphere, atmosphere, biosphere form the main shells of the Earth, differing in chemical composition, thickness and state of matter.

Internal structure of the Earth

Chemical composition of the Earth(Fig. 1) is similar to the composition of other terrestrial planets, such as Venus or Mars.

In general, elements such as iron, oxygen, silicon, magnesium, and nickel predominate. The content of light elements is low. The average density of the Earth's substance is 5.5 g/cm 3 .

There is very little reliable data on the internal structure of the Earth. Let's look at Fig. 2. It depicts the internal structure of the Earth. The Earth consists of the crust, mantle and core.

Rice. 1. Chemical composition of the Earth

Rice. 2. Internal structure Earth

Core

Core(Fig. 3) is located in the center of the Earth, its radius is about 3.5 thousand km. The temperature of the core reaches 10,000 K, i.e. it is higher than the temperature of the outer layers of the Sun, and its density is 13 g/cm 3 (compare: water - 1 g/cm 3). The core is believed to be composed of iron and nickel alloys.

The outer core of the Earth has a greater thickness than the inner core (radius 2200 km) and is in a liquid (molten) state. The inner core is subject to enormous pressure. The substances that compose it are in a solid state.

Mantle

Mantle- the Earth’s geosphere, which surrounds the core and makes up 83% of the volume of our planet (see Fig. 3). Its lower boundary is located at a depth of 2900 km. The mantle is divided into a less dense and plastic upper part (800-900 km), from which it is formed magma(translated from Greek means “thick ointment”; this is the molten substance of the earth’s interior - a mixture chemical compounds and elements, including gases, in a special floor liquid state); and the crystalline lower one, about 2000 km thick.

Rice. 3. Structure of the Earth: core, mantle and crust

Earth's crust

Earth's crust - the outer shell of the lithosphere (see Fig. 3). Its density is approximately two times less than the average density of the Earth - 3 g/cm 3 .

Separates the earth's crust from the mantle Mohorovicic border(often called the Moho boundary), characterized by a sharp increase in seismic wave velocities. It was installed in 1909 by a Croatian scientist Andrei Mohorovicic (1857- 1936).

Since the processes occurring in the uppermost part of the mantle affect the movements of matter in the earth's crust, they are combined under the general name lithosphere(stone shell). The thickness of the lithosphere ranges from 50 to 200 km.

Below the lithosphere is located asthenosphere- less hard and less viscous, but more plastic shell with a temperature of 1200 ° C. It can cross the Moho boundary, penetrating into the earth's crust. The asthenosphere is the source of volcanism. It contains pockets of molten magma, which penetrates into the earth's crust or pours out onto the earth's surface.

Composition and structure of the earth's crust

Compared to the mantle and core, the earth's crust is a very thin, hard and brittle layer. It is composed of a lighter substance, which currently contains about 90 natural chemical elements. These elements are not equally represented in the earth's crust. Seven elements - oxygen, aluminum, iron, calcium, sodium, potassium and magnesium - account for 98% of the mass of the earth's crust (see Fig. 5).

Peculiar combinations of chemical elements form various rocks and minerals. The oldest of them are at least 4.5 billion years old.

Rice. 4. Structure of the earth's crust

Rice. 5. Composition of the earth's crust

Mineral is a relatively homogeneous natural body in its composition and properties, formed both in the depths and on the surface of the lithosphere. Examples of minerals are diamond, quartz, gypsum, talc, etc. (You will find characteristics of the physical properties of various minerals in Appendix 2.) The composition of the Earth's minerals is shown in Fig. 6.

Rice. 6. General mineral composition Earth

Rocks consist of minerals. They can be composed of one or several minerals.

Sedimentary rocks - clay, limestone, chalk, sandstone, etc. - formed by sedimentation of substances in aquatic environment and on land. They lie in layers. Geologists call them pages of the history of the Earth, because they can learn about natural conditions that existed on our planet in ancient times.

Among sedimentary rocks, organogenic and inorganogenic (clastic and chemogenic) are distinguished.

Organogenic Rocks are formed as a result of the accumulation of animal and plant remains.

Clastic rocks are formed as a result of weathering, destruction by water, ice or wind of the products of destruction of previously formed rocks (Table 1).

Table 1. Clastic rocks depending on the size of the fragments

Breed name	Size of bummer con (particles)
	More than 50 cm
	5 mm - 1 cm
	1 mm - 5 mm
Sand and sandstones	0.005 mm - 1 mm
	Less than 0.005mm

Chemogenic Rocks are formed as a result of the precipitation of substances dissolved in them from the waters of seas and lakes.

In the thickness of the earth's crust, magma forms igneous rocks(Fig. 7), for example granite and basalt.

Sedimentary and igneous rocks when immersed to great depths under the influence of pressure and high temperatures undergo significant changes, becoming metamorphic rocks. For example, limestone turns into marble, quartz sandstone into quartzite.

The structure of the earth's crust is divided into three layers: sedimentary, granite, and basalt.

Sedimentary layer(see Fig. 8) is formed mainly by sedimentary rocks. Clays and shales predominate here, and sandy, carbonate and volcanic rocks are widely represented. In the sedimentary layer there are deposits of such minerals, like coal, gas, oil. All of them are of organic origin. For example, coal is a product of the transformation of plants of ancient times. The thickness of the sedimentary layer varies widely - from complete absence in some areas of land up to 20-25 km in deep depressions.

Rice. 7. Classification of rocks by origin

"Granite" layer consists of metamorphic and igneous rocks, similar in their properties to granite. The most common here are gneisses, granites, crystalline schists, etc. The granite layer is not found everywhere, but on continents where it is well expressed, its maximum thickness can reach several tens of kilometers.

"Basalt" layer formed by rocks close to basalts. These are metamorphosed igneous rocks, denser than the rocks of the “granite” layer.

Power and vertical structure the earth's crust are different. There are several types of the earth's crust (Fig. 8). According to the simplest classification, a distinction is made between oceanic and continental crust.

Continental and oceanic crust vary in thickness. Thus, the maximum thickness of the earth’s crust is observed under mountain systems. It is about 70 km. Under the plains the thickness of the earth's crust is 30-40 km, and under the oceans it is thinnest - only 5-10 km.

Rice. 8. Types of the earth's crust: 1 - water; 2- sedimentary layer; 3—interlayering of sedimentary rocks and basalts; 4 - basalts and crystalline ultrabasic rocks; 5 – granite-metamorphic layer; 6 – granulite-mafic layer; 7 - normal mantle; 8 - decompressed mantle

The difference between the continental and oceanic crust in the composition of rocks is manifested in the fact that there is no granite layer in the oceanic crust. And the basalt layer of the oceanic crust is very unique. In terms of rock composition, it differs from a similar layer of continental crust.

The boundary between land and ocean (zero mark) does not record the transition of the continental crust to the oceanic one. The replacement of continental crust by oceanic crust occurs in the ocean at a depth of approximately 2450 m.

Rice. 9. Structure of the continental and oceanic crust

There are also transitional types of the earth's crust - suboceanic and subcontinental.

Suboceanic crust located along continental slopes and foothills, can be found in marginal and Mediterranean seas. It represents continental crust with a thickness of up to 15-20 km.

Subcontinental crust located, for example, on volcanic island arcs.

Based on materials seismic sounding - the speed of passage of seismic waves - we obtain data on the deep structure of the earth’s crust. Yes, Kola ultra-deep well, which for the first time made it possible to see rock samples from a depth of more than 12 km, brought many unexpected things. It was assumed that at a depth of 7 km a “basalt” layer should begin. In reality, it was not discovered, and gneisses predominated among the rocks.

Change in temperature of the earth's crust with depth. The surface layer of the earth's crust has a temperature determined by solar heat. This heliometric layer(from the Greek helio - Sun), experiencing seasonal temperature fluctuations. Its average thickness is about 30 m.

Below is an even thinner layer, characteristic feature which is a constant temperature corresponding to the average annual temperature of the observation site. The depth of this layer increases in continental climates.

Even deeper in the earth's crust there is a geothermal layer, the temperature of which is determined by the internal heat of the Earth and increases with depth.

The increase in temperature occurs mainly due to the decay of radioactive elements that make up rocks, primarily radium and uranium.

The amount of temperature increase in rocks with depth is called geothermal gradient. It varies within a fairly wide range - from 0.1 to 0.01 °C/m - and depends on the composition of rocks, the conditions of their occurrence and a number of other factors. Under the oceans, temperature increases faster with depth than on continents. On average, with every 100 m of depth it becomes warmer by 3 °C.

The reciprocal of the geothermal gradient is called geothermal stage. It is measured in m/°C.

The heat of the earth's crust is an important energy source.

The part of the earth's crust that extends to depths accessible to geological study forms bowels of the Earth. The Earth's interior requires special protection and reasonable use.

The Earth belongs to the terrestrial planets, and, unlike gas giants such as Jupiter, has a solid surface. It is the largest of the four terrestrial planets in the Solar System, both in size and mass. In addition, the Earth among these four planets has the highest density, surface gravity and magnetic field. It is the only known planet with active plate tectonics.

The Earth's interior is divided into layers according to chemical and physical (rheological) properties, but unlike other terrestrial planets, the Earth has a distinct outer and inner core. The outer layer of the Earth is a hard shell consisting mainly of silicates. It is separated from the mantle by a boundary with a sharp increase in the velocities of longitudinal seismic waves - the Mohorovicic surface. The solid crust and viscous upper part of the mantle make up the lithosphere. Below the lithosphere is the asthenosphere, a layer of relatively low viscosity, hardness and strength in the upper mantle.

Significant changes in the crystalline structure of the mantle occur at a depth of 410-660 km below the surface, encompassing the transition zone that separates the upper and lower mantle. Beneath the mantle is a liquid layer consisting of molten iron with admixtures of nickel, sulfur and silicon - the Earth's core. Seismic measurements show that it consists of 2 parts: a solid inner core with a radius of ~1220 km and a liquid outer core with a radius of ~2250 km.

Form

The shape of the Earth (geoid) is close to an oblate ellipsoid. The discrepancy between the geoid and the ellipsoid that approximates it reaches 100 meters.

The Earth's rotation creates an equatorial bulge, so the equatorial diameter is 43 km larger than the polar one. Highest point The surface of the Earth is Mount Everest (8848 m above sea level), and the deepest is Mariana Trench(10,994 m below sea level). Due to the convexity of the equator, the most distant points on the surface from the center of the Earth are the summit of the Chimborazo volcano in Ecuador and Mount Huascaran in Peru.

Chemical composition

The mass of the Earth is approximately 5.9736·1024 kg. Total number atoms that make up the Earth, ≈ 1.3-1.4·1050. It consists mainly of iron (32.1%), oxygen (30.1%), silicon (15.1%), magnesium (13.9%), sulfur (2.9%), nickel (1.8 %), calcium (1.5%) and aluminum (1.4%); the remaining elements account for 1.2%. Due to mass segregation, the core region is thought to be composed of iron (88.8%), some nickel (5.8%), sulfur (4.5%), and about 1% other elements. It is noteworthy that carbon, which is the basis of life, is only 0.1% in the earth's crust.

Geochemist Frank Clark calculated that the earth's crust is slightly more than 47% oxygen. The most common rock-forming minerals in the earth's crust consist almost entirely of oxides; the total content of chlorine, sulfur and fluorine in rocks is usually less than 1%. The main oxides are silica (SiO 2), alumina (Al 2 O 3), iron oxide (FeO), calcium oxide (CaO), magnesium oxide (MgO), potassium oxide (K 2 O) and sodium oxide (Na 2 O) . Silica serves mainly as an acidic medium and forms silicates; the nature of all major volcanic rocks is connected with it.

Internal structure

The Earth, like other terrestrial planets, has a layered internal structure. It consists of hard silicate shells (crust, extremely viscous mantle), and a metallic core. The outer part of the core is liquid (much less viscous than the mantle), and the inner part is solid.

Internal heat

The planet's internal heat is provided by a combination of residual heat left over from the accretion of matter that occurred during the early stages of Earth's formation (about 20%) and the radioactive decay of unstable isotopes: potassium-40, uranium-238, uranium-235 and thorium-232. Three of these isotopes have half-lives of more than a billion years. At the planet's center, temperatures may rise to 6,000 °C (10,830 °F) (greater than the surface of the Sun), and pressures may reach 360 GPa (3.6 million atm). Part of the thermal energy of the core is transferred to the earth's crust through plumes. Plumes lead to the appearance of hot spots and traps. Since most of the heat produced by the Earth is provided by radioactive decay, at the beginning of the Earth's history, when the reserves of short-lived isotopes were not yet depleted, the energy release of our planet was much greater than it is now.

The Earth loses the most energy through plate tectonics, the rise of mantle material at mid-ocean ridges. The last main type of heat loss is heat loss through the lithosphere, with more heat loss in this way occurring in the ocean, since the earth's crust there is much thinner than beneath the continents.

Lithosphere

Atmosphere

Atmosphere (from ancient Greek ?τμ?ς - steam and σφα?ρα - ball) is a gas shell surrounding planet Earth; consists of nitrogen and oxygen, with trace amounts of water vapor, carbon dioxide and other gases. Since its formation, it has changed significantly under the influence of the biosphere. The appearance of oxygenic photosynthesis 2.4-2.5 billion years ago contributed to the development of aerobic organisms, as well as the saturation of the atmosphere with oxygen and the formation of the ozone layer, which protects all living things from harmful ultraviolet rays.

The atmosphere determines the weather on the Earth's surface and protects the planet from cosmic rays, and partly from meteorite bombardments. It also regulates the main climate-forming processes: the water cycle in nature, circulation air masses, heat transfers. Molecules of atmospheric gases can capture thermal energy, preventing it from going into outer space, thereby increasing the temperature of the planet. This phenomenon is known as the greenhouse effect. The main greenhouse gases are water vapor, carbon dioxide, methane and ozone. Without this thermal insulation effect, the average surface temperature of the Earth would be between −18 and −23 °C (even though it is actually 14.8 °C), and life would likely not exist.

The lower part of the atmosphere contains about 80% of its total mass and 99% of all water vapor (1.3-1.5 1013 tons), this layer is called troposphere. Its thickness varies and depends on the type of climate and seasonal factors: for example, in polar regions it is about 8-10 km, in the temperate zone up to 10-12 km, and in tropical or equatorial regions it reaches 16-18 km. In this layer of the atmosphere, the temperature drops by an average of 6 °C for every kilometer as you move in height. Above is the transition layer - the tropopause, which separates the troposphere from the stratosphere. The temperature here is between 190-220 K.

Stratosphere- a layer of the atmosphere, which is located at an altitude of 10-12 to 55 km (depending on weather conditions and time of year). It accounts for no more than 20% of the total mass of the atmosphere. This layer is characterized by a decrease in temperature to an altitude of ~25 km, followed by an increase at the border with the mesosphere to almost 0 °C. This boundary is called the stratopause and is located at an altitude of 47-52 km. The stratosphere contains the highest concentration of ozone in the atmosphere, which protects all living organisms on Earth from harmful ultraviolet radiation from the Sun. The intense absorption of solar radiation by the ozone layer causes a rapid increase in temperature in this part of the atmosphere.

Mesosphere located at an altitude of 50 to 80 km above the Earth's surface, between the stratosphere and thermosphere. It is separated from these layers by the mesopause (80-90 km). This is the coldest place on Earth, the temperature here drops to −100 °C. At this temperature, the water in the air freezes quickly, sometimes forming noctilucent clouds. They can be observed immediately after sunset, but the best visibility is created when it is from 4 to 16 ° below the horizon. Most of the meteorites that enter the earth's atmosphere burn up in the mesosphere. From the surface of the Earth they are observed as falling stars. At an altitude of 100 km above sea level there is a conventional boundary between the earth’s atmosphere and space - Karman line.

IN thermosphere the temperature quickly rises to 1000 K, this is due to the absorption of short-wave solar radiation in it. This is the longest layer of the atmosphere (80-1000 km). At an altitude of about 800 km, the increase in temperature stops, since the air here is very rarefied and weakly absorbs solar radiation.

Ionosphere includes the last two layers. Here, molecules are ionized under the influence of the solar wind and auroras occur.

Exosphere- the outer and very rarefied part of the earth's atmosphere. In this layer, particles are able to overcome the second escape velocity of the Earth and escape into outer space. This causes a slow but steady process called atmospheric dissipation. Mostly particles of light gases escape into space: hydrogen and helium. Hydrogen molecules, which have the lowest molecular weight, can more easily reach escape velocity and escape into space at a faster rate than other gases. It is believed that the loss of reducing agents such as hydrogen was a necessary condition for the sustained accumulation of oxygen in the atmosphere to be possible. Consequently, the ability of hydrogen to leave the Earth's atmosphere may have influenced the development of life on the planet. Currently, most of the hydrogen entering the atmosphere is converted to water without leaving the Earth, and the loss of hydrogen occurs mainly from the destruction of methane in the upper atmosphere.

Chemical composition of the atmosphere

At the Earth's surface, dried air contains about 78.08% nitrogen (by volume), 20.95% oxygen, 0.93% argon and about 0.03% carbon dioxide. The volumetric concentration of the components depends on the humidity of the air - the content of water vapor in it, which ranges from 0.1 to 1.5% depending on the climate, time of year, and area. For example, at 20 °C and a relative humidity of 60% (the average humidity of room air in summer), the oxygen concentration in the air is 20.64%. The remaining components account for no more than 0.1%: hydrogen, methane, carbon monoxide, sulfur oxides and nitrogen oxides and other inert gases, except argon.

Also, there are always particulates in the air (dust is particles organic materials, ash, soot, plant pollen, etc., with low temperatures- ice crystals) and water droplets (clouds, fog) - aerosols. The concentration of particulate dust decreases with altitude. Depending on the time of year, climate and location, the concentration of aerosol particles in the atmosphere changes. Above 200 km, the main component of the atmosphere is nitrogen. At an altitude of over 600 km, helium predominates, and from 2000 km, hydrogen (“hydrogen corona”) predominates.

Biosphere

The biosphere (from ancient Greek βιος - life and σφα?ρα - sphere, ball) is a collection of parts of the earth's shells (litho-, hydro- and atmosphere), which is populated by living organisms, is under their influence and is occupied by the products of their vital activity . The biosphere is the shell of the Earth populated by living organisms and transformed by them. It began to form no earlier than 3.8 billion years ago, when the first organisms began to emerge on our planet. It includes the entire hydrosphere, the upper part of the lithosphere and bottom part atmosphere, that is, inhabits the ecosphere. The biosphere is the totality of all living organisms. It is home to several million species of plants, animals, fungi and microorganisms.

The biosphere consists of ecosystems, which include communities of living organisms (biocenosis), their habitats (biotope), and systems of connections that exchange matter and energy between them. On land they are separated mainly by latitude, altitude and differences in precipitation. Terrestrial ecosystems located in the Arctic or Antarctic high altitudes or in extremely dry areas, relatively poor in plants and animals; species diversity peaks in humid tropical forests equatorial belt.

Earth's magnetic field

To a first approximation, the Earth's magnetic field is a dipole, the poles of which are located next to the geographic poles of the planet. The field forms a magnetosphere, which deflects solar wind particles. They accumulate in radiation belts, two concentric torus-shaped regions around the Earth. Near the magnetic poles, these particles can “precipitate” into the atmosphere and lead to the appearance of auroras.

According to the "magnetic dynamo" theory, the field is generated in the central region of the Earth, where heat creates a flow electric current in a liquid metal core. This in turn leads to the emergence of magnetic field. Convection movements in the core are chaotic; magnetic poles drift and periodically change their polarity. This causes reversals in the Earth's magnetic field, which occur on average several times every few million years. The last reversal occurred approximately 700,000 years ago.

Magnetosphere- a region of space around the Earth that is formed when a stream of charged solar wind particles deviates from its original trajectory under the influence of a magnetic field. On the side facing the Sun, its bow shock is about 17 km thick and is located at a distance of about 90,000 km from Earth. On the night side of the planet, the magnetosphere elongates, acquiring a long cylindrical shape.

When charged particles high energy collide with the Earth's magnetosphere, radiation belts (Van Allen belts) appear. Auroras occur when solar plasma reaches the Earth's atmosphere in the region of the magnetic poles.

The Earth is the object of study for a significant amount of geosciences. The study of the Earth as a celestial body belongs to the field, the structure and composition of the Earth is studied by geology, the state of the atmosphere - meteorology, the totality of manifestations of life on the planet - biology. Geography describes the relief features of the planet's surface - oceans, seas, lakes and waters, continents and islands, mountains and valleys, as well as settlements and societies. education: cities and villages, states, economic regions, etc.

Planetary characteristics

The Earth revolves around the star Sun in an elliptical orbit (very close to circular) with average speed 29,765 m/s at an average distance of 149,600,000 km over a period, which is approximately equal to 365.24 days. The Earth has a satellite, which revolves around the Sun at an average distance of 384,400 km. The inclination of the earth's axis to the ecliptic plane is 66 0 33 "22". The period of revolution of the planet around its axis is 23 hours 56 minutes 4.1 s. Rotation around its axis causes the change of day and night, and the tilt of the axis and revolution around the Sun causes the change of times year.

The shape of the Earth is geoid. The average radius of the Earth is 6371.032 km, equatorial - 6378.16 km, polar - 6356.777 km. The surface area of ​​the globe is 510 million km², volume - 1.083 10 12 km², average density - 5518 kg / m³. The mass of the Earth is 5976.10 21 kg. The earth has a magnetic and closely related electric field. The Earth's gravitational field determines its close to spherical shape and the existence of an atmosphere.

According to modern cosmogonic concepts, the Earth was formed approximately 4.7 billion years ago from scattered material in the protosolar system gaseous substance. As a result of differentiation of the Earth's substance, under the influence of its gravitational field, under conditions of heating of the earth's interior, various types of chemical composition, state of aggregation And physical properties shells - geosphere: core (in the center), mantle, crust, hydrosphere, atmosphere, magnetosphere. The composition of the Earth is dominated by iron (34.6%), oxygen (29.5%), silicon (15.2%), magnesium (12.7%). The Earth's crust, mantle, and inner core are solid (the outer core is considered liquid). From the surface of the Earth towards the center, pressure, density and temperature increase. The pressure at the center of the planet is 3.6 10 11 Pa, the density is approximately 12.5 10³ kg/m³, and the temperature ranges from 5000 to 6000 °C. The main types of the earth's crust are continental and oceanic; in the transition zone from the continent to the ocean, crust of an intermediate structure is developed.

Shape of the Earth

The figure of the Earth is an idealization that is used to try to describe the shape of the planet. Depending on the purpose of the description, various models of the shape of the Earth are used.

First approximation

The roughest form of description of the figure of the Earth at the first approximation is a sphere. For most problems general geoscience this approximation seems sufficient to be used in the description or study of certain geographical processes. In this case, the oblateness of the planet at the poles is rejected as an insignificant remark. The Earth has one axis of rotation and an equatorial plane - a plane of symmetry and a plane of symmetry of meridians, which characteristically distinguishes it from the infinity of sets of symmetry of an ideal sphere. Horizontal structure geographic envelope characterized by a certain zonality and a certain symmetry relative to the equator.

Second approximation

At a closer approach, the figure of the Earth is equated to an ellipsoid of revolution. This model, characterized by a pronounced axis, an equatorial plane of symmetry and meridional planes, is used in geodesy for calculating coordinates, constructing cartographic networks, calculations, etc. The difference between the semi-axes of such an ellipsoid is 21 km, the major axis is 6378.160 km, the minor axis is 6356.777 km, the eccentricity is 1/298.25. The position of the surface can easily be theoretically calculated, but it cannot be determined experimentally in nature.

Third approximation

Since the equatorial section of the Earth is also an ellipse with a difference in the lengths of the semi-axes of 200 m and an eccentricity of 1/30000, the third model is a triaxial ellipsoid. This model is almost never used in geographical studies; it only indicates the complex internal structure of the planet.

Fourth approximation

The geoid is an equipotential surface that coincides with the average level of the World Ocean; it is the geometric locus of points in space that have the same gravitational potential. Such a surface has an irregular complex shape, i.e. is not a plane. The level surface at each point is perpendicular to the plumb line. Practical significance and the importance of this model lies in the fact that only with the help of a plumb line, level, level and other geodetic instruments can one trace the position of level surfaces, i.e. in our case, the geoid.

Ocean and land

A general feature of the structure of the earth's surface is its distribution into continents and oceans. Most of the Earth is occupied by the World Ocean (361.1 million km² 70.8%), land is 149.1 million km² (29.2%), and forms six continents (Eurasia, Africa, North America, South America, and Australia) and islands. It rises above the level of the world's oceans by an average of 875 m (the highest height is 8848 m - Mount Chomolungma), mountains occupy more than 1/3 of the land surface. Deserts cover approximately 20% of the land surface, forests - about 30%, glaciers - over 10%. The height amplitude on the planet reaches 20 km. The average depth of the world's oceans is approximately 3800 m (the greatest depth is 11020 m - the Mariana Trench (trench) in Pacific Ocean). The volume of water on the planet is 1370 million km³, the average salinity is 35 ‰ (g/l).

Geological structure

Geological structure of the Earth

The inner core is thought to be 2,600 km in diameter and composed of pure iron or nickel, the outer core is 2,250 km thick of molten iron or nickel, and the mantle, about 2,900 km thick, is composed primarily of hard rock, separated from the crust by the Mohorovic surface. The crust and upper mantle form 12 main moving blocks, some of which support continents. Plateaus are constantly moving slowly, this movement is called tectonic drift.

Internal structure and composition of the “solid” Earth. 3. consists of three main geospheres: the earth's crust, mantle and core, which, in turn, is divided into a number of layers. The substance of these geospheres differs in physical properties, condition and mineralogical composition. Depending on the magnitude of the velocities of seismic waves and the nature of their changes with depth, the “solid” Earth is divided into eight seismic layers: A, B, C, D ", D ", E, F and G. In addition, a particularly strong layer is distinguished in the Earth the lithosphere and the next, softened layer - the asthenosphere. Ball A, or the earth's crust, has a variable thickness (in the continental region - 33 km, in the oceanic region - 6 km, on average - 18 km).

The crust thickens under the mountains and almost disappears in the rift valleys of mid-ocean ridges. At the lower boundary of the earth's crust, the Mohorovicic surface, the velocities of seismic waves increase abruptly, which is mainly associated with a change in the material composition with depth, the transition from granites and basalts to ultrabasic rocks of the upper mantle. Layers B, C, D", D" are included in the mantle. Layers E, F and G form the Earth's core with a radius of 3486 km. At the border with the core (Gutenberg surface), the speed of longitudinal waves sharply decreases by 30%, and transverse waves disappear, which means that the outer core (layer E, extends to a depth of 4980 km) liquid Below the transition layer F (4980-5120 km) there is a solid inner core (layer G), in which transverse waves again propagate.

The following chemical elements predominate in the solid crust: oxygen (47.0%), silicon (29.0%), aluminum (8.05%), iron (4.65%), calcium (2.96%), sodium (2.5%), magnesium (1.87%), potassium (2.5%), titanium (0.45%), which add up to 98.98%. The rarest elements: Po (approximately 2.10 -14%), Ra (2.10 -10%), Re (7.10 -8%), Au (4.3 10 -7%), Bi (9 10 -7%) etc.

As a result of magmatic, metamorphic, tectonic and sedimentation processes, the earth's crust is sharply differentiated; complex processes of concentration and dispersion of chemical elements take place in it, leading to the formation of various types of rocks.

It is believed that the upper mantle is close in composition to ultramafic rocks, dominated by O (42.5%), Mg (25.9%), Si (19.0%) and Fe (9.85%). In mineral terms, olivine reigns here, with fewer pyroxenes. The lower mantle is considered an analogue of stony meteorites (chondrites). The Earth's core is similar in composition to iron meteorites and contains approximately 80% Fe, 9% Ni, 0.6% Co. Based on the meteorite model, the average composition of the Earth was calculated, which is dominated by Fe (35%), A (30%), Si (15%) and Mg (13%).

Temperature is one of the most important characteristics of the earth's interior, allowing us to explain the state of matter in various layers and build a general picture of global processes. According to measurements in wells, the temperature in the first kilometers increases with depth with a gradient of 20 °C/km. At a depth of 100 km, where the primary sources of volcanoes are located, the average temperature is slightly lower than the melting point of rocks and is equal to 1100 ° C. At the same time, under the oceans at a depth of 100-200 km the temperature is 100-200 ° C higher than in the continents. the density of matter in layer C at 420 km corresponds to a pressure of 1.4 10 10 Pa and is identified with phase transition into olivine, which occurs at a temperature of approximately 1600 ° C. At the boundary with the core at a pressure of 1.4 10 11 Pa and a temperature of about 4000 ° C, silicates are in a solid state, and iron is in a liquid state. In the transition layer F, where iron solidifies, the temperature can be 5000 ° C, in the center of the earth - 5000-6000 ° C, i.e., adequate to the temperature of the Sun.

Earth's atmosphere

Earth's atmosphere, total mass of which 5.15 · 10 15 tons, consists of air - a mixture of mainly nitrogen (78.08%) and oxygen (20.95%), 0.93% argon, 0.03% carbon dioxide, the rest is water vapor , as well as inert and other gases. Maximum land surface temperature 57-58 °C (in tropical deserts of Africa and North America), the minimum is about -90 ° C (in the central regions of Antarctica).

The Earth's atmosphere protects all living things from the harmful effects of cosmic radiation.

Chemical composition of the Earth's atmosphere: 78.1% - nitrogen, 20 - oxygen, 0.9 - argon, the rest - carbon dioxide, water vapor, hydrogen, helium, neon.

The Earth's atmosphere includes :

• troposphere (up to 15 km)
• stratosphere (15-100 km)
• ionosphere (100 - 500 km).

Between the troposphere and stratosphere there is a transition layer - the tropopause. In the depths of the stratosphere under the influence sunlight an ozone shield is created that protects living organisms from cosmic radiation. Above are the meso-, thermo- and exospheres.

Weather and climate

The lower layer of the atmosphere is called the troposphere. Phenomena that determine the weather occur in it. Due to the uneven heating of the Earth's surface by solar radiation, large masses of air constantly circulate in the troposphere. The main air currents in the Earth's atmosphere are the trade winds in the band up to 30° along the equator and the westerly winds of the temperate zone in the band from 30° to 60°. Another factor in heat transfer is the ocean current system.

Water has a constant cycle on the surface of the earth. Evaporating from the surface of water and land, under favorable conditions, water vapor rises up in the atmosphere, which leads to the formation of clouds. Water returns to the surface of the earth in the form of precipitation and flows down to the seas and oceans throughout the year.

Quantity solar energy, which the Earth's surface receives decreases with increasing latitude. The further from the equator, the smaller the angle of incidence of the sun's rays on the surface, and the greater the distance that the ray must travel in the atmosphere. As a consequence, the average annual temperature at sea level decreases by about 0.4 °C per degree of latitude. The surface of the Earth is divided into latitudinal zones with approximately the same climate: tropical, subtropical, temperate and polar. The classification of climates depends on temperature and precipitation. The most widely recognized is the Köppen climate classification, which distinguishes five broad groups - humid tropics, desert, humid mid-latitudes, continental climate, cold polar climate. Each of these groups is divided into specific groups.

Human influence on the Earth's atmosphere

The Earth's atmosphere is significantly influenced by human activity. About 300 million cars annually emit 400 million tons of carbon oxides, more than 100 million tons of carbohydrates, and hundreds of thousands of tons of lead into the atmosphere. Powerful producers of atmospheric emissions: thermal power plants, metallurgical, chemical, petrochemical, pulp and other industries, motor vehicles.

Systematic inhalation of polluted air significantly worsens people's health. Gaseous and dust impurities can give the air an unpleasant odor, irritate the mucous membranes of the eyes and upper respiratory tract and thereby reduce their protective functions, and cause chronic bronchitis and lung diseases. Numerous studies have shown that against the background of pathological abnormalities in the body (diseases of the lungs, heart, liver, kidneys and other organs), the harmful effects of atmospheric pollution are more pronounced. Important environmental problem Acid rain began to fall. Every year, when fuel is burned, up to 15 million tons of sulfur dioxide enters the atmosphere, which, when combined with water, forms a weak solution of sulfuric acid, which falls to the ground along with rain. Acid rain negatively affects people, crops, buildings, etc.

Ambient air pollution can also indirectly affect the health and sanitary living conditions of people.

The accumulation of carbon dioxide in the atmosphere can cause climate warming as a result of the greenhouse effect. Its essence lies in the fact that the layer of carbon dioxide, which freely transmits solar radiation to the Earth, will delay the return of thermal radiation to the upper layers of the atmosphere. In this regard, the temperature in the lower layers of the atmosphere will increase, which, in turn, will lead to the melting of glaciers, snow, rising levels of oceans and seas, and flooding of a significant part of the land.

Story

Earth formed approximately 4540 million years ago from a disk-shaped protoplanetary cloud along with other planets solar system. The formation of the Earth as a result of accretion lasted 10-20 million years. At first the Earth was completely molten, but gradually cooled, and a thin solid shell formed on its surface - the earth's crust.

Shortly after the formation of the Earth, approximately 4530 million years ago, the Moon formed. Modern theory of formation of a single natural satellite Earth claims that this happened as a result of a collision with a massive celestial body, which was called Theia.
The Earth's primary atmosphere was formed as a result of degassing of rocks and volcanic activity. Water condensed from the atmosphere to form the World Ocean. Despite the fact that the Sun by that time was shining 70% weaker than now, geological data shows that the ocean did not freeze, which may be due to greenhouse effect. About 3.5 billion years ago, the Earth's magnetic field formed, protecting its atmosphere from the solar wind.

The formation of the Earth and the initial stage of its development (lasting approximately 1.2 billion years) belong to pre-geological history. The absolute age of the oldest rocks is over 3.5 billion years and, starting from this moment, the geological history of the Earth begins, which is divided into two unequal stages: the Precambrian, which occupies approximately 5/6 of the entire geological chronology (about 3 billion years), and Phanerozoic, covering the last 570 million years. About 3-3.5 billion years ago, as a result of the natural evolution of matter, life arose on Earth, the development of the biosphere began - the totality of all living organisms (the so-called living matter of the Earth), which significantly influenced the development of the atmosphere, hydrosphere and geosphere (at least in parts of the sedimentary shell). As a result of the oxygen catastrophe, the activity of living organisms changed the composition of the Earth's atmosphere, enriching it with oxygen, which created the opportunity for the development of aerobic living beings.

A new factor that has a powerful influence on the biosphere and even the geosphere is the activity of mankind, which appeared on Earth after the appearance of man as a result of evolution less than 3 million years ago (unity regarding dating has not been achieved and some researchers believe - 7 million years ago). Accordingly, in the process of development of the biosphere, formations and further development noosphere - the shell of the Earth, which is greatly influenced by human activity.

High growth rate of the world population (number earth's population was 275 million in 1000, 1.6 billion in 1900 and approximately 6.7 billion in 2009) and the increasing influence of human society on natural environment put forward the problems of rational use of all natural resources and nature conservation.

Planet Earth belongs to the terrestrial planets, which means that the surface of the Earth is solid and the structure and composition of the Earth is in many ways similar to other terrestrial planets. The earth is the most major planet earthly group. The Earth has the largest size, mass, gravity and magnetic field. The surface of planet Earth is still very young (by astronomical standards). 71% of the planet's surface is occupied by a water shell and this makes the planet unique; on other planets, water on the surface could not be in a liquid state due to the inappropriate temperatures of the planets. The ability of the oceans to retain the heat of water makes it possible to coordinate the climate, transferring this heat to other places using currents (the most famous warm current is the Gulf Stream in the Atlantic Ocean).

The structure and composition is similar to many other planets, but there are still significant differences. All elements of the periodic table can be found in the composition of the earth. Everyone knows the structure of the Earth from an early age: a metallic core, a large layer of the mantle and, of course, the earth’s crust with a wide variety of topography and internal composition.

Composition of the Earth.

Studying the mass of the Earth, scientists came to the conclusion that the planet consists of 32% iron, 30% oxygen, 15% silicon, 14% magnesium, 3% sulfur, 2% nickel, 1.5% of the earth consists of calcium and 1.4 % from aluminum, and the remaining elements account for 1.1%.

Structure of the Earth.

The Earth, like all terrestrial planets, has a layered structure. At the center of the planet is a core of molten iron. The interior of the core is made of solid iron. The entire core of the planet is surrounded by viscous magma (harder than under the surface of the planet). The core also includes molten nickel and other chemical elements.

The planet's mantle is a viscous shell that accounts for 68% of the planet's mass and about 82% of the planet's total volume. The mantle consists of silicates of iron, calcium, magnesium and many others. The distance from the Earth's surface to the core is more than 2800 km. and all this space is occupied by the mantle. Usually the mantle is divided into two main parts: upper and lower. Above the 660 km mark. The upper mantle is located before the earth's crust. It is known that, from the time of the formation of the Earth to the present day, it has undergone significant changes in its composition; it is also known that it was the upper mantle that gave birth to the earth’s crust. The lower mantle is located, accordingly, below the boundary of 660 km. to the core of the planet. The lower mantle has been little studied due to difficult accessibility, but scientists have every reason to believe that the lower mantle has not suffered major changes in its composition over the entire existence of the planet.

The earth's crust is the uppermost, solid shell of the planet. The thickness of the earth's crust remains within 6 km. at the bottom of the oceans and up to 50 km. on the continents. The earth's crust, like the mantle, is divided into 2 parts: the oceanic earth's crust and the continental earth's crust. The oceanic crust consists mainly of various rocks and sedimentary cover. The continental crust consists of three layers: sedimentary cover, granite and basalt.

During the life of the planet, the composition and structure of the Earth underwent significant changes. The planet's topography is constantly changing, tectonic plates either shift, forming large mountainous reliefs at their junctions, or move apart, creating seas and oceans between them. The movement of tectonic plates occurs due to changes in the temperatures of the mantle underneath them and under various chemical influences. The composition of the planet was also subject to various external influences, which led to its change.

At one point, the Earth reached a state where life could appear on it, which is what happened. lasted a very long time. Over these billions of years, it was able to grow or mutate from a single-celled organism into multicellular and complex organisms, which is what humans are.