Layer of the earth's surface. Evolution of the earth in natural history

In terms of the geographical envelope, we can talk about several structural levels studied by geography:

A) geocomponent. Geocomponents are sets of homogeneous natural formations on the earth's surface. Distinguish main components (rocks, air, water, plants, animals) and derivatives(soil, ice, frozen rocks).

b) individual parts of the Earth, occupied predominantly by one specific component, are distinguished under the name geospheres. These are concentric spheres nested within each other. Four of them are fully or partially included in the geographical envelope - lithosphere, atmosphere, hydrosphere– form almost continuous shells. Biosphere, understood as a collection of living organisms, does not occupy an independent space, but is included in the above-mentioned spheres. It is located in a thin layer mainly in the area of ​​their contact.

Within these four geospheres there are subordinates – second order- geospheres that do not form a continuous layer: cryosphere(sphere of cold), pedosphere(soil sphere), etc. Of the main geospheres, only the hydrosphere completely belongs to the geographical envelope. The upper part of the atmosphere and most of the lithosphere are not included in the geographic envelope. Therefore, these parts are not specifically studied by geography.

Geospheres form a more complex structural level of the geographic envelope than the geocomponent one. This is the second structural level of the geographical shell - geospheric. Geospheres are arranged in tiers, in accordance with the density of matter. The higher the density, the lower the geosphere is located.

c) The next structural level – geosystemic. Geosystems are complex formations that arose as a result specific interaction of geocomponents. The simplest geocomponents are formed through the interaction of matter at an inert level of organization: glaciers, together with the bed containing them and adjacent layers of air; a river basin, considered as a system of water flows together with the part of the earth's surface that it occupies, and the ground rocks that interact with surface runoff, etc.

More complex relationships exist in geosystems that include matter at various levels of organization. They are most characteristic of the earth's surface. These are natural territorial and natural aquatic, that is, marine, complexes - PTK and PAC.

Geosystems can include not only natural components. For example, human society. Influence with its technical means, structures, etc. Human society, together with the natural environment, forms geotechnical systems– cities, industrial hubs, agricultural lands, etc.

Geosystems replace each other mainly in the horizontal direction and form horizontal structure of the geographical envelope.

There are three levels of dimension of geosystems:

Planetary;

Regional;

Local.

VERTICAL (TIERED) STRUCTURAL GEOGRAPHICAL ENVIRONMENT OR GEOSPHERE STRUCTURAL LEVEL

Lithosphere is a complex formation of predominantly solid matter that envelops the Earth’s mantle in a layer of 50 to 200 km. The lithosphere lies on the asthenosphere - a plastic layer located in the upper mantle of the Earth. The asthenosphere is plastic; atmospheric plates move along it.

The upper part of the lithosphere, a layer from 30 to 60 km on continents, and up to 5–10 km under the oceans, is called earth's crust. The layer of the upper mantle is separated from the earth's crust by the Mohorovicic section - a section of a sharp change in the density of matter.

The structure of the Earth as a whole is discussed in detail in the course of general geology. Let us recall only the facts that are most significant geographically. So, the Earth consists of a core, mantle and crust. The properties of the earth's crust change sharply at the boundary of the earth's crust and mantle. This is where the Mohorovicic (Moho) line is drawn. The Earth's density decreases from the center - 11.0 for the center of the core, in g/cm3, to 5.3 - 3.4 in the mantle and 2.6 for the surface of the earth's crust. The average density of the earth's crust is 5.52 g/cm3.

The earth is a magnet - a dipole. Its magnetic poles are located in the northern and southern hemispheres at a short distance from the geographic poles.

The lithosphere on continents is three-layered. Its upper layer is formed sedimentary breeds, the average one is conventionally called granite. Beneath the oceans, the granite layer is thin or absent. It is composed of “acidic” (granite) light igneous rocks. Its density is 2.7 – 2.8 g/cm2. The lower layer of the lithosphere is called basalt. It is formed by heavier rocks, its density approaches 3.0 g/cm2. Unlike the granite layer, the basalt layer spreads both under continents and oceans. Moreover, under the oceans the basalt layer is thinner than under the continents.

There are different types of the earth's crust: two main ones - continental and oceanic - and one intermediate - transitional.

The continental crust consists of three layers: sedimentary, granite and basalt. The middle layer is about 35 km. Continental crust has lower density than oceanic. Therefore, it rises (floats) above the oceanic one. Oceanic crust two-layer. Basalt layer- basic. It is covered by a thin sedimentary layer. There is no granite layer. The thickness of the oceanic crust is 5–10 km, the thickness of the sedimentary layer is usually less than 1 km.

Transition type of earth's crust located between areas of continental and oceanic crust. This is a two-layer crust, consisting (unlike oceanic) of a very thick layer of sedimentary rocks, underlain by basalt. It is known in the marginal seas of East Asia (from the Bering Sea to South China), the Sunda Archipelago, and other areas of the world.

Three main types of rocks take part in the structure of the earth's crust: igneous, sedimentary, metamorphic.

Igneous rocks are formed by cooling of magma. Depending on the conditions in which this process occurs, intrusive(at depth) and effusive(extruded to the surface) rocks. Intrusive materials include granite, gabbro, etc. Igneous materials include basalt, liparite, volcanic tuff, volcanic glass, etc.

Sedimentary Rocks are formed on the earth's surface in various ways. Some of them are formed from the destruction products of other rocks - clastics. Their sizes vary: from blocks and boulders to dusty particles. Some sedimentary rocks are formed due to the vital activity of organisms - organogenic. These are limestones (chalk, shell rocks, etc.), siliceous rocks, hard and brown coal, and some ores. Occupy a significant place in the earth's crust chemogenic sedimentary rocks. They are formed due to chemical reactions occurring on the earth's surface - mainly in the aquatic environment. These include limestones and marls, salts (palite, anhydrite), metal ores, etc.

Metamorphic rocks are formed from other rocks under the influence of various factors: height, temperature, pressure, in the depths of contact with rocks of a different chemical composition or a different physical state. These are gneisses, crystalline schists, marble. Most of the volume of the earth's crust is occupied by crystalline rocks of igneous and metamorphic origin - about 90%. But for the geographic envelope, what is more important is the thin and discontinuous layer of sedimentary rocks, which for the most part is in direct contact with air and water. The most common in the sedimentary layer are clays and shales (50%), sands and sandstones (23.6%), and limestones (23.4%).

The earth's crust formed over an extremely long period of time. Its most ancient sections are about 4 billion years old. The most ancient elements of the continental crust are ancient Precambrian platforms. They have a different foundation. This is the bottom layer. It consists of metamorphic rocks, crushed into folds, broken into blocks. Broken by igneous intrusions. The foundation rests on a horizontal layer of complex sedimentary rocks. This is the top layer. It was formed much later than the foundation. Over the last 0.5 million years, ancient platforms have been characterized by stability and the absence of folding movement.

Highlight platforms in the northern hemisphere - North American, Russian, Siberian, Chinese; in the southern hemisphere - South American, African, Arabian, Hindustan, Australian, Antarctic.

In geological history, sedimentary rocks and mountain-building processes have repeatedly captured large areas of the earth's crust. During 550 - 600 million years, the Caledonian, Hercynian, Pacific (Mesozoic) and Alpine folding took place. In their areas there are ancient and young mountains.

Ancient are called mountains that are characterized by low heights and amplitudes of relief, smoothed forms. These are the Urals, the mountains of Central Asia, Europe, Altai, Sayans, etc.

Young They call mountains of an alpine appearance - high, strongly dissected, with sharp outlines. These are the Alps, Himalayas, Caucasus, Andes, Cordillera, etc.

Hydrosphere is located between the earth's crust and the atmosphere and is a collection of oceans and seas, surface waters, ice and snow.

The bulk of the water is concentrated in the oceans (96.5%). Water is present on Earth in three phases: solid (ice), liquid and vapor (gases). Two types of water form the continental and oceanic parts of the hydrosphere: fresh and salty. The bulk of fresh water is concentrated in groundwater and glaciers. The volume of groundwater, especially in the lower parts of the earth's crust, is not precisely known and is estimated approximately. According to Lvovich (1974), the total volume of fresh water on Earth is 28.25 million km 3, or 2% of the total volume of the hydrosphere, 98% is water, mineralized to varying degrees. These are waters of oceans and seas (96.5%), salty waters of lakes and a significant part of groundwater. Of the 2% fresh water, 85% is concentrated in polar glaciers, which are not yet available for human use.

So, we have a diverse species presence of water in the hydrosphere, that is, in the geographic envelope. Despite this diversity, the hydrosphere is one. Its unity is associated with the common origin of water - its entry from the Earth's mantle - and with continuous water exchange. The waters of the World Ocean cover most of the planet's surface - 70.8% and form an almost continuous water shell of the Earth.

The United World Ocean has historically been divided into separate parts – oceans. Inside each ocean there are smaller parts - seas, bays, straits, estuaries, etc.

The world's oceans are a large settling basin. It accumulates various substances coming from land. Almost all elements of the periodic table are present in sea water. The average salinity is 35 ‰, that is, 1,000 kg of sea water contains 35 kg of salts. The main part of the salts is sodium and magnesium chloride. Maximum salinity is observed in tropical and partially subtropical regions - where there is more evaporation (E) and relatively little precipitation (x). In the equatorial zone there is a slight decrease in salinity. It decreases even more in temperate, subpolar and polar regions.

Gases are also dissolved in the water of oceans and seas. Especially O 2 and CO 2. There is a constant exchange of gases between the ocean and the atmosphere, so that the ocean acts as a regulator of their content in the atmosphere.

The density of sea water is important. Its average value is 1.025 g/cm3. Salty sea water is at its maximum density at its freezing temperature. Therefore, the cooled seawater sinks down. This is due to the fact that such water is the most dense, and therefore heavy. It is only due to the flow of fresh water that the oceans become covered with ice. This is due to the fact that unsalted, thin waters have a different freezing point – higher.

A relatively large volume of water that forms in certain areas of the World Ocean, has relatively constant physical, chemical, biological properties, and forms a single complex (natural aquatic) is called oceanic water mass.

Water masses in the oceans are analogues of natural territorial complexes on land. The boundaries between water masses in the ocean are less clearly defined than the boundaries of natural territorial complexes on land. Vertically, there are four main water masses or structural zones: surface, intermediate, deep and bottom.

Surface structural zone extends to approximately depths of 300 m. Its waters actively interact with the atmosphere. Sometimes this layer is called oceanic troposphere– by analogy with the troposphere of the atmosphere.

Active mixing of water occurs in the surface layer; it is rich in O 2 and CO 2 and organisms. Its physical characteristics and salinity are subject to fluctuations due to atmospheric influences.

Surface water is captured currents, which form specific circulations. In the horizontal direction, the surface oxen are separated oceanic fronts to different water masses. The following types of water masses are distinguished:

A) equatorial, with a water temperature of 26 – 28 0, salinity of 33 – 35 ‰, O 2 3 – 4 g/m 3 content and a relatively low saturation of life forms;

b) tropical. They are divided into northern tropical and southern tropical, with water temperatures from 18 to 27 0 C, salinity 34.5 - 35.5 ‰, O 2 2 content - 4 g / m 3;

V) subtropical. They are divided into northern and subtropical with temperatures from 15 to 28 0 C, salinity from 35 to 37 ‰, O 2 4 - 5 g/m 3 content;

G) subpolar. They are divided into subarctic and subantarctic, with temperatures from 5 to 20 0 C, salinity 34 - 35 ‰, oxygen content 4 - 6 g/m 3. They are very rich in life forms: fish, mammals (whales, seals, etc.). It is in these water masses that the main fishing areas are located.

d) polar. They are divided into Arctic and Antarctic water masses, with low temperatures, from 5 to 2 0 C, low salinity 32 - 34 ‰, very rich in O 2 - 5 - 7 g / m 3. Most of the year they are covered with ice, but nevertheless they are rich in life, especially in contact zones (rocky shores, ice edges, etc.).

Transitional or intermediate structural zone located at depths from 300 to 2,000 m.

Deep water masses occupy most of the ocean's volume. They are characterized by low temperature (2 - 3 0 C), the absence of seasonal fluctuations, as well as seasonal changes in salinity and oxygen content.

Bottom waters fill the deepest parts of the ocean. Like deep ones, they are formed as a result of the subsidence of cold polar surface water masses.

In the bottom waters there is a slight increase in temperature, which is associated with the flow of heat from the depths.

Ocean fronts, formed in zones of contact and interaction of various water masses, are marked by vortex movements of water - cyclonic and anticyclonic, accumulation of life, active interaction with the atmosphere. They are dynamic and unstable. Mostly not confined to specific areas.

Surface waters of land- rivers, lakes, swamps. They make up a small percentage - only 0.014% of the world's water reserves. But they play a significant role in natural processes occurring in the geographical environment.

Rivers– the most active element of these waters. They contain approximately 2,100 km 3 of water, while 47,000 km 3 flows into the ocean per year. This means that the volume of water in the rivers is renewed every 16 days. For comparison, let's say that ocean waters pass through a large cycle in about 2.5 thousand years, along with drain, the most important characteristic of rivers is their nutrition. It can be snow, rain, glacial, underground. Large rivers have mixed feeding, which includes rain and underground, and often snow and glacial. This depends on the depth of the pool and the diversity of its landscapes. The annual flow of rivers is closely related to their nutrition. Thus, rivers predominantly snow-fed have pronounced spring floods and summer low-water periods. Glacially fed rivers are characterized by predominantly summer flow, since it is in summer that glaciers are in the mountains (Amu Darya, Syr Darya, Kuban, Terek, etc.). The runoff in rivers is fed by rain depending on precipitation. Precipitation, and therefore runoff, can be summer in a monsoon climate, winter in Mediterranean areas, uniform throughout the year (rivers of Western Europe).

Consequently, rivers are determined to a greater extent by climatic conditions. It is no coincidence that our great climatologist A.I. Voeikov said: “Rivers are a product of climate.”

Flowing river waters have kinetic energy, produce significant work - they erode the riverbed, transport erosion products - alluvium. River sediments form alluvial plains. For example, alluvial plains include: Amazonian, West Siberian, East Siberian, Congolese, etc. Alluvium is composed of deltas at the mouths of the Nile, Lena, Volga, Parana rivers, as well as river terraces on the slopes of valleys.

In the modern era, there is a process of pollution of surface waters with organic and inorganic substances of industrial and agricultural origin. As a result, some lakes become ecttrophic, that is, rapidly overgrown with algae. Pollution of surface waters with petroleum products, chemical waste, and plant protection products is dangerous.

Noteworthy is the difference in the chemical composition of salts dissolved in sea and river waters. In ocean waters, sulfate chlorides predominate; in rivers, carbonates predominate (up to 60% of the mass of salts). There are only 0.3% of them in sea water.

Lakes. Their role in the geographic environment is important and diverse. Lakes: a) regulators of river flow; b) they often serve as large freshwater accumulators. For example, Baikal: 23 10 12 m 3 of water, Tanganyika: 18.9 10 12, Lake Superior: 16.6 10 12 m 3 of water; c) lakes contain stocks of valuable fish species; d) minerals are mined in some lakes; e) lakes play a significant role in the water balance of land surface waters.

The total area occupied by the lakes is estimated at approximately 2 million km 2, with a total water volume of more than 1.76 10 14 m 3. This is four times the total annual flow of all the world's rivers.

In the second half of the 20th century, people created about 10 thousand artificial lakes - reservoirs. The volume of their waters is 5 10 12 m 3. The largest number are in Russia, Ukraine, Central Asia, the USA, Canada, and India. Their meanings and functions: water regulation, reclamation, navigation, fishery, etc. Hundreds of thousands of ponds have been created that have water and fishery significance.

Swamps. This is an area of ​​land with sharply excessive moisture, stagnant or weakly flowing water regimes and specific hydrophytic vegetation. They occupy 2% of the land (their area is 2.7 10 6 km 2). Swamps serve as accumulators of atmospheric, river, and groundwater. Slowly releasing these waters into rivers, they thereby regulate low-water flow.

The groundwater. They are found in the thickness of the rocks of the upper part of the earth's crust in liquid, solid (permafrost), and vapor states. Based on their origin, there are different types of groundwater: infiltration– formed as a result of seepage of rain, melt and river water from the surface; condensation– arise in the pores and cracks of rocks from water vapor.

Based on their physical state, groundwater is of seven types:

1. Gravitational – move under the influence of gravity, fill cracks and voids in the earth's crust, move along them, and also occupy closed depressions on the earth's surface (forming oceans, seas, lakes).

2. Capillary– fill small pores in soils and rocks, are held by surface tension forces, move depending on the temperature and humidity gradient of the rock, even against the gravity gradient. Thanks to this, they reach the surface. Gravity and capillary groundwater actively participate in moisture circulation .

3. Film water– envelops soil particles and is attracted to it by the force of surface tension. Therefore, it weakly participates in moisture circulation and is poorly used by plants.

4. Hygroscopic– envelops small aggregates, soils, and is removed only with strong heating.

5. Water of crystallization physically bound in minerals (gypsum, etc.). Therefore, when it is removed, their physical properties change.

6. Constitutional water. It is chemically bound in minerals in such a way that when it is removed, the minerals are destroyed.

Groundwater- This is the first layer from the earth's surface, constantly existing. Groundwater, as a rule, is fresh and belongs to the zone of active water exchange.

Interformational waters– underground waters lying below groundwater are separated from them by layers of waterproof rocks. Located at a depth of 200 - 300 m, they belong to zone of relatively active water exchange. They are partially discharged into deep river valleys and into the ocean, mostly fresh or slightly mineralized - up to 10 g/l of salts. In the case when interstratal waters are under hydrostatic pressure, they are called pressure or artesian.

Slow water exchange zone is located below sea level. Its underground waters are discharged only into the ocean. They are predominantly salted (up to 50 g/l), and sometimes are brines (over 50 g/l).

Cryosphere. It is characterized by negative and zero temperatures. These include seasonal and perennial replacement cover; seasonal and permafrost; soils and rocks containing ice in voids; mountain glaciers and ice sheets; cracked and buried ice, etc. The cryosphere also includes migrating clouds containing snow and ice, including noctilucent clouds.

The cryosphere is a discontinuous and variable shell of the Earth in configuration.

Cryolithozone– the upper layer of the earth’s crust, which has negative temperatures and is characterized by the presence of groundwater and seasonal freezing of soils. The total area of ​​permanent snow cover on land is 2 million km 2 in the northern hemisphere and 14 million km 2 in the southern hemisphere. In addition, in high-mountain glaciers and permanent sea ice, the snow cover area is about 14 million km 2. Consequently, the total area of ​​snow cover in both hemispheres is about 30 million km 2, that is, about 6% of the entire surface of the planet is covered with snow. Along with this, a huge area on land and sea ice is occupied by seasonal (temporary) snow - in the northern hemisphere at least 59 million km 2, in the southern hemisphere - about 2 million km 2. On seasonal sea ice, snow cover covers an area of ​​24 million km2. And in general, the total area of ​​permanent and temporary snow on Earth in both hemispheres is about 113 million km 2, that is, 22% of the Earth's surface.

Permanent snow cover serves as a source of formation of many ices - mountain and continental glaciers. They form thick ice sheets in Antarctica, Greenland, on the Franz Josef Islands, Spitsbergen, and Iceland. Glaciers contain almost 69% of all fresh water on Earth. 85% of the ice is contained in the Antarctic ice sheet. It is estimated that the melting of this ice would increase the level of the World Ocean by 50 - 60 m and would lead to the flooding of approximately 20 million km 2 of land, the very one that is especially densely populated and intensively developed.

Glaciers and ice sheets move under the influence of gravity and produce enormous destructive work - exaration(plowing) of surface rocks, transport destruction products and deposit them - moraines, as well as entire strata of pebbles, gravel, sand.

Snow cover, both permanent and temporary, has a great impact on geographical processes. White snow is highly reflective, so most of the sun's rays are reflected from it into the atmosphere. Seasonal snow cover in winter stores a significant amount of water, which is released in the spring.

Permafrost or permafrost- this is a part of the earth’s crust, which for a long time is characterized by an average zero or negative temperature (t 0 C). Under such conditions, water remains in the solid phase all year round. Permafrost is distributed over an area of ​​21 million km2 - 14% of the land. Most of it is concentrated in the northern hemisphere - Northern Eurasia, Canada, the Arctic islands, Greenland; in the southern hemisphere - the Antarctic islands, the mountain ranges of the Southern Andes. Its distribution is characterized by pronounced asymmetry - in the northern hemisphere 20 million, in the southern hemisphere - 1 million km 2. Solifluction flows– movement along the slopes of liquefied rocks. Permafrost prevents tree roots from penetrating the soil, so only a few plants grow on it that have superficial root system(Daurian larch, etc.).

Atmosphere - outer gaseous shell of the Earth. It has a tiered structure. Air is held near the earth's surface by gravity. The lower part of the atmosphere immediately adjacent to the earth's surface is called troposphere. Its average thickness is 11 km (in polar latitudes - 8 km, in equatorial latitudes - 17 km). More than 80% of the total mass of the atmosphere is concentrated here. The troposphere receives heat from the earth's surface. The gas composition of the troposphere is formed by living organisms, products of rock weathering, and sedimentation. There is a clearly expressed decrease in temperature with altitude by 0.6 0 C for every 100 m of altitude (h). Characterized by intense air movement. Vertical and horizontal movements of air masses occur. The troposphere contains the bulk of all atmospheric moisture in the form of water vapor and water droplets (clouds, fog), ice crystals, and hail. Trade winds, monsoons, hurricanes and other phenomena originate and develop in the troposphere. At the upper boundary of the troposphere, it ends with a thin transition layer - the tropopause. Above the tropopause there is no longer atmospheric convection.

Stratosphere observed up to an altitude of 20 km. The temperature does not drop. It is everywhere - 60-70 0 C - this is in the lower stratosphere. Above there is a layer of constant temperature increase. This phenomenon is caused by the heating of ozone due to short-wave radiation - the upper stratosphere. In another way, the stratosphere is called the ozone sphere, since an increased content of O 3 is observed in it (altitude about 25 km). Located above the stratosphere mesosphere– up to an altitude of 80 km. Here the temperature drops to – 90 0 C. Even higher is ionosphere up to an altitude of 800 – 1000 km. The temperature rises to 220 0 C at an altitude of about 150 km, to 1,500 0 C at an altitude of about 600 km. The temperature of the high layers of the atmosphere is determined by the speed of kinetic movement of particles. The thermosphere (or ionosphere) absorbs X-rays from the solar corona. Above 1,000 km is located exosphere(external atmosphere). In it, the speed of movement of atoms and molecules reaches the second cosmic speed - 11.2 km/sec. This allows them to overcome gravity and disperse into outer space. The most intensive removal is of H 2 atoms, which form a corona around the earth's atmosphere - up to altitudes of 2-3 thousand km.

Atmospheric composition. Air consists of a combination of constant and variable components. Constant gases include gases (N - 78%, O 2 - 21%, argon - 0.93%), as well as neon, helium, krypton, xenon, etc. Variable components include carbon dioxide, water vapor, ozone, aerosols. Carbon dioxide (CO 2) occupies only 0.03% of air volume. Its content fluctuates according to the seasons of the year, changes over many years and varies in different regions of the globe. Depends on natural processes and human economic activities. Water vapor enters the atmosphere from the underlying surface. Its content is even more variable, depending on the time of year and day. Carbon dioxide and water vapor serve as atmospheric filters that block long-wave radiation from the earth's surface. Arises greenhouse effect of the atmosphere. It is very important as a thermodynamic factor.

Due to the intensive development of industry, plowing of land and other economic activities, the dust content of the air will sharply increase, the turbidity of the atmosphere will increase, which leads to a decrease in incoming solar radiation. Aerosols are particles suspended in the air: volcanic dust, combustion products (smoke), mineral dust, spores and pollen, microorganisms, crystals of sea salts. Most aerosols are found in the troposphere. Some of the aerosols reach the stratosphere thanks to the flights of airplanes and rockets. Here they are stable and can stay for more than 2 years. The accumulation of aerosols in the stratosphere is a factor in changing the planetary climate.

The part of the atmosphere that has a constant gas composition is called homosphere. In higher layers of the atmosphere, under the influence of ultraviolet and corpuscular radiation from the Sun, dissociation of molecules occurs. This part of the atmosphere (above 90 - 100 km) is called heterosphere.

In the troposphere, there are simultaneously several dozen air masses that constantly move, change their physical characteristics, that is, transform, and bring with them their characteristic weather: hot, dry, cold, etc.

Air masses (AM)- these are large volumes of air, comparable to large parts of continents and oceans, relatively uniform in temperature, evaporation, precipitation, air humidity, and other characteristics.

Atmospheric fronts– boundary layers separating these masses. There is intense air movement here, because there are air masses with different temperatures, humidity, and therefore density. On the fronts are born huge vortex movements of air - cyclones and anticyclones. In the frontal zone, precipitation occurs and there is a sharp change in weather. Thus, atmospheric fronts are the most dynamic parts of the troposphere.

Air masses can be grouped into types:

1. equatorial air (EA). It is formed in the equatorial zone, therefore it is characterized by high temperature and evaporation. These properties are also typical for sushi. Therefore, equatorial air is not divided into sea (M) and continental (C). In summer, equatorial air enters the subequatorial belt and brings heavy precipitation to these works (x).

2. tropical air (TV) – air masses are formed in tropical and subtropical latitudes over oceans and land (Sahara Desert, Arabian Peninsula, Mexico, Australian deserts). In summer, continental tropical air forms over arid regions of temperate latitudes (northern Asia, Mongolia, northern China, the Great Basin of North America). Continental tropical air is characterized by high temperatures and low humidity. Over arid regions, the air mass contains a significant amount of aerosol particles and, above all, mineral dust. Tropical sea air is cooler than continental air and contains a large amount of moisture. Due to this, strong evaporation occurs from the surface of the ocean.

3. temperate air (HC) – It is formed in temperate zones (in the subtropics in winter) and is distinguished by its diversity. Continental temperate air develops above continental air; in summer it warms up greatly, becomes humid and approaches continental tropical air in physical properties. In winter, continental temperate air cools greatly and becomes dry due to little evaporation. Maritime temperate air is formed over the oceans in mid-latitudes and is characterized by increased humidity and temperature; In winter it brings thaws and precipitation, in summer it brings cool, cloudy weather with precipitation. In summer, the air of temperate latitudes occupies the subarctic or subantarctic belt.

Arctic (Antarctic) air (АВ, AntВ) is formed over ice and snow covers, which become very cold in winter, especially during the polar night. It is characterized by low temperatures, low moisture content and high transparency. Distinguish continental arctic air– it forms over the glaciers of Greenland, Antarctica, the islands of the Arctic basin, and in winter - over the ice fields of the ocean; And sea ​​arctic air– over open water surfaces of the Arctic Ocean and Southern Ocean. The first is very cold and dry, the second is warmer and humid. The invasion of Arctic air and Antarctic air into temperate latitudes always brings cold temperatures in summer and severe frosts in winter. In winter, Arctic air and Antarctic air also occupy the subarctic and subantarctic zones.

Biosphere– a set of living organisms inhabiting a geographical area. Life is concentrated in a narrow, several tens of meters thick, near-surface layer of the Earth. However, in a dispersed form (mainly in the form of bacteria) it penetrates up to 3 km deep into the earth's crust (under the oceans to a depth of 0.5 - 1 km from the bottom) and captures the entire troposphere.

In modern classifications, the organic world of the Earth is divided into four kingdoms: granules, which include blue-green algae, fungi, plants and animals.

An important feature of living organisms is their ability to adapt to different living conditions and change. In this regard, the science of ecology studies the relationships between organisms and the environment.

Bacteria are distinguished by great ecological diversity. They are distributed in the air up to the height of the ozone screen, in water to the entire depth of the ocean, in soils, in the weathering crust, mainly above the groundwater horizon, in some mineral deposits (oil, gas, etc.).

Lichens perform specific ecological functions. They are unpretentious, but light-loving, and therefore are usually pioneers of vegetation. They settle on rock outcrops and other unsuitable places for life. Thus, lichens contribute to the development of unsuitable places.

The ecological properties of plants and animals are the most studied. These are light, heat, moisture, soil conditions, and the degree of air pollution. For example, in relation to moisture they distinguish xerophytes– plants of dry habitats (feather grass, wormwood, etc.), mesophytes– plants in habitats with moderate moisture (more meadow and forest grasses), hygrophytes- inhabiting waterlogged habitats (low areas of floodplains, rivers, swamps). Some plants live in water - hydrophytes etc. They play a very important role edaphic(soil) conditions. Plants anchor their root systems in the soil and receive moisture and nutrients from it. Soil properties such as particle size distribution, porosity, humus content, soluble salts, structure, etc. are important. For many animals the soil- the main or only environment of existence.

Communities of organisms. Organisms form regular groups on the earth's surface, which are formed during the long-term adaptation of organisms to each other and to environmental conditions. Such groups are called biocenoses. The organic world of sushi - the most important functions are performed by plants. They play the role of creators of organic matter and free oxygen in the atmosphere. Groups of land plants are divided into: the largest types of vegetation are divided into formations, then into phytocenoses.

There are 22 types of vegetation on the surface of the continents: tundra, taiga, broad-leaved, steppe, shrub-woody, subtropical, etc. Each type of vegetation is characterized by certain features structures And speakers, character tiers And connections between organisms reproduction intensity living matter, etc.

Vegetation types are located depending on climatic conditions, forming horizontal and altitudinal zones. For example, in conditions of large amounts of heat and moisture, tropical rainforests with a multi-tiered structure of vegetation cover, an abundance of species, high intensity of processes of growth, death and decomposition of organic residues. With a lack of moisture, various options develop steppe And desert types of vegetation. In subpolar and polar regions, where there is insufficient heat and a short growing season, tundra And Arctic deserts.

Land animals also form regular groups of individuals that are in complex relationships with each other, with vegetation, and with the abiotic environment. Such groups are called zoocenoses. They are less stable spatially than phytocenoses due to the mobility of animals; however, each phytocenosis is characterized by a certain zoocenosis.

Together, phytocenosis, zoocenosis and microorganisms form biocenosis .

Organic world of the ocean. Living organisms inhabit the entire thickness of ocean waters. Based on the type of habitat and lifestyle, marine organisms are grouped into three groups:

1. plankton– passively moving, mainly vertically, unicellular algae and some species of animals (unicellular crustaceans, jellyfish). They connect the power supply chains of the surface and deep layers.

2. nekton– actively moving animals – fish, cetaceans, cephalic mollusks, etc.

3. benthos - organisms living at the bottom.

Plant organisms develop mainly in the layer up to 400 m depth. Light penetrates here, so photosynthesis is possible. In total there are about 10 thousand species of marine plants. Algae predominates. Animals are distributed in all layers of the ocean (about 160 thousand species). Among them, mollusks, crustaceans, fish, and protozoa predominate.

Below the depth of light penetration there are no plants, therefore, primary organic production is not created, and animals feed on the remains of organisms coming from above. The organic world in the ocean is distributed unevenly, depending on temperature, light, salinity, transparency, the presence of nutrients, the nature of the soil, etc.

Distribution of living matter. A set of organisms expressed in material-energy terms (mass, chemical composition, energy) is called living substance. The main characteristic of living matter is biomass. It is distributed very unevenly in the geographical area. The most general pattern in its distribution, characteristic of the entire geographical envelope, is concentration of biomass in contact areas of contrast media.

The main contact zone of the geographic shell, its focus is the boundary of land and ocean with the atmosphere. The maximum of living matter, confined to the focus of the geographic envelope, decreases, both up and down.

The vast majority of biomass is concentrated on land. Land biomass is approximately 200 times greater than ocean biomass. We are talking about living biomass. On land, phytomass is three orders of magnitude greater than zoomass; in the oceans, zoomass is approximately 26 times greater than phytomass.

Both among the animals and plants of the ocean, plankton dominates.

Let us separately dwell on the concept of soil cover. Soil called the surface layer of the earth's crust, resulting from the action of water, air, and organisms on rocks. Soil is a special natural formation that has fertility, that is, the ability to provide plants with assimilable mineral salts, moisture, and produce crops.

The soil is home to many different organisms, bacteria, soil microfauna, fungi, root systems of higher plants, and some animals (worms, larvae, etc.). They do a great job by converting dead organic residues into mineral compounds that are absorbed by plants.

Like the cryosphere, soil belongs to derivative(not the main one) components geographical shell, because it was formed later than the main components (lithosphere, atmosphere, hydrosphere and biosphere) and is the result of their interaction.

The soil cover does not form an integral sphere covering the entire planet (like the main geospheres of the Earth), but is located only on the earth’s crust, and only on the continents.

Soils, as the main components of the geographical envelope, have clearly expressed tiered structure(soil horizons). This indicates that they are under the strong influence of gravity(like the earth’s crust, the hydrosphere, and the atmosphere).

Analysis of the composition and structure of the geographic shell allows us to talk about the role of individual components in it. Both the main geocomponents and derivatives (cryosphere, pedosphere) are necessary for the normal functioning of the geographic envelope.

The destruction or even a significant reduction of geocomponents (for example, the ice sheets of Antarctica, Greenland, or the vast swamps of Polesie, the West Siberian Plain) can entail far-reaching consequences that will affect the entire geographical envelope, because it is an integral system.

F. N. Milkov identifies and justifies one more area:

Landscape sphere- this is the center of the geographical shell, its active core. The landscape sphere is a thin layer of direct contact and energetic interaction between the earth's crust, the air troposphere and the water shell. It is saturated with organic life, and therefore we can say about it that it is the biological focus of the geographical shell of the Earth. The landscape sphere is a place of transformation of solar energy into various types of earthly energy, it is environment most favorable for the development of life. It is to this that, as V.I. Vernadsky puts it, the “condensation of life” of the biosphere is confined.

We can say that the landscape sphere is a set of aquatic-territorial landscape complexes on land, in the ocean and on glaciers. It arises at the junction of the earth's crust with the atmosphere and represents qualitatively new education, which cannot be attributed to any of the above areas.

The landscape sphere is close to the biosphere, but there are differences between them:

1. The landscape sphere has a global distribution. It is developed even where there is no biosphere or, according to Milkov (1990), biostrome (living cover). For example, where there is no biostrome - the ice sheet of Antarctica, fresh lava covers;

2. The landscape sphere layer is larger than the biosphere layer. In addition to vegetation and fauna, on land it includes ground layers of air, soil, and modern weathering crust. Against the background of the geographical shell, the landscape sphere is a very thin horizon, with a thickness of from several tens to 200 - 250 m.

F. N. Milkov rightly emphasizes that the landscape sphere plays the role of a vibrating generator and transformer of interstructural matter and energy, which can be considered up to the outer boundaries of the geographic envelope.

Isolating the landscape sphere does not mean separation and especially oppositions geographical shell. Cognition as part of a whole only possible in close connection and against the background the entire geographical area. At the same time, vertical border background All move apart more as the taxonomic rank of landscape complexes increases.

"! In today's episode of the Club I will answer the question from mother Anya and her son Dani (7 years old): "If there was no magma, would the Earth cool?"

In order for me to answer this question, we need to understand the structure of the Earth. And an ordinary egg will help us with this. The top of the egg is covered with a thin layer of hard but fragile shell. If we clear it, there will be a layer of white substance underneath - protein. And in the very middle we will see a yellow ball - the yolk.

Our Earth is structured in much the same way. On top is a thin layer of the earth's crust. Then comes a layer called the mantle, and in the very middle is the core.

Let's do a thought experiment and take a trip deep into the Earth. Your baby has probably already tried to dig a deep, deep hole in a sandbox or on the beach? But no matter how much he dug, he could not dig deeper than the uppermost layer of the earth's crust - the soil (remember, we already examined the structure of the soil in one of the previous issues of the Club). If people whose specialty was drilling deep, deep wells—drillers—came to his aid, they could help him get to a depth of 4-5 km. There you can find ancient rocks that were formed back in the days when the Earth was young, as well as what are called minerals - oil, gas, various ores. But everything that people extract from the depths of the Earth is still in the very top layer, in that “shell” that surrounds the egg planet.

Even the deepest well that people managed to drill in the earth's crust never reached the next layer of the earth's interior - the mantle. This well is located in Russia, on the Kola Peninsula, and goes 12 km into the earth’s surface. This is so deep! But compared to the Earth, such a well is the same as a needle prick for a large apple, which did not even pierce its skin!

Therefore, scientists cannot say for sure what is happening inside the Earth. We can obtain information about everything that is deeper only indirectly (that is, we learn not from experience, but by inference). For example, studying volcanic eruptions and waves that travel across the globe after earthquakes or powerful explosions.

Today, most scientists adhere to this model of the structure of the Earth:

Inside the Earth there is a solid inner core with a radius of 1300 km, consisting mainly of an iron-nickel alloy with an admixture of other heavy elements. The temperature in the center of the Earth is enormous - according to some estimates, it reaches 5500 degrees Celsius! This is almost the same as on the surface of the Sun!

Around it to a depth of 2900 km there is a layer of the outer core. It consists of the same substance, only in a molten, viscous-flowing state.

Further, to a depth of 1000 km, there is a layer of mantle - a hot solid substance (its temperature varies from 500 to 4000 degrees Celsius). It contains almost the entire volume of the planet’s matter (85%) and accounts for 2/3 of the mass of the entire Earth. The mantle is divided into lower and upper.

In the upper layer of the mantle there is a separate layer of viscous plastic substance called the asthenosphere. It is on it that lithospheric plates “float” - sections of the uppermost, solid layer of the Earth, which make up the earth’s crust. Its thickness is small: 5 km under the oceans and 30-40 km under the continents. Due to the movement of lithospheric plates (slow or catastrophic - in the form of earthquakes), the shape of the earth's surface changes: new mountains, seas and other relief elements are formed.

It is here, in the uppermost layers of the Earth - the crust and asthenosphere, at depths from 15 to 250 km, that magmas (liquid silicate melt) are formed, which, pouring out in the form of lava through volcanoes, solidifies, forming igneous rocks (granites, basalts, etc.) .

Invite your child to make everyone's favorite soda-vinegar volcano and watch it erupt. To do this, you can cover a bottle of the mixture with plasticine, put a tablespoon of soda in it and carefully add a little vinegar.

What will happen if all the Earth's magma cools?

The process of cooling of the Earth has been going on since the very beginning of its existence. Once upon a time the Earth was a hot ball. But gradually its surface cooled, and a solid crust appeared. The crust is constantly moving, drifting and changing its structure due to the fact that there is a layer of liquid mantle material underneath it. If this layer hardens, then volcanoes will stop erupting and all tectonic activity will stop, which means that lithospheric plates will no longer move and the process of mountain building will stop. But this is unlikely to have any impact on life on the planet. But when the Earth cools down completely (which will happen, according to various estimates, in 1-3 billion years), earthlings will face much greater troubles.

First, the Earth will become cold. After all, solar energy is enough to warm the surface of our planet to a depth of only about 30 m. The Earth receives its main heat from its depths. And if this heat is not there, then the difference between day and night temperatures on the planet will become very significant, even a “blanket” of the atmosphere and hydrosphere will not save.

Secondly, the Earth will lose its magnetic field. According to modern concepts, the magnetic field is generated during the rotation of the planet’s liquid core. If the core freezes and the “geodynamo” stops, then the Earth will remain defenseless against the flow of radiation particles that fly to our planet from the Sun. And this, most likely, will lead to the death of all highly organized forms of life (including humans).

But the cooling of the Earth is not scary for us. After all, by the time the Earth cools down, it will still be impossible to live on it due to the fact that the Sun will increase in size and its radiation will dry up all the oceans on the planet. Therefore, humanity will have to take care in advance to find a new space home and leave their home planet. So the task of future generations (including our children) is to direct their strength and skills to preparing for the future colonization of other planets by earthlings. And the first step in this direction will be the manned flight to Mars planned in the coming decades.

I hope, Danya, I answered your question?

And so that I can answer your questions, send them to me by email tavika2000 @ yandex.ua(remove spaces) with the note "Whychek Club". All questions sent to the Club, regardless of whether the answer was published or not, will be entered into a prize draw, which will take place on the first Friday of autumn, September 6. I will provide details about it later.