Geographical zoning. Geographic envelope Geographic zoning in brief
Studying the content of the paragraph provides an opportunity:
Ø to form an idea of the geographic shell as a natural body;
Ø to deepen knowledge about the essence of the periodic law of geographic zoning;
Ø to deepen the understanding of the peculiarities of the natural conditions of individual geographic zones of the Earth.
Peculiarities geographic envelope. The geographic envelope was formed simultaneously with the development of the Earth, therefore its history is part of the general history of the development of the Earth. ( What is a geographic envelope? What constituents of the geographic envelope have you already studied in the course of geography and biology?)
All the constituent parts of the geographic envelope are in contact, interpenetration and interaction . There is a continuous exchange of matter and energy between them. Life is concentrated in the geographic envelope.
In its development, the geographic envelope went through three stages. The beginning of the first - inorganic - can be considered the appearance of the atmosphere. At the second stage, a biosphere was formed in the geographic envelope, which transformed all the processes that had taken place in it earlier. At the third - modern - stage, human society appeared in a geographic shell. Man began to actively transform the geographic envelope.
Due to the fact that the geographic shell of the Earth is the environment of human life and activity, and the human impact on nature increases every year, it contains sociosphere with technosphere and anthroposphere.
The sociosphere (from the Latin societas - society) is a part of the geographical envelope, which includes humanity with its inherent production and production relations, as well as a part of the natural environment mastered by man.
Technosphere (from the Greek. Technе - art, skill) - a set of artificial objects within the geographic shell of the Earth, created by man from the substance of the surrounding nature. The growing anthropogenic pressure on the biosphere, which caused the inclusion of elements of the technosphere and other means and products of human activity in the biosphere, contributes to the transition of the biosphere to a qualitatively new state.
The anthroposphere (from the Greek antropos - man) covers humanity as a set of organisms. The life of any organism in all forms of its manifestation is possible only with constant interaction with the outside world and the continuous flow of energy into the organism from outside. All types of living beings ultimately use the same energy - the energy of the Sun, but the forms of manifestation and use of this energy are different.
Geographic zoning It is expressed in the regular change of geographic zones from the equator to the poles and the distribution of geographic zones within these zones. The largest latitudinal-zonal unit of the geographic envelope is the geographic belt, which is distinguished by its features radiation balance and general atmospheric circulation... Relative homogeneity of the climate is characteristic within the belt, which is reflected in other components of nature (soils, vegetation, fauna, etc.) ( Remember what geographic zones are distinguished on Earth? What is their total number?).
The shape and area of the belts depend on many factors, the main of which are: the proximity of oceans and seas, relief, sea currents. In geographic zones stand out geographic (natural) zones... Their release is associated, first of all, with the uneven distribution of heat and moisture on the Earth's surface. ( Why?) They are more often elongated in the latitudinal direction (Africa), but under the influence of the configuration of the continents and orographic factors, they can have a meridional direction (North America).
VV Dokuchaev and L.S. Berg made a great contribution to the development of the theory of geographic zoning. V.V.Dokuchaev based his doctrine of natural zones on the proposition that each natural zone (tundra, taiga, steppe, desert and other zones) is a natural complex in which the components of living and inanimate nature are interrelated and interdependent. This served as the basis for the classification natural areas developed by L. S. Berg.
Further development of the law of geographic zoning was periodic law of geographic zoning, which was formulated in 1956 by famous geographers A.A. Grigoriev and M.I.Budyko. The essence of the periodic law is that geographic zones at different latitudes have a number of properties that are periodically repeated (for example, the zone of forest-steppe and savannah, deciduous forests of the temperate zone and forests of humid subtropics, etc.) According to this law, the differentiation of the geographical envelope lie: the amount absorbed solar energy, (annual value of the radiation balance of the earth's surface); the amount of incoming moisture (annual precipitation); the ratio of the radiation balance to the amount of heat required to evaporate the annual amount of precipitation (radiation dryness index). The value of the dryness index in different zones ranges from 0 to 4-5. The periodicity is also manifested in the fact that the value of the dryness index close to one is repeated three times between the pole and the equator (Fig ....).
These conditions are characterized by the highest biological productivity of landscapes (with the exception of equatorial forests (gilea).
Thus, geographic zoning is expressed in the regular change of geographic zones from the equator to the poles and in the distribution of geographic zones within these zones. The very list of names of geographical zones emphasizes their symmetrical position in relation to the equator. The proportion of the area of each geographic zone in relation to the total area of the globe is well shown in the figure (Fig ...).
Along with zoning, azonality or regionality is distinguished. Azonality means the spread of any geographic phenomenon out of connection with the zonal features of a given territory. The main reasons for azonality are the geological structure, tectonic features, the nature of the relief, etc. In the presence of these factors, large areas of the geographic envelope acquire individual unique features, which complicates its structure and violates the zoning pattern. Azonality is most often and clearly manifested in the mountains and foothills.
Features of the geographic zones of the Earth. Equatorial belt occupies 6% of the total land area of the Earth. It is represented by equatorial forests ( Determine the boundaries of the equatorial belt from the map)
A feature of the equatorial belt is the extremely high intensity of all natural processes (geomorphological, biochemical and others), as a result of which a powerful weathering crust is formed. The reason for the high intensity of the processes is, first of all, the constantly hot and humid climate.
Subequatorial belts occupy about 11% of the total land area. ( Using the map, determine the location of the subequatorial belts). Most of the area of the subequatorial belts, as well as the equatorial, falls on the World Ocean. Here the belts are clearly expressed and can be identified by the trade wind currents. The belts of both hemispheres in the Pacific and Atlantic oceans are shifted northward compared to their position on land.
An essential feature of the subequatorial belts is the variable circulation of the atmosphere, when there is a seasonal change of the equatorial air to the tropical, and vice versa, which determines the presence of dry and humid (rainy) seasons.
There are two natural zones in the subequatorial belts: savanna(savannas and woodlands), which is the main area, and the zone variable wet forests- narrow, transitional from giles to savannas.
The eastern outskirts of the continents within these belts are influenced by monsoons and trade winds.
Tropical belts. In general, they occupy 35% of the entire land area of the Earth. (Determine their location on the map)... In these latitudes, dry and hot air dominates both on the continents and on the oceans. By natural features within the tropical zones distinguish zones: forests, savannah and woodlands, semi-deserts and deserts (Using the atlas, define the boundaries of the natural zones of tropical zones).
Subtropical belts occupy an area equal to 15% of the entire land area (Determine their location on the map and compare the distribution in longitude in the northern and southern hemispheres)... The peculiarity of the nature of these belts is determined by their geographical position and is expressed in the prevalence here tropical(in summer) and moderate(in winter) air masses. In the western oceanic regions of these zones (see map), nature is Mediterranean with dry summers and wet winters. The eastern coastal areas (see map) have a monsoon climate with high summer humidity. The inland areas have an arid climate. In general, natural zones are distinguished in the subtropical zones: forests, forest-steppes, steppes, semi-deserts and deserts.
The natural conditions of the subtropical zones are favorable for human life, therefore, these territories have long been developed and settled. Here forests are heavily reduced, in their place are fields, cotton plantations, tea, citrus fruits, etc.
Moderate belts characterized by the asymmetry of their location in the Northern and Southern Hemispheres (Determine from the map the location of the belts in the northern and southern hemispheres)... The great extent of the territory from east to west and from north to south causes a wide variety of natural conditions. According to its natural characteristics, the temperate zone is divided into moderately warm dry and moderately cold damp. In the first, natural zones are distinguished: semi-deserts and deserts, steppes, forest-steppes; in the second: the zone of taiga (coniferous forests), deciduous forests, small-leaved and mixed forests. ( Using the atlas, define the boundaries of the natural zones of the temperate zone of the northern hemisphere)
Subarctic belt located on the northern outskirts of Eurasia and North America. Its southern border is largely determined by the impact of sea currents. In Europe, under the influence of a warm current, the belt occupies a narrow strip of land and is located north of the Arctic Circle, while in the northeastern part of Eurasia, where there is no action of this current, it expands and reaches 60 ° N. NS. In North America (the Hudson Bay area), under the influence of a cold current, its boundary drops to 50 ° N. sh., that is, to the latitude of Kiev. The southern boundary of the belt roughly corresponds to the 10 ° C isotherm of the warmest month of the year. This is the limit of the northern distribution of forests. Permafrost is widespread everywhere, which in some places begins already at a depth of 30 cm. Natural zones: tundra, forest-tundra and woodlands.
Subantarctic belt is almost entirely in the oceanic expanses. Only a few islands are dry land. The largest of them are Falkland, Kerguelen, South Georgia and others. The islands have oceanic tundra conditions, high humidity, strong winds, poor moss and lichen vegetation. On some islands, the tundra can be traced up to 50 ° S. NS.
Arctic and Antarctic belts (Determine their geographic location) although they are located on territories with different underlying surfaces - the first on the oceanic expanses, the second on the mainland Antarctica, but they have more in common than different ones: low temperatures in winter and summer ( Determine the temperature of the warmest month), strong winds, absence or small amount of vegetation, etc. The arctic tundra zone, arctic and antarctic deserts are distinguished.
Questions and tasks
Many physical and geographical phenomena in the geographic envelope are distributed in the form of stripes elongated along the parallels, or at some angle to them. This property of geographic phenomena is called zoning (the law of geographic zoning). The concept of natural zoning dates back to ancient Greek scientists. So, in the V century. BC. Herodotus and Eudonyx marked five zones of the Earth: tropical, two temperate and two polar. A great contribution to the doctrine of natural zoning was made by the German geographer Humboldt, who established the climatic and plant zones of the Earth ("Geography of Plants", 1836). In Russia, the concept of geographic zoning was expressed in 1899 by Dokuchaev in his book “The doctrine of the zones of nature. Horizontal and vertical soil zones ”. Professor Grigoriev is responsible for research on the causes and factors of zoning. He came to the conclusion about the great role of the ratio of the radiation balance and the amount of annual precipitation (1966).
It is currently believed that natural zoning is represented by
component zoning;
landscape zoning.
All components of the geographic envelope are subject to the World Law of Zoning. Zoning is noted for climatic indicators, plant groupings, and soil types. It also manifests itself in hydrological and geochemical phenomena, as a derivative of climatic and soil-plant conditions.
The zonality of physical and geographical phenomena is based on the regularity of the arrival of solar radiation, the arrival of which decreases from the equator to the poles. However, this distribution of solar radiation is superimposed on the transparency factor of the atmosphere, which is azonal, since it is not related to the shape of the Earth. The air temperature depends on solar radiation, the distribution of which is influenced by another azonal factor - the properties of the earth's surface - its heat capacity and thermal conductivity. This factor leads to an even greater violation of zoning. The distribution of heat on the Earth's surface is also greatly influenced by oceanic and air currents that form heat transfer systems.
The atmospheric precipitation is even more difficult to distribute on our planet. On the one hand, they have a zonal character, and on the other hand, they are associated with the position of the territory in the western or eastern part of the continents and the height of the earth's surface.
The combined effect of heat and moisture is the main factor that determines most of the physical and geographical phenomena. Since the distribution of moisture and heat is oriented in latitude, then all the phenomena associated with climate are oriented in latitude. As a result, a latitudinal structure is formed on the Earth, called the geographic zonation.
Zonality is manifested in the distribution of the main climatic characteristics: solar radiation, temperature and atmospheric pressure, which leads to the formation of a system of 13 climatic zones. Plant groups on Earth also form elongated stripes, but of a more complex configuration than climatic zones. These are called vegetation zones. The soil cover is closely related to vegetation, climate and the nature of the relief, which allowed V.V. Dokuchaev to identify genetic soil types.
In the 1950s, geographers Grigoriev and Budyko developed Dokuchaev's law of zoning and formulated the periodic law of geographic zoning. This law establishes the repetition of the same type of geographic zones within the belts - depending on the ratio of heat and moisture. So, there are forest zones in the equatorial, subequatorial, tropical and temperate zones. Steppes and deserts are also found in different geographic zones. The presence of the same type of zones in different belts is explained by the repetition of the same ratios of heat and moisture.
Thus, the zone is a large part of the geographic zone, which is characterized by the same indicators of the radiation balance, annual precipitation and evaporation. At the beginning of the last century, Vysotsky proposed a moisture coefficient equal to the ratio of precipitation to evaporation. Later, Budyko, to substantiate the periodic law, introduced an indicator - the radiation dryness index, which is the ratio of the incoming amount of solar energy to the cost of heat for evaporation of atmospheric precipitation. It has been established that there is a close relationship between geographic zones and the amount of solar heat input and the radiation index of dryness.
Geographic zones are internally heterogeneous, which is primarily associated with the azonal circulation of the atmosphere and moisture transfer. With this in mind, sectors are allocated. As a rule, there are three of them: two oceanic (western and eastern) and one continental. Sectorality is a geographical zoning, which is expressed in the change of the main natural indicators in longitude, that is, from the oceans inland.
Landscape zoning is determined by the fact that the geographic envelope in the process of its development has acquired a "mosaic" structure and consists of many natural complexes of unequal size and complexity. By definition F.N. Milkova PTK is a self-regulated system of interconnected components, functioning under the influence of one or more components acting as a leading factor.
Vertical waist
Altitudinal zonality - part of the vertical zoning of natural phenomena and processes related only to mountains. Due to the regular decrease in air temperatures with height, the ratio of heat and moisture, runoff conditions, relief formation, soil and vegetation cover and related animals change.
Climbing a high mountain is accompanied by the change of several belts of vegetation, as when moving from the equator to the poles. Unlike natural zones, there are few animals here, but there are many birds of prey (the largest bird of prey is the condor. It hovers over the Andes at an altitude of up to 7 thousand meters). In each type environment there is its own community of animals and plants even within the same natural zone, but on different continents (natural complex). Simultaneously with zonal factors, associated with the internal energy of the Earth (relief, height, configuration of continents) act.
Anywhere in the world, zonal and zonal factors act simultaneously. The set of altitude zones in the mountains depends on the geographical position of the mountains themselves, which determines the nature of the lower belt, and the height of the mountains, which determines the nature of the upper tier. The sequence of altitudinal belts coincides with the sequence of changes in natural zones on the plains. But in the mountains the belts change faster, there are belts that are characteristic only of mountains - subalpine and alpine meadows.
Altitudinal zonation of mountain systems is diverse. It is closely related to latitudinal zones. With altitude, the climate, soil and vegetation cover, hydrological and geomorphological processes are transformed, the slope exposure factor is sharply expressed, etc. With a change in the components of nature, natural complexes change - high-altitude natural belts are formed. The phenomenon of the change of natural-territorial complexes with height is called altitudinal zoning, or vertical altitudinal zoning.
The formation of types of altitudinal zonation of mountain systems is determined by the following factors:
- > Geographical position mountain system. The number of mountain high-altitude belts in each mountain system and their altitude position are basically determined by the latitude of the place and the position of the territory in relation to the seas and oceans. As we move from north to south, the altitude position of natural belts in the mountains and their set gradually increase.
- > The absolute height of the mountain system. The higher the mountains rise and the closer they are to the equator, the more altitudinal zones they have. Therefore, each mountain system develops its own set of altitudinal belts.
- > Relief. The relief of mountain systems (orographic pattern, degree of dissection and evenness) determines the distribution of snow cover, moisture conditions, preservation or removal of weathering products, affects the development of soil and vegetation cover and thereby determines the diversity of natural complexes in the mountains. For example, the development of leveling surfaces contributes to an increase in the areas of high-altitude zones and the formation of more homogeneous natural complexes.
- > Climate. This is one of the most important factors shaping the altitudinal zonation. With the rise in the mountains, temperature, humidity, solar radiation, wind direction and strength, types of weather change. The climate determines the nature and distribution of soils, vegetation, fauna, etc., and, consequently, the variety of natural complexes.
Exposition of slopes. It plays an essential role in the distribution of heat, moisture, wind activity, and, consequently, the processes of weathering and distribution of soil and vegetation cover. On the northern slopes of each mountain system, the altitudinal belts are usually located lower than on the southern slopes.
The position, change in boundaries and the natural appearance of high-altitude belts is influenced by and economic activity person.
Already in the Neogene, latitudinal zones existed on the plains of Russia, almost analogous to modern ones, but due to the warmer climate, there were no zones of arctic deserts and tundras. In the Neogene-Quaternary time, significant changes in natural zones took place. This was caused by active and differentiated neotectonic movements, cooling of the climate and the emergence of glaciers in the plains and mountains. Therefore, natural zones shifted to the south, the composition of their flora (strengthening of deciduous boreal and cold-resistant flora of modern coniferous forests) and fauna changed, the youngest zones were formed - the tundra and the Arctic desert, and in the mountains - alpine, mountain-tundra and nival-glacial belts.
During the warmer Mikulin interglacial (between the Moscow and Valdai glaciations), natural zones shifted to the north, and altitudinal belts occupied higher levels. At this time, the structure of modern natural zones and high-altitude belts is being formed. But due to climate change in the Late Pleistocene and Holocene, the boundaries of zones and belts shifted several times. This is confirmed by numerous relict botanical and soil finds, as well as spore-pollen analyzes of Quaternary deposits.
In the mountains, when climbing up, the amount and composition of solar radiation changes, the amount of precipitation and atmospheric pressure decrease. A change in climatic conditions leads to a change in the same direction in geomorphological processes, the composition of vegetation, the characteristics of soils and the nature of the animal world. This makes it possible to distinguish vertical belts in mountain systems.
Vertical belts are similar to horizontal zones in the sense that they change when moving up in approximately the same order (starting from the latitudinal zone in which the mountainous country is located) in which latitudinal zones change when moving from the equator to the poles. But vertical belts are not exact copies of similar latitudinal zones, since they are influenced by local conditions (dissection of the relief, difference in slope exposures, mountain heights, history of terrain development, etc.).
Despite some features of the similarity of vertical zonation in different mountain systems, the latter manifests itself in different ways on different continents and geographic latitudes. The severity of vertical zonation, i.e., the number of vertical belts, their height, continuity of extension, floristic and faunal composition depend on the position of the mountain system, its latitude, direction of ridges, degree of dissection, history of formation and some other reasons.
Let us demonstrate this using the example of two mountain systems (the Verkhoyansk Range and the Greater Caucasus).
a) The Verkhoyansk ridge, or rather a whole system of ridges, is several times larger in size than the system of ridges of the Greater Caucasus. Despite this, the Verkhoyansk ridge has a less diverse nature, i.e., within its limits, there are fewer vertical belts than in the Greater Caucasus, and similar belts of these mountain systems differ sharply in the nature of vegetation, soils and fauna.
The Verkhoyansk ridge is located in the temperate zone, in the taiga zone, in the north-east of Siberia. The climate here is very harsh. Near the ridge there is a "pole of cold"; the soil is frozen all year round; piercing winds blow; the amount of precipitation is insignificant (200-300 mm per year).
The slopes of the ridge from the base to a height of about 1,000 m are covered with taiga, in the northern part of the sparse larch (Larix dahurica). The latter is adapted to live in the harshest conditions, on frozen ground. Podzolic soils are developed under the taiga. The taiga belt is replaced by a belt of subalpine shrubs (on podzolic soils), the most widespread of which is the dwarf cedar (Pinus pumila), a creeping species of cedar pine. Above 1000-1500 m, the loach belt begins, that is, mountain lichen-crushed stone tundra with reindeer lichen (Cladonia), partridge grass (Dryas punctata), Potentilla nivea, etc. Such is the sparse vegetation of the Verkhoyansk Range.
b) The Greater Caucasus is located on the border of the temperate and subtropical climatic zones. This alone makes us suppose a variety of natural conditions in the Greater Caucasus in the form of a significant number of vertical belts and their differences on the northern and southern slopes. In addition, the vertical zoning is complicated here by an increase in dryness from west to east. All these factors greatly diversify the vertical zonation in the Greater Caucasus and lead to its differences on the northern and southern slopes, as well as in the west and east.
When climbing the mountains from the side of the Rion Lowland, we will encounter the following vertical belts:
- 1. Belt of relict Colchis forests, developed mainly on podzolic-yellow-earth soils. The basis of the forest here is broad-leaved species: Gartvis oak (Quercus hartwissiana), Georgian oak (Quercus iberica), noble chestnut (Castanea satwa), oriental beech (Fagus orientalis), hornbeam (Carpinus caucasica). Evergreen shrubs are developed in the undergrowth: Pontic rhododendron ( Rhododendron ponticum), laurel (Laurus nobiles), etc.
- 2. From a height of 600 m and up to a height of about 1200 m, a belt of beech forests (dark and humid) stretches, consisting mainly of eastern beech, to which other broad-leaved species join. Mountain-forest brown soils are developed in this: belt.
- 3. Even higher stretches a belt of coniferous and coniferous-broad-leaved forests, consisting of Caucasian spruce (Picea orientalis), Caucasian fir. (Abies nordmanniana) and oriental beech; under them are developed mountain-podzol and mountain-forest brown soils.
- 4. From a height of about 2000 m, the subalpine belt begins - tall-grass meadows and thickets of the Caucasian rhododendron (Rhododendron caucasicum) on mountain-meadow soils. The alpine belt stretches even higher, where alpine meadows, developed on mountain-meadow soils, alternate with almost bare rocks and talus. And, finally, the last one is the nival belt - the area of distribution of eternal snows and glaciers.
The northern slope of the Western Caucasus differs from the southern one by the absence of a belt of Colchis forests, which is here replaced by a belt of oak forests, consisting mainly of oak (Quercus petraca). The rest of the vertical belts are somewhat different from the above ones in their floristic composition.
A completely different character of vertical zonation is observed in the Eastern Caucasus. At the foot of the slope there are deserts and semi-deserts of the Kura lowland on gray, brown and chestnut soils, deserts and semi-deserts in the extreme east rise into the mountains to an altitude of 800 m. Their main representative is Hansen's wormwood (Artemisia Hanseniana). Above, there is a belt of steppes, on mountain chernozems and dark chestnut soils, which gradually wedges out when moving to the west.
Above (on average, at an altitude of 500-1200 m) there is a belt of oak forests with an admixture of other broad-leaved species (Georgian oak, Caucasian hornbeam) on brown soils. Where forests have been cleared, upland-xerophytic vegetation (shhiblyak), consisting mainly of a tree (Paliurus spina), is widely developed.
At an altitude of 1200-2000 m, there is a belt of beech and beech-hornbeam forests, which at the upper border of the forest are replaced by thickets of eastern oak (Quercus macranthera). There are no coniferous forests in the Eastern Caucasus. Brown forest soils.
At an altitude of 2000-2500 m, subalpine meadows are developed, which differ from those of the Western Caucasus in their strong steppe and low grass stand (alpine steppes). Above, they turn into alpine meadows. Mountain meadow soils. And, finally, at the maximum heights, the nival belt is developed, which is insignificantly widespread in the Eastern Caucasus.
The northern slope of the Eastern Caucasus (including Dagestan) is distinguished by the absence at the foot of the deserts, by the greater xerophytic nature of alpine meadows (alpine steppes on mountain meadow-steppe soils) and by the large development of alpine-xerophytic vegetation.
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Introduction
Natural zoning is one of the earliest laws in science, ideas about which deepened and improved simultaneously with the development of geography. Zoning, the presence of natural belts on the famous Ecumene was found by Greek scientists of the 5th century. BC. Herodotus (485-425 BC) and Eudonyx of Cnidus (400-347 BC), distinguishing five zones: tropical, two temperate and two polar. And a little later, the Roman philosopher and geographer Posidonius (135-51 BC) further developed the doctrine of natural zones that differ from one another in climate, vegetation, hydrography, peculiarities of the composition and occupation of the population. The latitude of the area received from him an exaggerated meaning, to the extent that it allegedly affects the "ripening" of precious stones.
The German natural scientist A. Humboldt made a great contribution to the doctrine of natural zoning. Main feature his works were that he considered each natural phenomenon as part of a single whole, connected with the rest of the environment by a chain of causal dependencies.
Humboldt's zones are bioclimatic in their content. His views on zoning are most fully reflected in the book "Geography of Plants", due to which he is deservedly considered one of the founders of the science of the same name.
The zonal principle was used already in the early period of the physical and geographical zoning of Russia, dating back to the second half of the XVIII - early XIX centuries. This refers to the geographical descriptions of Russia by A.F. Bishinga, S.I. Pleshcheeva and E.F. Zyablovsky. The zones of these authors had a complex, natural-economic character, but due to the limited knowledge they were extremely schematic.
Modern concepts of geographic zoning are based on the works of V.V. Dokuchaev and F.N. Milkov.
The views of V.V. Dokuchaev was largely facilitated by the works of his numerous students - N.M. Sibirtseva, K. D. Glinka, A.N. Krasnova, G.I. Tanfilieva and others.
Further successes in the development of natural zoning are associated with the names of L.S. Berg and A.A. Grigoriev.
A.A. Grigoriev is the author of theoretical research on the causes and factors of geographic zoning. He comes to the conclusion that in the formation of zoning, along with the magnitude of the annual radiation balance and the amount of annual precipitation, their ratio, the degree of their proportionality, plays an enormous role. He also did a lot of work on characterizing the nature of the main geographic zones of the land. At the center of these largely original characteristics are the physical and geographical processes that determine the landscapes of belts and zones.
Zoning is the most important property, an expression of the orderliness of the structure of the geographic shell of the Earth. Specific manifestations of zoning are extremely diverse and are found both in physical-geographical and economic-geographical objects. Below we will talk briefly about the geographic shell of the Earth, as the main object of study, and then specifically and in detail about the law of zoning, its manifestations in nature, namely, in the system of winds, the existence of climatic zones, zoning of hydrological processes, soil formation, vegetation, etc. etc.
1 . Geographic envelopeOf the earth
1.1 General characteristics of the geographic envelope
The geographic envelope is the most complex and diverse (contrasting) part of the Earth. Its specific features were formed in the course of long-term interaction of natural bodies in the conditions of the earth's surface.
One of characteristic features shells - a wide variety of material composition, significantly exceeding the variety of matter, both the interior of the Earth and the upper (outer) geospheres (ionosphere, exosphere, magnetosphere). In the geographic envelope, matter occurs in three states of aggregation, has a wide range of physical characteristics - density, thermal conductivity, heat capacity, viscosity, fragmentation, reflectivity, etc.
The wide variety is striking chemical composition and the activity of the substance. The material formations of the geographic envelope are heterogeneous in structure. Allocate inert, or inorganic, substance, living (the organisms themselves), bioinert substance.
Another feature of the geographic envelope is a wide variety of types of energy entering it and forms of its transformation. Among the numerous transformations of energy, a special place is occupied by the processes of its accumulation (for example, in the form of organic matter).
The uneven distribution of energy on the earth's surface, caused by the sphericity of the Earth, the complex distribution of land and ocean, glaciers, snows, the relief of the earth's surface, and a variety of types of matter determine the disequilibrium of the geographic envelope, which serves as the basis for the emergence of various movements: energy flows, air circulation, water, soil solutions, migration of chemical elements, chemical reactions, etc. The movements of matter and energy connect all parts of the geographic envelope, determining its integrity.
In the course of the development of the geographic envelope as a material system, its structure became more complex, the diversity of the material composition and energy gradients increased. At a certain stage in the development of the shell, life appeared - the highest form of motion of matter. The emergence of life is a natural result of the evolution of the geographic envelope. The activity of living organisms has led to a qualitative change in the nature of the earth's surface.
A set of planetary factors is essential for the emergence and development of the geographic envelope: the mass of the Earth, the distance to the Sun, the speed of rotation around the axis and along the orbit, the presence of a magnetosphere, which provided a certain thermodynamic interaction - the basis of geographic processes and phenomena. Study of the nearest space objects - planets Solar system- showed that only on the Earth there were conditions favorable for the emergence of a rather complex material system.
In the course of the development of the geographic envelope, its role as a factor in its own development (self-development) increased. Of great independent importance are the composition and mass of the atmosphere, ocean and glaciers, the ratio and size of the areas of land, ocean, glaciers and snows, the distribution of land and sea over the earth's surface, the position and configuration of relief forms of various scales, different types natural environment, etc.
At a fairly high level of development of the geographic envelope, its differentiation and integration, complex systems have arisen - natural territorial and aquatic complexes.
Let us list some of the most important parameters of the geographic envelope and its large structural elements.
The earth's surface area is 510.2 million km 2. The ocean occupies 361.1 million km 2 (70.8%), land - 149.1 million km 2 (29.2%). There are six large land masses - continents, or continents: Eurasia, Africa, North America, South America, Antarctica and Australia, as well as numerous islands.
The average height of the land is 870 m, the average ocean depth is 3704 m. The oceanic space is usually subdivided into four oceans: the Pacific, Atlantic, Indian and Arctic.
There is an opinion about the advisability of allocating the Antarctic waters of the Pacific, Indian and Atlantic oceans to the special Southern Ocean, since this region is distinguished by a special dynamic and thermal regime.
The distribution of continents and oceans across hemispheres and latitudes is uneven, which is the object of special analysis.
For natural processes, the mass of objects is important. The mass of the geographic envelope cannot be accurately determined due to the uncertainty of its boundaries.
1.2 Horizontal structure of the geographic envelope
The differentiation of the geographic envelope in the horizontal direction is expressed in the territorial distribution of geosystems, which are represented by three levels of dimension: planetary, or global, regional and local. The most important factors that determine the structure of geosystems at the global level are the sphericity of the Earth and the closedness of the space of the geographic envelope. They determine the belt-zonal nature of the distribution of physical and geographical characteristics and the isolation, circularity of movements (gyres).
The distribution of land, ocean and glaciers is also an important factor that determines the well-known mosaicism not only of the external appearance of the earth's surface, but also of the types of processes.
The dynamic factor affecting the direction of movement of matter in the geographic envelope is the Coriolis force.
The listed factors determine the general features of the atmospheric and oceanic circulation, which depends on the planetary structure of the geographic envelope.
At the regional level, differences in the locations and outlines of continents and oceans, the relief of the land surface, which determine the features of the distribution of heat and moisture, types of circulation, the features of the location of geographic zones and other deviations from the general picture of planetary laws, come to the fore. In regional terms, the position of the territory relative to the coastline, center or centerline of the mainland or water area, etc. is essential.
The nature of the interaction between regional geosystems (maritime or continental climate, monsoon circulation or the prevalence of western transport, etc.) depends on these spatial factors.
The configuration of the regional geosystem, its borders with other geosystems, the degree of contrast between them, etc. are of great importance.
At the local level (small parts of the region with an area from tens of square meters to tens of square kilometers), the differentiation factors are various details of the relief structure (meso- and microforms - river valleys, watersheds, etc.), the composition of rocks, their physical and Chemical properties, the shape and exposure of slopes, the type of moisture and other particular features that give the earth's surface fractional heterogeneity.
1. 3 Belt-zone structures
Many physical and geographical phenomena are distributed on the earth's surface in the form of stripes elongated mainly along parallels or sublatitudinal (i.e., at some angle to them) stripes. This property of geographic phenomena is called zoning. Such a spatial structure is characteristic, first of all, of climatic indicators, plant groupings, soil types; it manifests itself in hydrological and geochemical phenomena, as a derivative of the former. The zonality of physical and geographical phenomena is based on the well-known regularity of the arrival of solar radiation on the earth's surface, the arrival of which decreases from the equator to the poles according to the cosine law. If it were not for the peculiarities of the atmosphere and the underlying surface, then the arrival of solar radiation - the energy basis of all processes in the shell - would be precisely determined by this law. However, the earth's atmosphere has different transparency depending on the cloudiness, as well as dustiness, the amount of water vapor and other components and impurities. The distribution of atmospheric transparency has, among others, a zonal component, which is easy to see on a satellite image of the Earth: on it, cloud bands form belts (especially along the equator and in temperate and polar latitudes). Thus, a more variegated picture of the transparency of the atmosphere, which acts as a differentiating factor of solar radiation, is superimposed on the correct regular decrease in the arrival of solar radiation from the equator to the poles.
The air temperature depends on solar radiation. However, the nature of its distribution is influenced by another differentiating factor - the thermal properties of the earth's surface (heat capacity, thermal conductivity), which causes an even greater mosaic distribution of temperatures (in comparison with solar radiation). The distribution of heat, and therefore the surface temperature, is influenced by oceanic and air currents that form heat transfer systems.
Atmospheric precipitation is even more difficult to distribute on the globe. They have two distinct components: zonal and sectoral, associated with the position in the western or eastern part of the continent, on land or at sea. The regularities of the spatial distribution of the listed climatic factors are presented on the maps of the Physico-Geographical Atlas of the World.
The combined effect of heat and moisture is the main factor that determines most of the physical and geographical phenomena. Since the distribution of moisture and, especially, heat is retained latitudinal orientation, then all phenomena derived from climate are oriented accordingly. A conjugate spatial system with a latitudinal structure is created. It is called geographic zonation. The belt structure of natural phenomena on the earth's surface was first noted quite clearly by A. Humboldt, although about thermal zones, i.e. based on geographic zonation, they knew back in Ancient Greece... At the end of the last century V.V. Dokuchaev formulated the world law of zoning. In the first half of this century, scientists began to talk about geographic zones - elongated territories with the same type of nature of many physical and geographical phenomena and their interactions.
2 . Zoning law
2.1 Zoning concept
In addition to territorial differentiation in general, the most characteristic structural feature of the geographic envelope of the Earth is a special form of this differentiation - zoning, i.e. natural change in all geographical components and geographical landscapes in latitude (from the equator to the poles). The main reasons for zoning are the shape of the Earth and the position of the Earth relative to the Sun, and the premise is the fall of the sun's rays on the earth's surface at an angle gradually decreasing in both directions from the equator. If it were not for this cosmic prerequisite, there would be no zoning. But it is also obvious that if the Earth were not a ball, but a plane, as you like oriented to the flow of the sun's rays, the rays would fall on it everywhere in the same way and, therefore, would heat the plane equally at all its points. There are features on Earth that outwardly resemble latitudinal geographic zoning, for example, a sequential change from south to north of terminal moraine belts, piled up by a retreating ice sheet. Sometimes they talk about the zonality of the relief of Poland, because here from north to south strips of coastal plains, end-moor ridges, Orednipolsky lowlands, uplands on a folded-block base, ancient (Hercynian) mountains (Sudetes) and young (Tertiary) folded mountains replace each other (Carpathians). They even talk about the zoning of the Earth's mega-relief. However, only that which is directly or indirectly caused by a change in the angle of incidence of the sun's rays on the earth's surface, and can refer to truly zonal phenomena. That which is similar to them, but arises for different reasons, should be called differently.
G. D. Richter, following A.A. Grigoriev, proposes to distinguish between the concepts of zoning and zonality, dividing the belts into radiation and thermal. The radiation belt is determined by the amount of incoming solar radiation, which naturally decreases from low to high latitudes.
This influx is influenced by the shape of the Earth, but not by the nature of the earth's surface, which is why the boundaries of the radiation belts coincide with the parallels. The formation of thermal zones is no longer controlled only by solar radiation. Here, the properties of the atmosphere (absorption, reflection, scattering of radiant energy), and the albedo of the earth's surface, and heat transfer by sea and air currents are also important, as a result of which the boundaries of the thermal zones cannot be combined with parallels. As for the geographic zones, their essential features are due to the ratio of heat and moisture. This ratio depends, of course, on the amount of radiation, but also on factors that are only partially tied to latitude (the amount of advective heat, the amount of moisture in the form of precipitation and runoff). That is why the zones do not form continuous stripes, and their extension along the parallels is rather special case than the general law.
If we summarize the above considerations, then they can be reduced to the thesis: zoning acquires its specific content in the special conditions of the geographic shell of the Earth.
For the understanding of the principle of zoning itself, it is rather indifferent whether we call a belt a zone or a zone a belt; these shades have more taxonomic than genetic significance, for the amount of solar radiation equally forms the basis for the existence of both belts and zones.
2.2 Periodic law of geographic zoning
The discovery by V. Dokuchaev of geographical zones as integral natural complexes was one of the largest events in the history of geographical science. After that, for almost half a century, geographers were engaged in concretizing and, as it were, "material filling" of this law: the boundaries of the zones were specified, their detailed characteristics were made, the accumulation of factual material made it possible to distinguish subzones within the zones, the heterogeneity of zones along the strike was established (identification of provinces), the reasons pinching out zones and deviating their direction from the theoretical, a grouping of zones was developed within the limits of larger taxonomic subdivisions - belts, etc.
A fundamentally new step in the problem of zoning was made by A.A. Grigoriev and M.I. Budyko, who summed up the physical and quantitative basis for the phenomena of zoning and formulated the periodic law of geographic zoning, which underlies the structure of the Earth's landscape envelope.
The law is based on the consideration of three closely interrelated factors. One of them is the annual radiation balance (R) of the earth's surface, i.e. the difference between the amount of heat absorbed by this surface and the amount of heat given off by it. The second is the annual amount of precipitation (r). The third, called the radiation dryness index (K), represents the ratio of the first two:
where L is the latent heat of vaporization.
Dimension: R in kcal / cm 2 per year, r - in g / cm 2, L - in kcal / g per year, - in kcal / cm 2.
It turned out that the same K value is repeated in zones belonging to different geographic zones. In this case, the K value determines the type of landscape zone, and the R value determines the specific nature and appearance of the zone (Table I). For example, K> 3 in all cases indicates the type of desert landscapes, but depending on the value of R, i.e. from the amount of heat, the appearance of the desert changes: at R = 0-50 kcal / cm 2 per year, it is a desert of a temperate climate, at R = 50-75, it is a subtropical desert, and at R> 75, it is a tropical desert.
If K is close to one, this means that there is proportionality between heat and moisture: as much precipitation falls as it can evaporate. This index provides biocomponents with uninterrupted evaporation and transpiration processes, as well as soil aeration. Deviation of K in both directions from unity creates disproportions: with a lack of moisture (K> 1), the uninterrupted flow of evaporation and transpiration processes is disturbed, with an excess of moisture (K<1) - процессов аэрации; и то и другое сказывается на биокомпонентах отрицательно.
The significance of the works of M.I. Budyko and A.A. Grigoriev is twofold: 1) the characteristic feature of zoning is emphasized - its periodicity, which can be comparable with the importance of D.I. Mendeleev of the periodic law of chemical elements; 2) tentative quantitative indicators have been established for drawing the boundaries of landscape zones.
2.3 LandeshaftszonesNS
Modern ideas about the connections and interactions of individual components of the Earth's landscape envelope make it possible to construct a theoretical model of landscape zones on land using the example of the so-called homogeneous ideal continent (Fig. 1). Its dimensions correspond to half the land area of the globe, its configuration corresponds to its location in latitudes, and its surface is a low plain; in place of mountain systems, the types of zones are extrapolated.
It is necessary to draw two main conclusions from the scheme of a hypothetical continent: 1) most of the geographic zones have no west-east strike and, as a rule, do not encircle the globe, and 2) each belt has its own sets of zones.
The explanation for this is that the land and sea on Earth are unevenly distributed, the coasts of the continents are washed in some cases by cold, in others - by warm sea currents, and the relief of the land is very diverse. The distribution of zones also depends on the circulation of the atmosphere, i.e. from the direction of advection of heat and moisture. If the meridional transfer predominates (i.e. coincides with the latitudinal change in the amount of radiation heat), the zoning will often be latitudinal, in the case of a western or eastern (i.e. zonal) transfer, latitudinal zoning is rather an exception, the zones acquire different stripes and outlines (stripes, spots, etc.) and not very long. At the same time, the essential features of natural zones are formed under the influence of humidification and advection of heat (or cold) in the warm season.
The analysis of the actual picture of geographic zoning should be preceded by the division of the earth's surface into geographic zones. Now the belts are usually distinguished: polar, subpolar, temperate, tropical, subtropical, subequatorial and equatorial. In other words, the geographic zone is understood as the latitudinal subdivision of the geographic envelope, determined by the climate. However, the main point of identifying geographical zones is to outline only the most general features of the distribution of the primary factor of zoning, i.e. heat, so that against this general background one can outline the first largest details (also of a rather general nature) - landscape zones. This requirement is fully satisfied by the division of each hemisphere into cold, moderate and hot belts. The boundaries of these belts are drawn according to isotherms, which in specific values reflect the influence of all factors on the distribution of heat - insolation, advection, the degree of continentality, the height of the Sun above the horizon, the duration of illumination, etc. According to V. B. Sochava, only three belts should be considered the main links of planetary zoning: northern extratropical, tropical and southern extratropical.
Recently, in the geographical literature, there has been a tendency to increase not only the number of geographical zones, but also the number of landscape zones. V.V. Dokuchaev in 1900 spoke about seven zones (boreal, northern forest, forest-steppe, chernozem, dry steppes, aerial, lateritic), L.S. Berg (1938) - about 12, P.S. Makeev (1956) already describes about three dozen zones. In the Physico-Geographical Atlas of the World, 59 zonal (that is, those that fit into zones and subzones) types of land landscapes are identified.
A landscape (geographic, natural) zone is a large part of a geographic belt characterized by the dominance of any one zonal type of landscape.
The names of landscape zones are most often given on the basis of a geobotanical characteristic, since the vegetation cover is an extremely sensitive indicator of a variety of natural conditions. There are, however, two points to keep in mind. First, the landscape zone is not identical to either the geobotanical, or soil, or geochemical, or any other zone objectively distinguished by a separate component of the Earth's landscape envelope. In the landscape zone of the tundra, there is not only a type of tundra vegetation, but also forests along the river valleys. In the landscape zone of the steppes, soil scientists place both the zone of chernozems, and the zone of chestnut soils, etc. Second: the appearance of any landscape zone is created not only by the totality of modern natural conditions, but also by the history of their formation. In particular, the taxonomic composition of flora and fauna does not in itself give an idea of zoning. The features of the zonality of vegetation and the animal world are communicated by the adaptation of their representatives (and even more so, their communities, biocenoses) to the ecological situation and, as a consequence, the development in the process of evolution of a complex of life forms that corresponds to the geographical content of the landscape zone.
In the early stages of the study of zoning, it was taken for granted that the zoning of the southern hemisphere is just a mirror image of the zoning of the northern hemisphere, somewhat damaged by the smaller dimensions of the continental spaces. As will be seen from what follows, such assumptions did not come true, and they have to be abandoned.
An extensive literature is devoted to the experience of dividing the globe into landscape zones and the description of zones. The division schemes, despite some differences, in all cases convincingly prove the reality of landscape zones.
3 . NSroyaleezoning
3.1 Forms of manifestation
Due to the zonal distribution of solar radiant energy on the Earth, they are zonal: temperatures of air, water and soil, evaporation and cloudiness, precipitation, baric relief and wind systems, properties of air masses, climates, the nature of the hydrographic network and hydrological processes, features of geochemical processes, weathering and soil formation, types of vegetation and life forms of plants and animals, sculptural forms of relief, to a certain extent types of sedimentary rocks, and finally, geographical landscapes, united in this connection into a system of landscape zones.
The zoning of thermal conditions was already known to the geographers of ancient times; some of them also have elements of ideas about the natural zones of the Earth. A. Humboldt established the zonality and altitudinal zonation of vegetation. But the honor and merit of the genuine scientific discovery of geographical zoning belongs to V.V. Dokuchaev. It led to tremendous shifts in the content of geography and its theoretical basis. V.V. Dokuchaev called zoning a world law. However, it would be a mistake to take this literally, since the scientist, of course, had in mind the universality of the manifestation of zoning only on the surface of the globe.
As you move away from the earth's surface (up or down), the zoning gradually fades. For example, in the abyssal region of the oceans, a constant and rather low temperature (from -0.5 to + 4 °) prevails everywhere, sunlight does not penetrate here, there are no plant organisms, the water masses practically remain almost completely at rest, i.e. there are no reasons that could cause the appearance and change of zones on the ocean floor. Some hint of zoning could be seen in the distribution of marine sediments: coral deposits are confined to tropical latitudes, diatom oozes - to polar ones. But this is only a passive reflection on the seabed of those zonal processes that are characteristic of the ocean surface, where the areas of coral colonies and diatoms are really located according to the laws of zoning. The remains of diatom shells and the products of the destruction of coral structures are simply "projected" to the bottom of the sea, regardless of the conditions that exist there.
Zoning is also blurred in the high layers of the atmosphere. The energy source of the lower atmosphere is the earth's surface illuminated by the Sun. Consequently, solar radiation plays an indirect role here, and the processes in the lower atmosphere are regulated by the supply of heat from the earth's surface. As for the upper atmosphere, the most significant phenomena for it are a consequence of the direct influence of the Sun. The reason for the decrease in temperature with height in the troposphere (on average 6 ° per kilometer) is the distance from the main energy source for the troposphere (the Earth). The temperature of the high layers does not depend on the earth's surface and is determined by the balance of the radiant energy of the air particles themselves. Apparently, the boundary of influences lies at an altitude of about 20 km, because above (up to 90-100 km) a dynamic system operates, independent of the tropospheric one.
Zonal differences in the earth's crust are rapidly disappearing. Seasonal and daily temperature fluctuations cover a layer of rocks no more than 15-30 m thick; at this depth, a constant temperature is established, the same all year round and equal to the average annual air temperature of the area. Below the constant layer, the temperature increases with depth. And its distribution, both in the vertical and horizontal directions, is further connected not with solar radiation, but with the energy sources of the earth's interior, which, as you know, support azonal processes.
In all cases, zoning fades as one approaches the boundaries of the landscape envelope, and this can serve as an auxiliary diagnostic indicator for establishing these boundaries.
The position of the Earth in the Solar System and, in part, the size of the Earth are of considerable importance in the phenomena of zoning. Pluto, the outermost member of the solar system, receives 1,600 times less heat from the Sun than the Earth, there are no zones: its surface is a continuous ice desert. The moon, due to its small size, could not keep the atmosphere around it. That is why there is no water or organisms on our satellite, and there are no visible traces of zoning. There is a rudimentary visible zoning on Mars: two polar caps and the space between them. Here the reason for the embryonic nature of the zones is not only the distance from the Sun (it is one and a half times greater than the Earth's), but also the small mass of the planet (0.11 Earth), as a result of which the force of gravity is less (0.38 Earth) and the atmosphere is extremely rarefied: at 0 ° and a pressure of 1 kg / cm 2, it would be "compressed" into a layer only 7 m thick, and the roof of any of our city houses would be outside the air shell of Mars under these conditions.
The law of zoning has met and still has objections from some authors. In the 1930s, some Soviet geographers, mainly soil scientists, set about "revising" Dokuchaev's law of zoning, and the doctrine of climatic zones was even declared scholastic. The real existence of zones was denied by such a consideration: the earth's surface in its appearance and structure is so complex and mosaic that it is possible to distinguish zonal features on it only by means of great generalization. In other words, there are no specific zones in nature; they are the fruit of an abstract logical construction. The helplessness of such argumentation is striking, because: 1) any general law (of nature, society, thinking) is established by the method of generalization, abstraction from particulars, and it is with the help of abstraction that science moves from cognition of a phenomenon to cognition of its essence; 2) no generalization is able to reveal what is not really there.
However, the "campaign" against the zonal concept also brought positive results: it served as a serious impetus for more detailed than that of V.V. Dokuchaev, the development of the problem of the internal heterogeneity of natural zones, to the formation of the concept of their provinces (facies). Let us note in passing that many opponents of zoning soon returned to the camp of its supporters.
Other scientists, without denying zoning in general, only deny the existence of landscape zones, believing that zoning is only a bioclimatic phenomenon, because it does not affect the lithogenic basis of the landscape created by azonal forces.
The fallacy of reasoning stems from a misunderstanding of the lithogenic basis of the landscape. If we refer to it as a whole the entire geological structure underlying the landscape, then, of course, there is no zonality of landscapes taken in the totality of their components, and it will take millions of years to change the entire landscape. It is useful, however, to remember that land landscapes arise in the areas of contact between the lithosphere and the atmosphere, hydrosphere and biosphere. Therefore, the lithosphere must be included in the landscape to the depth to which its interaction with exogenous factors extends. Such a lithogenic base is inextricably linked and changes in conjunction with all other components of the landscape. It is impossible to separate it from the bioclimatic terms, and, therefore, it becomes as zonal as these latter. By the way, the living matter included in the bioclimatic complex is azonal in nature. It acquired zonal features in the course of adaptation to specific environmental conditions.
3.2 Distribution of heat on Earth
There are two main mechanisms in the heating of the Earth by the Sun: 1) solar energy is transmitted through world space in the form of radiant energy; 2) radiant energy absorbed by the Earth is converted into heat.
The amount of solar radiation received by the Earth depends on:
from the distance between the Earth and the Sun. Earth is closest to the Sun in early January, farthest in early July; the difference between these two distances is 5 million km, as a result of which, in the first case, the Earth receives 3.4% more, and in the second, 3.5% less radiation than with the average distance from the Earth to the Sun (at the beginning of April and at the beginning of October);
from the angle of incidence of the sun's rays on the earth's surface, which in turn depends on the geographical latitude, the height of the Sun above the horizon (changing during the day and according to the seasons), the nature of the relief of the earth's surface;
from the transformation of radiant energy in the atmosphere (scattering, absorption, reflection back into world space) and on the surface of the Earth. The average albedo of the Earth is 43%.
The picture of the annual heat balance by latitudinal zones (in calories per square centimeter per minute) is presented in Table II.
The absorbed radiation decreases towards the poles, while the long-wavelength radiation practically does not change. Temperature contrasts arising between low and high latitudes are softened by heat transfer by sea and mainly air currents from low to high latitudes; the amount of heat transferred is indicated in the last column of the table.
For general geographic conclusions, the rhythmic fluctuations of radiation due to the change of seasons are also important, since the rhythm of the thermal regime in a particular locality also depends on this.
According to the peculiarities of the irradiation of the Earth at different latitudes, one can also outline the "rough" contours of the thermal zones.
In the belt, enclosed between the tropics, the rays of the Sun at noon all the time fall at a large angle. The sun is twice a year at its zenith, the difference in the length of the day and night is small, the flow of heat in a year is large and relatively uniform. This is a hot belt.
Between the poles and the polar circles, day and night can separately last more than a day. On long nights (in winter) there is strong cooling, since there is no heat inflow at all, but on long days (in summer) the heating is insignificant due to the low standing of the Sun above the horizon, reflection of radiation by snow and ice and waste of heat on melting snow and ice. This is a cold belt.
The temperate zones are located between the tropics and the polar circles. Since the Sun is high in summer and low in winter, temperature fluctuations throughout the year are quite large.
However, in addition to geographical latitude (therefore, solar radiation), the distribution of heat on the Earth is also influenced by the nature of the distribution of land and sea, relief, terrain height above sea level, sea and air currents. If we take these factors into account, then the boundaries of the thermal zones cannot be aligned with the parallels. That is why isotherms are taken as boundaries: annual isotherms to highlight the belt in which the annual amplitudes of air temperature are small, and isotherms of the warmest month to highlight those belts where temperature fluctuations in the year are sharper. According to this principle, such heat zones are distinguished on Earth:
1) warm, or hot, limited in each hemisphere by the annual isotherm + 20 °, passing near the 30th northern and 30th southern parallels;
2-3) two temperate zones, which in each hemisphere lie between the annual isotherm of + 20 ° and the isotherm of + 10 ° of the warmest month (July or January, respectively); in Death Valley (California), the highest July Temperature on the globe is + 56.7 °;
4-5) two cold zones in which the average temperature of the warmest month in this hemisphere is less than + 10 °; sometimes two areas of eternal frost are distinguished from the cold zones with an average temperature of the warmest month below 0 °. In the northern hemisphere, this is the interior of Greenland and possibly the area around the pole; in the southern hemisphere - everything that lies south of the 60th parallel. Antarctica is especially cold; here in August 1960 at Vostok station the lowest air temperature on the Earth was recorded -88.3 °.
The connection between the temperature distribution on Earth and the distribution of incoming solar radiation is quite clear. However, a direct relationship between the decrease in the average values of the incoming radiation and the decrease in temperature with increasing latitude exists only in winter. In the summer, for several months in the North Pole region, due to the longer here the duration of the day, the amount of radiation is noticeably higher than at the equator (Fig. 2). If in summer the temperature distribution corresponded to the distribution of radiation, then the summer air temperature in the Arctic would be close to tropical. This is not the case only because there is an ice cover in the polar regions (the albedo of snow at high latitudes reaches 70-90% and a lot of heat is spent on melting snow and ice). If it were absent in the Central Arctic, the summer temperature would be 10-20 °, winter 5-10 °, i.e. a completely different climate would have formed, in which the Arctic islands and coasts could be clothed with rich vegetation, if it had not been prevented by the many-day and even many-month polar nights (the impossibility of photosynthesis). It would be the same in Antarctica, only with shades of "continentality": summer would be warmer than in the Arctic (closer to tropical conditions), winter - colder. Therefore, the ice cover of the Arctic and Antarctic is more a cause than a consequence of low temperatures at high latitudes.
These data and considerations, without violating the actual, observed regularity of the zonal distribution of heat on the Earth, pose the problem of the genesis of heat belts in a new and somewhat unexpected section. It turns out, for example, that glaciation and climate are not a consequence and a cause, but two different consequences of one common cause: some change in natural conditions causes glaciation, and already under the influence of the latter, decisive climate changes occur. And yet, at least a local change in climate must precede glaciation, for the existence of ice requires quite definite conditions of temperature and humidity. The local mass of ice can affect the local climate, allowing it to grow, then change the climate of a wider area, gaining an incentive to grow further, and so on. When such a sprawling "lichen ice" (Gernet's term) covers a huge area, it will lead to a radical change in climate in this area.
3.3 Baricheskterrain and wind system
zoning geographic baric
In the Earth's baric field, the zonal distribution of atmospheric pressure, symmetric in both hemispheres, is clearly visible.
The maximum pressure values are confined to the 30-35th parallels and the regions of the poles. Subtropical high pressure zones are expressed throughout the year. However, in summer, due to air warming over the continents, they burst, and then separate anticyclones are isolated over the oceans: in the northern hemisphere - the North Atlantic and North Pacific, in the southern - South Atlantic, South Indian, South Pacific and New Zealand (northwest of New Zealand ).
The minimum atmospheric pressure is at the 60-65th parallels of both hemispheres and in the equatorial zone. The equatorial baric depression is stable during all months, being located in its axial part on average about 4 ° N. NS.
In the middle latitudes of the northern hemisphere, the baric field is diverse and changeable, since here vast continents alternate with oceans. In the southern hemisphere, with its more homogeneous water surface, the pressure field changes only slightly. From 35 ° S NS. toward Antarctica, the pressure drops rapidly, and a low-pressure strip surrounds Antarctica.
In accordance with the baric relief, the following wind zones exist:
1) equatorial calm belt... Winds are comparatively rare (as the ascending movements of strongly heated air predominate), and when they do happen, squallists are also variable;
2-3) trade wind zones of the northern and southern hemispheres;
4-5) calm areas in anticyclones of the subtropical high pressure belt; the reason is the domination of descending air movements;
6-7) in the middle latitudes of both hemispheres - zones of prevalence of westerly winds;
8-9) in the circumpolar spaces the winds blow from the poles towards the baric depressions of the middle latitudes, i.e. are common here winds with an easterly component.
The actual circulation of the atmosphere is more complex than is reflected in the above climatological scheme. In addition to the zonal type of circulation (air transport along the parallels), there is also a meridional type - the transport of air masses from high latitudes to low latitudes and vice versa. In a number of areas of the globe, under the influence of temperature contrasts between land and sea and between the northern and southern hemispheres, monsoons arise - stable air currents of a seasonal nature, changing direction from winter to summer to the opposite or close to the opposite. On the so-called fronts (transition zones between different air masses), cyclones and anticyclones are formed and move. In the middle latitudes of both hemispheres, cyclones originate mainly in the zone between the 40th and 60th parallels and rush to the east. The region of tropical cyclones lies between 10 and 20 ° north and south latitude above the warmest parts of the oceans; these cyclones move westward. Those anticyclones that follow cyclones are more mobile than the more or less stationary anticyclones of the subtropical high pressure belt or winter baric highs over the continents.
Air circulation in the upper troposphere, tropopause and stratosphere is different than in the lower troposphere. There, jet streams play an important role - narrow zones of strong winds (on the jet axis 35-40, sometimes up to 60-80 and even up to 200 m / s) with a thickness of 2-4 km, and in length - tens of thousands of kilometers (sometimes they encircle the entire globe), going generally from west to east at an altitude of 9-12 km (in the stratosphere - 20-25 km). Known jet streams of middle latitudes, subtropical (between 25 and 30 ° N at an altitude of 12-12.5 km), western stratospheric in the Arctic circle (only in winter), eastern stratospheric on average along 20 ° N. NS. (only in summer). Modern aviation is forced to reckon with jet streams, which either noticeably slow down the aircraft's speed (oncoming), or increase it (passing).
3.4 Climatic zones of the Earth
The climate is the result of the interaction of many natural factors, the main of which are the arrival and consumption of the sun's radiant energy, atmospheric circulation, which redistributes heat and moisture, and moisture circulation, which is practically inseparable from atmospheric circulation. Atmospheric circulation and moisture circulation generated by the distribution of heat on the Earth, in turn, affect the thermal conditions of the earth, and, consequently, everything that is directly or indirectly controlled by them. Cause and effect are so closely intertwined here that all three factors must be seen as a complex unity.
Each of these factors depends on the geographical location of the area (latitude, altitude) and the nature of the earth's surface. Latitude determines the amount of solar radiation inflow. The temperature and pressure of the air, the moisture content in it, and the conditions for the movement of winds change with height. The features of the earth's surface (ocean, land, warm and cold sea currents, vegetation, soil, snow and ice cover, etc.) strongly affect the radiation balance and, therefore, the circulation of the atmosphere and moisture circulation. In particular, under the powerful transforming influence of the underlying surface on air masses, two main types of climate are formed: marine and continental.
Since all factors of climate formation, except for the relief and location of land and sea, tend to zonality, it is quite natural that climates are also zonal.
B.P. Alisov divides the globe into the following climatic zones (Fig. 4):
1. Equatorial zone. Light winds prevail. Differences in temperature and humidity between the seasons are very small and less than daily. Average monthly temperatures are from 25 to 28 °. Precipitation - 1000-3000 mm. Hot, humid weather with frequent showers and thunderstorms prevails.
Subequatorial zones. A seasonal change in air masses is characteristic: in summer the monsoon blows from the equator, in winter - from the tropics. Winter is only slightly cooler than summer. With the dominance of the summer monsoon, the weather is approximately the same as in the equatorial zone. Inside the continents, precipitation rarely exceeds 1000-1500 mm, but on the slopes of the mountains facing the monsoon, the amount of precipitation reaches 6000-10,000 mm per year. Almost all of them fall out in the summer. The winter is dry, the daily temperature amplitude increases compared to the equatorial zone, the weather is cloudless.
Tropical zones of both hemispheres. The predominance of trade winds. The weather is mostly clear. Winter is warm, but noticeably colder than summer. In tropical areas, one can distinguish three types of climate: a) areas of stable trade winds with cool, almost rainless weather, high air humidity, with developed fogs and strong breezes on the coasts (the western coast of South America between 5 and 20 ° N, the Sahara coast, the Namib desert); b) trade wind areas with passing rains (Central America, West Indies, Madagascar, etc.); c) hot arid regions (Sahara, Kalahari, most of Australia, northern Argentina, southern half of the Arabian Peninsula).
Subtropical zones. Distinct seasonal variation of temperature, precipitation and winds. It is possible, but very rare, snowfall. With the exception of monsoon areas, anticyclonic weather prevails in summer and cyclonic activity in winter. Climate types: a) Mediterranean with clear and quiet summers and rainy winters (Mediterranean, central Chile, Cape land, southwestern Australia, California); b) monsoon areas with hot rainy summers and relatively cold and dry winters (Florida, Uruguay, northern China); c) dry areas with hot summers (southern coast of Australia, Turkmenistan, Iran, Taklamakan, Mexico, dry west of the USA); d) regions evenly humidified throughout the year (southeast Australia, Tasmania, New Zealand, middle part of Argentina).
Temperate climate zones. Cyclonic activity is observed over the oceans in all seasons. Frequent precipitation. The prevalence of westerly winds. Strong temperature differences between winter and summer and between land and sea. Snow falls in winter. The main types of climates: a) winters with unstable weather and strong winds, in summer the weather is calmer (Great Britain, the Norwegian coast, the Aleutian Islands, the coast of the Gulf of Alaska); b) different variants of the continental climate (inner part of the USA, south and southeast of the European part of Russia, Siberia, Kazakhstan, Mongolia); c) transitional from mainland to oceanic (Patagonia, most of Europe and the European part of Russia, Iceland); d) monsoon regions (Far East, Okhotsk coast, Sakhalin, northern Japan); e) areas with wet cool summers and cold snowy winters (Labrador, Kamchatka).
Subpolar zones. Large temperature differences between winter and summer. Permafrost.
Polar zones. Large annual and small daily temperature fluctuations. Little precipitation. Summer is cold and foggy. Climate types: a) with relatively warm winters (the coast of the Beaufort Sea, Baffinova Zemlya, Severnaya Zemlya, Novaya Zemlya, Spitsbergen, Taimyr, Yamal, Antarctic Peninsula); b) with cold winters (the Canadian archipelago, the New Siberian Islands, the coasts of the East Siberian and Laptev seas); c) with very cold winters and summer temperatures below 0 ° (Greenland, Antarctica).
3.5 Zonalhydrological processes
The forms of hydrological zoning are varied. The zoning of the thermal regime of waters in connection with the general features of the temperature distribution over the Earth is obvious. The mineralization of groundwater and the depth of their occurrence have zonal features - from ultra-fresh and close to the day surface in the tundra and equatorial forests to brackish and salty waters of deep occurrence in deserts and semi-deserts.
The runoff coefficient is zonal: in Russia in the tundra it is 0.75, in the taiga - 0.65, in the zone of mixed forests - 0.30, in the forest-steppe - 0.17, in the steppe and semi-deserts - from 0.06 to 0.04 ...
Zonal relationships between different types of runoff: in the glacial belt (above the snow line) runoff takes the form of the movement of glaciers and avalanches; in the tundra, soil runoff prevails (with temporary aquifers within the soil) and surface runoff of a bog type (when the water table is above the surface); in the forest zone, groundwater runoff dominates, in steppes and semi-deserts - surface (slope) runoff, and in deserts there is almost no runoff. The channel runoff also bears the stamp of zoning, which is reflected in the water regime of rivers, which depends on the conditions of their feeding. M.I. Lvovich notes the following features.
In the equatorial belt, river runoff is abundant all year round (Amazon, Congo, rivers of the Malay Archipelago).
Summer runoff due to the predominance of summer precipitation is typical for the tropical belt, and in the subtropics - for the eastern outskirts of the continents (Ganges, Mekong, Yangtze, Zambezi, Parana).
In the temperate zone and on the western outskirts of the continents in the subtropical zone, four types of river regime are distinguished: in the Mediterranean zone, the predominance of winter runoff, since the maximum precipitation is here in winter; the predominance of winter runoff with an even distribution of precipitation in the year, but with strong evaporation in summer (British Isles, France, Belgium, Netherlands, Denmark); the predominance of spring rainfall (eastern part of Western and Southern Europe, most of the United States, etc.); predominance of spring snow runoff (Eastern Europe, Western and Central Siberia, northern USA, southern Canada, southern Patagonia).
In the boreal-subarctic zone, snow supply in summer, and runoff dry up in permafrost regions in winter (northern outskirts of Eurasia and North America).
In high-latitude zones, water is in a solid phase almost all year round (Arctic, Antarctica).
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ZONALITY is a geographical (natural zoning), a special form of territorial differentiation of the geographic envelope of the Earth, expressed in a sequential change in natural conditions and landscapes from the equator to the poles.
The main reasons for zoning are: the shape of the Earth and the position of the Earth relative to the Sun, which cause an uneven inflow of solar radiation in latitude to the Earth's surface. Component zoning is distinguished (climate, water, soil, vegetation, fauna, etc.) and complex, or landscape, zoning. Landscape zoning is expressed in the regular change of geographic zones and zones within these zones. Some Russian physicogeographers (A. A. Grigoriev, G. D. Richter) distinguish between the concepts of zoning and zonality, highlighting the "radiation" and "heat" belts. The "radiation" belt is determined only by the amount of incoming solar radiation, which naturally decreases from the equator to the poles; therefore, the boundaries of these belts are located sublatitudinally. The formation of "thermal" and, moreover, climatic and geographical zones is also influenced by the circulation of the atmosphere, the distribution of continents and oceans, the albedo of the earth's surface, ocean currents, etc., in connection with which the position of their boundaries is not always close to sublatitudinal. The separation of the actual geographical zones on land depends on the ratio of heat and moisture (hydrothermal regime), which varies not only in latitude, but also from the coasts to the interior of the continents (the so-called circumoceanic zoning or sector). In general terms, we are talking about the continental and oceanic sectors, which are characterized by different systems (spectra) of zones. For example, the oceanic sectors are generally characterized by forest zones; for continental sectors - zones of steppes, semi-deserts and deserts. Systems of geographic zones change not only in space, but also in time due to global changes in thermal conditions and the ratio of heat and moisture (for example, during periods of continental glaciers), which leads to the expansion of some zones due to the reduction or even complete disappearance of others (the so-called hyperzonality ).
Zoning is most pronounced on the vast plains, in the mountains it manifests itself in the form of altitudinal zonation. In the World Ocean, in addition to surface (latitudinal) zoning, vertical and bottom zoning is also distinguished (see the article World Ocean Zoning).
Zoning gradually fades with distance from the earth's surface when approaching the upper and lower boundaries of the geographic envelope. Zonal differences in the earth's crust disappear at a depth of 15-30 m, where seasonal and daily fluctuations in the temperature of rocks cease; weakened in the abyssal region of the oceans, where a constant temperature prevails (from 0.7 to 2 ° C) and where sunlight does not penetrate. Zoning is also blurred when approaching the upper border of the troposphere.
The manifestations of zoning have been known since antiquity. Herodotus distinguished three heat zones: cold, temperate and hot; Eudoxus of Cnidus in the 4th century BC, on the basis of the assumption of the sphericity of the Earth (and the related dependence of the inclination of the incidence of sunlight on latitude), distinguished five climatic zones: tropical, two temperate and two polar. An outstanding role in the development of the theory of zoning was played by the works of the German natural scientist A. Humboldt, especially his classic work Pictures of Nature (1808), which substantiated the basic patterns of distribution of vegetation depending on climate: latitudinal and vertical zoning. Modern concepts of zoning are based on the works of V.V.Dokuchaev, who was the first (1898) who formulated it as the most important, fundamental world law of nature, covering all natural components and complexes and manifested everywhere on land and sea, on plains and in mountains. In his works, natural-historical (natural) zones are considered as complex formations, all components of which (climate, water, soil, flora and fauna) are so interconnected that a change in one of them entails a change in the entire complex. In the 20th century, a significant contribution to the development of the doctrine of zoning was made by the works of L. S. Berg and A. A. Grigoriev. In the monograph Landscape-Geographical Zones of the USSR (1931), Berg called natural zones landscape and emphasized that they consist of a natural combination of landscapes, the natural properties of which determine the characteristics of the life and economic activities of people living within these zones. In total, within the geographic envelope of the Earth, Berg identified 13 natural zones. In a series of works (1938-1946), Grigoriev came to the conclusion that in the formation of zoning, along with the magnitude of the annual radiation balance and the average annual precipitation, their ratio, the degree of their proportionality, plays a huge role. In 1948, M.I.Budyko suggested using the radiation index of dryness as a characteristic of the relationship between climatic factors and the geographical zoning of soils and vegetation: r = R / Lx, where R is the annual radiation balance of the underlying surface, x is the annual precipitation, L is the latent heat. evaporation. The relationship between the distribution of geographic zones and the parameters of the radiation index of dryness and radiation balance R, obtained by Budyko, showed that the tundra zone corresponds to the lowest value of the dryness index, and the zone of deserts corresponds to the highest. In 1956, Grigoriev and Budyko formulated the periodic law of geographic zoning, which underlies the structure of the geographic shell of the Earth. Its essence boils down to the fact that similar zonal types of landscapes are formed in different geographic zones with different heat supply, but under conditions similar in moisture content.
Within the terrestrial land, Grigoriev identified 9 zones (according to the thermal factor) and 24 zones (according to the balance of heat and moisture). In 2004, Russian physicogeographers (B.A. Alekseev, G.N. Golubev, E.P. Romanova) presented a new belt-zonal model of the Earth's land, where 13 geographical zones and 36 landscape zones were identified and the main planetary patterns of anthropogenic transformation of natural Wednesday.
Lit .: Grigoriev A.A., Budyko M.I.On the periodic law of geographic zoning // Reports of the Academy of Sciences of the USSR. 1956. T. 110. No. 1; Lukashova E.N. The main patterns of natural zoning and its manifestation on the land of the Earth // Bulletin of Moscow State University. Ser. 5. Geographic. 1966. No. 6; Ryabchikov A.M.The structure and dynamics of the geosphere, its natural development and human change. M., 1972; Isachenko A.G. Theory and methodology of geographical science. M., 2004; Alekseev B. A., Golubev G. N., Romanova E. P. Global model of modern landscapes of the world // Geography, society, environment. M., 2004. T. 2: Functioning and current state of landscapes.
Many physical and geographical phenomena in the geographic envelope are distributed in the form of stripes elongated along the parallels, or at some angle to them. This property of geographical phenomena is called zoning (the law of geographic zoning).
The concept of natural zoning dates back to ancient Greek scientists. So, in the V century. BC. and Eudonyx marked five zones of the Earth: tropical, two temperate and two polar. A great contribution to the doctrine of natural zoning was made by the German geographer, who established the climatic and plant zones of the Earth ("Geography of Plants", 1836). In Russia, the concept of geographic zoning was expressed in 1899 in the book “The doctrine of natural zones. Horizontal and vertical soil zones ”. The professor is responsible for research on the causes and factors of zoning. He came to the conclusion about the great role of the ratio of the radiation balance and the amount of annual precipitation (1966).
It is currently believed that natural zoning is represented by
- component zoning;
- landscape zoning.
All components geographic envelope are subject to the World Law of Zoning. Zoning is noted for climatic indicators, plant groupings, and soil types. It also manifests itself in hydrological and geochemical phenomena, as a derivative of climatic and soil-plant conditions.
The zonality of physical and geographical phenomena is based on the regularity of the arrival of solar radiation, the arrival of which decreases from the equator to the poles. However, such a distribution of solar radiation is superimposed on the transparency factor of the atmosphere, which is azonal since it is not related to the shape of the earth. The air temperature depends on solar radiation, the distribution of which is influenced by another azonal factor - the properties of the earth's surface - its heat capacity and thermal conductivity. This factor leads to an even greater violation of zoning. The distribution of heat on the Earth's surface is also greatly influenced by oceanic and air currents that form heat transfer systems.
The atmospheric precipitation is even more difficult to distribute on our planet. On the one hand, they have a zonal character, and on the other hand, they are associated with the position of the territory in the western or eastern part of the continents and the height of the earth's surface.
The combined effect of heat and moisture is the main factor that determines most of the physical and geographical phenomena. Since the distribution of moisture and heat is oriented in latitude, then all the phenomena associated with climate are oriented in latitude. As a result, a latitudinal structure is formed on the Earth, called geographic zonation.
Zonality is manifested in the distribution of the main climatic characteristics: solar radiation, temperature and atmospheric pressure, which leads to the formation of a system of 13 climatic zones... Plant groups on Earth also form elongated stripes, but of a more complex configuration than climatic zones. They are called vegetation zones... The soil cover is closely related to vegetation, climate and the nature of the relief, which allowed V.V. Dokuchaev to identify genetic soil types.
In the 50s of the XX century, geographers Grigoriev and Budyko developed Dokuchaev's zonality law and formulated periodic law of geographic zoning... This law establishes the repetition of the same type of geographic zones within the belts - depending on the ratio of heat and moisture. So, there are forest zones in the equatorial, subequatorial, tropical and temperate zones. Steppes and deserts are also found in different geographic zones. The presence of the same type of zones in different belts is explained by the repetition of the same ratios of heat and moisture.
Thus, zone- This is a large part of the geographic belt, which is characterized by the same indicators of the radiation balance, annual precipitation and evaporation. At the beginning of the last century, Vysotsky proposed a moisture coefficient equal to the ratio of precipitation to evaporation. Later, Budyko, to substantiate the periodic law, introduced an indicator - the radiation dryness index, which is the ratio of the incoming amount of solar energy to the cost of heat for evaporation of atmospheric precipitation. It has been established that there is a close relationship between geographic zones and the amount of solar heat input and the radiation index of dryness.
Geographic zones are internally heterogeneous, which is primarily associated with the azonal circulation of the atmosphere and moisture transfer. With this in mind, sectors are allocated. As a rule, there are three of them: two oceanic (western and eastern) and one continental. Sectorality – it is a geographical zoning, which is expressed in the change of the main natural indicators in longitude, that is, from the oceans inland.
Landscape zoning is determined by the fact that the geographic envelope in the process of its development has acquired a "mosaic" structure and consists of many natural complexes of unequal size and complexity. By definition F.N. Milkova PTK is a self-regulating system of interconnected components, functioning under the influence of one or more components acting as a leading factor.
