Latitudinal zonality and altitudinal zonation, their differences and connections between them. Geographical zones

Latitudinal zonation– a natural change in physical-geographical processes, components and complexes of geosystems from the equator to the poles. Latitudinal zoning is due to the spherical shape of the Earth's surface, as a result of which there is a gradual decrease in the amount of heat coming to it from the equator to the poles.

Altitudinal zone– a natural change in natural conditions and landscapes in the mountains as the absolute height increases. Altitudinal zonation is explained by climate change with height: a drop in air temperature with height and an increase in precipitation and atmospheric moisture. Vertical zonality always begins with the horizontal zone in which the mountainous country is located. Above the belt, they change generally in the same way as the horizontal zones, up to the region of polar snows. Sometimes the less accurate name “vertical zonality” is used. It is inaccurate because the belts have a horizontal rather than vertical extension and replace each other in height (Figure 12).

Figure 12 – Altitudinal zonation in the mountains

Natural areas– these are natural-territorial complexes within geographical zones of land, corresponding to types of vegetation. In the distribution of natural zones in the belt, relief plays an important role, its pattern and absolute heights - mountain barriers that block the path of air flow contribute to the rapid change of natural zones to more continental ones.

Natural zones of equatorial and subequatorial latitudes. Zone moist equatorial forests (hylaea) is located in the equatorial climate zone with high temperatures (+28 °C) and large amounts of precipitation throughout the year (more than 3000 mm). The zone is most widespread in South America, where it occupies the Amazon basin. In Africa it is located in the Congo Basin, in Asia - on the Malacca Peninsula and the islands of Greater and Lesser Sunda and New Guinea (Figure 13).

Figure 13 – Natural zones of the Earth

Evergreen forests are dense, impenetrable, and grow on red-yellow ferrallite soils. Forests are distinguished by species diversity: an abundance of palm trees, lianas and epiphytes; Mangroves are widespread along the sea coasts. There are hundreds of species of trees in such a forest, and they are located in several tiers. Many of them bloom and bear fruit all year round.

The fauna is also diverse. Most of the inhabitants are adapted to life in trees: monkeys, sloths, etc. Land animals include tapirs, hippos, jaguars, and leopards. There are a lot of birds (parrots, hummingbirds), a rich world of reptiles, amphibians and insects.

Savanna and woodland zone located in the subequatorial belt of Africa, Australia, and South America. The climate is characterized by high temperatures and alternating wet and dry seasons. The soils are of a peculiar color: red and red-brown or reddish-brown, in which iron compounds accumulate. Due to insufficient moisture, the vegetation cover is an endless sea of grasses with isolated low trees and thickets of bushes. Woody vegetation gives way to grasses, mainly tall grasses, sometimes reaching 1.5–3 meters in height. Numerous species of cacti and agaves are common in American savannas. Certain types of trees have adapted to the dry period by storing moisture or retarding evaporation. These are African baobabs, Australian eucalyptus trees, South American bottle tree and palm trees. The fauna is rich and diverse. The main feature of the savannah fauna is the abundance of birds, ungulates and the presence of large predators. Vegetation promotes the spread of large herbivores and predatory mammals, birds, reptiles, and insects.

Zone variable-humid deciduous forests from the east, north and south it is framed by the hylaia. Here, both evergreen rigid-leaved species characteristic of the Giles and species that partially shed their foliage in summer are common; Lateritic red and yellow soils are formed. The fauna is rich and diverse.

Natural zones of tropical and subtropical latitudes. In the tropical zone of the Northern and Southern Hemispheres it predominates tropical desert zone. The climate is tropical desert, hot and dry, therefore the soils are underdeveloped and often saline. Vegetation on such soils is sparse: rare tough grasses, thorny bushes, saltworts, and lichens. The fauna is richer than the plant world, since reptiles (snakes, lizards) and insects are able to remain without water for a long time. Mammals include ungulates (the gazelle antelope, etc.), capable of traveling long distances in search of water. Near water sources there are oases - “spots” of life among dead desert spaces. Date palms and oleanders grow here.

In the tropical zone it is also represented zone of humid and variable-humid tropical forests. It formed in the eastern part of South America, in the northern and northeastern parts of Australia. The climate is humid with consistently high temperatures and high amounts of rainfall that occur during the summer monsoons. Variably moist, evergreen forests grow on red-yellow and red soils, rich in species composition (palm trees, ficus trees). They are similar to equatorial forests. The fauna is rich and diverse (monkeys, parrots).

Subtropical hard-leaved evergreen forests and shrubs characteristic of the western part of the continents, where the climate is Mediterranean: hot and dry summers, warm and rainy winters. Brown soils have high fertility and are used for cultivating valuable subtropical crops. The lack of moisture during periods of intense solar radiation led to the appearance of adaptations in plants in the form of hard leaves with a waxy coating that reduce evaporation. Hard-leaved evergreen forests are decorated with laurels, wild olives, cypresses, and yews. In large areas they have been cut down, and their place is taken by fields of grain crops, orchards and vineyards.

Subtropical rainforest zone located in the east of the continents, where the climate is subtropical monsoon. Precipitation occurs in summer. The forests are dense, evergreen, broad-leaved and mixed, growing on red soils and yellow soils. The fauna is diverse, there are bears, deer, and roe deer.

Zones of subtropical steppes, semi-deserts and deserts distributed in sectors in the interior of continents. In South America the steppes are called pampas. The subtropical dry climate with hot summers and relatively warm winters allows drought-resistant grasses and grasses (wormwood, feather grass) to grow on gray-brown steppe and brown desert soils. The fauna is distinguished by species diversity. Typical mammals are ground squirrels, jerboas, goitered gazelles, kulans, jackals and hyenas. Lizards and snakes are numerous.

Natural areas of temperate latitudes include zones of deserts and semi-deserts, steppes, forest-steppes, and forests.

Deserts and semi-deserts temperate latitudes occupy large areas in the interior of Eurasia and North America, and small areas in South America (Argentina), where the climate is sharply continental, dry, with cold winters and hot summers. Poor vegetation grows on gray-brown desert soils: steppe feather grass, wormwood, camel thorn; in depressions on saline soils - solyanka. The fauna is dominated by lizards, snakes, turtles, jerboas, and saigas are common.

Steppes occupy large areas in Eurasia, South and North America. In North America they are called prairies. The climate of the steppes is continental, arid. Due to lack of moisture, there are no trees and a rich grass cover (feather grass, fescue and other grasses). The most fertile soils, chernozem soils, are formed in the steppes. In summer the vegetation in the steppes is sparse, but in the short spring many flowers bloom; lilies, tulips, poppies. The fauna of the steppes is represented mainly by mice, gophers, hamsters, as well as foxes and ferrets. The nature of the steppes has changed largely under human influence.

To the north of the steppes there is a zone forest-steppes. This is a transitional zone, with areas of forest interspersed with significant areas covered with herbaceous vegetation.

Broad-leaved and mixed forest zones presented in Eurasia, North and South America. When moving from the oceans into the continents, the climate changes from marine (monsoon) to continental. Vegetation changes depending on the climate. The zone of broad-leaved forests (beech, oak, maple, linden) turns into a zone of mixed forests (pine, spruce, oak, hornbeam, etc.). To the north and further into the continents, coniferous species (pine, spruce, fir, larch) are common. Among them there are also small-leaved species (birch, aspen, alder).

The soils in the broad-leaved forest are brown forest, in the mixed forest - sod-podzolic, in the taiga - podzolic and permafrost-taiga. Almost all forest zones of the temperate zone are characterized by a wide distribution swamps

The fauna is very diverse (deer, brown bears, lynxes, wild boars, roe deer, etc.).

Natural zones of subpolar and polar latitudes. Forest-tundra is a transition zone from forests to tundra. The climate in these latitudes is cold. The soils are tundra-gley, podzolic and peat-bog. The vegetation of the open forest (low larches, spruce, birch) gradually turns into tundra. The fauna is represented by inhabitants of the forest and tundra zones (snowy owls, lemmings).

Tundra characterized by treelessness. A climate with long, cold winters and damp and cold summers. This leads to severe freezing of the soil, forming permafrost. Evaporation here is low, organic matter does not have time to decompose, and as a result, swamps are formed. On humus-poor tundra-gley and peat-bog soils of the tundra, mosses, lichens, low grasses, dwarf birch trees, willows, etc. grow. According to the nature of the vegetation of the tundra, there are mosses, lichens, shrubs. The fauna is poor (reindeer, arctic fox, owls, pieds).

Arctic (Antarctic) desert zone located in polar latitudes. Due to the very cold climate with low temperatures throughout the year, large areas of land are covered with glaciers. The soils are almost undeveloped. In ice-free areas there are rocky deserts with very poor and sparse vegetation (mosses, lichens, algae). Polar birds settle on the rocks, forming “bird colonies”. In North America there is a large ungulate - the musk ox. Natural conditions in Antarctica are even more severe. Penguins, petrels, and cormorants nest on the coast. Whales, seals, and fish live in Antarctic waters.

Related information.

Latitudinal (geographical, landscape) zoning means a natural change in various processes, phenomena, individual geographic components and their combinations (systems, complexes) from the equator to the poles. Zoning in its elementary form was known to the scientists of Ancient Greece, but the first steps in the scientific development of the theory of world zoning are associated with the name of A. Humboldt, who at the beginning of the 19th century. substantiated the idea of the climatic and phytogeographic zones of the Earth. At the very end of the 19th century. V.V. Dokuchaev elevated latitudinal (in his terminology, horizontal) zoning to the rank of a world law.
For the existence of latitudinal zonality, two conditions are sufficient - the presence of a flux of solar radiation and the sphericity of the Earth. Theoretically, the flow of this flow to the earth's surface decreases from the equator to the poles in proportion to the cosine of latitude (Fig. 1). However, the actual amount of insolation reaching the earth's surface is also influenced by some other factors that are also of an astronomical nature, including the distance from the Earth to the Sun. As you move away from the Sun, the flow of its rays becomes weaker, and at a sufficiently long distance the difference between the polar and equatorial latitudes loses its significance; Thus, on the surface of the planet Pluto, the estimated temperature is close to -230°C. When you get too close to the Sun, on the contrary, all parts of the planet become too hot. In both extreme cases, the existence of water in the liquid phase, life, is impossible. The Earth is thus most “successfully” located in relation to the Sun.
The inclination of the earth's axis to the ecliptic plane (at an angle of about 66.5°) determines the uneven supply of solar radiation over the seasons, which significantly complicates the zonal distribution of heat and exacerbates zonal contrasts. If the earth's axis were perpendicular to the plane of the ecliptic, then each parallel would receive almost the same amount of solar heat throughout the year and there would be practically no seasonal changes in phenomena on Earth. The daily rotation of the Earth, which causes the deviation of moving bodies, including air masses, to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, introduces additional complications into the zonation scheme.

Rice. 1. Distribution of solar radiation by latitude:

Rc - radiation at the upper boundary of the atmosphere; total radiation:
- on the surface of the land,
- on the surface of the World Ocean;
- average for the surface of the globe; radiation balance: Rc - on the land surface, Ro - on the ocean surface, R3 - on the surface of the globe (average value)
The mass of the Earth also affects the nature of zonation, although indirectly: it allows the planet (unlike, for example, the “light” Moon) to retain an atmosphere, which serves as an important factor in the transformation and redistribution of solar energy.
With a homogeneous material composition and the absence of irregularities, the amount of solar radiation on the earth's surface would vary strictly along latitude and would be the same at the same parallel, despite the complicating influence of the listed astronomical factors. But in the complex and heterogeneous environment of the epigeosphere, the flow of solar radiation is redistributed and undergoes various transformations, which leads to a violation of its mathematically correct zoning.
Since solar energy is practically the only source of physical, chemical and biological processes that underlie the functioning of geographical components, latitudinal zonality must inevitably appear in these components. However, these manifestations are far from unambiguous, and the geographical mechanism of zoning turns out to be quite complex.
Already passing through the thickness of the atmosphere, the sun's rays are partially reflected and also absorbed by clouds. Because of this, the maximum radiation reaching the earth's surface is observed not at the equator, but in the zones of both hemispheres between the 20th and 30th parallels, where the atmosphere is most transparent to sunlight (Fig. 1). Over land, the atmospheric transparency contrasts are more significant than over the ocean, which is reflected in the drawing of the corresponding curves. The curves of the latitudinal distribution of the radiation balance are somewhat smoother, but it is clearly visible that the ocean surface is characterized by higher values than the land. The most important consequences of the latitudinal-zonal distribution of solar energy include zonality of air masses, atmospheric circulation and moisture circulation. Under the influence of uneven heating, as well as evaporation from the underlying surface, four main zonal types of air masses are formed: equatorial (warm and humid), tropical (warm and dry), boreal, or masses of temperate latitudes (cool and wet), and arctic, and in Southern Hemisphere Antarctic (cold and relatively dry).
The difference in the density of air masses causes disturbances in thermodynamic equilibrium in the troposphere and mechanical movement (circulation) of air masses. Theoretically (without taking into account the influence of the Earth’s rotation around its axis), air currents from the heated equatorial latitudes should have risen and spread to the poles, and from there cold and heavier air would have returned in the surface layer to the equator. But the deflecting effect of the planet’s rotation (Coriolis force) introduces significant amendments to this scheme. As a result, several circulation zones or belts are formed in the troposphere. The equatorial belt is characterized by low atmospheric pressure, calms, rising air currents, for the tropical - high pressure, winds with an eastern component (trade winds), for moderate - low pressure, westerly winds, for the polar - low pressure, winds with an eastern component. In summer (for the corresponding hemisphere), the entire atmospheric circulation system shifts towards “its” pole, and in winter - towards the equator. Therefore, in each hemisphere, three transition zones are formed - subequatorial, subtropical and subarctic (subantarctic), in which the types of air masses change according to the seasons. Thanks to atmospheric circulation, zonal temperature differences on the earth's surface are somewhat smoothed out, however, in the Northern Hemisphere, where the land area is much larger than in the Southern, the maximum heat supply is shifted to the north, to approximately 10-20° N latitude. Since ancient times, it has been customary to distinguish five heat zones on Earth: two cold and temperate and one hot. However, such a division is purely conditional; it is extremely schematic and its geographical significance is small. The continuous nature of changes in air temperature near the earth's surface makes it difficult to distinguish between thermal zones. Nevertheless, using the latitudinal-zonal change in the main types of landscapes as a complex indicator, we can propose the following series of thermal zones, replacing each other from the poles to the equator:
1) polar (Arctic and Antarctic);
2) subpolar (subarctic and subantarctic);
3) boreal (cold-temperate);
4) subboreal (warm-temperate);
5) pre-subtropical;
6) subtropical;
7) tropical;
8) subequatorial;
9) equatorial.
The zonality of atmospheric circulation is closely related to the zonality of moisture circulation and humidification. A peculiar rhythmicity is observed in the distribution of precipitation by latitude: two maxima (the main one at the equator and a secondary one at boreal latitudes) and two minima (at tropical and polar latitudes) (Fig. 2). The amount of precipitation, as is known, does not yet determine the conditions of moisture and moisture supply of landscapes. To do this, it is necessary to correlate the amount of annual precipitation with the amount that is necessary for the optimal functioning of the natural complex. The best integral indicator of moisture demand is the evaporation value, i.e. maximum evaporation theoretically possible under given climatic (and above all temperature) conditions. G.N. Vysotsky first used this ratio back in 1905 to characterize the natural zones of European Russia. Subsequently N.N. Ivanov, independently of G.N. Vysotsky introduced into science an indicator that became known as the Vysotsky-Ivanov humidification coefficient:
K = r / E,
where r is the annual amount of precipitation; E - annual evaporation value1.
Figure 2 shows that latitudinal changes in precipitation and evaporation do not coincide and, to a large extent, even have the opposite character. As a result, on the latitudinal curve K in each hemisphere (for land), two critical points are identified where K passes through 1. The value K = 1 corresponds to the optimum of atmospheric moisture; at K >1, moisture becomes excessive, and at K< 1 - недостаточным. Таким образом, на поверхности суши в самом общем виде можно выделить экваториальный пояс избыточного увлажнения, два симметрично расположенных по обе стороны от экватора пояса недостаточного увлажнения в низких и средних широтах и два пояса избыточного увлажнения в высоких широтах (рис. 2). Разумеется, это сильно генерализованная, осреднённая картина, не отражающая, как мы увидим в дальнейшем, постепенных переходов между поясами и существенных долготных различий внутри них.

Rice. 2. Distribution of precipitation, evaporation

And the moisture coefficient by latitude on the land surface:

1 - average annual precipitation; 2 - average annual evaporation;

3 - excess of precipitation over evaporation; 4 - excess

Evaporation over precipitation; 5 - moisture coefficient
The intensity of many physical-geographical processes depends on the ratio of heat supply and moisture. However, it is easy to notice that latitudinal-zonal changes in temperature conditions and moisture have different directions. If solar heat reserves generally increase from the poles to the equator (although the maximum is somewhat shifted to tropical latitudes), then the humidification curve has a pronounced wave-like character. Without touching on methods for quantitatively assessing the ratio of heat supply and humidification, we will outline the most general patterns of changes in this ratio along latitude. From the poles to approximately the 50th parallel, an increase in heat supply occurs under conditions of constant excess moisture. Further, as one approaches the equator, an increase in heat reserves is accompanied by a progressive increase in dryness, which leads to frequent changes in landscape zones, the greatest diversity and contrast of landscapes. And only in a relatively narrow strip on both sides of the equator is there a combination of large heat reserves with abundant moisture.
To assess the influence of climate on the zonation of other components of the landscape and the natural complex as a whole, it is important to take into account not only the average annual values of heat and moisture supply indicators, but also their regime, i.e. intra-annual changes. Thus, temperate latitudes are characterized by seasonal contrast in thermal conditions with a relatively uniform intra-annual distribution of precipitation; in the subequatorial zone, with small seasonal differences in temperature conditions, the contrast between the dry and wet seasons is sharp, etc.
Climatic zonality is reflected in all other geographical phenomena - in the processes of runoff and hydrological regime, in the processes of swamping and the formation of groundwater, the formation of weathering crust and soils, in the migration of chemical elements, as well as in the organic world. Zoning is clearly manifested in the surface thickness of the World Ocean. Geographic zoning finds a particularly vivid, and to a certain extent integral, expression in vegetation cover and soils.
Separately, it should be said about the zonality of the relief and the geological foundation of the landscape. In the literature one can find statements that these components do not obey the law of zonation, i.e. azonal. First of all, it should be noted that it is unlawful to divide geographical components into zonal and azonal, because in each of them, as we will see, the influence of both zonal and azonal patterns is manifested. The relief of the earth's surface is formed under the influence of so-called endogenous and exogenous factors. The first include tectonic movements and volcanism, which are of an azonal nature and create morphostructural features of the relief. Exogenous factors are associated with the direct or indirect participation of solar energy and atmospheric moisture, and the sculptural relief forms they create are distributed zonally on Earth. It is enough to recall the specific forms of the glacial relief of the Arctic and Antarctic, thermokarst depressions and heaving mounds of the Subarctic, ravines, gullies and subsidence depressions of the steppe zone, aeolian forms and drainless saline depressions of the desert, etc. In forest landscapes, a thick vegetation cover restrains the development of erosion and determines the predominance of “soft” weakly dissected relief. The intensity of exogenous geomorphological processes, such as erosion, deflation, karst formation, significantly depends on latitudinal and zonal conditions.
The structure of the earth's crust also combines azonal and zonal features. If igneous rocks are undoubtedly of azonal origin, then the sedimentary layer is formed under the direct influence of climate, the life activity of organisms, and soil formation and cannot but bear the stamp of zonality.
Throughout geological history, sedimentation (lithogenesis) occurred differently in different zones. In the Arctic and Antarctic, for example, unsorted clastic material (moraine) accumulated, in the taiga - peat, in deserts - clastic rocks and salts. For each specific geological era, it is possible to reconstruct the picture of the zones of that time, and each zone will have its own types of sedimentary rocks. However, throughout geological history, the system of landscape zones has undergone repeated changes. Thus, the results of lithogenesis of all geological periods, when the zones were completely different from what they are now, are superimposed on the modern geological map. Hence the external diversity of this map and the absence of visible geographical patterns.
From the above it follows that zonation cannot be considered as some simple imprint of the modern climate in earthly space. Essentially, landscape zones are spatiotemporal formations; they have their own age, their own history and are variable both in time and space. The modern landscape structure of the epigeosphere developed mainly in the Cenozoic. The equatorial zone is distinguished by the greatest antiquity; as we move towards the poles, zonality experiences increasing variability, and the age of modern zones decreases.
The last significant restructuring of the world zonation system, which mainly affected high and moderate latitudes, was associated with continental glaciations of the Quaternary period. Oscillatory zone displacements continue here in post-glacial times. In particular, over the past millennia there has been at least one period when the taiga zone in some places advanced to the northern edge of Eurasia. The tundra zone within its modern boundaries arose only after the subsequent retreat of the taiga to the south. The reasons for such changes in the position of zones are associated with rhythms of cosmic origin.
The effect of the law of zoning is most fully reflected in the relatively thin contact layer of the epigeosphere, i.e. in the landscape sector itself. As one moves away from the surface of land and ocean to the outer boundaries of the epigeosphere, the influence of zonality weakens, but does not completely disappear. Indirect manifestations of zoning are observed at great depths in the lithosphere, practically throughout the stratosphere, i.e. thicker than sedimentary rocks, the connection of which with zonation has already been discussed. Zonal differences in the properties of artesian waters, their temperature, mineralization, and chemical composition can be traced to a depth of 1000 m or more; The horizon of fresh groundwater in zones of excessive and sufficient moisture can reach a thickness of 200-300 and even 500 m, while in arid zones the thickness of this horizon is insignificant or completely absent. On the ocean floor, zonation is indirectly manifested in the nature of bottom silts, which are predominantly of organic origin. It can be considered that the law of zonation applies to the entire troposphere, since its most important properties are formed under the influence of the subaerial surface of the continents and the World Ocean.
In Russian geography, the importance of the law of zonation for human life and social production has long been underestimated. Judgments V.V. Dokuchaev on this topic was regarded as an exaggeration and a manifestation of geographical determinism. The territorial differentiation of population and economy has its own patterns, which cannot be completely reduced to the action of natural factors. However, to deny the influence of the latter on the processes occurring in human society would be a gross methodological mistake, fraught with serious socio-economic consequences, as all historical experience and modern reality convince us of.
The law of zonation finds its most complete, complex expression in the zonal landscape structure of the Earth, i.e. in the existence of a system of landscape zones. The system of landscape zones should not be imagined as a series of geometrically regular continuous strips. Also V.V. Dokuchaev did not imagine the zones as an ideal belt shape, strictly delimited by parallels. He emphasized that nature is not mathematics, and zoning is just a pattern or a law. As we further studied the landscape zones, it was discovered that some of them were broken, some zones (for example, the zone of broad-leaved forests) were developed only in the peripheral parts of the continents, others (deserts, steppes), on the contrary, gravitated towards inland areas; the boundaries of the zones deviate to a greater or lesser extent from parallels and in some places acquire a direction close to the meridional; in the mountains, latitudinal zones seem to disappear and are replaced by altitudinal zones. Similar facts gave rise in the 30s. XX century Some geographers claim that latitudinal zoning is not a universal law at all, but only a special case characteristic of large plains, and that its scientific and practical significance is exaggerated.
In reality, various kinds of violations of zonality do not refute its universal significance, but only indicate that it manifests itself differently in different conditions. Every natural law operates differently in different conditions. This also applies to such simple physical constants as the freezing point of water or the magnitude of the acceleration of gravity. They are not violated only under laboratory experimental conditions. In the epigeosphere, many natural laws operate simultaneously. Facts that at first glance do not fit into the theoretical model of zonality with its strictly latitudinal continuous zones indicate that zonality is not the only geographical pattern and it alone cannot explain the entire complex nature of territorial physical-geographic differentiation.

Latitudinal zonality and altitudinal zonality – geographical concepts, characterizing a change in natural conditions, and, as a consequence, a change in natural landscape zones, as one moves from the equator to the poles (latitudinal zonality), or as one rises above sea level.

Latitudinal zonation

It is known that the climate in different parts of our planet is not the same. The most noticeable change in climatic conditions occurs when moving from the equator to the poles: The higher the latitude, the colder the weather becomes. This geographical phenomenon is called latitudinal zoning. It is associated with the uneven distribution of thermal energy from the Sun over the surface of our planet.

Plays a major role in climate change tilt of the earth's axis in relation to the Sun. In addition, latitudinal zonality is associated with different distances of the equatorial and polar parts of the planet from the Sun. However, this factor influences the temperature difference at different latitudes to a much lesser extent than the axis tilt. The Earth's axis of rotation, as is known, is located at a certain angle relative to the ecliptic (the plane of motion of the Sun).

This tilt of the Earth's surface leads to the fact that the sun's rays fall at right angles on the central, equatorial part of the planet. Therefore, it is the equatorial belt that receives maximum solar energy. The closer to the poles, the less the sun's rays warm the earth's surface due to the greater angle of incidence. The higher the latitude, the greater the angle of incidence of the rays, and the more of them are reflected from the surface. They seem to glide along the ground, ricocheting further into outer space.

It should be taken into account that the tilt of the earth's axis relative to the Sun changes throughout the year. This feature is associated with the alternation of seasons: when it is summer in the southern hemisphere, it is winter in the northern hemisphere, and vice versa.

But these seasonal variations do not play a special role in the average annual temperature. In any case, the average temperature in the equatorial or tropical zone will be positive, and in the region of the poles - negative. Latitudinal zoning has direct influence on climate, landscape, fauna, hydrology and so on. When moving towards the poles, the change in latitudinal zones is clearly visible not only on land, but also in the ocean.

In geography, as we move towards the poles, the following latitudinal zones are distinguished:

Equatorial.
Tropical.
Subtropical.
Moderate.
Subarctic.
Arctic (polar).

Altitudinal zone

Altitudinal zonation, just like latitudinal zonation, is characterized by changing climatic conditions. Only this change occurs not when moving from the equator to the poles, but from sea level to the highlands. The main differences between lowland and mountainous areas are the difference in temperature.

Thus, with a rise of one kilometer relative to sea level, the average annual temperature decreases by approximately 6 degrees. In addition, atmospheric pressure decreases, solar radiation becomes more intense, and the air becomes more rarefied, cleaner and less saturated oxygen.

When an altitude of several kilometers (2-4 km) is reached, air humidity increases and the amount of precipitation increases. Further, as you climb the mountains, the change in natural zones becomes more noticeable. To some extent, this change is similar to the change in landscape with latitudinal zonation. The amount of solar heat loss increases with increasing altitude. The reason for this is the lower density of air, which plays the role of a kind of blanket that blocks the sun's rays reflected from the earth and water.

At the same time, the change in altitudinal zones does not always occur in a strictly defined sequence. This change may occur differently in different geographic areas. In tropical or arctic regions, the full cycle of changes in altitudinal zones may not be observed at all. For example, in the mountains of Antarctica or the Arctic region there are no forest belts or alpine meadows. And in many mountains located in the tropics there is a snow-glacier (nival) belt. The most complete change of cycles can be observed in the highest mountain ranges on the equator and in the tropics - in the Himalayas, Tibet, the Andes, and the Cordillera.

Altitudinal zones are divided into several types, starting from the very top to the bottom:

Nival belt. This name comes from the Latin “nivas” - snowy. This is the highest altitude zone, characterized by the presence of eternal snow and glaciers. In the tropics it begins at an altitude of at least 6.5 km, and in the polar zones - directly from sea level.
Mountain tundra. It is located between the belt of eternal snow and alpine meadows. In this zone, the average annual temperature is 0-5 degrees. The vegetation is represented by mosses and lichens.
Alpine meadows. Located below the mountain tundra, the climate is temperate. The flora is represented by creeping shrubs and alpine herbs. They are used in summer transhumance for grazing sheep, goats, yaks and other mountain domestic animals.
Subalpine zone. It is characterized by a mixture of alpine meadows with rare mountain forests and shrubs. It is a transition zone between high mountain meadows and forest belt.
Mountain forests. The lower belt of mountains, with a predominance of a wide variety of tree landscapes. Trees can be either deciduous or coniferous. In the equatorial-tropical zone, the bases of the mountains are often covered with evergreen forests - jungles.

Latitudinal zonation

Latitudinal (geographical, landscape) zoning means a natural change in physical-geographical processes, components and complexes (geosystems) from the equator to the poles.

The belt distribution of solar heat on the earth's surface determines the uneven heating (and density) of atmospheric air. The lower layers of the atmosphere (troposphere) in the tropics are heated strongly by the underlying surface, and in the subpolar latitudes they are weakly heated. Therefore, above the poles (up to a height of 4 km) there are areas with high pressure, and near the equator (up to 8-10 km) there is a warm ring with low pressure. With the exception of subpolar and equatorial latitudes, westerly air transport predominates throughout the rest of the space.

The most important consequences of the uneven latitudinal distribution of heat are the zonality of air masses, atmospheric circulation and moisture circulation. Under the influence of uneven heating, as well as evaporation from the underlying surface, air masses are formed that differ in their temperature properties, moisture content and density.

There are four main zonal types of air masses:

1. Equatorial (warm and humid);

2. Tropical (warm and dry);

3. Boreal, or temperate latitude masses (cool and wet);

4. Arctic, and in the southern hemisphere Antarctic (cold and relatively dry).

Uneven heating and, as a result, different densities of air masses (different atmospheric pressure) cause a violation of thermodynamic equilibrium in the troposphere and the movement (circulation) of air masses.

As a result of the deflecting effect of the Earth's rotation, several circulation zones are formed in the troposphere. The main ones correspond to four zonal types of air masses, so there are four of them in each hemisphere:

1. Equatorial zone, common to the northern and southern hemispheres (low pressure, calms, rising air currents);

2. Tropical (high pressure, easterly winds);

3. Moderate (low pressure, westerly winds);

4. Polar (low pressure, easterly winds).

In addition, three transition zones are distinguished:

1. Subarctic;

2. Subtropical;

3. Subequatorial.

In transition zones, types of circulation and air masses change seasonally.

The zonality of atmospheric circulation is closely related to the zonality of moisture circulation and humidification. This is clearly manifested in the distribution of precipitation. The zonation of precipitation distribution has its own specificity, a peculiar rhythm: three maxima (the main one at the equator and two minor ones in temperate latitudes) and four minima (in polar and tropical latitudes).

The amount of precipitation in itself does not determine the conditions of moisture or moisture supply of natural processes and the landscape as a whole. In the steppe zone, with 500 mm of annual precipitation, we are talking about insufficient moisture, and in the tundra, with 400 mm, we are talking about excess moisture. To judge moisture, you need to know not only the amount of moisture entering the geosystem annually, but also the amount that is necessary for its optimal functioning. The best indicator of moisture demand is evaporation, i.e., the amount of water that can evaporate from the earth's surface under given climatic conditions, assuming that moisture reserves are unlimited. Volatility is a theoretical value. It should be distinguished from evaporation, i.e. actually evaporating moisture, the amount of which is limited by the amount of precipitation. On land, evaporation is always less than evaporation.

The ratio of annual precipitation to annual evaporation can serve as an indicator of climatic moisture. This indicator was first introduced by G. N. Vysotsky. Back in 1905, he used it to characterize the natural zones of European Russia. Subsequently, N.N. Ivanov constructed isolines of this ratio, which was called the humidification coefficient (K). The boundaries of landscape zones coincide with certain values of K: in the taiga and tundra it exceeds 1, in the forest-steppe it is 1.0 - 0.6, in the steppe - 0.6 - 0.3, in the semi-desert 0.3 - 0.12, in the desert - less than 0.12.

Zoning is expressed not only in the average annual amount of heat and moisture, but also in their regime, that is, in intra-annual changes. It is well known that the equatorial zone is characterized by the most even temperature regime; four thermal seasons are typical for temperate latitudes, etc. The zonal types of precipitation regime are varied: in the equatorial zone precipitation falls more or less evenly, but with two maximums; in subequatorial latitudes, summer precipitation is pronounced maximum, in the Mediterranean zone - winter maximum, temperate latitudes are characterized by a uniform distribution with a summer maximum, etc.

Climatic zonality is reflected in all other geographical phenomena - in the processes of runoff and hydrological regime, in the processes of swamping and the formation of groundwater, the formation of weathering crust and soils, in the migration of chemical elements, in the organic world. Zoning is clearly manifested in the surface layer of the ocean (Isachenko, 1991).

Latitudinal zoning is not consistent everywhere - only Russia, Canada and North Africa.

Provinciality

Provinciality refers to changes in the landscape within a geographic zone when moving from the outskirts of the continent to its interior. Provinciality is based on longitudinal and climatic differences as a result of atmospheric circulation. Longitudinal and climatic differences, interacting with the geological and geomorphological features of the territory, are reflected in soils, vegetation and other components of the landscape. The oak forest-steppe of the Russian Plain and the birch forest-steppe of the West Siberian Lowland are an expression of provincial changes in the same forest-steppe type of landscape. The same expression of provincial differences in the forest-steppe type of landscape is the Central Russian Upland, dissected by ravines, and the flat Oka-Don Plain, dotted with aspen bushes. In the system of taxonomic units, provinciality is best revealed through physiographic countries and physiographic provinces.

Sector

A geographic sector is a longitudinal segment of a geographic zone, the unique nature of which is determined by longitudinal-climatic and geological-orographic intra-belt differences.

The landscape and geographical consequences of the continental-oceanic circulation of air masses are extremely diverse. It was noticed that as one moves away from the ocean coasts into the interior of the continents, there is a natural change in plant communities, animal populations, and soil types. The term sectorality is currently accepted. Sectoring is the same general geographical pattern as zoning. There is a certain analogy between them. However, if both heat supply and moisture play an important role in the latitudinal-zonal change of natural phenomena, then the main factor of sectorality is moisture. Heat reserves do not change significantly along longitude, although these changes also play a certain role in the differentiation of physical-geographical processes.

Physiographic sectors are large regional units that extend in a direction close to the meridional and replace one another in longitude. Thus, in Eurasia there are up to seven sectors: humid Atlantic, moderate continental Eastern European, sharply continental East Siberian-Central Asian, monsoon Pacific and three others (mostly transitional). In each sector, zoning acquires its own specificity. In the oceanic sectors, zonal contrasts are smoothed out; they are characterized by a forest spectrum of latitudinal zones from taiga to equatorial forests. The continental spectrum of zones is characterized by the predominant development of deserts, semi-deserts, and steppes. Taiga has special features: permafrost, dominance of light-coniferous larch forests, absence of podzolic soils, etc.

Latitudinal zonality (landscape, geographic) is understood as a natural change in physical-geographical processes, components and complexes (geosystems) from the equator to the poles.

The reason for zonality is the uneven distribution of solar radiation across latitude.

The uneven distribution of solar radiation is determined by the spherical shape of the Earth and the change in the angle of incidence of solar rays on the earth's surface. Along with this, the latitudinal distribution of solar energy also depends on a number of other factors - the distance from the Sun to the Earth and the mass of the Earth. As the Earth moves away from the Sun, the amount of solar radiation coming to the Earth decreases, and as it approaches, it increases. The mass of the Earth affects zonation indirectly. It holds the atmosphere, and the atmosphere contributes to the transformation and redistribution of solar energy. The tilt of the earth's axis at an angle of 66.5° determines the uneven seasonal supply of solar radiation, which complicates the zonal distribution of heat and moisture and enhances zonal contrast. The deviation of moving masses, including air, to the right in the northern hemisphere and to the left in the southern hemisphere introduces additional complexity into zoning.

The heterogeneity of the surface of the globe - the presence of continents and oceans, the variety of relief forms - further complicate the distribution of solar energy, and therefore zonality. Physical, chemical, biological processes occur under the influence of solar energy, and it follows that they have a zonal character.

The mechanism of geographic zonation is very complex, so it manifests itself in various components, processes, and individual parts of the epigeosphere in a far from unambiguous manner.

The results of the zonal distribution of radiant energy - the zonality of the radiation balance of the earth's surface.

The maximum total radiation occurs not at the equator, but in the space between the 20th and 30th parallels, since the atmosphere here is more transparent to the sun's rays.

Radiant energy in the form of heat is spent on evaporation and heat transfer. The heat consumption on them varies quite complexly with latitude. An important consequence of the uneven latitudinal transformation of heat is the zonality of air masses, atmospheric circulation and moisture circulation. Under the influence of uneven heating and evaporation of moisture from the underlying surface, zonal types of air masses with different temperatures, moisture content, and density are formed. Zonal types of air masses include equatorial (warm, humid), tropical (warm, dry), boreal temperate (cool and wet), Arctic, and in the southern hemisphere, Antarctic (cold and relatively dry) air masses. Uneven heating, and therefore different densities of air masses (different atmospheric pressure) cause a violation of thermodynamic equilibrium in the troposphere and the movement of air masses. If the earth did not rotate, then the air would rise within the equatorial latitudes and spread to the poles, and from them return to the equator in the surface part of the troposphere. The circulation would have a meridional character. However, the rotation of the Earth introduces a serious deviation from this pattern, and several circulation patterns are formed in the troposphere. They correspond to 4 zonal types of air masses. In this regard, in each hemisphere there are 4 of them: equatorial, common to the northern and southern hemispheres (low pressure, calms, rising air currents), tropical (high pressure, easterly winds), moderate (low pressure, westerly winds) and polar (low pressure, easterly winds). Here, 3 transition zones are distinguished - subarctic, subtropical, subequatorial, in which the types of circulation and air masses change according to the seasons.

Atmospheric circulation is the driving force, the mechanism for transforming heat and moisture. It smoothes out temperature differences on the earth's surface. The distribution of heat determines the allocation of the following thermal zones: hot (average annual temperature above 20°C); two moderate (between the annual isotherm of 20°C and the isotherm of the warmest month of 10°C); two cold ones (the temperature of the warmest month is below 10°C). Inside cold zones, “perpetual frost areas” are sometimes distinguished (the temperature of the warmest month is below 0°C).

The zonality of atmospheric circulation is closely related to the zonality of moisture circulation and humidification. The amount of precipitation and the amount of evaporation determine the conditions of moisture and moisture supply of landscapes as a whole. Humidification coefficient (determined by the ratio Q / Use, where Q is the annual precipitation, and Use.

– annual evaporation value) is an indicator of climatic humidification. The boundaries of landscape zones coincide with certain values of the moisture coefficient: in the taiga - 1.33; forest-steppe – 1–0.6; steppes – 0.6–0.3; semi-desert – 0.3–0.12.

When the humidification coefficient is close to 1, humidification conditions are optimal, and when the humidification coefficient is less than 1, humidification is insufficient.

An indicator of heat and moisture availability is the dryness index M.I. Budyko R / Lr, where R is the radiation balance, Lr is the amount of heat required to evaporate the annual amount of precipitation.

Zoning is expressed not only in the average annual amount of heat and moisture, but also in their regime - intra-annual changes. The equatorial zone is characterized by an even temperature regime; temperate latitudes are characterized by four seasons. Climatic zonation is manifested in all geographical phenomena - in runoff processes, hydrological regime.

Geographical zoning is very clearly visible in the organic world. Due to this circumstance, landscape zones received their names based on characteristic types of vegetation: arctic, tundra, taiga, forest-steppe, steppe, dry-steppe, semi-desert, desert.

No less clearly expressed is the zonation of the soil cover, which anticipated the development of V.V. Dokuchaev's teachings on natural zones. In the European part of Russia, from north to south, there is a consistent progression of soil zones: arctic soils, tundra-gley, podzolic soils of the taiga zone, gray forest and chernozems of the forest-steppe, chernozems of the steppe zone, chestnut soils of the dry steppe, brown semi-desert and gray-brown desert soils.

Zoning is manifested both in the relief of the earth's surface and in the geological foundation of the landscape. The relief is formed under the influence of endogenous factors, which are of an azonal nature, and exogenous, developing with the direct or indirect participation of solar energy, which is of a zonal nature. Thus, the Arctic zone is characterized by: mountainous glacial plains, glacial streams; for the tundra – thermokarst depressions, heaving mounds, peat mounds; for the steppe - ravines, gullies, subsidence depressions, and for the desert - aeolian landforms.

The structure of the earth's crust exhibits zonal and azonal features. If igneous rocks are of azonal origin, then sedimentary rocks are formed with the direct participation of climate, soil formation, and runoff, and have clearly defined zonal features.

In the world's oceans, zonation is most clearly visible in the surface layer; it also manifests itself in its underlying part, but with less contrast. At the bottom of the oceans and seas, it is indirectly manifested in the nature of bottom sediments (silts), which are mostly of organic origin.

From the above it follows that zonality is a universal geographical pattern that manifests itself in all landscape-forming processes and in the placement of geosystems on the earth’s surface.

Zoning is a product of not only the modern climate. Zoning has its own age and its own history of development. Modern zonation developed mainly in the Cenazoic. Kainazoi (era of new life) is the fifth era in the history of the earth. It follows the Mesozoic and is divided into two periods - Tertiary and Quaternary. Significant changes in landscape areas are associated with continental glaciations. The maximum glaciation extended over more than 40 million km2, while the dynamics of glaciation determined the displacement of the boundaries of individual zones. Rhythmic shifts of the boundaries of individual zones can also be traced in recent times. At certain stages of the evolution of the taiga zone, it extended to the shores of the Arctic Ocean; the tundra zone within its modern boundaries has existed only in the last millennia.

The main reason for the shift in zones is macroclimatic changes. They are closely related to astronomical factors (fluctuations in solar activity, changes in the Earth's rotation axis, changes in tidal forces).

The components of geosystems are rebuilt at different speeds. So, L.S. Berg noted that vegetation and soils do not have time to rebuild, so relict soils and vegetation can persist for a long time in the territory of the “new zone”. An example is: podzolic soils on the coast of the Arctic Ocean, gray forest soils with a second humus horizon on the site of former dry steppes. The relief and geological structure are distinguished by great conservatism.