Regularities of the location of geographic zones on the planet. Planet belts

Thermal zones

Throughout the geological history of the Earth, the relationship between ocean and land has changed, which suggests that the heat balance of the planet was not constant. Geographic zoning changed, heat zones changed. It becomes obvious that the modern geographic zoning was once completely alien to the planet. Scientists believe that neither glaciers nor cold seas most of the time on Earth simply did not exist, and the climate was much warmer than now. The temperature contrasts between the poles and the equator were small, impenetrable forests grew in the Arctic region, and reptiles and amphibians populated the entire Earth. Thermal zoning first appeared in southern hemisphereand in northern hemisphere, its formation took place later.

The main process of forming zoning took place in Quaternary Cenozoic era, although its first signs appeared $ 70 million years ago. With the advent of man, the heat zones were already the same as they are now - one hot zone, two moderate, two cold zones... The boundaries between the belts underwent changes, for example, the border of the cold belt, once passed through the modern Moscow region and the Moscow region was occupied by the tundra zone. The mention of heat zones can be found in the Greek historian Plibia ($ 204 - $ 121 BC). According to him, there were $ 6 $ heat belts on Earth - two hot, two moderate, two cold. Travelers' notes also contain such information. These data suggest that people have long known about the existence of heat zones. They explained their presence by the fact that the Sun at different latitudes heats the surface of the Earth in different ways, and attributed this to the different angle of inclination of the sun's rays. In northern latitudes, the Sun is low above the horizon and gives little heat per unit area, so it is colder there. This is how the concept “ klimat ". This pattern was known as early as $ 2.5 thousand years ago and remained indisputable until recently. This explanation was questioned relatively recently.

Observations have shown that Arctic and Antarctic per unit area receives very little solar heat in the summer. But for a long polar day, the total radiation is much higher than at the equator, which means that it should also be warm there. However, summer temperatures rarely rise above $ 10 degrees. This means that the thermal regime cannot be explained by a single difference in the supply of solar heat. Today everyone knows that character also plays a big role. underlying surface. Albedosnow and ice is very large and reflects up to $ 90 $% of solar radiation, and the surface not covered with snow reflects only $ 20 $%. The albedo of the Arctic surface will decrease if snow and ice melt, and this will change the existing thermal zones of the northern hemisphere. As the water temperature rises in the Arctic basin, forests will replace the modern tundra. After the collapse of Gondwana, the process in the southern hemisphere went something like this.

Definition 1

Thermal zones Are vast territories located along the parallels around the globe with certain temperature conditions.

It must be said that the formation of heat belts on the planet depends on how it will be distributed over the surface of the Earth and on what will be spent, and not only on the amount of solar heat entering the limits of a particular zone.

Moisturizing belts

In natural processes, not only certain thermal conditions play a role, but conditions play an even greater role. humidification... Moisture is determined by two factors: the amount of precipitation and the intensity of their evaporation.

Definition 2

Moisturizing - This is the ratio between the amount of precipitation in a given area and the amount of moisture evaporated at a given temperature.

Their distribution on the planet, in principle, is also associated with geographic zoning. Their average number decreases from the equator to the poles, but this pattern is violated by geographic and climatic conditions.

The reasons are as follows:

• Free air circulation is disturbed by the location of the mountains;
• Downward and upward air currents in different parts of the planet;
• Variability in cloudiness distribution.

Mountains can be located both in the latitudinal and in the meridional direction and most of the precipitation is delayed windward slopesand with leewardvery little or no precipitation falls on the side. The equatorial region is dominated by ascending air currents - warmed up light air rises, reaches the saturation point and brings an abundance of precipitation. In tropical latitudes, air movement downward, the air moves away from the saturation point and dries up, therefore very little precipitation flows along the tropics, which contributed to the formation of deserts and dry steppes here. Precipitation zoning recovers north and south of the tropics and persists up to the poles. Distribution cloudiness also has its own meaning. Sometimes it happens that a different amount of precipitation falls on one street.

Evaporation determines the conditions of humidification on the planet and is entirely regulated by the amount of residual radiation. The quantity fumes characterized by the amount of moisture evaporated at a given temperature.

From the north to the tropics, the moistening of the Earth's surface decreases. In the taiga zone it is close to $ 1 $, in the steppe zone the moisture will be $ 2 $, and in deserts more than $ 3 $. In the south, the potential for evaporation is much greater than in the north.

Example 1

Consider an example... The soil in the steppes warms up to $ 70 $ degrees. The air is dry and hot. If the field is irrigated, everything will change, it will be more humid and cooler. The earth will come to life and turn green. The air here was hot, not because the influx of heat from the Sun is greater than in the north, but because there is very little moisture. Evaporation began from the irrigated field, and part of the heat was spent on this. Thus, the conditions for moistening the Earth's surface depend not only on fumesbut also from amount of precipitation.

Pressure belts

Normal is the atmospheric pressure at sea level at a latitude of $ 45 $ degrees at a temperature of $ 0 $ degrees. Under such conditions, it is $ 760 $ mm Hg, but it can vary over a wide range. The increased air pressure will be more than normal, and the lower will be less normal with a mark of $ 760 mm. rt. Art.

With altitude atmospheric pressure goes downbecause the air becomes thinner. The surface of the planet having different heights will have its own pressure value.

Example 2

for example, $ Perm $ is located at an altitude of $ 150 $ m above sea level and every $ 10.5 $ m the pressure will decrease by $ 1 $ mm. This means that at the height of Perm, normal atmospheric pressure will not be $ 760 mm, but $ 745 $ mm Hg. Art.

Due to the fact that during the day there is a change in temperature and air movement, the pressure will be go up twice and go down twice... In the first case, in the morning and in the evening, in the second case, in the afternoon and midnight. On the continents, during the year, the maximum pressure will be observed in winter, and minimum in summer.

The distribution of pressure over the Earth's surface is zonal, because the surface is heated unevenly, which leads to a change in pressure.

There are $ 3 $ belts on the planet, where low pressure and $ 4 $ high pressure dominated belts. Low atmospheric pressure will be in equatorial latitudes and in temperate latitudes, but here it will change with the seasons. High atmospheric pressure is typical for tropical and polar latitudes.

Remark 1

At the surface of the Earth, the formation of belts of atmospheric pressure is influenced by the uneven distribution of solar heat and the rotation of the Earth. In view of the fact that the hemispheres are heated by the sun in different ways, there will be some displacement of the pressure belts: in the summer period - the shift goes to the north, in the winter period - to the south.

Consider the main zonal-regional patterns of the Earth.

1. Geographic zones,due to the spherical shape of the planet and the distribution of solar radiation. The zonal heterogeneity of the geographic envelope is primarily the result of the latitudinal distribution of the energy of geographic and biological processes on the spherical Earth - solar radiation, the atmospheric circulation caused by it and the moisture turnover caused by these processes. Education geographic zones is not associated with endogenous factors, like ocean and continental rays, but with exogenous ones. Exogenous factors are superimposed on endogenous ones.

At the present stage of the development of terrestrial nature, the following main planetary belts are distinguished: 1) equatorialhot and humid, 2) tropicalhot and dry, 3) moderate;in the northern hemisphere it is warm with a large amplitude of humidity in the regions, in the southern - with an oceanic climate; 4) borealcool and damp; five) polarfrosty and damp.

2. Geographic zones,nature features of which are due to the inclination of the Earth's axis of rotation to the plane of the ecliptic For this reason, transition belts are created - subequatorial, subtropicaland subpolarwith a pronounced seasonal rhythm of moisture in the subequatorial, heat and moisture in the subtropical, heat in the subpolar.

Thus, in each hemisphere, eight zones are allocated. In the southern hemisphere, the boundary between the temperate and subpolar belts is indistinct.

The names of geographic zones are associated with their geographic location at specific latitudes of the globe.

Thus, the belts encompass the Earth in continuous rings and include both continents and oceans.

3. Sectorality.The zonality is certainly combined with the sectoriality. Depending on the intensity and absolute value of the exchange of air masses in the ocean - atmosphere - mainland system, different parts of the land receive more or less heat and moisture and differ in the nature of the seasonal rhythm. Therefore, each belt breaks up into parts, and the same type of parts of different belts on the spherical surface of the Earth form sectors stretched from north to south.

Sectoris a taxonomic unit smaller than a ray. On the continents - western oceanic, central continentaland eastern oceanicsectors. On the oceans, respectively, warm and cold currents - westernand orientalsectors.

In the distribution of atmospheric humidity, two regularities are equal: a) latitudinal,expressed in the alternation of zones of minimum and maximum precipitation (Fig. 83), and b) longitudinal,or intrazonal sector.

At low latitudes, excessively provided with heat, differentiation into zones, and then we will see that into zones, is due to the water balance. At high latitudes, heat is of decisive importance, the amount of which here progressively decreases according to the cosine of latitude.

Strictly speaking, belts and sectors, zones and regions are not entirely equal. They express rather the general and the specific: the geographic belt and zones appear in each sector and region in their specific forms, the similarities of which give reason to unite them.

The universal hydrothermal index, which would correspond to the boundaries of the belts, is unknown. The versatility of interactions in nature and the multiplicity of landscape components make us skeptical about the search for such numerical expressions, especially if we take into account feedbacks: the vegetation cover not only reacts to soil and climate moisture, but also changes it.

Moisture indicators - the ratio of precipitation and evaporation - remain important.

The leading role of water along with heat in the landscape envelope system is based not only on plant nutrition and the formation of land waters. The moisture turnover determines the migration of chemical elements and the geochemical features of landscapes, for example, the salinity of desert soils and the leaching regime of podzolic soils in the zone of coniferous forests.

4. Zoning.The combination of heat and moisture, or atmospheric humidification in each belt, except the equatorial one, is very different. On this basis, inside the belts are formed zones.They are called natural history, natural, geographic or landscape; these names can be taken as synonyms.

A zone or a ball belt in geometry is, as is known, a part of the surface of a ball, enclosed between two parallel planes intersecting the ball. In accordance with this, the aggregates of homogeneous natural formations, elongated from west to east perpendicular to the axis of rotation of the Earth, have long been called zones in science - climatic, soil, and vegetation.

If the zoning of individual components of nature, and primarily climate, vegetation and soil, is known from the experience of people long before geographical generalizations, £ othe doctrine of geographic zoning arose only at the turn of the 19th and 20th centuries

Belts and zones are parts and whole. The combination of zones forms a belt. In the ocean, there are no such narrow strips as land zones.

In the northern hemisphere, the following zones are distinguished: ice, tundra, coniferous forests or taiga, deciduous forests, forest-steppe, steppe, temperate desert, subtropical forests, tropical desert, savannah, equatorial forests.

Transitional zones are distinguished between the listed zones: forest-tundra between tundra and forest, semi-desert between steppe and desert, etc. The concept of "transitional zone" is conditional - some researchers consider them to be basic, especially forest-steppe.

Each zone is divided into subzones.For example, in the steppe zone, northern forb steppeson black soil and southern dry fescue-feather grasson dark chestnut soils.

Zones and subzones were named according to the vegetation cover of the land, since vegetation is the most striking indicator or indicator of a natural complex. However, vegetation zones cannot be mixed with geographic zones. So. when they say the steppe zone of vegetation, they mean the predominance of mesoxerophilous herbaceous plants in this area. The concept of "steppe zone" includes flat relief, semi-arid climate, chernozem or chestnut soils, steppe vegetation, as well as forests and flooded meadows in valleys and only this zone is characteristic animal world... In short, the steppes, like forests and swamps, although they are named according to the nature of the vegetation cover, are a natural complex. And now, when the steppes have been plowed up, the steppe zone still exists, because, although herbaceous vegetation has been replaced by cultural ones, other features of nature have been preserved.

5. Regionality.Oceanic-continental transport of heat and moisture differentiates zones into regions or provinces of zones. East-West differentiation is not the same indifferent latitudes. In the temperate zone, due to the western transfer, the region of greatest continentality is shifted from the center toeast (west-east dissymmetry).

The division into sectors and regions does not mean the limit of differentiation; any subzone and regions can be subdivided into smaller taxonomic units. Regional differences are largely due to the history of the development of the nature of the region. For example, in North-Western Europe, which experienced glaciation, conifers are represented only by European spruce (Picea excelsa) and pine (Pinus silvestris); siberian spruce (Picea abouata) occupies a small area in the north; Siberian pine or cedar (Pinus sibiri-sa)settled only to the Pechora basin.

In general, the geographic envelope is zonal-regional.

6. Various shape of zones.The configuration of the continents and their macrorelief determines the size and extent of the zones. In North America, the width of the steppe zones turned out to be greater than their length, and they acquired a "meridional strike". In Central Asia, the semi-desert zone has the shape of an arc. The essence of zoning does not change in this case.

7. Zones-analogs.Each of the continental zones has its own counterpart in the oceanic sectors. With excessive and sufficient moisture, two variants of the same zone arise, for example, the Atlantic taiga in Norway and the continental taiga in Siberia. With insufficient moisture, different zones affect the analogs, for example, deciduous forests near the ocean correspond to the inland steppes.

8. Vertical waistin mountainous countries.

9. Dissymmetry of geographic zoning.Geographic zoning is dissymmetrical about the equatorial plane. Solar radiation is distributed proportionally to cosop and therefore symmetrically in both hemispheres. Therefore, the geographic zones of the hemisphere are generally the same - two polar, two moderate, etc. But the lithogenic basis of zoning is antisymmetric, and the geographic zones of the northern hemisphere are very different from those in the southern. For example, a large forested area of \u200b\u200bthe northern hemisphere in the southern corresponds to the ocean and only a small region of forests in Chile; in the northern temperate zone, inland deserts occupy large areas, while in the southern they do not exist at all. Dissymmetry increases in the direction from the equator to middle latitudes. The northern and southern temperate zones are so different that each requires an independent description. KK Markov (1963) considers the polar dissymmetry of the geographic envelope to be a structure of the first order, above zoning. This statement is perfectly true. VB Sochava (1963) believes that it is the tropical and two extratropical belts that act as structures of the first order, against which dissymmetry manifests itself. This author is also right. The fact is that K. K. Markov and V. B. Sochava write about geographical formations of different structural levels: the first
about zones, the second about belts. There is no doubt that the geographical zones - tropical and extratropical - are structures of the first order, characteristic of both oceans and continents. The geographic zones on the continents of the northern hemisphere are fundamentally different from the zones in the ocean of the southern hemisphere, and in their formation the continental dissymmetry of the Earth is more significant than zoning.

10. Different rates of variability of nature.Separate areas of the biosphere are characterized by different rates of variability of nature in the process of its development. It is known that oceanic fauna changes relatively more slowly than terrestrial ones. Consequently, the ocean is a more conservative area than the continents.

And on land, the variability of nature is not the same in different zones. Moreover, this applies not only to the organic world, but to all geographical conditions. The nature of low latitudes is more conservative. In the life optimum of the equatorial belt, fluctuations in geographical conditions never drop to the minimum level at which organisms must adapt to new conditions and change. In temperate latitudes, even insignificant fluctuations in temperature or humidity of climate, geomorphological or hydrological conditions create a new environment for organisms and necessitate their restructuring; here some species of plants and animals drop out relatively quickly and others are formed.

11. Areas with large and small participation of living matter.Despite the fact that the entire biosphere develops with the continuous and active participation of living matter, it contains zones with both quantitatively large and quantitatively small direct participation of life (Gozhev, 1956). The former include gilea, savannah, steppe, forest-steppe and forest zones of temperate latitudes; to the second - ice, desert and semi-desert zones. About half of the World Ocean (in offshore areas) is also biologically ineffective. In the first group of land and ocean areas, living conditions are optimal, in the second, there is a pessimum.

12. The role of the progress of living matter in the development of the geographic envelope.The qualitative progress of inanimate matter has an upper limit - the transition from inanimate to living. The development of the modern geographic shell, the biosphere, is due to the progress of living matter.

The modern stage of development of the nature of the Earth's surface - the geographic shell - is the result of the evolution of organic life and its interaction with inert matter. Development was guided by the evolution of living matter for internal reasons and changes in geographic conditions. Therefore, the nature of the earth's surface - inanimate and living, can only be studied on the basis of their deepest interaction.

The main role of living matter in the geographic envelope is to increase its energy by accumulating solar energy. This is the energy basis for the development of the Earth.

The formation of the Earth as a cosmic body - geological history - the appearance of life - the evolution of the organic world - the development of the geographic shell - the appearance of man - all these are stages of the general progress of matter.

13. Integrity - interaction - development.The most essential features of the geographic envelope as a complex natural system, its essence is integrity, interaction of parts and development.

1. Integrity - manifests itself in the fact that a change in one component of a natural complex inevitably causes a change in all the others and the entire system as a whole. Changes made in one place in the shell are reflected in the entire shell.

2. Rhythm Is the recurrence of similar phenomena in time. Rhythms are periodic (have the same duration) and cyclical (have an unequal duration). In addition, rhythms are distinguished daily, annual, secular, supersecular. Change of day and night, change of seasons, cycles of solar activity (11 years, 22 years, 98 years) are also examples of rhythms. Most of the rhythms are associated with changes in the position of the Earth in relation to the Sun and Moon. A certain rhythm can also be traced in mountain-building cycles (period 190-200 million years), glaciations and other phenomena.

3. Zoning - a regular change in all components of the geographic envelope and the envelope itself from the equator to the poles. Zoning is due to the rotation of the spherical Earth around the inclined axis and the flow of sunlight reaching the earth's surface. Due to the zonal distribution of solar radiation over the earth's surface, there is a regular change in climates, soils, vegetation and other components of the geographic envelope. On Earth, most exogenous phenomena are zonal.

So the processes of frost physical weathering are most active in the subpolar and polar latitudes. Temperature weathering and aeolian processes are characteristic of arid regions of the world (deserts and semi-deserts). Glacial processes take place in the polar and high mountain regions of the Earth. Cryogenic - are confined to polar, subpolar, temperate latitudes of the northern hemisphere. The formation of weathering crusts is also subordinated to zoning: the laterite type of weathering crust is characteristic of humid and hot climates; montmorillonite - for dry continental; hydromica - for moist cool, etc.

Zoning is manifested primarily in the existence of geographic zones on Earth, the boundaries of which rarely coincide with parallels, and sometimes their direction is generally close to the meridian (as, for example, in North America). Many zones are ruptured and expressed not throughout the continent. Zoning is typical only for flat areas. In the mountains there is altitudinal zonality ... In the change of horizontal zones and in the change of altitudinal zones, one can find similarities (but not identical). The mountains of each natural zone have their own spectrum altitudinal zonality (set of belts). The higher the mountains and closer to the equator, the more complete the range of altitudinal zones is. Some scientists (for example, S.V. Kalesnik) believe that the altitudinal zonation is a manifestation azonality ... Azonality on Earth is subject to phenomena caused by endogenous forces. The phenomenon of sectorality (western, central and eastern parts of the continents) is referred to azonal phenomena. A variety of azonality is considered intrazonality (intrazonal).

Differentiation of the geographic envelope is the division of a single planetary natural complex into objectively existing natural complexes of various orders (ranks).

The geographic envelope has never been the same everywhere. As a result of unequal development, it turned out to be composed of many natural complexes. A.G. Isachenko determines natural complex as a natural, historically determined and territorially limited combination of a number of components: rocks with their inherent relief, the surface air layer with its climatic features, surface and groundwater, soils, groupings of plants and animals.

According to N.A. Solntsev's definition, natural complex - This is an area of \u200b\u200bthe earth's surface (territory), which is a historically determined combination of natural components.

To identify natural complexes existing in nature, physical and geographical zoning is used.

With a huge variety of natural complexes that make up the geographic envelope, a system of taxonomic (ordinal) units is needed. There is no such unified system yet. When identifying taxonomic units, both zonal and non-zonal (azonal) factors of differentiation of the geographic envelope are taken into account.

Differentiation of the geographic envelope by azonal features is expressed in the division of the geographic envelope into continents, oceans, physico-geographic countries, physico-geographic regions, provinces, and landscapes. However, this approach in no way denies zonality as a general geographical pattern. In other words, all these natural complexes are necessarily zonal.

geographic envelope

geographic zone mainland

country zone

subzone region

provinces

landscape

Differentiation of the geographic envelope according to zonal features is expressed in its division into geographic zones, zones, subzones, landscapes.

The main unit of physical and geographical zoning is the landscape. By definition S.V. Kalesnik, landscape - This is a specific territory, homogeneous in origin and development history, with a single geological base, a single type of relief, a common climate, common hydrothermal conditions and soils, and the same biocenosis.

The smallest unit of physical and geographical zoning, the simplest, elementary natural complex is the facies.

Lesson number 22 Grade 7 11/29/2017 Lesson topic: "Practical work No. 5. « Analysis of thematic maps in order to identify the features of the location of geographic zones and natural zones of the Earth. "

The purpose of the lesson:to learn to determine the patterns of distribution of geographical zones and natural zones on separate continents and on the planet as a whole using thematic maps.

Lesson type: learning new material lesson

Equipment:textbook, atlas, map of geographic zones and natural zones of the world.

Basic conceptsZoning latitudinal - a regular change in natural components and natural complexes in the direction from the equator to the poles and the formation of geographic zones and natural zones.
Geographic zones of the Earth - the largest zonal subdivisions of the geographic envelope, extending in the latitudinal direction. Geographic zones are distinguished on the basis of taking into account the differences in the radiation balance, temperature regime and atmospheric circulation. This determines the formation of sharply different types of soil and vegetation cover. Geographic zones practically coincide with climatic zones and bear the same names (equatorial, subequatorial, tropical, etc.).
Natural areas - physical and geographical zones, large parts of geographic zones, regularly changing from the equator to the poles and from the oceans to the interior. The position of natural zones is determined mainly by differences in the ratio of heat and moisture. Natural areas have a significant commonality of soils, vegetation and other components of nature.
Altitudinal zonality - a natural change in natural complexes associated with a change in altitude, typical for mountainous areas

During the classes:

1.Organizational moment

2. Actualization of basic knowledge 1. Indicate the patterns of location of geographic zones on the planet.
- stretched in the direction from west to east along the geographical latitude;
- are repeated symmetrically about the equator;
- the boundaries of the belts are uneven due to the influence of the relief, currents, distance from the oceans.
2. Why are there several natural zones within one geographic zone?
Natural zones are influenced by air temperature and humidity, which may differ within one belt.
3. What natural areas are located in the temperate zone?
Taiga, mixed and deciduous forests, forest-steppe and steppes, deserts and semi-deserts, variable-humid monsoon forests, areas of altitudinal zoning.
4. Why is there a change in natural zones in the mountains? What determines their number?
A decrease in air temperature with height and an increase in precipitation is the main reason for the change in natural zones in the mountains, the height of the mountains and their proximity to the equator affect their amount.
5. In what geographic zones is Russia? What natural areas are most typical for it?
Rossya is located in the arctic zone (zone of arctic deserts), in the subarctic zone (zone of tundra and forest-tundra), in the temperate zone (taiga, mixed and deciduous forests, forest-steppe and steppe, deserts and semi-deserts, variable humid monsoon forests), subtropical zone ( dry and humid rigid-leaved forests and shrubs of the Mediterranean type), areas of altitudinal zonation.

II. The practical part. Africa.1. In what geographic zones is the mainland?
In the center is the equatorial belt, to the north and south of it is subequatorial, along the tropics there are tropical zones, the extreme north and south are subtropical zones.
2. What natural zones are there in these zones?
At the equator - evergreen humid equatorial forests, in the subequatorial zone - savannas and woodlands, in the tropical zone - deserts and semi-deserts, in the subtropics - rigid-leaved evergreen forests and shrubs. In the mountains - high-altitude zonation.
3. Why are equatorial forests located only in the western part of the mainland?
The Congo Basin and coastal lowlands are well moistened with air masses from the Atlantic Ocean (warm currents and trade winds). In the east, there is a high plateau - lower temperatures, little precipitation - a cold Somali current.
4. Why is the latitudinal location of belts and natural zones prevalent in Africa?
Plains prevail in the relief in Africa, therefore the law of latitudinal zoning is well manifested here.
Output.Africa is located on the equator, which runs almost in the middle of the mainland, therefore, symmetry in the location of belts and zones is well manifested on the mainland, because of the plains, the law of latitudinal zoning operates, belts and natural zones stretch along latitude, each geographical zone has its own natural zones. The law of altitudinal zonality is manifested in the mountains.

6. Reflection of educational activities

What's new I learned in the lesson ………

It was difficult for me ... ..

It was interesting to me……

7 homework

Paragraph 20, p. 76-79, tasks at the end of the paragraph