What is latitudinal zoning? How does it manifest itself? Natural zoning. Latitude and altitude zoning
Latitudinal zoning is a natural change in physical and geographical processes, components and complexes of geosystems from the equator to the poles. The primary cause of zoning is the uneven distribution of solar energy in latitude due to the spherical shape of the Earth and a change in the angle of incidence of sunlight on the earth's surface. In addition, latitudinal zoning also depends on the distance to the Sun, and the Earth's mass affects the ability to hold the atmosphere, which serves as a transformer and redistributor of energy. Zoning is expressed not only in the average annual amount of heat and moisture, but also in intra-annual changes. Climatic zoning is reflected in the runoff and hydrological regime, the formation of the weathering crust, waterlogging. Great influence is exerted on the organic world, specific forms of relief. The homogeneous composition and high mobility of the air smooth out the zonal differences with height.
Altitudinal zonality, altitudinal zoning is a natural change in natural conditions and landscapes in the mountains as the absolute height (altitude above sea level) increases.
Altitude zone, high-altitude landscape zone - a unit of high-altitude-zonal division of landscapes in the mountains. The high-rise belt forms a strip that is relatively uniform in natural conditions, often intermittent [
Altitudinal zonation is explained by climate change with height: per 1 km of rise, the air temperature decreases by an average of 6 ° C, air pressure and dustiness decrease, the intensity of solar radiation increases, cloudiness and precipitation increase to an altitude of 2--3 km. As the height increases, the landscape belts change, to some extent similar to latitudinal zoning. The amount of solar radiation increases with the radiation balance of the surface. As a result, the air temperature decreases with increasing altitude. In addition, there is a decrease in precipitation due to the barrier effect.
ZONES GEOGRAPHIC (Greek. Zone - belt) - wide stripes on the earth's surface, limited by similar features of hydroclimatic (energy-producing) and biogenic (life-food) natural resources.
Zones are part of geographic zones, but they encircle the land of the globe only that is, they have excess air and soil moisture throughout the belt. These are landscape zones of tundra, tundra forest and taiga. All other zones within one geographic latitude are replaced with a weakening of the oceanic influence, that is, with a change in the ratio of heat and moisture - the main landscape-forming factor. For example, in the strip of 40-50 ° northern latitude, both in North America and in Eurasia, zones of deciduous forests turn into mixed forests, then into conifers, in the interior of the continents they are replaced by forest-steppes, steppes, semi-deserts and even deserts. Longitudinal zones or sectors appear.
Several geographic terms have similar, but not the same, names. For this reason, people are often confused in their definitions, and this can radically change the meaning of everything they say or write. Therefore, now we will find out all the similarities and differences between latitudinal zoning and altitudinal zonality in order to get rid of the confusion between them forever.
In contact with
The essence of the concept
Our planet has the shape of a ball, which, in turn, is tilted at a certain angle relative to the ecliptic. This state of affairs has become the reason that sunlight unevenly distributed over the surface.
In some regions of the planet it is always warm and clear, in others there are showers, in others cold and constant frosts are inherent. We call this climate, which changes depending on the distance or approach to.
In geography, this phenomenon is called "latitudinal zoning", since the change in weather conditions on the planet occurs precisely depending on the latitude. Now we can make a clear definition of this term.
What is latitudinal zoning? This is a natural modification of geosystems, geographic and climatic complexes in the direction from the equator to the poles. In everyday speech, we often call such a phenomenon "climatic zones", and each of them has its own name and characteristics. Below you will find examples demonstrating latitudinal zoning, which will make it possible to clearly remember the essence of this term.
Note! The equator, of course, is the center of the Earth, and all parallels from it diverge to the poles as if in a mirror image. But due to the fact that the planet has a certain tilt relative to the ecliptic, the southern hemisphere is more illuminated than the northern one. Therefore, the climate on the same parallels, but in different hemispheres does not always coincide.
We figured out what zoning is and what its features are at the level of theory. Now let's put all this into practice, just by looking at the climate map of the world. So the equator is surrounded (sorry for the tautology) equatorial climatic zone... The air temperature here does not change throughout the year, however, as well as the extremely low pressure.
Winds at the equator are weak, but torrential rains are frequent. Showers go every day, but at the expense high temperature moisture evaporates quickly.
We continue to give examples of natural zoning, describing the tropical belt:
- There are pronounced seasonal temperature drops, not as much precipitation as at the equator, and not as low pressure.
- In the tropics, as a rule, it rains for six months, the second six months - dry and hot.
Also in this case, there are similarities between the southern and northern hemispheres. The tropical climate is the same in both parts of the world.
Next in line is temperate climate which covers most of the northern hemisphere... As for the southern part, there it stretches over the ocean, barely capturing the tail of South America.
The climate is characterized by the presence of four distinct seasons, which differ from each other in temperature and amount of precipitation. From school, everyone knows that the entire territory of Russia is located mainly in this natural zone, so each of us can easily describe all the weather conditions inherent in it.
The latter, the Arctic climate, differs from all others in record low temperatures, which practically do not change throughout the year, as well as in scanty amount of precipitation. It dominates at the poles of the planet, captures a small part of our country, the Arctic Ocean and the whole of Antarctica.
What does natural zoning affect
Climate is the main determinant of the entire biomass of a particular region of the planet. Due to this or that air temperature, pressure and humidity flora and fauna are formed, soils change, insects mutate. It is important that the color of human skin depends on the activity of the Sun, due to which the climate is actually formed. Historically, it happened:
- lives in the equatorial zone black population Earth;
- mulattoes live in the tropics. These racial families are the most resistant to bright sunlight;
- the northern regions of the planet are occupied by fair-skinned people who are accustomed to spending most of their time in the cold.
All of the above implies the law of latitudinal zoning, which is as follows: "The transformation of the entire biomass directly depends on climatic conditions."
Altitudinal zonality
Mountains are an integral part of the earth's relief. Numerous ridges, like ribbons, are scattered around the globe, some high and steep, others sloping. It is these hills that we understand as areas of altitudinal zonation, since the climate here is significantly different from the flat one.
The thing is that ascending into layers more distant from the surface, the latitude at which we remain is already does not have the desired effect on the weather... Pressure, humidity, temperature change. Based on this, you can give a clear interpretation of the term. The zone of high-altitude zoning is a change in weather conditions, natural areas and landscape as the altitude rises.
Altitudinal zonality
Illustrative examples
To understand in practice how the altitudinal zonation zone changes, it is enough to go to the mountains. Rising higher, you will feel how the pressure decreases, the temperature drops. The landscape will also change before your eyes. If you started from the zone of evergreen forests, then with height they will grow into shrubs, later into grass and moss thickets, and at the top of the cliff they will completely disappear, leaving bare soil.
Based on these observations, a law was formed that describes the altitudinal zonation and its features. When lifting to a great height the climate is getting colder and harsher, the animal and plant worlds are becoming scarce, Atmosphere pressure becomes extremely low.
Important! Special attention should be paid to the soils located in the area of high-altitude zonation. Their metamorphoses depend on the natural zone in which the mountain range is located. If it comes about the desert, then as the height increases, it will transform into mountain chestnut soil, and later into black soil. After that, on the way there will be a mountain forest, and behind it - a meadow.
Mountain ranges of Russia
Special attention should be paid to the ridges that are located in the home country. The climate in our mountains directly depends on their geographical position, so it is easy to guess that it is very harsh. Let's start, perhaps, with the high-altitude zone of Russia in the region of the Ural ridge.
At the foot of the mountains, there are birch and coniferous forests that are not demanding for heat, and as the height increases, they turn into moss thickets. The Caucasian ridge is considered high, but very warm.
The higher we go up, the more precipitation becomes. At the same time, the temperature drops slightly, but the landscape is changing fundamentally.
Another zone with high zonation in Russia is the Far Eastern regions. There, at the foot of the mountains, cedar thickets are spread, and the tops of the rocks are covered with eternal snow.
Natural zones latitudinal zonation and altitudinal zonation
Natural zones of the Earth. Geography grade 7
Output
Now we can figure out what are the similarities and differences in these two terms. Latitudinal zoning and altitudinal zoning have something in common - this is a change in climate, which entails a change in the entire biomass.
In both cases, weather conditions change from warmer to colder, pressure transforms, fauna and flora become scarcer. What is the difference between latitudinal zoning and altitudinal zonality? The first term has a planetary scale. Due to it, the climatic zones of the Earth are formed. But the altitudinal zonality is climate change only within a certain relief- mountains. Due to the fact that the height above sea level increases, the weather conditions change, which also entail the transformation of the entire biomass. And this phenomenon is already local.
Landscape zoning- a natural change in physical and geographical processes, components and geosystems from the equator to the poles.
Reason: uneven distribution of short-wave solar radiation due to the spherical shape of the Earth and the inclination of its orbit. Zoning is most pronounced in changes in the limate, vegetation, fauna, and soils. These changes in groundwater and lithogenic basis are less contrasting.
It is expressed primarily in the average annual amount of heat and moisture at different latitudes. First, it is a different distribution of the radiation balance of the earth's surface. The maximum is at 20 and 30 latitudes, since the cloudiness there is the smallest, in contrast to the equator. Hence, the uneven latitudinal distribution of air masses, atmospheric circulation and moisture circulation follows.
Zonal types of landscapes are landscapes formed in autonomous conditions (upland, eluvial), that is, under the influence of atmospheric moisture and zonal temperature conditions.
Drainage zones:
equatorial zone of abundant flow.
Tropical zones
Subtropical
Moderate
Subpolar
Polar
20. Geographic sectorality and its impact on regional landscape structures.
Sector law(otherwise azonality law , or provinciality , or meridionality ) - the regularity of the differentiation of the vegetation cover of the Earth under the influence of the following reasons: the distribution of land and sea, the relief of the green surface and the composition of rocks.
The sectoral law is a supplement to the law of geographic zoning, which considers the patterns of distribution of vegetation (landscapes) under the influence of the distribution of solar energy over the Earth's surface, depending on the incoming solar radiation, depending on latitude. The law of azonality considers the influence of the redistribution of the incoming energy of the sun in the form of changes in climatic factors when moving inland (the so-called increase in the continentality of the climate) or the oceans - the nature and distribution of precipitation, the number of sunny days, average monthly temperatures, etc.
Sector of the oceans. Expressed in distribution:
River runoff (desalination of ocean waters).
Suspended solids intake, nutrients.
Salinity of waters due to evaporation from the surface of the oceans.
and other indicators. In general, there is a significant depletion of oceanic waters in the depths of the oceans, the so-called ocean deserts.
On the continents, the sectoral law is expressed in:
Circus zoning, which can be of several types:
a) symmetric - the oceanic impact is manifested with the same strength and extent from all sides of the continent (Australia);
b) asymmetric - where the influence of the Atlantic Ocean prevails (as a consequence of the western transfer), as in the north of Eurasia;
v) mixed.
The growth of continentality as we move inland.
21. Altitudinal zonation as a factor of landscape differentiation.
Altitudinal zonality - part of the vertical zoning of natural processes and phenomena related only to mountains. Change of natural zones in the mountains from the foot to the top.
The reason is the change in heat balance with height. The magnitude of solar radiation increases with height, but the radiation of the earth's surface grows even faster, as a result, the radiation balance decreases, and the temperature also decreases. The gradient is higher here than in the latitudinal zonality.
With a drop in temperature, humidity also drops. A barrier effect is observed: rain clouds approach the windward slopes, rise, condense and precipitation falls. As a result, the already dry and humid air rolls over the mountain (to the leeward slope).
Each plain zone has its own type of altitudinal zonation. But this is only outwardly and not always, there are no analogs - alpine meadows, cold deserts of Tibet and the Pamirs. As one approaches the equator, the possible number of these types increases.
Examples: Ural - tundra and Goltsov belt. Himalayas - subtropical forest, coniferous forest, boreal coniferous forest, tundra. + Possibly eternal snow.
Differences from the zones: rarefaction of air, atmospheric circulation, seasonal fluctuations in temperature and pressure, geomorphological processes.
Latitudinal zoning (landscape, geographic) is understood as a natural change in physical and geographical processes, components and complexes (geosystems) from the equator to the poles.
The reason for the zoning is the uneven distribution of solar radiation in latitude.
The uneven distribution of solar radiation is due to the spherical shape of the Earth and a change in the angle of incidence of sunlight 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 arriving at the Earth decreases, and as it approaches, it increases. The mass of the Earth affects zoning indirectly. It holds the atmosphere, and the atmosphere promotes the transformation and redistribution of solar energy. The tilt of the earth's axis at an angle of 66.5 ° determines the uneven seasonal influx of solar radiation, which complicates the zonal distribution of heat, moisture and enhances the zonal contrast. The deviation of moving masses, including air masses, to the right - in the northern and to the left - in the southern hemisphere, add additional complexity to the zoning.
The heterogeneity of the surface of the globe - the presence of continents and oceans, a variety of landforms further complicate the distribution of solar energy, and, consequently, zoning. Physical, chemical, biological processes occur under the influence of solar energy, and hence it follows that they have a zonal character.
The mechanism of geographic zoning is very complex; therefore, it manifests itself in various components, processes, and individual parts of the epigeosphere by no means unambiguously.
The results of the zonal distribution of radiant energy are the zoning of the radiation balance of the earth's surface.
The maximum total radiation falls 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 for them is quite difficult to vary in latitude. An archival consequence of the uneven latitudinal transformation of heat is the zoning of air masses, atmospheric circulation and moisture rotation. Under the influence of uneven heating, evaporation of moisture from the underlying surface, zonal types of air masses with different temperatures, moisture content, and density are formed. Zonal air masses include equatorial (warm, humid), tropical (warm, dry), boreal temperate (cool and humid), arctic, and Antarctic (cold and relatively dry) air masses in the southern hemisphere. Unequal heating, and consequently, different density of air masses (different atmospheric pressure) cause disturbance of thermodynamic equilibrium in the troposphere and 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 near-ground troposphere. The circulation would be meridional. 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 for the northern and southern hemispheres (low pressure, calm, updrafts), tropical (high pressure, eastern winds), moderate (low pressure, western winds) and polar (low pressure, easterly winds). Here, there are 3 transition zones - subarctic, subtropical, subequatorial, in which the types of circulation and air masses change according to the seasons.
The circulation of the atmosphere is the mover, the mechanism for the transformation of heat and moisture. It smooths out temperature differences on the earth's surface. The distribution of heat determines the release of the following heat zones: hot (the average annual temperature is above 20 ° C); two moderate ones (between the annual isotherm of 20 ° С and the isotherm of the warmest month of 10 ° С); two cold ones (the temperature of the warmest month is below 10 ° С). Inside the cold zones, sometimes, "areas of eternal frost" are distinguished (the temperature of the warmest month is below 0 ° C).
The zoning of atmospheric circulation is closely related to the zoning of moisture circulation and humidification. The amount of precipitation and the amount of evaporation determine the conditions for moistening and moisture supply of landscapes as a whole. Moisture coefficient (determined by the ratio Q / Isp., Where Q is the annual precipitation, and Isp.
- annual value of evaporation) is an indicator of climatic humidification. The boundaries of the 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 moisture factor is close to 1, the moisture conditions are optimal, and when the moisture factor is less than 1, the moisture is insufficient.
The indicator of heat and moisture supply 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 mode - intra-annual changes. The equatorial zone is characterized by an even temperature regime; four seasons are typical for temperate latitudes. Climatic zoning manifests itself in all geographic phenomena - in runoff processes, hydrological regime.
Geographic zoning is very evident in the organic world. Due to this circumstance, the landscape zones got their names according to the characteristic types of vegetation: arctic, tundra, taiga, forest-steppe, steppe, dry-steppe, semi-desert, desert.
The zoning of the soil cover is no less clearly expressed, which anticipated the development of V.V. Dokuchaev's doctrine of zones of nature. In the European part of Russia, a sequential procession of soil zones is observed from north to south: 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 basement of the landscape. The relief is formed under the influence of endogenous factors of an azonal nature, and exogenous, developing with the direct or indirect participation of solar energy, which has a zonal character. Thus, the Arctic zone is characterized by: upland 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.
Zonal and azonal features appear in the structure of the earth's crust. If igneous rocks are of azonal origin, then sedimentary rocks are formed with the direct participation of climate, soil formation, runoff, and have pronounced features of zoning.
In the world's oceans, zoning is most clearly traced in the surface layer; it is also manifested in its underlying part, but in 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 zoning is a universal geographic pattern that manifests itself in all landscape-forming processes and in the placement of geosystems on the earth's surface.
Zoning is not only a product of the modern climate. Zoning has its own age and development history. The modern zoning developed mainly in the Kainaz. Kainazoy (era of new life) is the fifth era in the history of the earth. It follows the Mesozoic and is subdivided into two periods - Tertiary and Quaternary. Significant changes in landscape zones are associated with continental glaciations. The maximum glaciation extended for more than 40 million km2, while the dynamics of glaciation determined the displacement of the boundaries of individual zones. Rhythmic displacements of the boundaries of individual zones are also 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 the modern borders exists only in last millennia.
The main reason for the displacement of zones is macroclimatic changes. They are closely related to astronomical factors (fluctuations in solar activity, changes in the Earth's axis of rotation, changes in tidal forces).
The components of geosystems are rearranged at different rates. So, L.S. Berg noted that vegetation and soils do not have time to rebuild, therefore, relict soils and vegetation can remain on the territory of the "new zone" for a long time. An example can be considered: podzolic soils on the coast of the Arctic Ocean, gray forest soils with a second humus horizon in place of the former dry steppes. Relief and geological structure is distinguished by great conservatism.
Latitudinal (geographic, landscape) zoning means a natural change different processes, phenomena, individual geographical components and their combinations (systems, complexes) from the equator to the poles. Zoning in elementary form was already known to scientists 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 climatic and phytogeographic zones of the Earth. At the very end of the XIX century. V.V. Dokuchaev elevated latitudinal (in his terminology, horizontal) zoning to the rank of a world law.
For the existence of latitudinal zoning, 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. 3). However, the actual amount of insolation entering the earth's surface is influenced by some other factors that are also astronomical in nature, including the distance from the Earth to the Sun. As you move away from the Sun, the flux of its rays becomes weaker, and at a sufficiently far distance the difference between the polar and equatorial latitudes loses its significance; so, on the surface of the planet Pluto, the calculated temperature is close to -230 ° С. On the other hand, when you get too close to the Sun, it is too hot in all parts of the planet. In both extreme cases, the existence of water in the liquid phase, life, is impossible. Thus, the Earth is most “fortunately” located in relation to the Sun.
The inclination of the earth's axis to the plane of the ecliptic (at an angle of about 66.5 °) determines the uneven inflow of solar radiation by seasons, which significantly complicates the zonal distribution
warmth and sharpens 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 change of phenomena on the earth. The daily rotation of the Earth, causing 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 zoning scheme.
The mass of the Earth also affects the nature of zoning, albeit indirectly: it allows the planet (as opposed to, for example, "light
171 koy "of the Moon) to hold the 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 in latitude and would be the same on 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 geographic components, latitudinal zoning must inevitably appear in these components. However, these manifestations are far from unambiguous, and the geographic 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 the clouds. Because of this, the maximum radiation arriving at the earth's surface is observed not at the equator, but in the belts of both hemispheres between the 20th and 30th parallels, where the atmosphere is most transparent to the sun's rays (Fig. 3). Over land, the contrasts of atmospheric transparency are more significant than over the Ocean, which is reflected in the figure of the corresponding curves. The curves of the latitudinal distribution of the radiation balance are somewhat smoother, but it is clearly noticeable that the surface of the Ocean is characterized by higher numbers than the land. The most important consequences of the latitude-zonal distribution of solar energy include the zoning of air masses, atmospheric circulation and moisture rotation. 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 humid), 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 the axis), air currents from heated near-equatorial latitudes should rise up and spread to the poles, and from there the cold and heavier air would return in the surface layer to the equator. But the deflecting action 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. For equator-
The 172nd belt is characterized by low atmospheric pressure, calmness, ascending air currents, for tropical belts - high pressure, winds with an eastern component (trade winds), for moderate belts - low pressure, westerly winds, polar ones - low pressure, winds with an eastern component. In summer (for the corresponding hemisphere), the entire atmospheric circulation system shifts to its "own" pole, and in winter - to the equator. Therefore, in each hemisphere, three transitional belts are formed - subequatorial, subtropical and subarctic (subantarctic), in which the types of air masses change according to the seasons. Due 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 about 10 - 20 ° N. NS. Since ancient times, it has been customary to distinguish five heat zones on Earth: two cold and temperate and one hot. However, this division is purely conventional, it is extremely schematic and its geographical significance is not great. The continual nature of the change in air temperature near the earth's surface makes it difficult to delineate the thermal zones. Nevertheless, using the latitudinal-zonal change of 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-moderate);
5) pre-subtropical;
6) subtropical;
7) tropical;
8) subequatorial;
9) equatorial.
The zoning of atmospheric circulation is closely related to the zoning of moisture circulation and humidification. A peculiar rhythm is observed in the distribution of precipitation over latitude: two maxima (the main one at the equator and the minor one in boreal latitudes) and two minima (in tropical and polar latitudes) (Fig. 4). As is known, the amount of precipitation does not yet determine the conditions for the moisture and moisture supply of landscapes. To do this, it is necessary to correlate the amount of precipitation falling annually with the amount that is necessary for the optimal functioning of the natural complex. The best integral indicator of the need for moisture is the amount of evaporation, i.e., the limiting evaporation theoretically possible at given climatic (and above all temperatures)
conditions. G.N. Vysotsky was the first to use this ratio back in 1905 to characterize the natural zones of European Russia. Subsequently, N.N. Ivanov, independently of G.N.Vysotsky, introduced an indicator into science, which became known as moisture factor Vysotsky - Ivanova:
K = g / E,
where G- the annual amount of precipitation; E- annual value of evaporation 1.
1 For comparative characteristics atmospheric humidification, the dryness index is also used RfLr, proposed by M. I. Budyko and A. A. Grigoriev: where R- annual radiation balance; L- latent heat of vaporization; G- the annual amount of precipitation. In terms of its physical meaning, this index is close to the opposite indicator. TO Vysotsky-Ivanov. However, its application gives less accurate results.
In fig. 4 that the 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 TO in each hemisphere (for land) there are two critical points where TO goes through 1. The quantity TO- 1 corresponds to the optimum of atmospheric humidification; at K> 1 moisture becomes excessive, and when TO< 1 - insufficient. Thus, on the surface of the land in the very general view one can distinguish an equatorial belt of excessive moisture, two symmetrically located on both sides of the equator belts of insufficient moisture in low and middle latitudes and two belts of excessive moisture in high latitudes (see Fig. 4). Of course, this is a highly generalized, averaged picture that does not reflect, as we will see later, gradual transitions between belts and significant longitudinal differences within them.
The intensity of many physical and geographical processes depends on the ratio of tegoto supply and moisture. However, it is easy to see that the latitudinal-zonal changes in temperature conditions and moisture have different directions. If the reserves of solar heat generally increase from the poles to the equator (although the maximum is somewhat shifted to tropical latitudes), then the moisture curve has a sharply expressed wavy character. Without touching upon the methods of quantitatively assessing the ratio of heat supply and humidification, we outline the most general patterns changes in this ratio in latitude. From the poles to approximately the 50th parallel, the increase in heat supply occurs under conditions of a constant excess of moisture. Further, with approaching the equator, an increase in heat reserves is accompanied by a progressive increase in dryness, which leads to a frequent change of 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 reserves of heat with abundant moisture.
To assess the influence of climate on the zoning 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. So, for temperate latitudes, seasonal contrast of thermal conditions is characteristic with a relatively uniform intra-annual distribution of precipitation; in the subequatorial zone, with small seasonal differences in temperature conditions, the contrast between dry and wet seasons is sharply expressed, etc.
Climatic zoning is reflected in all other geographical phenomena - in the processes of runoff and hydrological regime, in the processes of waterlogging and the formation of groundwater
175 waters, the formation of the weathering crust and soil, in the migration of chemical elements, as well as in the organic world. Zoning is clearly manifested in the surface layer of the World Ocean. Geographic zoning is especially striking and to a certain extent integral expression in the vegetation cover and soils.
Separately, it should be said about the zoning of the relief and the geological foundation of the landscape. In the literature you can find statements that these components do not obey the law of zoning, i.e. azonal. First of all, it should be noted that it is illegal to divide the geographical components into zonal and azonal, because in each of them, as we will see, the influences of both zonal and azonal laws are manifested. The relief of the earth's surface is formed under the influence of the 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 forms of relief they create are distributed zonal on the Earth. Suffice it 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, for example, erosion, deflation, karst formation, significantly depends on latitudinal-zonal conditions.
The structure of the earth's crust also combines azonal and zonal features. If igneous rocks are of undoubtedly azonal origin, then the sedimentary stratum is formed under the direct influence of climate, the vital activity of organisms, soil formation and cannot but bear the stamp of zoning.
Throughout the entire geological history, sediment formation (lithogenesis) proceeded unevenly 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 a picture of the zones of that time, and each zone will have its own types of sedimentary rocks. However, over the course of geological history, the system of landscape zones has undergone repeated changes. Thus, the results of lithogenesis were superimposed on the modern geological map.
176 of all geological periods, when the zones were not at all the same as they are now. Hence the external variegation of this map and the absence of visible geographical patterns.
It follows from what has been said that zoning cannot be regarded as a simple imprint of the modern climate in the earth's space. Essentially, landscape zones are space-time formations, they have their own age, their own history and are changeable both in time and space. The modern landscape structure of the epigeosphere took shape mainly in the Cenozoic. The equatorial zone is distinguished by the greatest antiquity; with the distance to the poles, the zoning is experiencing more and more variability, and the age of the modern zones decreases.
The last significant restructuring of the world system of zoning, which captured mainly high and temperate latitudes, is associated with continental glaciations of the Quaternary period. Oscillatory displacements of zones continue here in the postglacial time. In particular, over the past millennia there has been at least one period when the taiga zone in places has advanced to the northern edge of Eurasia. The tundra zone within its present-day borders arose only after the subsequent retreat of the taiga to the south. The reasons for such changes in the position of the zones are associated with the rhythms of cosmic origin.
The action of the zoning law is most fully manifested in the relatively thin contact layer of the epigeosphere, i.e. in the actual landscape sphere. With distance from the surface of the land and ocean to the outer boundaries of the epigeosphere, the influence of zoning weakens, but does not completely disappear. Indirect manifestations of zoning are observed at great depths in the lithosphere, practically in the entire stratisphere, that is, in the thickness of sedimentary rocks, the relationship of which with zoning has already been mentioned. Zonal differences in the properties of artesian waters, their temperature, salinity, chemical composition can be traced down to a depth of 1000 m and more; freshwater horizon groundwater in zones of excessive and sufficient moisture it can reach a thickness of 200-300 and even 500 m, while in arid zones the thickness of this horizon is insignificant or it is completely absent. On the ocean floor, zoning is indirectly manifested in the nature of bottom silts, which are predominantly of organic origin. It can be considered that the law of zoning 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 domestic geography long time the significance of the law of zoning for human life and social production was underestimated. V.V. Dokuchaev's judgments on this topic are
177 were considered as an exaggeration and a manifestation of geographical determinism. The territorial differentiation of the population and economy has its own laws, which cannot be completely reduced to the action of natural factors. However, to deny the influence of the latter on the processes taking place in human society would be a gross methodological mistake, fraught with serious socio-economic consequences, as we are convinced by all historical experience and modern reality.
Various aspects of the manifestation of the law of latitudinal zoning in the field of socio-economic phenomena are discussed in more detail in Ch. 4.
The zonality law finds its most complete, complex expression in the zonal landscape structure of the Earth, i.e. in the existence of the system landscape zones. The system of landscape zones should not be thought of as a series of geometrically regular continuous stripes. Even V.V.Dokuchaev did not think of zones as an ideal belt shape, strictly delimited by parallels. He emphasized that nature is not mathematics, and zoning is just a scheme or law. As we further investigated the landscape zones, it was found that some of them were torn, some zones (for example, the zone of broad-leaved forests) are developed only in the peripheral parts of the continents, others (deserts, steppes), on the contrary, tend to the inland regions; the boundaries of the zones deviate to a greater or lesser extent from the parallels and in some places acquire a direction close to the meridian; in the mountains, latitudinal zones seem to disappear and are replaced by altitudinal zones. Such facts gave rise to the 30s. XX century some geographers argue that latitudinal zoning is not a universal law at all, but only a special case characteristic of the great plains, and that its scientific and practical significance is exaggerated.
In reality, however, various kinds of violations of zoning do not refute its universal significance, but only indicate that it manifests itself differently in different conditions... Every natural law operates in different ways under 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 the conditions of a laboratory experiment. Many natural laws operate simultaneously in the epigeosphere. The facts, which at first glance do not fit into the theoretical model of zoning with its strictly latitudinal continuous zones, indicate that zoning is not the only geographical regularity, and it is impossible to explain the entire complex nature of territorial physical-geographical differentiation only by it.
178 pressure peaks. In the temperate latitudes of Eurasia, the differences in average January air temperatures on the western periphery of the continent and in its inner extreme continental part exceed 40 ° C. In summer, it is warmer in the interior of the continents than in the periphery, but the differences are not so great. Generalized understanding of the degree of oceanic influence on temperature regime continents give indicators of the continentality of the climate. Exists different ways calculation of such indicators based on taking into account the annual amplitude of average monthly temperatures. The most successful indicator, taking into account not only the annual amplitude of air temperatures, but also the daily, as well as the lack of relative humidity in the driest month and the latitude of the point, was proposed by N.N. Ivanov in 1959. Taking the average planetary value of the indicator as 100%, the scientist divided the whole series of values obtained by him for different points of the globe into ten continental belts (in brackets, the numbers are given in percent):
1) extremely oceanic (less than 48);
2) oceanic (48 - 56);
3) temperate oceanic (57 - 68);
4) sea (69 - 82);
5) slightly marine (83-100);
6) slightly continental (100-121);
7) moderately continental (122-146);
8) continental (147-177);
9) sharply continental (178 - 214);
10) extremely continental (over 214).
On the diagram of the generalized continent (Fig. 5), the belts of continental climate are arranged in the form of concentric bands of irregular shape around the extremely continental cores in each hemisphere. It is easy to see that at almost all latitudes, continental varies widely.
About 36% of atmospheric precipitation falling on the land surface is of oceanic origin. As it moves inland, sea air masses lose moisture, leaving most of it on the periphery of the continents, especially on the slopes of mountain ranges facing the Ocean. The greatest longitudinal contrast in the amount of precipitation is observed in tropical and subtropical latitudes: abundant monsoon rains on the eastern periphery of the continents and extreme aridity in the central, and partly in the western regions affected by the continental trade winds. This contrast is aggravated by the fact that the evaporation rate sharply increases in the same direction. As a result, on the Pacific Ocean periphery of the tropics of Eurasia, the moisture coefficient reaches 2.0 - 3.0, while in most of the tropical zone it does not exceed 0.05,
The landscape-geographical consequences of the continental-oceanic circulation of air masses are extremely diverse. In addition to heat and moisture, various salts come from the Ocean with air currents; This process, called by G.N. Vysotsky impulseurization, is the most important cause of salinization in many arid regions. It has long been noticed that as the distance from the oceanic coasts to the interior of the continents, a natural change of plant communities, animal populations, and soil types takes place. In 1921, VL Komarov called this pattern meridional zoning; he believed that three meridional zones should be distinguished on each continent: one inland and two near-oceanic. In 1946 this idea was concretized by the Leningrad geographer A. I. Yaunputnin. In his
181 physical and geographical zoning of the Earth, he divided all continents into three longitudinal sectors- western, eastern and central and for the first time noted that each sector differs in its characteristic set of latitudinal zones. However, the English geographer A.J. Herbertson, who back in 1905 divided the land into natural belts and in each of them identified three longitudinal segments - western, eastern and central.
With the subsequent, deeper study of the pattern, which has come to be called the longitudinal sector, or simply sector, it turned out that the three-term sectoral division of the entire land mass is too schematic and does not reflect the entire complexity of this phenomenon. The sectoral structure of the continents has a clearly pronounced asymmetric character and is not the same in different latitudinal belts. So, in tropical latitudes, as already noted, a two-term structure is clearly outlined, in which the continental sector dominates, and the western one is reduced. In polar latitudes, sectorial physical and geographical differences are weakly manifested due to the dominance of fairly uniform air masses, low temperatures and excessive moisture. In the real belt of Eurasia, where the land has the greatest (almost 200 °) length in longitude, on the contrary, not only are all three sectors well expressed, but it is also necessary to establish additional, transitional stages between them.
The first detailed diagram the sectoral division of the land, implemented on the maps of the "Physico-geographical atlas of the world" (1964), was developed by E. N. Lukashova. There are six physical-geographical (landscape) sectors in this scheme. The use of quantitative indicators as criteria for sectoral differentiation - moisture and continental coefficients, and as a complex indicator - the boundaries of the distribution of zonal types of landscapes made it possible to detail and clarify the scheme of E. N. Lukashova.
Here we come to the essential question of the relationship between zoning and sector. But first it is necessary to pay attention to a certain duality in the use of terms. zone and sector. In a broad sense, these terms are used as collective, essentially typological concepts. So, speaking "desert zone" or "steppe zone" (in the singular), they often mean the whole aggregate of territorially separated areas with the same type of zonal landscapes, which are scattered in different hemispheres, on different continents and in different sectors of the latter. Thus, in such cases, the zone is not thought of as a single integral territorial block, or region, i.e. cannot be considered as an object of regionalization. But at the same time, the same ter-
182 mines can refer to specific, integral, territorially isolated units that correspond to the concept of the region, for example Desert zone Central Asia, Zone of the steppes of Western Siberia. In this case, we are dealing with objects (taxa) of regionalization. In the same way, we have the right to speak, for example, of the "western oceanic sector" in the broadest sense of the word as a global phenomenon that unites a number of specific territorial areas on different continents - in the Atlantic part Western Europe and the Atlantic part of the Sahara, along the Pacific slopes of the Rocky Mountains, etc. Each such piece of land is an independent region, but they are all analogues and are also called sectors, but understood in a narrower sense of the word.
The zone and sector in the broad sense of the word, which clearly has a typological connotation, should be interpreted as a common noun and, accordingly, write their names with a lowercase letter, while the same terms in the narrow (i.e., regional) sense and included in their own geographical name, - with a capital letter. Options are possible, for example: the Western European Atlantic sector instead of the Western European Atlantic sector; Eurasian Steppe Zone instead of Eurasian Steppe Zone (or Eurasian Steppe Zone).
There are complex relationships between zoning and sectorization. Sector differentiation largely determines the specific manifestations of the law of zoning. Longitudinal sectors (in a broad sense), as a rule, are elongated across the strike of latitudinal zones. When moving from one sector to another, each landscape zone undergoes a more or less significant transformation, and for some zones the boundaries of the sectors turn out to be completely insurmountable barriers, so that their distribution is limited to strictly defined sectors. For example, the Mediterranean zone is confined to the western oceanic sector, and the subtropical wet forest - to the eastern oceanic one (Table 2 and Fig. B) 1. The reasons for such seeming anomalies should be sought in the zonal-sector laws.
1 In fig. 6 (as in Fig. 5) all continents are brought together in strict accordance with the distribution of land in latitude, observing a linear scale along all parallels and the axial meridian, that is, in the Sanson equal-area projection. This transmits the actual area ratio of all contours. A similar, widely known and included in textbooks scheme of E.N. Lukashova and A.M. Ryabchikov was built without observing the scale and therefore distorts the proportions between the latitudinal and longitudinal extent of the conditional land mass and the areal relationships between individual contours. The essence of the proposed model is more accurately expressed by the term generalized continent instead of the often used perfect continent.
|
distribution of solar energy and especially atmospheric humidification.
The main criteria for the diagnosis of landscape zones are objective indicators of heat supply and moisture. It has been experimentally established that among the many possible indicators for our purpose, the most acceptable
|
ranks of landscape zones-analogues in terms of heat supply ". I - polar; II - subpolar; III - boreal; IV - subboreal; V - pre-subtropical; VI - subtropical; VII - tropical and subequatorial; VIII - equatorial; rows of landscape zones analogous to humidification: A - extra-arid; B - arid; B - semi-arid; G - semi-humid; D - humid; 1 - 28 - landscape zones (explanations in Table 2); T- the sum of temperatures for the period with average daily air temperatures above 10 ° С; TO- moisture coefficient. Scales - logarithmic
It should be noted that each such series of analogous zones fits into a certain range of values of the adopted heat supply indicator. So, the zones of the subboreal series lie in the range of the sum of temperatures 2200-4000 "C, subtropical - 5000 - 8000" C. Within the accepted scale, less clear thermal differences are observed between the zones of the tropical, subequatorial and equatorial belts, but this is quite natural, since in this case the determining factor of zonal differentiation is not heat supply, but humidification 1.
If the rows of analogous zones in terms of heat supply generally coincide with latitudinal belts, then the rows of humidification are of a more complex nature, containing two components - zonal and sectoral, and there is no unidirectionality in their territorial change. Differences in atmospheric humidification due to
1 Due to this circumstance, as well as due to the lack of reliable data in table. 2 and fig. Tropical and subequatorial belts 7 and 8 are united and the analogous zones related to them are not delimited.
187 are caught both by zonal factors during the transition from one latitudinal belt to another, and by sector factors, i.e., by longitudinal moisture advection. Therefore, the formation of analogous zones in terms of moisture in some cases is associated mainly with zoning (in particular, taiga and equatorial forest in the humid row), in others - by sector (for example, subtropical humid forest in the same row), and in others - by the coinciding effect both patterns. The latter case includes the zones of subequatorial variable moisture forests and forest savannas.
