Landscape zoning– a natural change in physical-geographical processes, components and geosystems from the equator to the poles.
Reason: uneven distribution of short-wave solar radiation due to the sphericity of the Earth and the inclination of its orbit. Zoning is most strongly manifested in changes in climate, vegetation, fauna, and soils. These changes are less contrasting in groundwater ah and lithogenic basis.
It is expressed primarily in the average annual amount of heat and moisture at different latitudes. Firstly, this is a different distribution of the radiation balance of the earth's surface. The maximum is at latitudes 20 and 30, since cloudiness there is the least, unlike the equator. This results in an uneven latitudinal distribution of air masses, atmospheric circulation and moisture circulation.
Zonal types of landscapes are landscapes formed in autonomous conditions (plain, eluvial), that is, under the influence of atmospheric moisture and zonal temperature conditions.
Drain zones:
equatorial zone of abundant flow.
Tropical zones
Subtropical
Moderate
Subpolar
Polar
20. Geographic sectorality and its impact on regional landscape structures.
Law of sectoring(otherwise law of azonality , or provincialism , or meridionality ) - the pattern of differentiation of the Earth's vegetation cover under the influence of the following reasons: the distribution of land and sea, the topography of the green surface and the composition of rocks.
The law of sectoring is a complement 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 incoming solar radiation depending on latitude. The law of azonality considers the influence of the redistribution of incoming solar energy in the form of changes in climatic factors when moving deeper into continents (the so-called increase in continental climate) or oceans - the nature and distribution of precipitation, the number of sunny days, average monthly temperatures, etc.
Ocean sector. Expressed in distribution:
River flow (desalinization of ocean waters).
Receipts of suspended substances, nutrients.
Salinity of waters caused by evaporation from the surface of the oceans.
and other indicators. In general, there is a significant depletion of ocean waters in the depths of the oceans, the so-called oceanic deserts.
On continents, the law of sectoring is expressed in:
Circumoceanic zoning, which can be of several types:
A) symmetrical - the oceanic impact manifests itself with equal strength and extent on all sides of the continent (Australia);
b) asymmetrical - where the influence of the Atlantic Ocean prevails (as a consequence of western transport), as in the north of Eurasia;
V) mixed.
Increasing continentality as we move deeper into the continent.
21. Altitudinal zonation as a factor of landscape differentiation.
Altitudinal zone – part of the vertical zonation of natural processes and phenomena that relates only to mountains. Change of natural zones in the mountains from the foot to the top.
The reason is a change in heat balance with altitude. The amount of solar radiation increases with altitude, but the radiation from the earth's surface grows even faster, as a result of which the radiation balance drops and the temperature also drops. The gradient here is higher than in the latitudinal zone.
As the temperature drops, the humidity also drops. A barrier effect is observed: rain clouds approach the windward slopes, rise, condense and precipitation occurs. As a result, the already dry and non-humid air flows over the mountain (towards the leeward slope).
Each flat zone has its own type of altitudinal zonation. But this is only external and not always, there are non-analogue ones - 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 Goltsy belt. Himalayas - subtropical forest, coniferous forest, boreal coniferous forest, tundra. + Possible permanent snow.
Differences from zones: air rarefaction, atmospheric circulation, seasonal fluctuations in temperature and pressure, geomorphological processes.
Latitudinal zoning is a natural change in physical-geographical processes, components and complexes of geosystems from the equator to the poles. The primary cause of zoning is uneven distribution solar energy in latitude due to the spherical shape of the Earth and the change in the angle of incidence of the sun's rays on the earth's surface. In addition, latitudinal zonality also depends on the distance to the Sun, and the mass of the Earth affects the ability to retain 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 zonation is reflected in the runoff and hydrological regime, the formation of weathering crust, and waterlogging. It has a great influence on the organic world and specific relief forms. Homogeneous composition and greater air mobility smooth out zonal differences with height.
Altitudinal zone, altitudinal zonation-- a natural change in natural conditions and landscapes in the mountains as the absolute height (altitude above sea level) increases.
An altitudinal zone, an altitudinal landscape zone, is a unit of altitudinal-zonal division of landscapes in the mountains. The altitudinal belt forms a strip, relatively homogeneous in natural conditions, often intermittent[
Altitudinal zonation is explained by climate change with altitude: per 1 km of ascent, the air temperature decreases by an average of 6 °C, air pressure and dust levels decrease, the intensity of solar radiation increases, and up to an altitude of 2-3 km, cloudiness and precipitation increase. As altitude increases, landscape zones change, somewhat similar to latitudinal zonality. The amount of solar radiation increases along with the radiation balance of the surface. As a result, the air temperature decreases as altitude increases. In addition, there is a decrease in precipitation due to the barrier effect.
GEOGRAPHICAL ZONES (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 geographical zones, but encircle the land globe only those in which excess air and soil moisture remains throughout the entire belt. These are landscape zones of tundra, tundra forests and taiga. All other zones within one geographical latitude change when the oceanic influence weakens, that is, when the ratio of heat and moisture—the main landscape-forming factor—changes. For example, in the zone of 40-50° northern latitude in both North America and Eurasia, zones of broad-leaved forests turn into mixed forests, then into coniferous ones, and deeper into the continents they are replaced by forest-steppes, steppes, semi-deserts and even deserts. Longitudinal zones or sectors arise.
Latitudinal zonation- natural changes in physical-geographical processes, components and complexes of geosystems from the equator to the poles.
Reasons for zoning
The primary reason for natural zonality is the uneven distribution of solar energy across latitude due to the spherical shape of the Earth and changes in the angle of incidence of solar rays on the earth's surface. In addition, the distance to the Sun, and the mass of the Earth affects the ability to retain the atmosphere, which serves as a transformer and redistribution of energy.
The inclination of the axis to the ecliptic plane is of great importance; the unevenness of the solar heat supply over the seasons depends on this, and the daily rotation of the planet causes the deviation of air masses. The result of differences in the distribution of radiant energy from the Sun is the zonal radiation balance of the earth's surface. The unevenness of heat supply affects the location of air masses, moisture circulation and atmospheric circulation.
Zoning is expressed not only in the average annual amount of heat and moisture, but also in intra-annual changes. Climatic zonation is reflected in the runoff and hydrological regime, the formation of weathering crust, and waterlogging. It has a great influence on the organic world and specific relief forms. The homogeneous composition and high air mobility smooth out zonal differences with height.
There are 7 circulation zones in each hemisphere. Latitudinal zoning is also evident in the World Ocean.
The main reason for latitudinal zonality is the change in the ratio of heat and moisture from the equator to the poles.
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Literature
- Dokuchaev V.V.: Horizontal and vertical soil zones. SPb.: type. St. Petersburg city administration, 1899. 28 p.
- Milkov F. N., Gvozdetsky N. A. Physical geography of the USSR. Part 1. - M.: Higher School, 1986.
An excerpt characterizing latitudinal zoning
Sonya, red as red, also held his hand and was all beaming in the blissful gaze fixed on his eyes, which she was waiting for. Sonya was already 16 years old, and she was very beautiful, especially at this moment of happy, enthusiastic animation. She looked at him without taking her eyes off, smiling and holding her breath. He looked at her gratefully; but still waited and looked for someone. The old countess had not come out yet. And then steps were heard at the door. The steps are so fast that they couldn't be his mother's.But it was she in a new dress, still unfamiliar to him, sewn without him. Everyone left him and he ran to her. When they came together, she fell on his chest, sobbing. She could not raise her face and only pressed it to the cold strings of his Hungarian. Denisov, unnoticed by anyone, entered the room, stood right there and, looking at them, rubbed his eyes.
“Vasily Denisov, a friend of your son,” he said, introducing himself to the count, who was looking at him questioningly.
- Welcome. I know, I know,” said the count, kissing and hugging Denisov. - Nikolushka wrote... Natasha, Vera, here he is Denisov.
The same happy, enthusiastic faces turned to the shaggy figure of Denisov and surrounded him.
- Darling, Denisov! - Natasha squealed, not remembering herself with delight, jumped up to him, hugged and kissed him. Everyone was embarrassed by Natasha's action. Denisov also blushed, but smiled and took Natasha’s hand and kissed it.
Denisov was taken to the room prepared for him, and the Rostovs all gathered in the sofa near Nikolushka.
The old countess, without letting go of his hand, which she kissed every minute, sat next to him; the rest, crowding around them, caught his every movement, word, glance, and did not take their rapturously loving eyes off him. The brother and sisters argued and grabbed each other's places closer to him, and fought over who should bring him tea, a scarf, a pipe.
Rostov was very happy with the love that was shown to him; but the first minute of his meeting was so blissful that his present happiness seemed not enough to him, and he kept waiting for something else, and more, and more.
Energy sources for natural processes
Not a single planet solar system does not have the opportunity to “boast” of such an extraordinary variety of natural landscapes as the Earth. In general, the very presence of landscapes by default is amazing fact. No one can give a comprehensive answer why heterogeneous natural components when favorable conditions united into a single inseparable system. But trying to explain exactly the reasons for such a motley landscape ensemble is a completely feasible task.
As is known, natural system The Earth lives and develops mainly due to two types of energy:
1. Solar (exogenous)
2. Intraterrestrial (endogenous)
These types of energy are equal in strength, but are useful in various aspects of the evolution of geographical space. Thus, solar energy, interacting with the earth’s surface, triggers a chain of global natural mechanisms responsible for the formation of climate, which, in turn, affects soil-plant, hydrological and external geological processes. Intraterrestrial energy, acting on the entire thickness of the lithosphere, naturally affects its surface, causing us to feel tectonic movements earth's crust and closely related seismic and magmatic phenomena. The end result of tectonic movements is the dismemberment of the earth's surface into morphostructures, which determine (the distribution of land and sea) and major differences in the relief of land and the bottom of the World Ocean.
All processes and phenomena caused by the contact of solar radiation with the daytime surface are called zonal. They cover mainly the surface, penetrating to an insignificant depth (on the scale of the entire Earth). The opposite of them azonal processes- this is the result of the impact on the earth’s crust of energy flows generated as a result of internal geological development(functioning) of the Earth. As already mentioned, these flows, having a deep origin, cover the entire tectonosphere with their influence and set it in motion, which is certainly transmitted to the earth’s surface. The most important intraterrestrial processes that provide energy food for azonality include the following:
Gravitational differentiation of terrestrial matter (when lighter elements rise up and heavier elements fall down). This explains the structure of the Earth: the core consists almost entirely of iron, and the atmosphere, the outer shell of the earth, is a physical mixture of gases;
Alternating change in the radius of the Earth;
Energy of interatomic bonds in minerals;
Radioactive decay of chemical elements (mainly thorium and uranium).
If every point on the earth's surface received the same amount of energy (both external and internal), then the natural environment in zonal and azonal terms would be homogeneous. But the shape of the Earth, its size, material composition and astronomical features exclude this possibility, and therefore energy is distributed extremely unequally over the surface. Some parts of the Earth receive more energy, others less. As a result, the entire surface is divided into more or less homogeneous areas. This homogeneity is internal, but the areas themselves differ from each other in all respects. In classical Russian science about the nature of the Earth, zonally homogeneous units of regional land zoning are called landscape areas; azonally homogeneous - landscape countries, and in general terms the borders of countries coincide with the borders of morphostructures.
The real existence of such natural formations is beyond doubt, but in natural conditions their spatial structure, of course, is much more complex than in the modern scientific understanding.
In addition to the above-described types of energy, other equally powerful ones influence the Earth, but they do not play a fundamental role in the differentiation of the natural environment. Their significance lies in the regulation of natural mechanisms at the global level. They also introduce significant deviations into zonal and azonal processes, changing the direction of movement of air and water masses, causing the change of seasons, ebbs and flows in the Ocean and even the lithosphere. That is, they make some amendments to the structure of material and energy flows, establish the rhythmicity and cyclicity of all natural phenomena. These types of energy include the energy of the axial and orbital rotation of the Earth, gravitational interaction with other celestial bodies, mainly with the Moon and the Sun.
Z o nality
The surface of planet Earth is characterized by two opposing qualities - zonality and azonality.
Zoning in physical geography is a set of interrelated phenomena on the Earth’s surface, caused by the interaction of solar radiation with the daytime surface and leading to the formation of landscape zones on land and belts on the surface and bottom of the World Ocean.
Zoning on land (terrestrial landscape sphere)
On land, zonality is expressed in the existence of landscape zones, internally homogeneous territories with a certain climatic regime, soil and vegetation cover, exogenous geological processes and hydrological features - the density of the hydrographic network (total water content of the territory), as well as the regime of water bodies and groundwater.
Landscape zones on land, as mentioned above, are formed under the direct influence of climate on the earth's surface. Of all the climatic elements (temperature, precipitation, pressure, humidity, cloudiness), in this section we will be interested in only two - air temperature and precipitation (frontal, convective, orographic), that is, heat and precipitation that the landscape zone is supplied with during the year.
For the formation of a landscape zone, both the absolute amount of heat and moisture and their combination are important.
The ideal combination is considered to be close to 1:1 (evaporation is approximately equal to the amount of precipitation), when the thermal characteristics (heat supply, evaporation) of the zone allow all precipitation falling during the year to evaporate. At the same time, they do not simply evaporate without any benefit, but perform certain work in natural complexes, “reviving” them.
In general, the combination of heat and moisture is characterized by five options:
1. There is a little more precipitation than can evaporate - forests develop.
2. Precipitation falls exactly as much as can evaporate (or a little less) - forest-steppes and natural savannas develop.
3. Significantly less precipitation falls than can evaporate - steppes develop.
4. Much less precipitation falls than can evaporate - deserts and semi-deserts develop.
5. Much more precipitation falls than can evaporate; in this case, the “excess” water, not being able to completely evaporate, flows into the depressions and, if the geological features of the area allow, causes waterlogging. Swamps mainly develop in tundra and forest landscapes. Although wetlands can also be found in dry zones. This is already connected with the hydrogeological qualities of the area.
Thus, the combination of these climatic elements (heat and moisture) depends zone type(forest, forest-steppe, steppe, semi-desert, desert). The specific character of the zone(forest equatorial, forest temperate, tropical desert, temperate desert, etc.).
So, with all the diversity of land landscape zones, they can be divided into five types:
1. Desert areas
2. Semi-desert zones
3. Steppe zones (including tundra)
4. Forest-steppe zones
5. Forest areas
It is the combination of heat and moisture that determines zone type. Specific character of the zone depends on the geographic zone in which it is located. There are seven belts in total on Earth:
1. Arctic belt
2. Antarctic belt
3. Temperate zone of the Northern Hemisphere
4. Temperate zone of the Southern Hemisphere
5. Subtropical zone of the Northern Hemisphere
6. Subtropical zone of the Southern Hemisphere
7. Tropical zone (including areas of subequatorial and equatorial climate)
In each belt are formed all types natural areas. It is precisely by this criterion that a geographical zone is distinguished - by the full development of zoning.
Zoning options on land
The climate, on which the type and character of the natural zone depends, is formed under the influence of three main factors:
1. Amount of solar radiation
2. Circulation of air masses
3. The nature of the underlying surface (n For example, the Arctic and Antarctic territories are such largely due to their white surface, which reflects almost all solar radiation received per year)
The quantitative and qualitative characteristics of all three factors undergo significant changes in latitude, longitude and in the vertical direction. This causes changes in indicators and main climatic elements (air temperature and precipitation). Following temperature and precipitation, natural areas change, as well as their internal qualities.
Since changes in thermal conditions and atmospheric moisture occur in all directions across the Earth’s surface, therefore, there are two main zonation options on land:
1. Horizontal zoning
2. Vertical zoning
Horizontal zoning exists in two types:
a) latitudinal zoning;
b) meridional zoning.
Vertical zoning represented on land altitudinal zonation.
Zoning in the World Ocean
In the World Ocean, zonality is expressed in the existence of surface-water and bottom oceanic belts.
Zoning options in the World Ocean
All the options and types of zoning presented above are also observed in the World Ocean. Vertical zonation in the oceanosphere exists in the form depth zonality of the bottom (provincial zonation).
Horizontal zoning
The phenomenon of horizontal zoning reveals itself in the form of latitudinal and meridional zoning.
Latitudinal zonation
Latitudinal zonality in physical geography is a complex change in zonal natural phenomena and components (climate, soil and vegetation cover, hydrographic conditions, lithogenesis) in the direction from the equator to the poles. This is a general idea of latitudinal zonation.
Besides this integrated approach For this variant of zonality, we can talk about the zonality of any one component of nature or a separate phenomenon: for example, zonality of soil cover, zonality of atmospheric precipitation, bottom silts, etc.
Also in physical geography, there is a landscape approach to latitudinal zoning, which considers it as a change in natural zones on land (and their landscapes in particular) and/or oceanic belts in the World Ocean from the equator to the poles (or in the opposite direction).
Latitudinal zonation on land
The amount of incoming solar radiation varies with latitude. The closer a territory is to the equator, the more radiation heat it receives per square meter. In general terms, the phenomenon of latitudinal zoning is connected with this, which from a landscape point of view manifests itself in the fact that natural zones replace each other in latitude. Within each zone, latitudinal changes are also noticeable - in connection with this, any zone is divided into three subzones: northern, middle and southern.
From the poles to the equator, the average annual air temperature increases by about 0.4-0.5 degrees Celsius with each degree of latitude.
If we talk about heating the earth's surface by solar radiation, then it is necessary to make some clarifications. It is not the amount of radiation received from the Sun itself that sets the temperature regime of the area, but the radiation balance, or residual radiation - that is, the amount of solar energy remaining after subtracting the terrestrial radiation that leaves the surface without benefiting it (i.e. Not spent on landscape processes).
All radiation coming from the Sun to the Earth's surface is called total shortwave radiation. It consists of two parts - direct radiation And absent-minded. Direct radiation comes directly from the solar disk, scattered radiation comes from all points of the sky. Also, the Earth's surface receives radiation in the form of long-wave radiation earth's atmosphere (counter radiation from the atmosphere).
Some part of the total solar radiation is reflected ( reflected shortwave radiation). Hence, Not all total radiation participates in heating the surface. Reflectivity (albedo) depends on surface color, roughness and other physical characteristics. For example, the albedo of pure dry snow is 95%, sand is from 30 to 40%, grass is 20-25%, forest is 10-20%, and black soil is 15%. The Earth's overall albedo approaches 40%. This means that the planet as a whole “returns” to Space less than half of the total solar radiation coming to it.
The surface heated by the remaining part of the total radiation ( absorbed by radiation), and counterlong-wave atmospheric radiation, begins to emit long-wave radiation itself ( terrestrial radiation, or intrinsic radiation of the earth's surface).
As a result, after all the “losses” (reflected radiation, terrestrial radiation), the active layer of the Earth remains some part of the energy, which is called residual radiation, or radiation balance. Residual radiation is spent on all landscape processes: heating of soil and air, evaporation, biological renewal, etc.
The sun's rays can affect the soil to a maximum depth of 30 meters. This is a general maximum for the entire Earth, although different climatic zones have their own maximum penetration of solar heat into the soil. This layer of the earth's crust is called solar thermal, or active. Below the maximum base of the active layer there is a layer of constant annual temperature ( neutral layer). It has a thickness of several meters, and sometimes tens of meters (depending on the climate, thermal conductivity of the rocks and their dampness). After it begins the most extensive layer - geothermal , spreading over the entire earth's crust. The temperature in it is determined by the internal (endogenous) heat of the Earth. From the maximum base of the neutral zone, the temperature increases with depth (on average 1 degree Celsius per 33 meters).
Latitudinal zoning has cyclical spatial structure - types of zones are repeated, replacing each other in the direction from south to north (or vice versa - depending on the starting point). That is in every belt one can observe a gradual change in landscape zones - from forest to desert. The existence of such cyclicity (especially in the tropical geographical zone) is facilitated by the interlatitudinal (zonal) circulation of the atmosphere. The mechanism of such circulation directly or indirectly divides the entire surface of the Earth into dry and wet (or relatively wet) belts, which alternate from the equator to the poles. The equatorial zone turns out to be wet, the purely tropical - generally dry, the temperate - relatively wet, and the polar zones - relatively dry. These belts of atmospheric moisture generally correspond to the largest natural zones (vast forests and deserts) of the main climatic zones (equatorial, tropical, temperate, polar).
Arctic belt characterized by two types of deserts (ice and arctic), tundra (northern analogue of the steppe), forest-tundra (analogous to the forest-steppe) and even a forest zone - northern and partly middle taiga. This type of forest landscape is an extremely depressed type of forest that develops in conditions of fairly low temperatures throughout the year. The difference between the northern taiga and the forests of temperate latitudes is approximately the same as the difference between the forests of the latter and the equatorial forests.
IN temperate zone natural zonality is already observed in its full form, in contrast to the Arctic, the type of landscapes of which is regulated not by a combination of heat and moisture, but by the temperature factor. Exactly low temperatures Arctic belt and interfere with the development of classical natural zones in this polar region.
Subtropical zone is isolated from the temperate and tropical, and exists as an independent one only because its zonation is also developed according to the classical scheme - from deserts to forests (dry Mediterranean and wet monsoon). This is a very interesting phenomenon, because in general the subtropics are a transitional zone that exists at the junction of two largest regions that differ in the geographical types of air masses. For example, regions with an equatorial climate cannot be distinguished into an independent landscape belt only because of the inadequate development of zoning.
Latitudinal zonation in the World Ocean
The surface of the World Ocean (and even its bottom), however, is also not free from the influence of climate. In the Ocean, in accordance with climatic zones, oceanic surface water landscape belts(differing from each other, first of all, in water temperature, as well as in the mode of movement of water masses, salinity, density, organic matter, etc.), replacing each other in the latitudinal direction.
The names of oceanic zones correspond to the names of climatic zones crossing the ocean: oceanic temperate zone, oceanic tropical zone, etc.
The physical and chemical state of ocean water is also projected onto the bottom (similar to the effect of the atmosphere on land). This is how they are formed bottom oceanic belts, which also follow each other in latitude and are distinguished on the basis of differences in bottom sediments.
Thus, the belts in the Ocean (surface and bottom) can be compared with geographic zones on land.
Reasons for the violation of the horizontal structure of latitudinal zonation on land
The world law of latitudinal zoning, it would seem, should establish a clear latitudinal-zonal change in landscape belts and zones on Earth. This should be favored by the completely correct zonal distribution of solar radiation and inter-latitudinal air exchange, which determines the alternation of dry and wet zones. However, the real picture of the alternation of landscape zones is far from such an impeccable scheme. And if the belts at least somehow “try” to correspond to the parallels, then most zones Not extend in perfect stripes along parallels to cross the entire continent from west to east; they are represented by broken areas, often have an irregular shape, and in some cases generally have a submeridional (along the meridians) extension. Some zones gravitate towards the eastern parts of the continents, others - towards the central and western sectors. And the zones themselves as a whole lack internal homogeneity. In a word, we have a rather complex zonal pattern, which only partially corresponds to the theoretically correct scheme.
The reason for this “imperfection” lies in the fact that the Earth’s surface is to a certain extent not uniform in the azonal plane. There are three fundamental geological reasons that influence the “wrong” location and extent of natural zones:
1. Division of the earth's surface into continents and oceans, and uneven
2. Division of the earth's surface into large morphostructural landforms
3. Diverse material composition of the surface, expressed in the fact that it is composed of various rocks
The first factor contributes to the development of meridional zoning; the second factor is vertical (in particular, altitudinal) zoning; the third factor is “petrographic zoning” (conditional factor).
Meridional zoning (on land)
The Earth's surface is divided into continents and oceans. In ancient times there was no land; the entire planet was covered with sea water. After the appearance of the first continent, the coexistence of continents, islands and oceans was not interrupted, only their relative positions changed. Further continental ocean pattern will, of course, change due to never-ending tectonic movements (horizontal and vertical), and with it the zoning pattern.
Meridional zoning- change of landscape zones from the ocean coasts towards the central parts of the continents. Longitudinal changes in nature can also be traced within the zones. This phenomenon owes its existence to the continental-oceanic transport of air masses and sea currents.
It makes sense to consider meridional zoning only on land, since on the surface of the ocean this phenomenon is inexpressive.
The role of continental-oceanic transport of air masses in the development of meridional zoning on land
Continental-oceanic transport of air masses clearly manifests itself in monsoons - powerful air currents moving from the ocean to the mainland in summer. The mechanism of formation and development of monsoons is very complex, but its fundamental principles can be outlined in a simplified diagram, which looks like this.
The surface of water and land differs in physical characteristics, in particular thermal conductivity and reflectivity. In summer, the surface of the oceans warms more slowly than the surface of the land. As a result, the air over the ocean is colder than over land. There is a difference in air density, and therefore in atmospheric pressure. Air always moves towards lower pressure.
According to the method and place of formation, monsoons can be divided into two types - tropical and extratropical. The first type is an integral part of the mechanism of interlatitudinal (zonal) atmospheric circulation, the second type is the continental-oceanic transport of air masses in its pure form.
In winter, the exact opposite process occurs. The land cools quickly, and the air above it becomes very cold. The ocean, which has been slowly warming throughout the summer, is also slowly releasing heat to the atmosphere. As a result, the atmosphere over the ocean in winter is warmer than over land.
This is the general picture of the seasonally changing transfer of air from the ocean to the mainland and in the opposite direction. The first is more important for us.
The air moving in summer from the ocean to the mainland carries a huge amount of moisture and in most cases insulates the areas of the continents close to the coasts. Therefore, the coastal parts where such air transfer occurs are generally wetter and slightly warmer than the central areas (in particular, the difference between summer and winter temperatures is smoothed out).
As you can see, in winter the direction of air changes to the opposite, and, therefore, in the cold season, the coastal areas of the mainland are at the mercy of dry and cold continental air.
From this situation we can conclude that the further the area is from the ocean, the less sea moisture it receives during the warm season. However, this statement is true only for the continent of Eurasia, which is extremely elongated from west to east. In most cases, the penetration of sea air moisture from the ocean to the middle parts of the continent is prevented by high mountain ranges (the nature of the distribution of precipitation of marine origin over the surface of the continent is influenced not only by the size of the continent and its topography, but also continental configuration; these factors will be discussed later).
The role of sea currents in the development of meridional zoning on land
The ocean influences the continents not only through its air masses, which form over the same water areas (in permanent and seasonal pressure systems) and move through the mechanism of general atmospheric circulation. Continents are also affected air of sea currents.
The geographical approach to the analysis of climatic nuances obliges us to divide all currents observed in the World Ocean, first of all, into:
Warm;
Cold;
Neutral.
Warm currents propelling relatively warm sea air along the continental coastline, provoke increased convection (upward air currents) and thereby contribute to heavy precipitation over the coastal regions of the continents and smooth out the difference in air temperature between winter and summer. In this paragraph it is worth mentioning the famous Gulf Stream, which originates in the warm waters of the Gulf of Mexico and moves along the western coast of Europe - right up to Murmansk. Western Europe its mild, warm, humid maritime climate is largely due to this current, the effect of which weakens in the eastern direction (towards the Urals). For comparison: the cold Labrador Current, which encircles the Canadian peninsula of the same name, makes its climate much colder and drier than the European one, although this region of Canada lies at the same latitudes as the countries of northern and central Europe.
Cold currents, moving relatively cold sea air along the mainland coast, provoke a weakening of convection and thereby contribute to the drying of coastal air and an increase in the temperature contrast between winter and summer.
Neutral currents do not make any significant amendments or additions to the zonal climate picture of the continents.
Factors influencing the nature of the distribution of sea moisture over the surface of the continent
The nature of the distribution of sea air moisture (precipitation of marine origin) over the surface of the continent (and, in particular, how far moist sea air will move towards the middle parts of the continent) is influenced by three main factors:
1. Relief of the mainland (especially high peripheral ridges)
2. Size of the continent
3. Mainland configuration
(Everything said below applies not only to moist sea air that moves from the ocean to the mainland, but also to warm ocean currents that enhance convection).
Peripheral relief called the relief of the outlying parts of the continents. Moist sea air moving from the ocean to the mainland can be intercepted by a high mountain range that runs along (parallel to) the coastline. This is called the barrier effect.
The opposite effect occurs extremely rarely and on a limited scale, when mountain ranges located parallel to each other (submeridional or sublatitudinal) act as conductors of moist sea air towards the center of the continent. In relation to the coastline, such ridges should be located perpendicularly or at a slight angle.
Continent size- a significant factor, but it should still be considered as exceptional. The only continent on Earth is characterized by its enormous size - Eurasia. It goes without saying that sea air loses almost all its moisture on its way to its middle parts.
(The essence of this factor is that sea moisture Not can reach continental areas that are very far from the oceans).
Mainland configuration defined as his outline, which consists of two components:
1. General outline (all possible contractions and expansions of the continent in certain parts, the degree of elongation in the latitudinal or meridional direction, etc.)
2. Peripheral outline (general ruggedness of the continent’s immediate coastline)
Configuration factor Not independent; it is subject to the two previous conditions (especially the continent size factor), as well as many other unique physiographic “nuances” (regional and local) characteristic of a particular region of the Earth. Naturally, moist sea air can move further towards the center of the continent in those places where the continent narrows or where there is an extensive horizontal depression in the form of a marginal or semi-enclosed sea, as well as an oceanic bay.
Expression of meridional zonation on land
Meridional zoning on land is expressed in the existence of the so-called landscape sectors.
In connection with the continental-oceanic transport of air masses, all geographical zones, except the equatorial one, are divided into landscape sectors,which correspond climatic regions.
In each geographical zone there are oceanic (western and eastern), central and intermediate sectors. And, as already mentioned, one or another type of natural area gravitates towards the corresponding sector. Since the eastern oceanic sectors of the continents are moistened more (due to the pronounced activity of monsoons and the passage of warm currents) than the western oceanic sectors, forest landscapes gravitate precisely to the eastern edges of the continents (when, both in the western oceanic and central parts, there is a predominance of desert and steppe PCs). The only exception is Eurasia, where both the western and eastern outskirts are almost identical in the degree of atmospheric moisture.
Although such a scheme is not a universal and only correct law.
Vertical zoning
Vertical zoning (or landscape layering) is a change in the properties and components of the landscape sphere (terrestrial and bottom-oceanic) depending on the relief.
On the ground this option zoning exists in two types:
1. Altitudinal zonation (characteristic of land)
2. Deep zoning (characteristic of the ocean and seabed)
Altitudinal zonation
The hypsometric role of large landforms in the zonal differentiation of land
The reason for altitudinal zonation is the division of the land surface into morphostructures (large landforms caused by endogenous processes).
Altitudinal (hypsometric) zoning is a change in the properties and components of the terrestrial landscape sphere depending on the relief, that is, with a change in the position of the terrain relative to the average level of the Ocean.
Altitudinal zonation is directly related to changes in air temperature and precipitation as absolute altitude increases. As the altitude of the area increases, the temperature decreases, and the amount of precipitation in certain places and up to a certain altitude increases. In general, the arrival of solar radiation increases with altitude, but long-wave effective radiation also increases to an even greater extent. This is why the temperature decreases by 0.5-0.6 degrees for every hundred meters of altitude. An increase in precipitation occurs due to the fact that the air, moving upward, cools and is thus freed from moisture.
Hypsometric (altitude) effect can already be traced on the plains. At higher elevations, the boundaries of landscape zones are thereby pushed north. The lowlands favor the advancement of their borders in the opposite direction. Thus, highlands and lowlands largely contribute to changing the boundaries of landscape zones, increasing or decreasing their area.
In the mountains, horizontal zoning disappears; it is replaced by altitudinal zonation. Altitude zones can be conditionally called analogues of classical natural zones. The phenomenon of altitudinal zonation is part of a general geographical pattern - altitudinal zonation, which is expressed V in general changing nature with absolute height.
The ideal altitudinal zoning scheme is a smooth transition from horizontal zoning To altitudinal zone- and further to the last mountain belt, characteristic of a particular mountainous country. In a simplified form, such a transformation can be represented as follows. This or that part of any natural zone, having reached a certain height (several hundred meters) above sea level, begins to gradually “transform” into a high-altitude (mountain) zone - due to the inevitable decrease in air temperature (and sometimes with an increase in precipitation) . Ultimately the zone changes altitude zone. The territory continues to rapidly “gain height”, and the first belt is replaced by the next (and so on until the very last mountain belt).
On vast plains, where lowlands and hills alternate (for example, on the Russian Plain), natural zones, of course, cannot “step over” the boundary after which the zone could turn into an altitudinal zone. But anyway high-risezoning- this is a general change in terrestrial nature with a decrease and/or increase in the altitude of the area. And in this regard, strictly speaking, it does not matter whether the natural zone has been transformed into an altitudinal zone or not.
On the other hand, we also have the right to say that “full-fledged” altitudinal zoning begins where a certain part of the zone has crossed a certain boundary, beyond which absolute height can have a serious cooling effect on landscapes. Within the first hundreds of meters from sea level, this effect is almost unnoticeable, although it is still recorded.
The development of altitudinal zoning is facilitated by the division of the earth's surface into morphostructures - into plains and mountains of different heights. The land, therefore, has a multi-tiered structure. The plains have two high-altitude tiers - highlands and lowlands. Mountains have a three-tiered structure: low-mountain, mid-mountain, and high-mountain. Natural zones adapt to this structure of the earth's surface, gradually changing and subsequently, having reached a certain climatic feature, transforming into altitudinal zones.
Orographic role large forms relief in the zonal sushi differentiation
Was discussed above hypsometric role large landforms in landscape differentiation of the natural environment. But morphostructures influence changes in the properties of the zonal structure of the earth’s surface not only with the help of the hypsometric (altitude) factor, but alsoalso with the help of three additional effects:
Barrier effect;
- "tunnel" effect;
The effect of slope orientation.
The essence orographic role lies in the fact that morphostructures “at their own discretion” redistribute atmospheric and radiation heat, as well as precipitation over the Earth’s surface.
Strictly speaking, the orographic features of large landforms have practically nothing to do with the phenomenon of altitudinal zonation as such. The analysis of the orographic factor could be taken outside the scope of the topic, in which the altitudinal zonation itself is directly studied. But, on the other hand, for obvious reasons we also cannot limit ourselves to only considering the factor of absolute height when studying the role of large landforms in the zonal differentiation of land.
Barrier effect manifests itself in the fact that high and medium-altitude mountain ranges prevent the penetration of warm or cold, wet or dry air masses into any territory. The effect of the barrier depends on the height of the mountain ranges and their extent. In the Northern Hemisphere, the sublatitudinal (along the parallels) strike prevents the advance of air masses from the Arctic (for example, the Crimean Mountains, which trap cold air masses and make the climate of the southern coast of Crimea subtropical). The submeridional (along the meridians) extension prevents the penetration of air, for example, from the oceans.
Plains also have a barrier effect, but to a much lesser extent.
However, high mountains do not always act only as barriers. In some cases they act as conductors, or tunnels, for certain air masses. This is facilitated by the parallel arrangement of the ridges relative to each other. And here again we can recall the Cordillera of North America. The ridges of this mountain system generally parallel to each other, and this favors the penetration of cold Arctic air as far south as Mexico. Therefore, the climate of the central US states is generally colder than the Mediterranean, but these regions have the same distance from the poles. This feature of the relief of North America largely contributes to the submeridional extension of landscape zones in the center of the continent.
An additional factor in the differentiation of the mountains themselves (and to a lesser extent the plains) is slope orientation in relation to the cardinal points - that is, insolation and circulation orientation. Windward slopes tend to receive more rainfall, while southern slopes tend to receive more sunshine.
More about altitudinal zonation (mountain zonality)
Phenomenon altitudinal zone is part altitudinal zonation.
Altitudinal zonation can only be observed in the mountains. Since the absolute height of points on the surface of any mountain system changes quite quickly, the change in climatic elements occurs there sharply and rapidly. This causes a rapid change in altitudinal zones in the vertical direction. Sometimes it is enough to walk or drive a few kilometers to find yourself in a different altitude zone. This is one of the main differences between mountain zonation and plain zonation.
Mountain systems differ from each other:
1. Number of altitude zones
2. The nature of the change in altitudinal zones
(Landscape types of belts are the same for all mountains).
Number (set) of altitude zones depends on several factors:
Position of the mountain system in the zonal-belt structure;
Mountain heights;
Horizontal profile (plan) of a mountainous country.
Position of the mountain system in the zonal-belt structure- a fundamental factor. Simply put, this is the position of a mountain system in a certain geographical zone and zone. If, for example, the mountains are located in the forest zone of the tropical geographical zone and if they are high enough, then, naturally, in this case the mountainous country has the entire set of altitude zones. In a temperate geographic zone, even if the mountains are very high, all stages of changing types of mountain landscapes are not observed, since the counting of zones begins from one or another natural zone of the temperate zone (in the zonal structure of the temperate zone, by definition, there cannot be any tropical-subtropical forests , nor other types of natural complexes characteristic of the mountains of the tropical zone).
Thus, the set of belts initially depends on the geographic zone, geographic sector, and geographic zone in which the mountains are located.
Mountain height is also an important factor. In the same equatorial or subequatorial strip, ancient low mountains will never acquire, for example, mountain coniferous-broad-leaved forests, and certainly not a nival belt - a zone of eternal snow and glaciers.
Horizontal profile (plan) of the mountain system- this is the relative position of the ridges and their orientation in relation to the sun and prevailing winds. But it depends largely on this factor the nature of the change in altitudinal zones, by which we mean the following features:
- “speed” of changing belts;
The nature of their relative position;
Absolute heights of the upper and lower boundaries of the belts;
Outlines of belts;
Belt sizes;
The presence of gaps in the classical sequence (and other features).
If different mountains are located in the same conditions of the zonal-belt structure, have similar altitudinal characteristics, but are very different in horizontal profile (plan), then the nature of the change of belts and the general contrast of the landscape-belt pattern will be different for them.
To a lesser extent, the number of altitude zones depends on the horizontal profile.
The above factor, even within the same mountain system, greatly influences landscape differentiation. Different parts of the mountainous country have their own range of belts and their own pattern of change.
In addition, a mountainous country can cross several natural zones and even several natural belts. All this seriously complicates the differentiation of landscapes within one mountain system.
Altitudinal zonation can be considered as altitudinal-zonal superstructure in the general scheme of the horizontal-zonal series of any region of the Earth.
The types of altitudinal zones are conditionally identical to the types of flat landscape zones and they change in the same sequence as the zones. But in the mountains there are high-altitude zones that have no analogues on the plains - alpine and subalpine meadows. These landscapes are characteristic only of mountains due to the climatic and geological uniqueness of mountainous countries.
The names of the types of altitudinal zones, in principle, correspond to the names of the types of plain zones, only the word “mountain” is attached to the designation of a mountain zone: mountain-forest belt, mountain-steppe, mountain-tundra, mountain-desert, etc.
Provincial zonation of the ocean floor
Part of the vertical zoning (landscape tiers) is provincial zoning of the ocean floor (bottom provinciality).
Bottom provincialism is a change in the nature of the ocean floor in the direction from continental (or island) coasts to the middle parts of the World Ocean.
This phenomenon exists mainly due to two interrelated factors:
1. Increasing distance of the bottom from the ocean surface (increasing depth)
2. Increasing distance of the bottom directly from continents or islands
Let's consider the essence of the first factor. The greater the depth, the less sunlight and atmospheric heat penetrates to the bottom of the ocean (or sea). Light and heat are of great importance for the bottom-oceanic version of the landscape sphere. All zonal physical-geographical processes (biological, hydrological, lithological, etc.) occurring at the bottom of the Ocean and in the bottom layer of sea water are associated with their quantity.
But the bottom provincialism Not is the result solely of an increase in depth. It is largely due to other reasons - in particular, how far the ocean floor is from the nearest continent or large island. The features of bottom sedimentation, which change significantly as the bottom moves away directly from the continental coasts, largely depend on this factor.
Deep layers of the ocean floor
ocean floor has five deep tiers:
1. Littoral
2. Sublittoral
3. Batial
4. Abyssal
5. Ultra Abyssal
Littoral– this is a tidal zone; she may fluctuate within wide limits- depending on the levelness of the coast.
Sublittoral- this is the zone located below the low tide level and corresponding to the continental shelf. This is the most active and organically diverse part of the world's ocean floor. It reaches a depth of 200 to 500 meters.
Batial– a zone of the seabed, approximately corresponding to the continental slope (depth limits - 200-2500 meters). The organic world is much poorer than the previous area.
Abyssal– deep-sea surface of the ocean floor. In depth it corresponds to the ocean bed. Here bottom waters They do not move as fast as surface ones. The temperature stays around 0 degrees Celsius all year round. Sunlight practically does not reach these depths. Among plants, only some bacteria can be found, as well as saprophytic algae. The thickness of the geological sediments of this part of the oceans consists mainly of various organogenic silts (diatomaceous, globigerina) and red clay.
Ultra-abyssal parts of the bottom are in the gutters. These depths are very poorly studied.
Expression of provincialism
At the regional level, this pattern is expressed in the existence bottomoceanic provinces, each of which approximately corresponds to a certain deep layer of the ocean floor (since the depth factor is decisive).
Benthic provinces should not be confused with bottombelts, replacing each other in latitude, the formation of which is associated with the influence of interrelated factors of latitudinal zonation on the bottom of the World Ocean.
Important: the bottom province is Part bottom oceanic belt.But the fundamental difference between them is that bottom provinces (as opposed to bottom belts) differ Not only by the nature of lithogenesis and sediments, but also by the characteristics of the organic world, physical and chemical properties bottom layer of water.
So, in each bottom oceanic belt, in approximate correspondence with the deep tiers, the following bottom provinces are formed:
Subtidal provinces;
Batial provinces;
Abyssal provinces;
- (ultra-abyssal provinces).
Bottom provinces replace each other in the direction from the continental coasts to the middle parts of the Ocean. This phenomenon is called provincial zonation of the ocean floor.
Bottom provinciality is a phenomenon that is inherent only to the bottom of the World Ocean. With some degree of relativity, it can be defined as deep zoning. Continuing this thought, we can state that from a landscape point of view it is inappropriate to talk about the deep zonation of the water column of the ocean or sea. Although from a purely hydrological point of view, such a phenomenon has a right to exist.
"Petrographic zoning"
All the factors discussed above influenced a particular area through climate - solar radiation and air flows with certain meteorological qualities (humidity, temperature, etc.). That is, they had a climatic nature. But it turns out that the material composition and geological structure of the near-surface layer of the earth’s crust is also of great importance in landscape differentiation. All the chemical and physical properties of rocks play a role here, on which the hydrogeological features of the territory also depend. Only the phrase “petrographic zonation” is not complete in terms of zonation itself, since this phenomenon does not play a decisive role in the distribution of natural zones on the earth’s surface, but only changes the configuration of the latter. And general zonal pattern, due to the diverse petrographic composition, takes on an even more complex appearance than if the entire surface were composed of any one rock (for example, clay or sand). This pattern can be seen very clearly in the mountains, where rocks replace each other very quickly and, at times, unpredictably.
On the plains, landscapes containing, in addition to classic sandy and clayey rocks, more nutritious (carbonate) rocks are capable of significantly pushing the boundaries of the temperate zone zones to the north and thereby expanding their area. You don’t have to look far for examples. The Izhora plateau near St. Petersburg is composed of limestones Ordovician period, on which fertile soils formed and subsequently formed a mixed forest, characteristic of more southern regions.
Sands can push the taiga zone far to the south, right up to the southern border of the forest-steppe zone, into which real coniferous forests.
If you look at this phenomenon from a slightly different angle, it turns out that any zone has such a quality as landscape preview. Its essence lies in the fact that no zone begins or ends abruptly; it always appears in the form of isolated inclusions or branches in a more northern zone and disappears in similar inclusions in a more southern one. For example, in the taiga there are patches of mixed forests; in the steppes there are also copses consisting of coniferous and deciduous trees. In mixed forests one can observe steppe landscapes, which gradually disappear into semi-deserts. And so on. In any zone you can find islands from neighboring regions. This phenomenon is also called extrazonality. The reasons for this, in addition to the petrographic properties of the surface, can also be explained by the different exposure of macro- and mesoslopes, which large plains also have.
In terms of the strength of its influence on the general zonation scheme, the material composition turns out to be equal to the hypsometric factor on the plains.
A z o n a l e n t y
The processes observed directly on the Earth's surface are not only exogenous (solar) in nature. In the upper part of the earth's crust, a number of phenomena are discovered that are an external continuation of deep geological processes occurring in the bowels of our planet. Such surface disturbances are called azonal because they do not belong to the category of zonal processes that are triggered by short-wave electromagnetic solar radiation (when it comes into contact with the daytime surface).
Azonality in physical geography is defined as a set of interconnected geological phenomena on the Earth's surface, caused by the energy of endogenous processes.
Specifics of azonal phenomena
There are not so many azonal phenomena. These include entirely tectonic movements. They can be divided according to different criteria.
By direction, tectonic movements are divided into:
Vertical movements;
Horizontal movements.
By impact on the original occurrence of rocks:
Slow epeirogenic (does not lead to significant disturbance of rock formation);
Dislocation movements (cause various discontinuous and folded deformations of rocks - horsts, grabens, faults, thrusts, orogenic synclines and anticlines).
Tectonic movements serve as a trigger for the occurrence of seismic and magmatic (intrusive and effusive, or volcanic) phenomena, which are also classified as azonal.
In the depths of the Earth, geological processes, for some reason, occur with different intensities. Because of this, some areas of the earth’s crust receive more energy for further evolution, while others (relatively mature) receive much less. Consequently, tectonic movements of the earth's crust in its different parts differ from each other in strength, speed and direction. This difference ultimately leads to the formation on land (and the ocean floor) of large landforms (plains and mountains), which are called morphostructures.
There is such a thing as order morphostructures. Later we will see that it is precisely this concept that has important for azonal physical-geographical zoning of land.
Morphological structures of various orders
It would not be superfluous to repeat: morphostructures are large relief forms, the genesis of which is dictated by intraterrestrial energy. They are components of tectonic structures (geostructures). When morphostructurally zoning the land surface, one should take into account the fact that the order of the morphostructure must coincide with the order of the tectonic structure.
Morphological structures higher order
Continental protrusions and oceanic trenches are tectonic structures of the highest order. If we consider them from a morphostructural point of view, then these forms of the Earth's megarelief are called geotextures.
Morphostructures of the 1st order on continents. Ancient platforms
Continents are composed of 1st order geostructures:
Platforms (ancient and young);
Movable belts.
In accordance with this division, in platform areas, morphostructures of the 1st order are vast plains, which on ancient platforms cover both slabs and shields (and, accordingly, occupy almost the entire area of ancient platforms).
The ancient platforms are mostly flat; mountains are quite rare. There are three categories of platform mountains:
1. "Relic":
a) remnants (isolated sharp outcrops of rocks left after the destruction of less stable rocks in the area) - ancient residual mountains;
b) ancient extinct volcanoes.
2.
Denudation:
a) erosional (table) mountains (arising from the erosional dissection of uplifts on shields and anteclises);
b) prepared (“exposed”) igneous formations (structural denudation mountains).
3. Epiplatform (block mountains)
Thus, on ancient platforms, “relict” mountains include single extinct volcanic cones (extremely rare) and remnants. Remnants and volcanoes are most often part of platform highlands, which will be discussed below. In addition, Precambrian platforms are characterized by denudation (erosion and preparation) mountains.
But there is another (third) category of platform mountains. These are blocky mountains. Areas of some ancient platforms that experienced epiplatform orogenesis in the Cenozoic are also characterized mountainous terrain, which is represented by short low blocky ridges. Such ridges are combined with elevated plains (plateaus, plateaus, etc.). The morphological complex of blocky ridges and elevated plains is often complicated by separate mountains (extinct or active volcanoes, as well as remnants). That is, in horizontal terms, these territories have a rather “chaotic”, irregular shape. Because of this, they are called highlands (or plateaus).
Mountains of ancient platforms are found mainly on shields.
Morphostructures of the 2nd order on ancient platforms
Ancient platforms consist of tectonic structures of the 2nd order:
Slabs;
Shields.
As a rule, the entire area of a plate is occupied by a vast plain - a system of hills and lowlands merged into one plain complex. Such a complex is called flat country(for example, the Russian lowland country, which occupies the plate of the same name on the East European Platform) and is a second-order morphostructure.
Any massive shield of one or another ancient platform (for example, the Baltic shield of the East European Platform) in most cases also corresponds to a generally different-altitude plain complex, which can consist of elevated basement plains, highlands and plateaus. Such an extensive plain complex is also considered a platform morphostructure of the 2nd order.
Morphological structures of the 3rd order on slabs of ancient platforms
This or that plate of the ancient platform breaks up into syneclises, anteclises, aulacogens and some other tectonic structures of the 3rd order. Syneclises are extensive depressions in the earth's crust. They correspond lowlands. Anteclises are extensive uplifts of the earth's crust. They are expressed in relief hills. Lowlands on syneclises and hills on anteclises are third-order morphostructures.
Morphostructures of epigeosynclinal mobile belts
Within the continents there are mobile belts three types: epigeosynclinal, epiplatform and rift (modern active rifts).
Any epigeosynclinal belt in itself is a mobile geostructure of the 1st order. It can be divided into epigeosynclinal areas - tectonic structures of the second order, which correspond to mobile morphostructures of the 2nd order - mountainous countries. For example, the Alpine-Himalayan belt is divided into the following regions: the Alps, the Pyrenees, the Greater Caucasus, the Himalayas, the Carpathians, etc. In morphostructural terms, they are mountainous countries.
Expression of azonality on land
If zonality on land is expressed in the existence of landscape zones, then azonality fully manifests itself in the form landscape countries.
When identifying a landscape country on the land surface, we should not forget that such a unit must have more or less uniform azonal characteristics at the regional level. This means that the territory must be located within the same macrorelief form, have more or less the same geological structure, origin, as well as a uniform tectonic regime.
These requirements are met on the ancient platform 2nd order morphostructures, which can be represented:
1. Flat country - on a slab
2. A complex of different-altitude basement plains, highlands and plateaus - on a massive shield
Within the epigeosynclinal belt, mountainous countries, which are mobile morphostructures of the 2nd order, meet these requirements.
Directly landscape countries are defined as azonal physical-geographical units of the first order.
Since the morphostructures are a single whole in all azonal characteristics, they are well suited for azonal landscape zoning of land.
Landscape countries- the main units of azonal zoning of the continental surface, which on the ancient platform and within the epigeosynclinal belt are almost always distinguished on the basis of morphostructures of the 2nd order.
On the plains, countries include segments of various natural zones (zones can also cross several countries), and in the mountains - a set of altitudinal zones.
Landscape countries according to azonal characteristics are divided into certain areas, from which azonal physical-geographical units of the second order are quite clearly distinguished - landscape areas, the boundaries of which on ancient platforms in most cases coincide with the boundaries of 3rd order morphostructures (individual hills, lowlands, etc.).
Landscape areas, in turn, also consist of smaller geosystems of the azonal series.
Some features of azonal landscape zoning of the East European Platform
Tectonic zoning of the Precambrian East European Platform, acceptable for adequate physical-geographical zoning of the Russian Federation and neighboring states, provides for its division into several large subordinate geostructures of the 2nd order - the Russian Plate, the Baltic Shield and the Ukrainian Shield.
The Russian plate corresponds to a flat country called the Russian Plain. Within its borders is the landscape country of the same name.
The vast Baltic Shield, which occupies a significant part of the Scandinavian Peninsula, all of Karelia and the Kola Peninsula, is, in physical and geographical terms, a landscape country called Fennoscandia.
The relatively small Ukrainian shield, which, although it is a 2nd order geostructure, Not stands out as an independent physical-geographical country. In the theory and practice of landscape science, this shield is considered as a landscape area, which is part of the Russian landscape country. Thus, we see that in the azonal zoning of continents, the shield of an ancient platform cannot always serve as the basis for identifying a landscape country.
Within Russian Federation and neighboring states, the Russian Plain includes about twenty landscape areas. Some of them: Central Russian, Upper Volga, Pechora, Polesskaya, Donetsk, Dnieper-Priazovskaya (Ukrainian Shield), etc.
Fennoscandia within the Russian Federation is called the Kola-Karelian landscape country. As the name itself suggests, it is divided into two regions - Kola and Karelian.
Intrazonality
The physical-geographical region (landscape), being completely homogeneous in terms of climate, tectonic regime and located within the same macroform of relief, nevertheless has a diverse, mosaic horizontal structure, like all other zoning units of higher ranks. A person who has a good sense of nature, when crossing any terrain, can notice that, for example, plant communities (and in general natural complexes) replace each other literally every few hundred meters along the way. And each of them is unique and inimitable. This is due to the diversity morphosculptural basis(geological foundation, or morpholithogenic basis) of each individual area.
In the process of geological development, the landscape acquires a unique and, most importantly, heterogeneous morpholithogenic ensemble, to which biocenoses (in particular, phytocenoses) adapt over time. The morpholithogenic base is a complex of various morphosculptures (hills, beams, ridges, etc.).
Each morphosculpture in the landscape consists of smaller forms of microrelief (for example, the top of a hill, its slopes, its foot, etc.)
Any form of microrelief is characterized by:
1. Microclimate
2. Moisturizing
3. Nutrition (trophism) of soil and rocks
This or that phytocenosis “selects” a certain form of microrelief within one morphosculpture, or ecotop(habitat), the conditions of which correspond to the needs of all plants in climate, moisture and soil nutrition. Therefore, the ecotope consists of:
1. Klimatopo (microclimate conditions)
2. Hygrotope (humidification conditions)
3. Edaphotopa (soil conditions)
For example, it is known that swamp vegetation settles in excessively moist places, pine trees - on poor, dry sandy and sandy loam soils (and birch generally grows in any conditions). This explains such a motley picture of natural complexes in relatively small area landscape. Moreover, any physical-geographical region has its own, individual morphosculptural complex. This makes the picture of nature even more diverse.
Microclimate
Each individual part of morphosculpture (in physical geography called facies) - for example, the slopes of a hill, its top, its foot - has its own microclimate. Differences in the microclimate of such relatively small natural formations lie in the unequal orientation of parts of the morphosculpture in relation to the sun's rays and wind - that is, to the cardinal directions. South-facing slopes are always warmer than opposite slopes. Consequently, in different parts of a hill or ravine, all microgeographic processes occur differently.
Hydration
Humidification of the territory consists of three elements:
1. Atmospheric humidification
2. Ground moisture
3. Smear moistening
Atmospheric humidification is a product of climate and has been discussed in previous chapters.
Ground moisture
Ground moisture is determined by the groundwater level, which varies depending on:
A) geological structure and the mechanical composition of the landscape foundation (the mechanical composition of the entire rock mass, the nature and sequence of their occurrence);
b) forms meso relief on which the facies is located.
Rocks that allow water to pass through well are called permeable. These include mainly sands and sandy loams. Water Not permeable rocks that poorly allow water to pass through (clays and heavy loams) or not at all, retain it at the surface, causing excessive moisture in the area. In such places, the groundwater level is always much higher than in those where sandy rocks allow almost all sediments to pass through them, which, having passed through the thickness of the sand, are quickly removed along with underground runoff (if the general flow allows terrain slope).
Negative morphosculptures(ravines, gullies, depressions, closed depressions between hills, etc.) almost always have a high level of groundwater, sometimes reaching the surface. Consequently, plants that need a lot of moisture settle in these places. Moreover, negative meso Landforms, due to their concavity, “take” water from the surrounding areas (water always flows into depressions). This increases the humidity of the area. Swamps or wetlands usually appear in such places.
Positive morphosculptures(hills, ridges, etc.) have a low groundwater level, and biocenoses that are unpretentious in relation to moisture are usually formed there. Positive meso relief forms, due to their convexity, are constantly freed from “excess” water.” And this dries out the area even more.
Depending on their moisture needs, all plants were divided into three groups:
1. Hygrophytes
2. Mesophytes
3. Xerophytes
Hygrophytes are very demanding of moisture.
Mesophytes grow in conditions of moderate moisture (this is the majority of plants in the middle (temperate) zone of Russia and other countries).
Xerophytes can exist in conditions of extreme water shortage (in deserts).
Smear moistening
This type of hydration is associated with drip water, which can be caused by surface runoff of rain and melt water (under the influence of gravity), floodplain overflow of watercourses (during floods and floods), and influx of water as a result of tides. Depending on this, sinter moisture is divided into three types:
1. Deluvial (surface runoff)
2. Poimnoye
3. Tidal
Consequently, sinter moisture depends on the topography and the proximity of reservoirs and watercourses.
Soil nutrition
The trophic (nutritional) properties of the morphosculptural complex of the landscape are associated with the mineral composition of the soil-forming and underlying rocks. Nutrient rocks include clays, loams, loess and those containing limestone. Sands and sandy loams, as well as rocks, are poor in terms of nutritional value. Plants have different nutrient requirements. Some of them are quite demanding on the soil, others “don’t care” where to grow; and still others are content with little. In this regard, all plants are divided into three groups:
1. Demanding on nutrients - megatrophs (eutrophs)
2. Moderately demanding of nutrients - mesotrophs
3. Not demanding on nutrients - oligotrophs
To the trees megatrophs include ash, maple, elm, white willow, walnut, hornbeam, beech, fir; To mesotrophs- aspens, downy birches, black alder, English oaks, rowan trees, larches and others; To oligotrophs– Scots pines, junipers, white acacias, warty birches, etc.
The nutritional value of the soil may also be related to the chemical composition of groundwater.
Having chosen a habitat (ecotope), the plant and animal world begins to develop according to its own unique laws, forming unique combinations and forms. Moreover, the biota (the totality of species of plants, animals and microorganisms in a certain territory), while evolving, strongly influences the components of the natural complex. That is why there cannot be complete coincidence in facies that are completely identical to each other. Two spruce forests that are completely identical at first glance will turn out to be different in terms of micro- and nanorelief parameters, the selection and grouping of plants, the lifestyle of insects, animals and birds, etc.
Now we should move on to the actual intrazonality. Each landscape contains such natural complexes that reflect its position in the zonal system of the earth's surface. That is, from these natural complexes one can immediately determine which zone the landscape belongs to. Such geosystems are called upright(automorphic), or typically zonal. They are typical for areas where the microclimate, moisture conditions and trophic properties of the surface are within average, normal values, characteristic of a specific landscape zone. All other geosystems that develop under conditions significantly deviating from “normal” are called intrazonal. Typically, upland PCs predominate over intrazonal PCs. But the opposite also happens. And this phenomenon is far from rare.
In principle, each zone is characterized by its own intrazonal complexes, which are unique to it. Therefore, any zone has its own intrazonal nearby. Nowhere on Earth will we find intrazonal tropical desert geosystems (oases) in temperate forests. Conversely, swamps, characteristic of central Eurasia and North America, cannot be found in the Sahara or even the Karakum Desert. The same can be said about mangroves, which are not characteristic of the landscapes of Greenland and Tierra del Fuego.
But natural complexes characteristic of the neighboring (more northern or southern) natural zone are a frequent and quite natural phenomenon, and it is called extrazonality, which has already been discussed above. At first glance, it is somewhat similar to intrazonality, but the functional causes and consequences of these two interesting phenomena are different.
About physical-geographical zoning
In a real situation, landscape zones and countries, of course, do not exist separately; they functionally and territorially complement each other in all respects. Therefore, the main task of theoretical research in physical geography is to connect them. By combining these regions, it is possible to identify derived units in which azonal and zonal characteristics coincide on a regional scale. Such units include the so-called provinces, formed from the intersection of zones and countries.
With further zoning within the province, from the “contact” of the remaining segment of the zone with different landscape areas “entering” its territory, provinces of the second order are obtained. Within a second-order province, the azonal characteristics are already quite uniform, but in zonal terms it can consist of segments of subzones. A segment of a subzone within a second-order province is defined as a third-order province.
Further, the combination becomes uncertain and unpredictable. In some cases, a third-order province can also be divided into some regional “azonal” territories. In this case, it breaks up, therefore, into provinces of the 4th order. But this does not always happen, of course. Sometimes azonal criteria break a 3rd order province directly into landscapes (the most striking example is individual volcanoes or any other volcanic formations of this scale; they are all independent landscapes). The last province is therefore optional unit, existing in some regions and absent in others. The next step after that is landscape area(or simply a landscape), distinguished, as we found out, also on the basis of azonal differences within provinces of the 3rd or 4th order.
If I carefully analyze such zoning, I can see that to divide a province of a higher order into subordinate provinces of lower ranks, it is necessary to use interleaving approach zonal and azonal indicators. Thus, within the main province, a part of the landscape area is allocated; after this, within the formed second-order province, the boundaries of the subzone segment are determined, which will allow us to establish the boundaries of the third-order province. Next, azonal differences are again looked for...
So, the most acceptable for us landscape zoning, suitable for both theory and practice, has not a scattered two-line structure, but a zonal-azonal structure. It looks very simple: 1st order province - 2nd order province - 3rd order province - (4th order province) - landscape area.
This scheme shows that, gradually narrowing the area of zoning, we will descend from a province of the highest order to a landscape region, throughout the entire space of which there are no zonal or azonal differences. Next, all that remains is to establish adequate boundaries of the landscape area. This is precisely the main final practical goal of domestic and foreign landscape science.
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, it decreases Atmosphere pressure, solar radiation becomes more intense, and the air becomes thinner, 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. Vegetable world represented by creeping shrubs and alpine grasses. 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.