Influence of relief. Terrain interaction
Terrain significantly influences the climate of many land areas, since exposure differences of slopes and barriers (in relation to the prevailing air flows) the role of mountain ranges causes various local differences in distribution air currents, air temperature, cloudiness, precipitation.
The basis of the surface of Eurasia is made up of large and small, closed and semi-closed basins. They create conditions for the formation of climates with well-defined continental features. Therefore, the degree of continental climate of the continent is very high. There are high annual amplitudes temperatures, small amounts of precipitation, the regime of which is often dominated by the summer maximum. Features of continentality appear in basins, even those located near the ocean, in the zone of western air transport temperate latitudes. On the territory of the Upper Rhine Basin, annual temperature amplitudes reach 20-25 0 C, and the amount of precipitation does not exceed 500-600 mm with a summer maximum, while in neighboring areas (Black Forest, Vosges) features typical of marine climates prevail.
The climate-forming role of the orographic structure of the relief in the territory is manifested differently North America. The presence of mountain barriers along the western and eastern outskirts – main feature mainland for that matter. In the center of the continent there is a strip of plains. Above them between the mountain rises, even in winter time a pressure trough is formed (a band of low atmospheric pressure). Air is drawn into it from high and low latitudes, fronts form, cyclones form. This weakens the degree of continentality of inland climates.
The barrier role of mountains has a certain influence on climates. Submeridionally elongated mountain ranges in temperate latitudes contribute to the transformation of air moving from the oceans to land. The Cordilleras, the Scandinavian Mountains, and a section of the Andes in the temperate zone significantly change the nature of the impact of western transport on the climates of territories located to the east of these mountain systems. Passing through mountain ranges, the hydrocarbon warms up and dries out, transforming from marine to continental.
The sublatitudinal mountain belt of Eurasia – the Alpine-Himalayan – is located closer to the southern coasts. The mountain systems of this belt play a barrier role for the equatorial monsoons in the south and southeast and for the meridional transport of magmas in the rest of the territory. Meridional transport is also hampered by mountain systems Central Asia and southern Siberia, also elongated sublatitudinally.
Significant differences in the climates of equatorial-tropical latitudes southern continents, largely depend on different structures the surfaces of these continents. In the east of Australia there is the mountain system of the Great Dividing Range, on the eastern slopes of which a large amount of precipitation falls, brought by mTVm with trade winds, passing through the ridges and, descending into the internal, highly heated plains of Australia, they heat up, move away from the saturation point and precipitation becomes impossible. This is one of the the most important reasons dryness of Australia. Mainland South America, on the contrary, is open east winds and Atlantic waters, saturated with moisture, freely enter the mainland. Their movement to the west is associated with a gradual decrease in precipitation. Along the Pacific coast of South America is located one of the longest and highest mountain systems of the continents - the Andes. The Andes in equatorial-tropical latitudes “lock” Vm and do not release them from the mainland without “squeezing” them to the end (Vm have to rise to a greater altitude - average height Andes 5000 m, at the same time their cooling occurs when the temperature drops to the dew point, the condensation process begins and orographic rains fall). Therefore, South America is the most wet continent planets.
Relief has a great influence on climate. A particularly significant influence on climate is exerted by large forms relief - mountains. Mountains trap air masses coming from cold places, such as the north. In this case, mountain ranges can serve as a boundary separating areas with different climatic conditions.
Thus, the climatic conditions of areas lying north of Caucasus Mountains, will be different than the southern ones.
Mountain ranges located perpendicular to the prevailing moist winds create favorable conditions for condensation of water vapor. Because of this, more precipitation falls on slopes facing the humid winds than on the opposite slopes.
The entire Black Sea coastline protected by the Caucasus Mountains is wet and warm winter. Average in Sochi winter temperature about 7°, in Batumi - about 8°. The amount of precipitation to the south is increasing, and Batumi, as you know, belongs to the rainiest areas in Russia. Colchis Lowland - Rioni Valley, surrounded on three sides mountain ranges and open from the west to the humid sea winds, is very different high humidity And high temperatures. Tea, bamboo, tangerines, lemons, rice and other subtropical plants are successfully cultivated here.
On the other side of the Caucasus ridge, in the area Mineralnye Vody, frosts in winter reach -30°, in Pyatigorsk average temperature January -5°. Even the relatively low Ural Mountains influence the distribution of precipitation: the amount of precipitation per western slope significantly higher than in the east; the average precipitation in Ufa is 599 mm, in Chelyabinsk - 366 mm. They are located approximately at the same latitude.
Big influence The Himalayas influence the distribution of precipitation. Southwestern is very warm and wet monsoon leaves on the southern slopes of the Himalayan mountains such an amount of moisture that is not observed almost anywhere else globe. Cherrapunji station is included in all textbooks as a place with maximum number precipitation: on average, 11,640 mm falls here annually, of which 10,150 fall from May to September.
From November to February there is only 130 mm of precipitation - a typical expression monsoon climate. On the coast of the Bay of Bengal, through which the monsoon penetrates into northeastern India, the amount of precipitation is only about 200 mm; it does not even approximately reach the same magnitude as in Cherrapunji, where showers are caused by the rise of moist air masses along the slopes of the ridge. In 1861, Cherrapunji received 22,900 mm of rainfall, of which 9,300 mm fell in July alone; On June 14, 1876, 1036 mm fell in one day! If this water did not drain and evaporate, it would give a layer more than 1 m deep. This daily amount of rain is approximately twice the normal annual rainfall for Moscow.
As altitude increases, a decrease in temperature occurs due to distance from the main source of heating - earth's surface- and increased heat loss by radiation! Closer to the earth's surface, denser, moist and dusty layers remain, blocking radiation emission.
The Cordilleras, Himalayas, and Karakoram most often exceed 4000 m and are in an area of permanent frost. On the slope of Elbrus, on the “Shelter of Nine”, for example, the average temperature in summer is about 0°, on the highest peak of Communism about -11°, on the peak of Chomolungma in the Himalayas about -28°. In winter, of course, it is even much colder there and, most importantly, they are dominated by strong winds and storms.
Relief is the basis of the landscape. It is the interface above which the external forces of the Earth act, and below which - internal forces. From the height of the territory above sea level, from the nature of the surface, its slope and steepness, from geological structure and underlying rocks depends on what soils are formed, what plants and animals live, how they are distributed atmospheric phenomena over these places.
As an element of the landscape, relief has strong influence on everyone else, but he himself depends on them. However, we can say that relief is the most resistant component of the landscape to change. When the relief changes over time, other components of the landscape associated with it and the landscape itself change.
RELIEF AND CLIMATE
The formation of relief is influenced by climate. The redistribution of the amount of heat and moisture, in turn, significantly depends on the relief. Therefore, in the same climatic zones and different landscapes are formed, dissimilar plant and animal communities emerge.
SLOPE EXPOSURE
South-facing slopes always heat up more than northern ones. It melts faster here in the spring, the surface of the slopes is better moistened, flowers bloom faster, and snow does not fall here longer in the fall and winter. These same slopes in the mountains are the most dangerous for avalanches.
Huge mountain ranges can be an obstacle on the way. For example, wet air c cannot overcome the wall of the Himalayas. “unload” all their moisture at their feet in the form of showers. The record amount of precipitation on the planet falls here. Evergreens grow on the windward slopes of the mountains rainforests. All territories beyond the Himalaya range are thus, as it were, in its shadow. Here are the spaces of Tibet with high mountain deserts, with harsh and extremely dry conditions with winter temperatures down to -50 ° C, although these territories are located in the subtropics by their location. Their height and dryness lead to the fact that the surface not protected by vegetation is subject to significant frost weathering. transports masses of loose soil and forms sand hills.
RELIEF, VEGETATION AND ANIMAL WORLD
Animals living in areas with different topography differ significantly: on the plains and in the mountains, in the lowlands and on the hills. Animals' adaptation helps them survive. For example, on the plains, the one who survives is the one who is able to quickly move across vast territories, is able to travel long distances for food, or is good at hiding from enemies.
Landscape plant communities are often tied to certain forms relief. When the topography changes, for example during landslides or landslides, eruptions or karst sinkholes, vegetation has to re-adapt to new living conditions.
RELIEF AND SOILS
Soil formation is associated with the characteristics of the topography, bedrock and loose sediments. Therefore, different soils are formed on different elements of the relief, differing in permeability to water, steepness, etc. The history of relief development can change over time: depressions appear in place of hills, and a dry ravine appears in place of a winding river. In this case, according to the remainders fossil soil it is possible to determine how the relief was formed in ancient times.
One of the important factors in the formation of relief is water, a derivative of climate. Relief influences the nutrition and flow of rivers, determining their direction. So, if the territory is flat, with shallow valleys, then conditions for swamping arise and landscapes appear on the plains.
RELIEF IS AN ELEMENT OF THE HUMAN ENVIRONMENT
Relief is not the most dependent landscape element on human activity, such as vegetation, climate or soil. But for several centuries human activity has become a landscape-forming factor. Man can not only change the shape of the relief, but also create new, anthropogenic forms. Human buildings are so grandiose (primarily this applies to big cities), that they even bend.
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RELIEF AND CLIMATE
Climate is one of the most important factors relief formation. The relationship between climate and topography is very diverse. Climate determines the nature and intensity of weathering processes, and it also determines to a large extent the nature of denudation, since the “set” and degree of intensity of acting exogenous forces depend on it. As mentioned above, in different climatic conditions Nor does such a property of rocks as their resistance to external forces remain constant. Therefore, in different climatic conditions, different, often very specific, forms of relief arise (see Part III). Differences in shapes are observed even when external forces act on homogeneous geological structures composed of lithologically similar rocks.
Climate influences the processes of relief formation both directly and indirectly, through other components of the natural environment: the hydrosphere, soil and vegetation cover, etc.
Thus, the emergence of the coastal deserts of the Namib (South-West Africa) and Atacama (South America) is due to the cold weather passing here. sea currents, whose existence western shores Africa and South America is a consequence of the general circulation of the atmosphere. Here, therefore, climate influences the relief through the hydrosphere.
Significant Impact relief formation processes are influenced by vegetation cover, which, by the way, is itself a function of climate. Thus, surface runoff in conditions of closed vegetation cover in the presence of well-developed turf or forest litter sharply weakens or is completely extinguished even on steep slopes. Surfaces with sparse vegetation cover or lacking it become easily vulnerable to erosion processes, and in the case of dry loose weathering products, also to wind activity.
Direct and indirect connections between climate and relief are the reason for the subordination of exogenous relief to a certain extent to climatic zonation. This distinguishes it from endogenous relief, the formation of which is not subject to zonation. Therefore, the relief of endogenous origin is called azonal.
At the beginning of this century, the German scientist A. Penck made an attempt to classify climates according to their relief-forming role. He identified three main types of climates: 1) nival (Latin nivalis - snowy), 2) humid (rich in liquid precipitation) and 3) arid (dry and hot). Subsequently, this classification was supplemented and detailed. Below is an abbreviated classification of climates according to their role in relief formation according to I. S. Shchukin, who distinguishes between nival, polar, humid and arid types of climates.
Nival climate. All seasons of the year are characterized by precipitation in solid form and in quantities greater than can melt and evaporate during the short and cold summer. The accumulation of snow leads to the formation of snowfields and glaciers. The main relief-forming factors in a nival climate are snow and ice in the form of moving glaciers. In places not covered with snow or ice, processes of physical (mainly frost) weathering develop intensively. Permafrost has a significant influence on relief formation. Nival climates are characteristic of high latitudes (Antarctica, Greenland, islands of the Arctic Ocean) and the top parts of mountains rising above the snow line.
Polar climate, or the climate of areas where permafrost occurs. This type of climate is characterized by long and severe winters, short and cool summer, significant cloudiness, low precipitation, low intensity solar radiation. All these conditions favor the emergence or preservation of previously formed (under even more severe climatic conditions) permafrost. The presence of the latter determines a number of processes characteristic of the polar climate and creating a number of specific forms of meso- and microrelief described in Chapter. 17.
One of the most important factors of denudation in areas of permafrost distribution is solifluction (Latin solum - soil, ground; fluxus - flow) - slow current thawing waterlogged soils and dispersed soils on the surface of the frozen base. At low temperatures In polar climates, even in summer, physical, predominantly frost weathering predominates. The polar climate is characteristic mainly of the tundra zone. In continental conditions it also extends to more southern regions landscape areas (Eastern Siberia and etc.).
Humid climate. In areas with a humid climate, the amount of precipitation that falls during the year is more than can evaporate and seep into the soil. Excess atmospheric water flows down either in the form of small streams over the entire surface of the slopes, causing planar denudation, or in the form of permanent or temporary linear watercourses (streams, rivers), as a result of the activity of which various erosional relief forms are formed - valleys, beams, ravines, etc. Erosion forms are dominant in humid climates. Thanks to a large number heat and moisture in areas with a humid climate, chemical weathering processes occur intensively. In the presence of soluble rocks, karst processes.
There are three humid climate zones on the globe: two of them are located in the temperate latitudes of the Northern and Southern Hemispheres, the third gravitates towards equatorial belt.
Arid climate. It is characterized by low precipitation, very dry air, intense evaporation, many times higher than the annual amount of precipitation, and little cloudiness. Vegetation cover under these conditions, it turns out to be very rarefied or completely absent, and physical, mainly temperature, weathering occurs intensively.
Erosion activity in an arid climate is weakened, and wind becomes the main relief-forming agent. The dryness of weathering products facilitates their rapid removal not only from open surfaces, but also from rock cracks. As a result, more resistant rocks are prepared, and, as a consequence, in an arid climate, the clearest reflection of geological structures in the relief is observed.
Areas with an arid climate are located on continents mainly between 20 and 30° northern and south latitude. Arid climates are also observed outside the mentioned latitudes, where their formation is associated with the size and orographic features of the continents. Yes, within East Asia The arid zone in the Northern Hemisphere extends to almost 50° N. w.
It should be noted that the transition from one morphological type climate to another is carried out gradually, as a result of which the change in the dominant processes of exogenous relief formation also occurs gradually.
At the border of two climates, relief forms are formed that are characteristic of both types and also acquire a number of specific features. Such transition zones are classified into special morphological subtypes of climates. The existence of transition zones is also facilitated by the instability of the boundaries between climatic zones throughout the year: following the movement of the sun, they shift either towards the poles or towards the equator.
The study of the spatial distribution of genetic types of Relief of exogenous origin and comparing them with modern climatic conditions of the corresponding regions shows that the relationship between climate and relief described above is violated in a number of places. Thus, in the northern half of Europe, landforms created by glacier activity are widespread, although at present there are no glaciers here, and this region is located in the humid climate zone of temperate latitudes. This “discrepancy” is explained by the fact that in the recent past (during glaciations), a significant part of Northern Europe was covered with ice and, therefore, was located in the nival climate zone. Here, a relief of glacial origin that has survived to this day, but found itself in climatic conditions that are now unusual for it, was formed. This relief was called relic(Latin relictus - abandoned). The study of this relief is of great scientific interest. Relic forms relief, along with sedimentary rocks and the remains of plant and animal organisms contained in them, make it possible to judge the paleoclimates of individual regions and the position of climatic zones at certain stages in the history of the Earth's development. The preservation of relict forms is due to the fact that the relief changes its appearance due to climate change much more slowly than is typical for the soil cover and especially the flora and fauna.
Consequently, the appearance of the exogenous relief of a number of regions of the earth's surface is determined not only by the characteristics of the modern climate, but also by the climate of past geological eras.
Climate is one of the most important factors in relief formation. The relationships between climate and relief are varied:
1. Climate determines the nature and intensity of weathering processes;
2. Determines the nature of denudation, since the “set” and degree of intensity of acting exogenous forces depend on it.
In different climatic conditions, such a property of rocks as their resistance to external forces does not remain constant. Therefore, different, often very specific, relief forms appear in different climatic zones. Climate influences the processes of relief formation both directly and indirectly through other components natural environment climatic zonation. This distinguishes it from endogenous relief, the formation of which is not subject to zonation. Therefore, the relief of endogenous origin is called.
azonal
1. At the beginning of the 20th century, the German scientist A. Penck made an attempt to classify climates according to their relief-forming role. He identified 3 main types of climates:
2. nival (lat. Niyalis - snowy);
3. humid (lat. Humidis - wet);
arid (Latin: Aridus – dry).
Subsequently, this classification was supplemented and detailed. Next, we will consider the classification of climates according to their role in relief formation.. 1. Nival climate
All seasons of the year are characterized by precipitation in solid form and in quantities greater than can evaporate during the short and cold summer. The accumulation of snow leads to the formation of snowfields and glaciers. Thus, the main relief-forming factors in a nival climate are snow and ice in the form of moving glaciers. In places not covered with snow and ice, processes of physical (mainly frost) weathering develop intensively. Permafrost has a significant influence on relief formation. Nival climate is typical polar regions
: Antarctica, Greenland, islands of the Arctic Ocean and the peaks of mountains rising above the snow line. 2. Climate subarctic belt and sharply continental regions. temperate zone The subarctic climate is formed on the northern edges of Eurasia and North America. It is characterized by long and harsh winters, cold summers, a small amount precipitation (less than 300 mm). Sharp continental climate temperate zone especially pronounced in Eastern Siberia. Typical for it are: large seasonal temperature fluctuations, little cloudiness and low
relative humidity. In areas with a humid climate, the amount of precipitation that falls during the year is more than can evaporate and seep into the soil. Excess atmospheric moisture flows either in the form of small streams over the entire surface of the slopes, causing planar denudation, or in the form of permanent or temporary linear watercourses (streams, rivers), as a result of which the formation of various forms erosional relief - ravines, gullies, river valleys. Erosion forms are dominant in humid climate conditions . In areas with a humid climate, chemical weathering processes occur intensively. If there are soluble rocks, karst processes are intensively developing . There are 3 humid climate zones on the globe: two of them are located in the temperate latitudes of the northern and southern hemispheres, the third gravitates towards the equatorial belt. This type of climate (by the nature of its relief-forming role) should include monsoon regions subtropics and temperate latitudes (eastern and southeastern edges of Eurasia and North America).
4. Arid climate. It is characterized by low precipitation, very dry air and high evaporation, many times higher than the annual amount of precipitation, and little cloudiness. The vegetation cover under these conditions turns out to be very sparse or absent altogether, and physical, mainly temperature, weathering occurs intensively. Erosion activity in an arid climate is weakened, and wind becomes the main relief-forming agent. The dryness of weathering products facilitates their rapid removal not only from open surfaces, but also from rock cracks. As a result, more resistant rocks are prepared, and as a result, in an arid climate, the clearest reflection of geological structures in the relief is observed. Areas with an arid climate are located on the continents mainly between 20 and 30º northern and southern latitudes, with the exception of those parts of the continents where a monsoon climate is developed within these latitudes.
Arid climates are also observed outside the above latitudes, where their formation is determined by the size and orographic features of the continents. Thus, within Central Asia, the arid zone in the northern hemisphere penetrates almost to 50º N latitude. An arid climate with accompanying processes of relief formation is developed along Africa and South America - in latitudes unusual for it, which is due to the coastal cold sea currents passing here ( Namib Desert and Atacama).
5. At the junction of two climate types, relief forms are formed that are characteristic of both types and also acquire a number of specific features. Such transitional zones are classified into special morphological climate subtypes .
6. The study of the spatial distribution of genetic types of relief of exogenous origin and comparing them with modern climatic conditions of the corresponding regions shows that the relationship between climate and relief described above is violated in a number of places. Thus, in the northern half of Europe, landforms created by glacier activity are widespread, although at present there are no glaciers here, and this region is located in the humid climate zone of temperate latitudes. relic This is explained by the fact that in the recent past (during glaciations), a significant part of northern Europe was covered with ice and, therefore, was located in the nival climate zone. Here, a relief of glacial origin that has survived to this day, but found itself in climatic conditions that are now unusual for it, was formed. This relief was called