Basic characteristics and forming factors of topography in Asian continent

(Asian climate) Under the comprehensive influence of solar radiation, atmospheric circulation and underlying surface, Asia has formed a complex climate.

Basic Features The Asian climate has a strong continental climate, a typical monsoon climate, a complete climate zone and complex climate types.

Asia is the continent with the strongest continental climate in the world. Leng Xia is warm in winter, the temperature in spring is higher than that in autumn, and the temperature in annual range is higher. In winter, the average temperature in 65438+ 10 is lower than 0℃ in two thirds of the areas, and Vilho Yansk-Oymyakon in the northeast of the mainland is the cold pole in the northern hemisphere. The monthly average temperature of 65438+ 10 is -45 ~-50℃, and the absolute minimum temperature is -7 1℃. In summer, the average temperature in July is mostly above 20℃, and the average temperature in the dry desert area of southwest Asia is above 35℃, and the absolute maximum temperature is 55℃. The annual temperature difference is very large, the temperature in cold areas is above 60℃, and the absolute annual temperature difference is as high as 10 1℃. In addition, the uneven seasonal distribution of precipitation in a vast area in a year is also a strong reflection of the nature of the mainland.

Monsoon climate The typical Asian monsoon climate is famous for its wide range, many types and great intensity. The monsoon climate starts from the south of Russian Far East in the north, passes through Japanese archipelago, Korean peninsula and eastern China, and reaches Southeast Asia and South Asia. Monsoon climate types include temperate, subtropical and tropical monsoon climate, and each type can be divided into continental and maritime monsoon climate. In the Asian monsoon region, the prevailing wind direction changes significantly with the seasons. In June, 438+ 10 and July, the variation of dominant wind direction exceeded 120, and the average frequency of dominant wind direction exceeded 40%. In the geography textbooks of universities and middle schools in China, the types of monsoon climate are listed only in Asia.

The Asian continent has all the climatic zones in the world from the equator to the Arctic. At the same time, Asia has all the major climate types in the world except temperate maritime climate types. The vertical belts and climate types of Asian alpine climate are also the most complete. Of all the continents in the world, only North America can be compared with Asia, and all other continents are much inferior.

Forming factors The formation of the main climatic characteristics in Asia is the result of the interaction and comprehensive influence of geographical location, area contour, atmospheric circulation, ocean current and topographic structure.

Location, area and continental shape-specific spatial location and huge area are prerequisites for the formation of Asian climate characteristics. The vast latitude and longitude in this area is not only the basic condition of a complete climate zone and complex climate types, but also leads to the strong continental characteristics of climate and the formation of monsoon climate. The huge area and complete outline, on the one hand, make Asia have a vast inland, expand the continental and dry climate range, and aggravate the degree of continental; On the other hand, it causes a huge thermal difference between the land surface and the vast ocean surface, which leads to the formation of monsoon climate. The western part of mid-latitude Asia borders Europe and is far from the Atlantic Ocean, so it lacks temperate maritime climate.

The fundamental reason for the formation of climate characteristics of atmospheric circulation lies in the state of the atmosphere itself, because the influence of other factors is exerted through atmospheric circulation activities. The atmospheric circulation in Asia is located in all the pressure zones from the polar regions to the equator, the corresponding atmospheric activity centers and the complete planetary wind system in the northern hemisphere. There are four atmospheric activity centers that play a major role in Asian climate: Siberian high on the mainland in winter; Indian depression on the European continent in summer; Aleutian low (subtropical low) and Hawaiian high (subtropical high) exist in the North Pacific all the year round. Siberian high and Aleutian low are very developed in winter. Siberian high almost controls the whole Asian continent, becoming the center of continental anticyclone and the source of dry and cold polar continental air mass. Under its control, the winter wind is strong, blowing from the land to the sea, and the ice ocean air mass invades to the south, resulting in frequent cold waves going south, and the weather is cold, dry and sunny. Aleutian low pressure becomes the confluence point of airflow from the west. Because of the huge pressure gradient between Aleutian low pressure and Siberian high pressure, the wind force in East Asia is particularly strong in winter. In summer, the continental high collapsed and the Indian low formed. Warm and humid air masses in the Pacific Ocean and the Indian Ocean blow from the ocean to the mainland, and the intertropical convergence zone and polar fronts bring abundant rain to the land. The weather is warm, humid and rainy. The different influences of different air masses in winter and summer lead to the formation of annual range and monsoon climate with huge temperature. The climate of the Asian continent has strong continental and typical monsoon characteristics.

Topographic structure The topographical structure with high and low surroundings in central Asia not only aggravates the complexity of climate types, but also promotes the formation of continental climate and typical monsoon climate. The alpine plains and vertical and horizontal Pangdashan belts in Central Asia make the climate types more complicated, and the mountain plateau itself has formed a unique climate type and a complex vertical climate zone. At the same time, the Qinghai-Tibet Plateau and Pamir Plateau in central China become cold sources in winter and heat sources in summer because of their huge heights, which strengthens the influence of winter and summer monsoon and makes it more active and powerful. The plateau also plays an important role in the southwest monsoon of South Asia in summer. Because of the branching effect of the plateau on westerly jet, the south branch jet located on the south side of the Qinghai-Tibet Plateau controls the advance and retreat of the southwest monsoon of South Asia. Only when the south branch jet jumps northward can the southwest monsoon rapidly advance to the whole Indian Peninsula. Therefore, the southwest monsoon in South Asia is sudden. Basins and plateaus surrounded by marginal mountains in the middle have typical continental climate characteristics, thus expanding the scope of continental climate and intensifying its intensity.

There are two currents that have a great influence on Asian climate, one is Kuroshio warm current, and the other is monsoon drift. On the one hand, the strong Kuroshio warm current raises the temperature in the coastal areas of the western Pacific Ocean, on the other hand, it raises the temperature and humidifies the Pacific air mass passing through it, thus strengthening the influence of the East Asian summer monsoon, making it wider and deeper, thus highlighting the characteristics of the East Asian monsoon climate. The monsoon drift in the Indian Ocean also has a great influence on the southwest monsoon in South Asia and Indochina Peninsula. In summer, the monsoon current along the northern coast of the Indian Ocean has basically the same effect on the climate in South Asia and other places as the Kuroshio warm current.

The climate types in Asia are very complicated. Geography textbooks for middle schools are divided into nine climate types, namely, tropical rain forest climate, tropical monsoon climate, tropical desert climate, Mediterranean climate, subtropical monsoon climate, temperate continental climate, temperate monsoon climate, sub-frigid coniferous forest climate, polar climate and alpine climate. Like the division of terrain combination area, climate type area can contain different climate types, and each climate type can be further divided into several subtypes.

The climatic characteristics of various climatic types in Asia are common with those of the same type in other continents (see tropical rain forest climate, etc. ), at the same time, they have particularity in the distribution range and the specific characteristics of climate elements. For example, the tropical rain forest climate in Asia is mainly distributed in Indonesia and other places. Compared with similar areas in South America and Africa, it has maritime and monsoon characteristics. The annual average temperature is 25 ~ 27℃, and the annual variation range is smaller, generally lower than 65438 0.5℃ and the highest is not more than 3℃. The regional distribution of precipitation varies greatly, and even semi-arid areas with annual precipitation of only a few hundred millimeters have appeared, which is not found in similar areas in South America and Africa. Compared with similar areas in North America and Europe, the subtropical, temperate and frigid climate types in Asia are strongly continental.