Main factors affecting climate in South America

The formation of climate characteristics in South America is mainly influenced by geographical location, topography, ocean currents and atmospheric circulation.

Geographical location and continental shape. This is the main factor that forms the climate characteristics of South America.

First, the location of land and sea. South America borders the Atlantic Ocean and the Pacific Ocean. It is obviously influenced by the ocean, and the range of arid climate zone is small.

Second, the latitude position. South America is roughly between north latitude12 and south latitude 56. The equator crosses the north, and about 2/3 of the area is located in the tropics. It belongs to the subtropical and temperate regions south of the Tropic of Capricorn, and there is no frigid climate except in mountainous areas.

Third, the outline of the mainland is triangular. It is wide in the north and narrow in the south, that is, the low latitude area is wide and the middle latitude area is narrow, which is an important reason why the tropical and subtropical climate area in South America is large and the temperate climate area is small, and the southern continent is fragile to the ocean.

Fourth, the terrain. The influence of topography on the climate in South America is mainly attributed to the Andes. The Andes is the main barrier to the climate in South America, which has a certain blocking effect on the entry of the east and west ocean air masses into the inland. The western edge of the Amazon plain, the west coast of Colombia and the west coast of Chile, south of 40 south latitude, are all covered by topographic precipitation, forming a rainy zone in South America. On the other hand, Patagonia Plateau, which is located on the leeward slope, is difficult to cause rainfall because of the foehn effect caused by the airflow from the west, the climate is arid and semi-arid, and the water vapor disappears. In the east of the Andes, there is a vast area. The plains and plateaus are very conducive to the Atlantic air mass to go deep inland to the west and flow from north to south, resulting in a rainy climate in the vast area on the eastern slope of the Andes. Tropical rain forest and savanna climate types are formed in the north and south of the equator, which are symmetrical in north and south and arranged east and west along the latitude. Third, the Andes is high and steep, and the vertical climate changes obviously. The South Andes has high latitude and abundant precipitation, which is easy to form glaciers.

Fifth, ocean currents. The east and west sides of the South American continent are respectively affected by the Brazilian warm current and the Peruvian cold current.

The Guyana Warm Current, which diverges from the northern part of the east coast, flows northwest along the coast, making the weather near the mouth of the Amazon River and the coastal areas of Guyana and Venezuela hot and humid. The Brazilian warm current from the southern branch of the east coast flows southward to the vicinity of the mouth of the La Plata River, which raises the coastal temperature and causes abundant precipitation.

On the west coast, there is a strong Peruvian cold current flowing northward, almost reaching the equator. The drop of coastal temperature causes inversion and low-level fog, so it is not easy to form convective rain, so the precipitation is insufficient, and the arid Atacama desert is formed between 20-30 degrees south latitude. The west coast north of 6 south latitude is affected by the warm and humid equatorial countercurrent, and the water temperature is high. When this high warm current meets the cold current from Peru, it is easy to cause airflow convergence and form a humid and rainy climate along the northwest coast. In addition, west wind drift bypasses the southern tip of the mainland, giving the west coast of southern Chile a temperate maritime climate.

Sixth, atmospheric circulation. The weather and climate in South America are mainly controlled by four atmospheric activity centers: the North Atlantic subtropical high, the South Atlantic subtropical high, the South Pacific subtropical high and the equatorial low. Their positions move north and south with the change of seasons, which affects the wind direction and air mass activities all over the mainland and forms different climates.

In July, the equatorial low moved northward to near north latitude 10. At this time, the sphere of influence of the two subtropical high in the South Atlantic and the South Pacific has expanded, and it can be connected in the northern inland of Argentina, while it seldom rains in the inland of South America. In June+10, 5438, the South American continent generally warmed up, and the equatorial trough moved south to the south of the equator, separating the two high pressures of the South Atlantic and the South Pacific. The interior of the mainland near the Tropic of Capricorn becomes the center of equatorial low pressure, which is controlled by unstable equatorial ocean air mass, resulting in rainy inland areas of Brazil and Paraguay.

In the vast northern part of eastern South America, northeast winds and southeast winds prevail all the year round, which are mainly controlled by the tropical North Atlantic air mass and the tropical South Atlantic air mass. The northeast wind of the tropical North Atlantic air mass reaches South America, which is unstable, warm and humid and brings abundant precipitation. July is mainly prevalent in the north of the equator. On June+10/October, 5438, it crossed the equator, and the northwest wind reached the parana river Valley, which was hot and humid. The tropical South Atlantic is warm, humid and unstable. In July, the air mass invaded the mainland with the southeast wind, and its influence extended to the vast area south of the equator and east of the Andes. In the south of 20 north latitude, the air mass blows to the southeast coast of Brazil with the northeast trade wind, goes deep inland, reaches the eastern slope of the Andes, and often meets the polar gas invading northward, forming polar front precipitation. In June+10, 5438, the influence of tropical South Atlantic air mass was limited to the eastern coast of Brazil Plateau. The rainy and hot season in the eastern part of the South American continent is mainly related to the advance and retreat of tropical air masses in the north and south with the seasons.

The west of South America, the west coast of 3-30 south latitude, is mainly influenced by the tropical South Pacific air mass. The air mass originated in the tropical high pressure area, and the airflow sank obviously, and then passed through the cold current ocean surface, which was cool and dry. The southeast wind prevailing here is close to the sea breeze, which is not easy to rain, forming a tropical arid climate, which is the least rainy zone in South America. The tropical South Pacific air mass moves northward near the equator, degenerates into a humid and unstable equatorial Pacific air mass, enters the coastal area north of the equator from the southwest wind, and produces abundant precipitation through topographic uplift. On the west coast of 30-37 south latitude, the center of high pressure moves southward in summer, controlled by the subtropical high in the South Pacific, and there is little precipitation. In winter, the center of high pressure moves northward, blowing northwest wind, bringing hot and humid unstable marine air mass, forming a Mediterranean climate with mild and rainy winter and cool and dry summer. On the west coast south of 37 south latitude, westerly winds prevail all the year round. Tropical ocean air mass and polar ocean air meet to produce polar front, and there are many cyclone rainstorms on the front, which makes the western slope of the Andes in southern Chile rainy and rainy. When the polar ocean gas crosses the Andes and reaches Patagonia Plateau, it will burn wind, resulting in a dry and rainy climate.