SA - Climate Lesson

Climate

Climate Types and Seasons

South America is a long continent that extends over many latitudes. The length of the continent, varying elevations, and shifts in wind currents cause the region to have extremes in weather and climate. The northern portion of the continent generally has a type A, tropical climate. Highland type H climates follow the Andes chain and exhibit their typical pattern of warmer temperatures at lower elevations and colder temperatures at higher elevations. The Atacama Desert and Patagonia both have type B climates because of a lack of precipitation, which stems from the rain shadow effect of the Andes Mountains. Type C climates dominate in Uruguay, the Pampas region of Argentina, and central Chile. These areas receive precipitation from the area's easterly winds. Since winds are named for the direction from which they originate, easterly winds are winds that start in the east and blow west. Easterlies in this area move moisture from the Atlantic on the eastern coast to the interior region of the continent. With adequate precipitation and a mild type C climate, the Pampas is well suited for both agriculture and human habitation. The Pampas provides some of the most abundant agricultural production on the planet. The western grasslands host large haciendas (prestigious agricultural units) with cattle ranching and livestock production.

 

Amazon Basin 

In the northern interior, on the eastern side of the Andes Mountain ranges, is the huge expanse of the Amazon Basin. A basin is a depression in the surface of the Earth's surface which helps direct the flow or drainage of water. Located between the Equator and the Tropic of Capricorn, tropical and humid with heavy precipitation is generally the climate rule. Rain forests and jungle fauna can be found on the eastern slopes. The Amazon Basin, which is characterized by a type A climate, is the least-densely populated region of South America and is home to isolated Amerindian groups. In the image of the Amazon Basin it is easy to see that the Amazon River flows from the west to the east and ends at its mouth where it flows into the Atlantic Ocean. 

 

High Elevation Lake

As you may recall, elevation influences climate. The surface of Lake Titicaca is at an elevation of about twelve thousand feet above sea level. Usually at such high elevations, the temperature dips below freezing and restricts agriculture. This, however, is not the case around Lake Titicaca. Since water heats and cools more slowly than land, the large lake acts as a solar energy collector by absorbing energy from the sun during the day and giving off that energy in the form of heat during the night. With abundant fresh water and the ability to grow food and catch fish, people continue to live around and on Lake Titicaca and maintain a subsistence lifestyle.

 

Rain Shadow Effect

When mountains are high they have the potential to change where precipitation falls. This is true because as air rises in elevation the water or moisture in the air cools and condenses. Eventually this process leads to precipitation on the windward side of the mountain. The dry air that is left proceeds over the mountain and causes deserts and other dry regions to form. The Andes Mountains and predominant wind patterns of the southern latitudes give Chile its diverse climatic regions.

 

Northern Chile

The prevailing winds reach northern Chile from the east and hit the Andes Mountain chain, some of the highest mountains on the continent. The height of the Andes causes any moisture from rain clouds to precipitate on the eastern slopes. The western side of the Andes Mountains in Northern Chile receive little or absolutely no precipitation, causing extreme desert conditions in the Atacama region of Chile.

 

Southern Chile and Argentina

Southern Chile receives a large amount of rainfall because the prevailing winds at that latitude come from the west and carry the moisture they have picked up from traveling over the Pacific Ocean. As the air rises up the western slopes of the Andes, the air then precipitates to release its moisture. Since the Andes are not as high in elevation in southern Argentina, the region called Patagonia does receive some precipitation on the rain shadow side. Even with precipitation reaching the eastern side of the mountains, it is not enough to prevent the area from having arid and dry conditions.

 

RESOURCES IN THIS MODULE ARE OPEN EDUCATIONAL RESOURCES (OER) OR CREATED BY GAVS UNLESS OTHERWISE NOTED. SOME IMAGES USED UNDER SUBSCRIPTION.