Traditionally, South America also includes some of the nearby islands. Aruba, Bonaire, Curaçao, Trinidad, Tobago, and the federal dependencies of Venezuela sit on the northerly South American continental shelf and are often considered part of the continent. Geo-politically, the island states and overseas territories of the Caribbean are generally grouped as a part or subregion of North America, since they are more distant on the Caribbean Plate, even though San Andres and Providencia are politically part of Colombia and Aves Island is controlled by Venezuela.
Other islands that are included with South America are the Galápagos Islands that belong to Ecuador and Easter Island (in Oceania but belonging to Chile), Robinson Crusoe Island, Chiloé (both Chilean) and Tierra del Fuego (split between Chile and Argentina). In the Atlantic, Brazil owns Fernando de Noronha, Trindade and Martim Vaz, and the Saint Peter and Saint Paul Archipelago, while the Falkland Islands are governed by the United Kingdom, whose sovereignty over the islands is disputed by Argentina. South Georgia and the South Sandwich Islands may be associated with either South America or Antarctica.
South America is home to the world's highest waterfall, Angel Falls in Venezuela; the largest river (by volume), the Amazon River; the longest mountain range, the Andes (whose highest mountain is Aconcagua at 6,962 m [22,841 ft]); the driest place on earth, the Atacama Desert; the largest rainforest, the Amazon Rainforest; the highest capital city, La Paz, Bolivia; the highest commercially navigable lake in the world, Lake Titicaca; and, excluding research stations in Antarctica, the world's southernmost permanently inhabited community, Puerto Toro, Chile.
As part of the Hadley model of atmospheric circulation, the equator is characterised by the ascending branches of separate meridional cells, driven by intense insolation. The vertical convection draws in air from the surrounding atmosphere, known as the trade winds. As these inwards flows of air converge they reduce horizontal wind speed, and as they rise, they form precipitation. The vertical convection also results in a net export of heat and freshwater from the lower atmosphere into the troposphere This system is known as the ITCZ. The location of the ITCZ is centred on the areas of highest insolation, although it is more stationary over the oceans than landmasses.
In the Atlantic region, the ITCZ is clearly developed, and the spatial extent of the ITCZ reaches a minimum close to the equator during the boreal spring (March–May), while extending to a maximum of 10°–15°N in late boreal summer (August). No comprehensive theory for ITCZ formation and spatial variation has been validated, although several hypotheses have been proposed. Some studies advance ideas that describe one or more atmospheric cells over the equator, while others state that the position of the ITCZ depends on Ekman pumping efficiency and moisture availability. Whichever hypothesis best represents the natural system, it is clear that the dynamics of the ITCZ are influenced by several other external climate systems. These include continental convection and equatorially asymmetric sea surface temperature (SST) distribution. This asymmetry is evident in the northward bias of the ITCZ´s location, which is maintained by a positive feedback between wind speed, evaporation and SST.