The Argentine Republic is a large country with an area exceeding 2.6 million sq km/1 million sq mi, about one-third the size of the United States and almost as large as India. It extends between 22° and 55°S and occupies the southern portion of South America, east of the crest-line of the Andes, which form its border with Chile. On the north it is bordered by Bolivia and Paraguay and on the east by Brazil and Uruguay. From the estuary of the Rio de la Plata to the southern tip of Tierra del Fuego its coastline is on the Atlantic Ocean.
The centre and east of the country are mostly flat and not very high; but the west has much mountainous country rising to the higher peaks of the Andes. These include Aconcagua, the highest mountain in South America, at 7,000 m/22,800 ft; north of here the range rarely falls below 3,000 m/10,000 ft. The northern Andes in Argentina have surprisingly low precipitation, so that the snowline may be as high as 6,000 m/20,000 ft.
The southern Andes have much more precipitation, similar to that on the western slopes in southern Chile, so that here there are glaciers and permanent snowfields. The high Andean region of Argentina is very sparsely populated.
Because of these great differences of latitude and altitude there are many differences of weather and climate within Argentina. The effect of the southern Andes is to produce a sharp contrast between the very cloudy and wet climate of southern Chile and the dry, almost desert conditions of Argentine Patagonia in the south, which is sheltered from the persistent westerly winds which blow in these latitudes. Argentina can be divided into four broad climatic regions: east central Argentina or the Pampas, the northeastern interior, western Argentina, and Patagonia or southern Argentina, to which should be added the distinctive mountain climate of the high Andes.
East Central Argentina or the Pampas
This area has a climate similar to that of Uruguay. It is well outside the tropics and has an adequate rainfall of between 500 mm/20 in and 1,000 mm/40 in per year. Winters are mild and summers warm, with more rainfall during the summer months. The rain falls on a few days so that wet, changeable weather is not very frequent and rain is often heavy. The annual rainfall decreases westwards and southwards and this is illustrated by the tables for Buenos Aires and Bahía Blanca in the south of the Pampas, and Victorica in the west. The weather here is moderately sunny with an average of four to five hours sunshine a day in winter and eight to nine hours in summer. The region does not often experience extremes of heat or cold. Frost may occur in most winter months but is not prolonged or severe. The climate is generally healthy and pleasant. This is the most important agricultural region of the country and occasional drought is the main economic hazard.
The Northeastern Interior
This region has a warmer climate than the Pampas and towards the north, where it includes part of the Gran Chaco region described for Paraguay, has a tropical or near-tropical climate (see the table for Asunción). Rainfall decreases westwards and the table for Santiago del Estero is representative of the drier western part. Temperatures remain quite high around the year. The combination of heat and humidity may at times be uncomfortable in the summer months as this is the cloudier, wetter season. For much of the time, however, conditions are sunny and dry. Occasional cold spells in winter may bring temperatures near or below freezing for a few hours but the winters are generally mild or even warm.
Western Argentina, including the northern Andes, is a dry region. Even on the higher mountains snowfall is light and the dryness matches that of northern Chile on the western side of the Andes. The eastern slopes and foothills of the Andes as far south as 35°S are a semi-arid region and the lowlands are a virtual desert. In many places the annual rainfall is below 250 mm/10 in and very unreliable. Droughts in this area are frequent and often prolonged. Rainfall is more frequent during the summer months, which are generally hot and very sunny. Sunshine hours average as much as ten hours a day in summer and between seven and eight in winter. The table for Mendoza is representative of this region.
Patagonia or Southern Argentina
The southern third of Argentina, south of Bahía Blanca, is a rather dry region compared with the very wet region of southern Chile on the other side of the Andes. In terms of temperature and changeable weather the region has a typical cool, temperate climate, rather similar to that of the British Isles; but the dryness is unusual for such a high latitude. The table for Sarmiento is representative of the coast and much of the interior. Towards the west, in the foothills of the Andes, rainfall is greater as cloud spills over from the western side of the range. The dryness of the eastern side continues to the cooler southern districts around the Strait of Magellan. The table for Punta Arenas, in southern Chile, is representative of the extreme south, where summers are distinctly cool. Winters are long with frequent frost and snow but, because of the influence of the ocean, the cold is never very severe or prolonged.
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