Geographical singularities of the Patagonian climate

Abstract

Patagonia (36°–56° S) is fully located in the belt of the southern hemisphere west winds, and because no other continental landmass stands in the way of the westerlies at these latitudes, the constancy and strength of these winds become decisive climatic factors. The westerly flow is fairly perpendicular to the Andean Range so as to create very sharp differences between both sides, mainly in precipitation. Thus, windward (Pacific side) mountainous wet Patagonia contrasts abruptly with leeward (Atlantic side) dry plateaus. This contrast is smoother north-ward, beyond the Patagonian limits, as the westerly flux slowly gives way to the subtropical anticyclonic prevalence. Because of this, both flanks of the Andes are equally dry north of parallel 32° S. Central Chile shows a clear Mediterranean climate, but the dry season shrinks dramatically south of 36° S until it disappears south of 40° S. Further south, on the Chilean flank of the Andes, the Patagonia climate clearly becomes an example of a cool temperate windward coastal area in midlatitudes. On the opposite side of the mountains, and because of their very presence, the climate of east Patagonia fits poorly in global classifications. Elsewhere on Earth, the eastern side of a continent at equivalent latitude would present a cool temperate climate, with a noted degree of continental and moderate rainfall. Instead, a windyrain-shadowed semidesert, strongly conditioned by the narrowness of the continent (<700 km) and the influence of the sub-Antarctic Ocean, spreads over extra-Andean Patagonia. The uniqueness of Patagonian current climate stems from large-scaled geographic factors that will be analyzed in this chapter.