Peruvian Current

ORIGINATING IN THE frigid waters off the coast of Antarctica, the Peruvian Current moves north along the western coast of South America. When in reaches the continental shelf along South America, the current rises, carrying cold water with it to the surface of the Pacific Ocean. The prevailing winds of the South Pacific and Earths rotation cause the Peruvian Current to rotate; the Coriolis Force causes the current to rotate clockwise. The Peruvian Current extends 125 mi. (201 km.) west from the coast of South America. As the current moves north through the coasts of Chile, Peru and Ecuador it splits into two masses where Cabo Blanco, Peru, meets the Gulf of Guyanquil. The main current turns west into the Pacific Ocean, while the remnant of the current moves along the coast of Ecuador. At that point, the second branch of the Peruvian Current also moves west, rejoining the main current near the Galapagos Islands.

The Peruvian Current is also known as the Humboldt Current after its discoverer, German scientist Alexander von Humboldt. The Peruvian Current affects Peru year round, and moderates the climate of Chile in spring and summer, when it displaces a subtropical center of high pressure. Ordinarily the coast of Chile would warm in spring and summer, but the onset of the Peruvian Current diminishes temperatures and forestalls any rain. The air that accompanies the current is dry, keeping the coast arid. Some weather stations along the Chilean coast have never recorded rainfall; others areas receive considerably less than 1 in. (2.5 cm.) of rain per year. The northern coast of Peru is dry from May to November, and receives light rain between December and April. Even though some areas of the coast are humid, rain nevertheless does not fall. The arid coastline supports few plants, and so sunlight either is absorbed by the land or radiates back into space. Rainfall along the southern coast of Ecuador totals 12 in. (30 cm.) per year, noindent though in the north, where the Peruvian Current weakens, rainfall increases tenfold. Some regions receive as many as 197 in. (500 cm.) of rain per year.

With Peru located near the equator, one might expect warm temperatures, but the Peruvian Current keeps the coast of Peru at 75 degrees F (24 degrees C). Lima varies from 70 degrees F (21 degrees C) in January and 50 degrees F (10 degrees C) in June. Areas inland from the current often record temperatures of 90 degrees F (32 degrees C). Periodically El Nino disrupts the Peruvian Current, bringing warm water from the tropical Pacific to the western coast of South America. Temperatures along the coast rise and rain falls on some parts of the coast.

As it cools the western coast of South America, the Peruvian Current creates a climate of unremitting dry-ness. Temperatures are moderate but rainfall is scant. Seabirds inhabit the western coast of South America but humans have only colonized the region in small numbers. The deserts of Chile are especially forbidding. Without rain, the land ceases to sustain plant life. In contrast to the sterility of the desert, life abounds in the ocean. The Peruvian Current carries plankton to the surface of the ocean, and fish feed on it in large numbers. Seabirds in turn feed on the fish. Despite creating an arid climate, the Peruvian Current teems with life.

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