Insofar as the effects of altitude on variations in temperature are concerned, the Andes present nearly every type of climatic zone possible, ranging from the hot regions (tierra caliente) to the cold treeless zone of the Alpine meadows (paramos) and farther up to the permanently snow- and ice-covered (glacial) areas. The altitudes of these vertical climatic zones vary with latitude and position. The snow line is highest in southern Peru and northern Chile, where it is about 5,800 meters (19,000 feet). The fact that it is much higher at this latitude (15-20 grades south) than at the equator, where the snow line is at about 4,600 meters (15,000 feet), is attributed to the extreme aridity of the Andes in that part of Peruand Chile.
The distribution and amount of precipitation are largely determined by the air currents and winds that blow over the continent. These in turn are strongly influenced by the surface relief, mainly the Andes. Ocean currents also have their impact on climatic conditions. The cold Peru current that washes the shores of Peru and northern Chile is largely responsible for the extreme aridity and comparatively low temperatures of this part of the continent. This aridity extends into southern Ecuador and approaches nearer to the equator than anywhere else on the earth. The Atacama desert in the coastal region of southern Peru and northern Chile is one of the world's driest deserts (with a average annual rainfall of less than 10 millimeters [0.5 inch]).