The atmosphere gets most of its heat from touching the warm face of the earth, The lowest layer of warm, turbulent air tends to rise and lose its heat aloft. The higher we go the cooler it gets, and on a average the temperature drops more than three degrees with every 1,000 feet above sea level.

The peaks of the Andes and other lofty mountains in equatorial regions are way up where the air is always below freezing. Their eternal snow caps are glaciers, renewed with snowfalls. Slowly they slide down the slopes to warmer levels where their edges melt in glacial streams.