The assemblage of high mountains ranges in southeastern Arizona is often referred to as the Sky Islands. Rainfall increases and the temperature decreases the higher up you go. At the highest elevations, conditions are wet enough and cool enough to support forests, making each isolated mountain range like a green island in a desert sea. These photographs were taken on the summit of Mt. Lemmon, the highest point in the Santa Catalina Mountains of Arizona. The elevation is over 9,000′ at this location.