Let's examine for a moment the annual rainfall in a mountain range called the Sierra Nevadas, located in California. Read Behavioral Objective #19.

Now one might ask oneself why is it that the rainfall is high on the western side on the western slopes and low on the eastern slopes. Remembering that the prevailing winds are westerly, that is that they are warm and come in from the ocean (A in figure), then they should be heavily laden with moisture. We also know now that as air rises it cools and in cooling is capable of holding less moisture. So as the westerly winds hit the Sierra Nevada Mountain Range, the air rises. As it rises it cools and as it cools it loses its moisture at a distance of about 40 kilometers from the ocean (D in figure).

Now, once it gets over the first major peak at about 45 kilometers from the ocean, the amount of rainfall decreases to a great extent. That is because the air has lost most of its moisture in rising and cooling and dropping its moisture in the valley along the coastal area (C in figure). It then descends and warms in the area of Celma and actually picks up moisture from this area, creating a very dry climate (B in figure). It rises, and at about 110 to 120 kilometers it begins to drop its moisture at Whitewolf. Then it comes to the area of Bighorn Peak and descends as cool, dry air. One would expect to find a very dry region on the eastern side of Bighorn.

Variations in elevation within a continent have no effect on weather patterns.

a. true

b. false