Figure 33 Giraffes inhabit the grasslands near Mount Kilimanjaro, Tanzania. Although Mount Kilimanjaro is near the equator, its top is covered by snow all year because of its high altitude.
Figure 34 A mountain range can form a barrier to the movement of humid air.
Applying Concepts Where does the heaviest rainfall occur?
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Not all locations at the same latitude have similar temperatures. As you've learned, temperature decreases as altitude increases. As Figure 33 shows, areas that are high above sea level, such as parts of East Africa, have lower average temperatures than areas at the same latitude that are closer to sea level.
Factors Affecting Precipitation
Like temperature, a region's pattern of precipitation depends on several factors. 
Factors that affect a region's precipitation include its latitude, the distribution of air pressure systems and global winds, and the existence of a mountain barrier. Recall that the maximum amount of water vapor that the air can hold is greater at high temperatures than at low temperatures. Thus, the warm air over the equator usually contains more moisture than the cold air over the poles. As a result, precipitation is generally higher near the equator than near the poles.
A desert is an extremely dry region, receiving less than 25 centimeters of rain per year. Deserts may be hot or cold. Many deserts receive almost no rain because they are located within high-pressure belts. A series of deserts can be found around 30° north and south of the equator.
The direction of prevailing winds can play an important role in the amount of precipitation a region receives. For example, a coastal region where the wind generally blows from the ocean onto land will receive a large amount of precipitation. However, if prevailing winds blow from the land toward the ocean, the region will receive much less precipitation.
The very dry high plains of western North America are the result of a mountain barrier. The moist air from the Pacific Ocean loses its moisture as it rises over the mountains of the West, as shown in Figure 34. As the air rises, it cools and its water vapor condenses. Rain or snow falls on the ocean side of the mountains. The air that reaches the far side of the mountains is much drier.
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