Idea for Use in the Classroom

Begin by having students open MapMaker Interactive and select the “Terrain” base map to identify mountainous areas on Earth (shown in darker relief), such as the Rocky Mountains of North America, the Himalayas of Asia, or the Andes of South America. Direct students to focus on a single mountainous area and then overlay the Precipitation and Rainfall layer at about 30 percent transparency. Ask: How does precipitation vary on either side of the mountain range? Students should find that one side of the mountain range tends to receive more precipitation than the other. Prompt students to brainstorm possible reasons for these patterns.

To emphasize the effect of mountains on precipitation patterns, direct students to focus on the Atacama Desert, which exists along the western edge of northern Chile. Have students compare the amount of precipitation and rainfall in this area of Chile to the other side of the Andes in Bolivia and Argentina. Using this information, students can suggest the direction in which atmospheric wind patterns likely move across this region of South America and then perform research to determine if they are correct.

As a class, research the difference between leeward and windward sides of mountains and apply this information to the Andes. To extend learning, students can compare the precipitation and wind patterns of the Andes to those of the Cascade Mountains in Oregon and Washington. Conclude by having students discuss how geographic factors can impact precipitation patterns and thus the availability of freshwater within surrounding ecosystems.

Noun

all weather conditions for a given location over a period of time.

Noun

study of places and the relationships between people and their environments.

leeward
Adjective

downwind, or facing away from prevailing winds.

Noun

all forms in which water falls to Earth from the atmosphere.

Noun

dry land on the side of a mountain facing away from prevailing winds.

rain shadow desert
Noun

arid area found on the leeward side of mountain ranges.

topographic
Adjective

having to do with maps based on natural and human-made features of the land, and marked by contour lines showing elevation.

windward
Adjective

facing or toward the wind.