Analyze and interpret quantitative data

Rainfall across a mountain range

Units 1, 4 and 9
10 points
About 23 minutes

You can use a calculator on this question, just like on exam day.

You read values and trends from a data table or described graph, explain what the data show about an environmental problem, and propose and justify a solution. On the exam: Question 2 of 3 in the 70-minute free-response section (Section II is 40% of the exam score).

The question and its sources

Weather stations sit along a line running west to east across a coastal mountain range at about 45° N. The prevailing winds blow from the ocean, which lies to the west, toward the mountains. Table 1 shows long-term averages for five stations.

Table 1: Climate data along a west-to-east line

Station	Distance east of the coast (km)	Elevation (m)	Mean annual precipitation (mm)	Mean annual temperature (°C)
A	0	20	1,500	11
B	40	600	2,300	9
C (mountain crest)	80	1,900	2,800	3
D	120	700	600	9
E	180	400	180	11

Source: Hypothetical data

Suggested time: 23 minutes

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Part (a)

1 point

Identify the station with the greatest mean annual precipitation.

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Part (b)

1 point

Describe the relationship between elevation and precipitation for Stations A, B and C, on the west side of the mountains.

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Part (c)

1 point

Explain why the west side of the mountains receives so much precipitation.

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Part (d)

1 point

Explain why Station E receives so little precipitation.

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Part (e)

1 point

Identify the global wind pattern that brings air from the ocean to these mountains at 45° N.

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Part (f)

1 point

Identify the biome most likely found near Station E.

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Part (g)

1 point

Explain why Station C has the lowest mean annual temperature.

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Part (h)

1 point

Identify the process by which trees in the forests on the western slopes move water from the soil back into the atmosphere.

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Part (i)

1 point

The rivers near Station E are fed mainly by snow that melts in spring and summer near Station C. Explain how warmer winters caused by climate change could reduce the water available in these rivers in late summer.

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Part (j)

1 point

Propose one realistic way that farms near Station E could adapt to a smaller late-summer water supply.

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