Question

18. Air masses formed over the Pacific Ocean are moved by prevailing westerlies where they encounter extensive north-south mountain ranges, such as the Sierra Nevadas and the Cascades. Which statement best describes the outcome of this encounter between a landform and an air mass? A) The cool, moist Pacific air heats up as it rises, releasing its precipitation as it passes the tops of the mountains, and this warm, now dry air cools as it descends on the leeward side of the range. B) The warm, moist Pacific air rises and cools, releasing precipitation as it moves up the windward side of the range, and this cool, now dry air mass heats up as it descends on the leeward side of the range. C) The cool, dry Pacific air heats up and picks up moisture from evaporation of the snowcapped peaks of the mountain range, releasing this moisture as precipitation when the air cools while descending on the leeward side of the range. D) These air masses are blocked by the mountain ranges, producing high annual amounts of precipitation on the windward sides of these mountain ranges. E) These air masses remain essentially unchanged in moisture content and temperature as they pass over these mountain ranges.

Answer 1

Answer:

B) The warm, moist Pacific air rises and cools, releasing precipitation as it moves up the windward side of the range, and this cool, now dry air mass heats up as it descends on the leeward side of the range

Explanation:

The air masses that have formed over the Pacific and move toward the western coast of the United States are warm and moist ones. As they reach the coastline they continue into the mainland, but only to come upon a natural barrier, a north-south mountain range. The warm and moist air starts to move up and starts to cool off, and as it does, condensation occurs, thus the windward side of the mountain range gets a lot of precipitation. The cool, but now dry air continuous its movement across the mountain range, and moves down its leeward side. As it moves down on the leeward side it heats up again, so it becomes a warm and dry air mass. This makes the leeward side very dry, so it is no wonder that it is dominated by desert and semi-desert.