Chapter 20 Test

An air mass is a large body of air with uniform temperature and

• uniform thickness
• uniform moisture
• abundant condensation nuclei.
• low pressure throughout

Which air masses influence much of the weather in North America, especially east of the Rocky Mountains?

• maritime tropical and continental polar
• maritime polar and continental polar
• continental polar and continental tropical
• maritime polar and maritime tropical

What causes most of the precipitation in the eastern two-thirds of the United States?

• maritime polar air masses
• Continental polar air masses
• continental tropical air masses
• maritime tropical air masses

Continental tropical air masses centered over northern Mexico have little influence on weather in the United States because they

• are too high in altitude
• rarely move outside their source region
• only move toward the equator
• never influence weather

An air mass changes

• the weather of the area over which it moves
• the elevation of underlying areas
• the rotation direction of cyclones
• weather that is hundreds of kilometers away from it.

What forms at the boundary between two different air masses of different properties?

• a temperature inversion
• a front
• a hurricane eyewall
• a storm surge

A warm front forms when

• cold air moves up over warmer air.
• a warm air mass meets another air mass of the same temperature
• warm air glides up over colder air
• the temperature in a warm air mass increases

Air masses are classified according to the

• direction in which they move
• speed of their movement
• surface over which they form
• temperature of their air at a certain time

What happens along a stationary front?

• Cold air rises over warm air
• The flow of air is neither toward the warm air mass nor toward the cold air mass.
• Air moves so rapidly upward that hurricanes form
• Wind stops completely

What forms when a cold front overtakes a warm front?

• a warm front
• an occluded front
• a cold front
• a stationary front