Weather Patterns and Storms - Ch20

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

• a 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.

Which of the following characteristics is NOT true of cold fronts?

• Violent weather such as thunderstorms occur along them.

• The temperature drops as they pass.

• Clear weather usually follows them.

• They move more slowly than warm fronts.

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.