What type of air mass forms over northern Mexico and affects the southwestern United States?

Continental tropical air mass.

What are warm, wet air masses that affect the west coast of the United States called?

Maritime tropical air masses.

What type of air affects the northern United States in winter and is cold and dry?

Continental polar air masses.

What is the result when a rapidly moving cold air mass runs into a slowly moving warm air mass?

Cold front.

What is formed when a warm air mass and a cold air mass meet with no movement?

Stationary front.

What is formed when a faster moving warm air mass collides with a cold air mass?

Warm front.

What type of clouds do thunderstorms form within?

Large cumulonimbus clouds.

What is a funnel-shaped cloud that touches Earth's surface called?

Tornado.

What wind speed must a tropical storm reach to be classified as a hurricane?

At least 119 kilometers/hour (74mph).

What is the eye of a hurricane characterized by?

It is calm.

How does lake-effect snow occur?

Cold air blows over large lakes, picks up moisture, and then moves over land.

What is usually the most dangerous aspect of a snowstorm?

Cold blowing wind.

What most often causes flooding?

Melting snow and spring rains.

What can produce flash floods?

Sudden storms, broken dams, and ice jams.

What should you do to protect yourself near flood waters?

Move to higher ground.

What should water from flooded sources be before drinking?

Boiled.

What has improved weather forecasting recently?

Computer technology.

What are people who study weather and try to predict it called?

Meteorologists.

Where does El Niño form?

Tropical Pacific Ocean.

How often does an El Niño event typically occur?

Every 2-7 years.

What do isobars on a map represent?

Lines joining places with the same air pressure.

What does a line with red half circles on a weather map indicate?

A warm front.

What connects places on a weather map that have the same temperature?

Isotherms.

What may bring many days of rain?

A stationary front.

What should a person avoid touching during a thunderstorm?

Objects made of metal.

What may people be asked to do before a hurricane occurs?

Evacuate or leave their homes.

What connects lines of equal pressure on a map?

Isobars.

What storms form within large cumulonimbus clouds?

Thunderstorms.

What should you do to be safe from the cold during a blizzard?

Find shelter from the wind and cover exposed parts of the body.

What occurs when a river overflows its banks?

A flood.

What are sudden, violent floods that occur within hours or minutes called?

Flash floods.

What do lines on a weather map with triangles and half-circles show?

The type and direction of movement of fronts.

What does air mass A represent in terms of temperature and humidity?

Cold and wet/humid.

What does air mass F represent in terms of temperature and humidity?

Warm and wet/humid.

Which air masses are likely to bring dry weather to the United States?

B & E.

How are air masses classified as continental or maritime and as polar or tropical?

A: Maritime Polar; B: Continental Polar; C: Maritime Polar; D: Maritime Tropical; E: Continental Tropical; F: Maritime Tropical.

Where is snow more likely at location W or location X due to lake effect snow?

Location X.

Where is a tornado more likely to occur, location Y or Z?

Location Y.