2. Air Masses and Fronts -
Vocabulary
Air Mass – A huge body of air that has similar
temperature, pressure, and humidity throughout.
Tropical – A warm air mass that forms in the tropics
and has low air pressure.
Polar – A cold air mass that forms north of 50° north
latitude or south of 50° south latitude and has high
air pressure.
Maritime – A humid air mass that forms over
oceans.
Continental – A dry air mass that forms over land.
3. Air Masses and Fronts -
Vocabulary
Front – The area where air masses meet
and do not mix
Occluded – Cut off, as the warm air mass at
an occluded front is cut off from the ground
by cooler air beneath it.
Cyclone – A swirling center of low air
pressure.
Anticyclone –A high-pressure center of dry
air.
4. Air Masses and Fronts – Main
Ideas
Four major types of air masses influence the
weather in North America: maritime tropical,
continental tropical, maritime polar,
continental polar.
When air masses collide, they form four
types of fronts: cold fronts, warm fronts,
stationary fronts, and occluded fronts.
Cyclones and decreasing air pressure are
associated with storms and precipitation.
5. Air Masses and Fronts –
Review Questions
What two main characteristics are used to
classify air masses?
What is a front? Name and describe four
types of fronts.
What is a cyclone? What type of weather
does it bring?
Why do maritime polar air masses have
more effect on the West Coast than the East
Coast?
6. Storms - Vocabulary
Storm – A violent disturbance in the atmosphere
Lightning – A sudden spark, or energy discharge,
caused when electrical charges jump between parts
of a cloud or between a cloud and the ground.
Tornado – A rapidly whirling, funnel-shaped cloud
that reaches down from a storm cloud to touch
Earth’s surface, usually leaving a destructive path.
Hurricane – A tropical storm that has winds of 119
kilometers per hour or higher; typically about 600
kilometers across.
7. Storms - Vocabulary
Storm surge – A dome of water that
sweeps across the coast where a
hurricane lands.
Evacuate – To move away temporarily.
8. Storms – Main Ideas
Thunderstorms and tornadoes form within
large cumulonimbus clouds. During
thunderstorms, avoid touching metal
objects.
A hurricane begins over warm water as a
low-pressure area. If you hear a hurricane
warning and are told to evacuate, leave the
area immediately.
Snow falls when humid air cools below 0°C.
If you are caught in a snowstorm, try to find
shelter from the wind.
9. Storms – Review Questions
What weather conditions are most likely to
cause thunderstorms and tornadoes?
What is the most common path for the
hurricanes that strike the United States?
What safety precautions should you take if
a tornado is predicted in your area? If a
hurricane is predicted?
10. Floods - Vocabulary
Flash flood – A sudden, violent flood
that occurs within a few hours, or even
minutes, of a heavy rainstorm.
11. Floods – Main Ideas
Floods occur when so much water
pours into a stream or river that it
overflows its banks on either side of
the channel.
The first rule of flood safety: Move to
higher ground and stay away from
flood waters.
12. Floods – Review Questions
How can precipitation cause flooding?
What should you do to stay safe during
a flood?
What is the difference between a flood
watch and a flood warning?
Name three tools that supply
information used in forecasting floods
and providing flood information.
13. Predicting the Weather -
Vocabulary
Meteorologist – Scientist who study the
causes of weather and try to predict it.
El Niño – an event that occurs every two to
seven years in the Pacific Ocean, during
which winds sift and push warm water
toward the coast of South America; it can
cause dramatic climate changes.
Isobar – Lines on a map joining places that
have the same air pressure.
Isotherm – Lines on a map joining places
that have the same temperature.
14. Predicting the Weather – Main
Ideas
Meteorologists interpret weather information
from local weather observers, instruments
carried by balloons, satellites, and weather
stations around the world.
Changes in weather technology have
occurred in two areas: gathering weather
data and using computers to make
forecasts.
Standard symbols on weather maps show
fronts, areas of high and low pressure, types
of precipitation, and temperatures.
15. Predicting the Weather –
Review Questions
What kinds of technology do meteorologists
use to help predict the weather?
Name at least three types of information you
could get from a weather map of your area.
What lines on a weather map connect points
that have the same temperature?
