Download Chapter 20 Worksheets

Chapter 20.1
Air Masses and Weather
While You Read 20.1
• What is an air mass and how does it typically
gain its specific characteristics?
An air mass is a large body of air with similar
characteristics throughout. It gains these
characteristics from the air temperature and
humidity in its place of origin. As it moves, it
takes these characteristics with it, but may
also change in response to new
surroundings.
After You Read
In the organizer below, record the characteristics of the
five main types of air masses.
Place of
origin
Direction of
movement
Weather
Impact
1. cA
Arctic Polar
Regions
Southerly
Extreme cold
Little precipitation
2. mP
High latitude
oceans
Southerly and
Fog, clouds,
toward U.S. center precipitation
3. cP
Inland Alaska and
Canada
Southeasterly
Cold, little precip,
except lake effect
snow
4. cT
Southern deserts
Northerly
Heat waves,
drought
5. mT
Warm tropical
oceans
Northerly and
toward the U.S.
center
Heat, humidity,
thunderstorms
20.2 Fronts and Lows
While You Read
1.
Define and explain the stage at which a low-pressure system
produces the most intense storm.
A low-pressure system creates the most intense storm
after about 12-24 hours, when its warm front
becomes occluded between cool air pushing
northward in front of it and cold air pushing
southward behind it.
2.
In your science notebook, revise your definition of a front.
Use information you find about each key term to help you
expand your definition.
1.Warm front forms when warm air advances on cooler
air; gradual slope as warm air rises slowly; large
areas of precipitation, lasting several days.
2.Cold front forms when cold air advances on warmer
air; steep slope as cold air sinks quickly, any
precipitation Is brief; brings thunderstorms or cool
breezes, depending on humidity in displaced warm
air
3. Occluded front forms when warm front is trapped
between two cold fronts often causes cloudiness,
precipitation.
4. Stationary front forms when front doesn’t move;
warmer air rises within the front, causing
precipitation; heavy storms due to stationary
precipitation.
20.3 Thunderstorms and Tornadoes:
While You Read
Thunderstorms develop:
1.
2.
3.
A) in moist, stable air
B) in warming temps of afternoon
C) at frontal boundaries or when warm air hits other
obstacles
This can cause
2. Lightning
4. Tornadoes
Which is
Which are
3. An electrical discharge when
Positive and negative charges in a
Thundercloud collide and form a spark.
5. Violently rotating
columns
of air that touch
the ground
20.3 After You Read
List and describe some ways that meteorologists predict tornadoes
and warn people of the related danger.
Meteorologists use conventional radar to map
precipitation in an area and Doppler radar to identify
the wind directions within a storm. Doppler radar can
identify the mesocyclone wind movements often
associated with tornadoes. Tornado watches and
warnings advise people of the possible tornado
danger at any given time.
20.4 Hurricanes and winter
storms: While You Read
1.
2.
3.
4.
5.
6.
Mild atmospheric disturbance over tropical ocean
Humid air rises
Air cools and condenses, releasing heat
Cycle of air movement continues
Coriolis effect rotates air in the storm
Storm moves according to global wind patterns
20.4 Hurricanes and winter
storms: While You Read
7.
a) storm surge
b) damaging winds
c) heavy rain
d) inland flooding
e) heavy surf
8. Storm weakens over cooler land or water
After You Read
List and describe the characteristics of a blizzard.
A blizzard is a special kind of mid-latitude low
pressure system. It has winds over
56km/hour, temperatures below -7ºC, and
falling or blowing snow that reduces visibility.
20.5 Forecasting Weather
While You Read
1.
2.
3.
4.
5.
6.
Visible and infrared pictures
Temperature, humidity, pressure
Surface observations
Station models
Surface weather map
Knowledge of local weather patterns
20.5 After You Read
Explain why it is important that weather station models and surface
maps be readable to meteorologists in any country.
In this way, meteorologists around the world
can share data, and forecast farther ahead
and provide necessary warnings of bad
weather.