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Weather: Chapter 3 NOTES
NAME: ____________________
Section 3.1
A. Types of air masses
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air mass:_______________________________________________________________________________
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classified according to ___________________________________________________________________
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during the time the air mass is over an area, __________________________________________________
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______________________________________________________________________________________
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Classified according to two characteristics: _______________________and _______________________.
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The maritime tropical, continental tropical, maritime polar and continental polar influence the weather in
North America
1. Maritime tropical
• humid air mass (m) Originates over the ___________________
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Form over the _____________________ and _____________ Ocean and move into the southeastern U.S.
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Form over the Pacific and affect the ___________________
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In summer they bring ________,___________ weather and in winter ___________________________
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Originates in _______________ air warm air mass (T) (Tropical)
2. Maritime Polar  _________________________ form over the icy cold North Pacific and North Atlantic Oceans
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Affect west coast bringing fog, rain, and cool temperatures
3. Continental tropical  dry air mass (c) Originates over the ______________________
4. Continental Polar cool air mass (P) Originates in________________ air
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Form over central and northern Canada and Alaska
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In winter continental polar masses bring ___________________________ air to much of North America
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___________________ occur with the CP ______________ with the MT
Which one affects us? ____________________________________________________
 moves northward across eastern US
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brings ________________ winters and_____ humid summers with hurricanes and thunderstorms
B. How air masses move
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In the United States, air masses are moved by:
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prevailing _________________________-pushes air masses west to east
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jet stream-bands of _____________________________ 10km above earth’s surface that carry air masses
C. fronts: ____________________________________________________________________
Types of fronts:
1. Warm front
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o
(symbol)
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When a warm humid air mass moves over a cold one showers or light snow will form
2. Cold front
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Since warm air holds more moisture than cool air, once the air reaches the ____________
heavy rain or snow will form.
brings strong storms (_______________) with clear, cooler days once it passes
(symbol)
3. Occluded front
 Two cold masses_______________________ a warm mass
o Warm air rises between them
 brings __________________________ and ________________
o (symbol)
4. Stationary front
 does ________________________
 These can bring many days of clouds and _________________________ until it moves.

(symbol)
D. Cyclones and Anticyclones
• Occur when boundaries between fronts get distorted by physical features or jet streams and air begins to
swirl.
• Cyclone- (L) ____________________________________________________________
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These play a large part of the weather in the United States and winds spin ____________________
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Cyclones and decreased air pressure are associated with clouds, wind, and precipitation
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Anticlone- ______________________________________, winds __________________, these cause dry,
clear weather
Section 3.2 Storms
Storm- A ___________________________ in the atmosphere
A. thunderstorms: ____________________________________________________________
_________________________________________________________________________
 always accompanied by ____________________, __________________, and usually __________________
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1. How they form
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formed from cumulonimbus clouds known as_______________________________
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Form on hot humid afternoons or when _____________________________________ along a cold front.
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Warm, humid air rises ____________________, the ___________________ forming dense thunderheads
All thunderstorms produce ________________________!
lightning:______________________________________________________________________________
_______________________________________________________
-temperature inside lightning flash can reach _____________________________
-at this temperature, ___________________________________________- sudden expansion
makes ______________________!
2. Thunderstorm damage
• Lightning can cause_____________, __________________ tree trunks
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Shock people, cause burns, and heart failure
• __________________________________
3. Thunderstorm safety
• Remain indoors away from phones, electrical appliances, and plumbing fixtures which can conduct
electricity.
• Avoid ____________________________________________________________.
• If you are stuck outside find a _______________ away from trees, poles, and fences and crouch down
B. tornado: __________________________________________________________________
__________________________________________________________________________
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strongest winds between ____________________________________________
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funnel less than _____________________ across
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always travel with a ______________________________ at speeds ranging from

____________________________________
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funnel is a mixture of __________________ and __________________________
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__________________________________- 800 tornadoes occur in the US each year
Tornadoes can occur everywhere in the country but are most likely to occur in tornado alley
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waterspout:____________________________________________________________
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tornados usually occur during _________________ and ___________________ and
most likely occur in ____________________________
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Tornadoes are ranked on the ________________ by the amount of the danger they cause.
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The scale goes from _______________________
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C. Hurricanes
1. Tropical depression: ______________________________________________________________
___________________________________________________________________________
2. Tropical storm: ____________________________________________________________________
______ ___________________________________________________________________________
3. Hurricane: _________________________________________________________________
_________________________________________________________________________
4. How Hurricanes Form
• Form in the _______________, ______________________, and Indian Ocean.
• Forms in the Atlantic north of the equator in August, September, or October
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It begins over warm ocean water as a _____________________ area, or a ________________ disturbance
It draws energy for the warm, humid air at the ocean’s surface
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Winds _______________________________ toward the area of lowest pressure at the __________.
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The lower the air pressure at the center of a storm the faster the winds blow toward the center
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Winds are ____________________ in a _______________________ around the center of the storm.
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At the center is a ring of clouds called the ______________________.
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Inside the eyewall is the “_____________” which is characterized by calm air and possible clear skies
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After the eye passes the storm resumes in the _________________________
5. How Hurricanes Move
• Hurricanes that form in the Atlantic are steered by ______________________________ toward the
Caribbean islands and the south eastern United States
• Once overland they gradually ________________________________.
6. Hurricane damage
 __________________: currents formed when hurricanes pile water up along the shore and blow it inland
 most damaging part of a hurricane because it can wash away _____________, destroy ________________
and ___________________coastlines
Section 3.3 Predicting the Weather
• _______________________________- scientists who study the causes of weather and try to predict it
• Meteorologists interpret weather information from:
• Satellites-__________________________ in the____________________ and take images of earth’s
surface, clouds, storms, and snow cover.
A. Weather Forecasting
Meteorologists interpret weather information from:
1.
2. Weather balloons- stay in the troposphere and lower stratosphere. They measure
_____________________________________________________________________
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3. _______________________ forecasts- instruments gather large amounts of data
4. Weather ______________________ around the world
 radar:_________________________________________________________________
 data is collected and put into a central computer at the __________________________
 data includes:______________________________________________________
 ________________________________________________________________
 makes a ________________________(a copy of the atmosphere in a computer)
maps are made and forecasts are reported to local stations across the country
weather forecasts are issued by the Weather Service at _________________________
forecasts are updated more often ___________________________________________
severe weather watch:___________________________________________________
severe weather warning:_________________________________________________
B. Reading weather maps
Isobar: _______________________________________________________________
Isotherm: ______________________________________________________________
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