Weather: Chapter 3 NOTES
Section 3.1
A. Types of air masses
NAME: ____________________

air mass:_______________________________________________________________________________
 classified according to ___________________________________________________________________
 during the time the air mass is over an area, __________________________________________________

______________________________________________________________________________________

Classified according to two characteristics: _______________________and _______________________.

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 ___________________
•
Form over the _____________________ and _____________ Ocean and move into the southeastern U.S.
•
Form over the Pacific and affect the ___________________
•
In summer they bring ________,___________ weather and in winter ___________________________
•
Originates in _______________ air  warm air mass (T) (Tropical)
2. Maritime Polar  _________________________ form over the icy cold North Pacific and North Atlantic Oceans
•
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

Form over central and northern Canada and Alaska

In winter continental polar masses bring ___________________________ air to much of North America

___________________ occur with the CP ______________ with the MT
Which one affects us? ____________________________________________________
 moves northward across eastern US
 brings ________________ winters and_____ humid summers with hurricanes and thunderstorms
B. How air masses move
• In the United States, air masses are moved by:
• prevailing _________________________-pushes air masses west to east
• jet stream-bands of _____________________________ 10km above earth’s surface that carry air masses
C. fronts: ____________________________________________________________________
Types of fronts:
1. Warm front


1

 o (symbol)

When a warm humid air mass moves over a cold one showers or light snow will form
2. Cold front


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) ____________________________________________________________
• These play a large part of the weather in the United States and winds spin ____________________
• Cyclones and decreased air pressure are associated with clouds, wind, and precipitation
• Anticlone- ______________________________________, winds __________________, these cause dry, clear weather
Section 3.2 Storms
StormA ___________________________ in the atmosphere
A. thunderstorms: ____________________________________________________________
_________________________________________________________________________
 always accompanied by ____________________, __________________, and usually __________________
2

1. How they form
• formed from cumulonimbus clouds known as_______________________________
•
Form on hot humid afternoons or when _____________________________________ along a cold front.
•
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
• 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: __________________________________________________________________
__________________________________________________________________________
 strongest winds between ____________________________________________
 funnel less than _____________________ across
 always travel with a ______________________________ at speeds ranging from

____________________________________
 funnel is a mixture of __________________ and __________________________

__________________________________- 800 tornadoes occur in the US each year

Tornadoes can occur everywhere in the country but are most likely to occur in tornado alley
 waterspout:____________________________________________________________
 tornados usually occur during _________________ and ___________________ and
 most likely occur in ____________________________
• Tornadoes are ranked on the ________________ by the amount of the danger they cause.
• The scale goes from _______________________
3

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
• 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
• Winds _______________________________ toward the area of lowest pressure at the __________.
• The lower the air pressure at the center of a storm the faster the winds blow toward the center
• Winds are ____________________ in a _______________________ around the center of the storm.
• At the center is a ring of clouds called the ______________________.
• Inside the eyewall is the “_____________” which is characterized by calm air and possible clear skies
• 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
_____________________________________________________________________
4

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: ______________________________________________________________
5

6