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Chapter 3 Section 1 Questions #1-25
1. An air mass is a huge body of air that has similar temperature, humidity, and air
pressure throughout it.
2. An air mass can cover millions of square kilometers and be up to 10 kilometers
high.
3.
Maritime Tropical
•Found in the
Location
tropics
•Forms over the
ocean
•Move North
Temperature
Moisture
Content
Pressure
•Hot
Maritime Polar
•Forms over the
North Pacific and
North Atlantic
oceans
Continental
Tropical
Continental
Polar
•Forms over the •Forms over
Southwest and
northern Mexico
Moves
•Affect the West •northeast
central and
northern Canada
and Alaska
coast more
•Cool
•Hot
•Bitter cold
•Dry
•Dry
•Humid
•Humid
Brings hot, dry
•Clear weather
•Brings summer •Brings fog, rain, •weather
(low
showers and
thunderstorms
and cool
temperatures
•Low
•High
precipitation)
•Low
•High
4.
5.
6.
7.
8.
9.
Maritime polar air masses, continental polar air masses, maritime tropical air
masses, and continental tropical air masses all affect the weather in North
America.
Maritime Tropical air masses form over the Pacific Ocean. They bring warm,
humid air to the East coast.
In the summer, maritime tropical air masses bring hot, humid weather, including
summer showers and thunderstorms. In the winter, they often bring heavy rain or
snow.
Maritime polar air masses often bring fog, rain, and cool temperatures to the West
Coast.
Continental tropical air masses usually form in the Southwestern part of the
United States.
Continental tropical air masses generally bring hot, dry weather.
10. Continental polar air masses form over central and northern Canada and Alaska.
They bring clear, cold, dry weather.
11. When Maritime tropical air masses collide with Continental polar air masses, they
form storms, especially during the summer.
12. Air masses in North America are moved by the prevailing westerlies, which
moves air masses in an eastern direction.
13. Air masses don’t mix easily because one is usually less dense than the other. This
is analogous to oil and vinegar.
14. Warm air is less dense than cool air. The less dense cool air will sink underneath
the warm air and form a cold front.
15. A front is an area where two air masses meet and do not mix.
16. Fronts have very variable weather that often includes storms.
17. A typical front is 15-200 kilometers wide and extends up to 10 kilometers high.
18. The four types of fronts are cold fronts, warm fronts, stationary fronts, and
occluded fronts.
19. A cold front is produced when cold air moves underneath warm air, forcing the
latter to rise.
20. If there is a lot of moisture in the warm air in a cold front, heavy rains often occur.
If there is not much moisture in the warm air, there may only be some cloudy
skies.
21. A stationary front is produced when two meeting air masses do not have enough
force to move each other, and face each other in a “stand-off”. These fronts
usually create rain, snow, fog, or clouds.
22. An occluded front is when two cool air masses squeeze a warm air mass between
them, forcing the warm air mass up until it is cut off from the ground. Occluded
fronts may lead to cloudy weather, and eventually rain or snow.
23. A cyclone is a swirling center of low air pressure. Cyclonic winds spin
counterclockwise. As previously mentioned, they associated with low pressure.
24. Cyclones are associated with storms and precipitation.
25. An anticyclone is the opposite of a cyclone: it is a high pressure center of dry air
that spins clockwise outward. They are usually associated with high pressure.