Outline of 17.1 Air Masses and Fronts
Name_____________________
Date_______________
Period__________
P1 Air Masses and Fronts
P3 Air Mass - A huge body of air that has similar
__________________________________________ throughout it.
P2 Types of Air Masses
P3 Scientists classify air masses according to two characteristics: 1.______________
and 2.______________.
P3 tropical (air mass) - A _________ air mass that forms in the tropics and has
______ air pressure.
P3 polar (air mass) - A ___________ air mass that forms north of _______ latitude
or south of _______ latitude and
has ______ air pressure.
P3 maritime (air mass) - A _________ air mass that forms over __________.
P3 continental (air mass) - A _________ air mass that forms over ___________.
P3 Four major types of air masses influence the weather in North America:
1.
2.
3.
4.
P3 Maritime Tropical ______________________ air masses form over
____________________.
In summer, maritime tropical air masses usually
____________________________. In winter, a humid air mass can bring heavy rain or
snow.
P3 Maritime Polar ___________________air masses form over the icy cold
______________________________ oceans. Maritime polar air masses affect the
__________________ more than the East Coast. Even in summer, these masses of cool,
humid air often bring ________________________________ to the West Coast.
P3 Continental Tropical ___________________ air masses form only in
________________ over dry areas of the Southwest and northern Mexico. Continental
tropical air masses cover a smaller area than other air masses. They occasionally move
northeast, bringing hot, dry weather to the southern _______________________.
P3 Continental Polar __________________________ air masses form over central
and northern _________________and ___________________. As you would expect,
continental polar air masses bring _________________ air. In ______________,
continental polar air masses bring clear, _________________ air to much of North
America. Air masses that form near the Arctic Circle can bring ____________________
with very low humidity. In summer, _________________ may occur when continental
polar air masses move_____________________________
____________________________________________________.
P2 How Air Masses Move
P3 Maritime polar air masses from the Pacific Ocean are blown onto the _________,
bringing heavy _______________. Continental polar air masses from central
________________ enter the United States between the Rocky Mountains and the Great
Lakes. These ___________________ air masses are then blown ___________, where
they affect the weather of the ________________________________________.
P2 Fronts
P3 The area where the air masses ____________________________ becomes a front.
When air masses meet at a front, the collision often causes
______________________________________.
P3 There are four types of fronts:
1.
2.
3.
4.
P3 Cold Fronts - When a rapidly moving cold air mass runs into a slowly moving
warm air mass, the _______cold air slides ________the lighter warm air. The warm air is
pushed _________. Cold fronts move quickly, so they can cause abrupt weather changes,
including ________________________. After a cold front passes through an area, cool,
dry air moves in, often bringing _____________________________.
P3 Warm Fronts - _______________________________ also accompany warm fronts.
Because warm fronts move more slowly than cold fronts, the weather may be
_______________________ for several days. After a warm front passes through an area,
the weather is likely to be __________________________. In winter, warm fronts bring
snow.
P3 Stationary Fronts Sometimes _____________________________ meet, but
neither one has enough __________to move the other. The two air masses face each
other in a “________________.” In this case, the front is called a stationary front. Where
the warm and cool air meet, water vapor in the warm air condenses into rain, snow, fog,
or clouds. If a stationary front remains stalled over an area, it may bring many days of
______________________________.
P3 Occluded Fronts The most ____________________weather situation occurs at an
occluded front. At an occluded front, a warm air mass is caught between two
___________air masses. The _____________ cool air masses move underneath the less
dense warm air mass and push it ______________________. The two cooler air masses
meet in the middle and __________________. The temperature near the ground becomes
cooler. The warm air mass is __________________, or occluded, from the
________________. As the warm air cools and its water vapor condenses, the weather
may turn cloudy and ____________________________.
P2 Cyclones and Anticyclones
P3 A swirling center of ______________ air pressure is called a cyclone.
Cyclones and decreasing air pressure are associated with storms and
precipitation. Anticyclones are _______-pressure centers of dry air.
Anticyclones are also called “highs”—H on a weather map.