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Air Masses
An air mass is just a large body of air that is all the same
temperature, density, and air pressure. Air masses can form over either
water or land. There are five kinds of air masses found in the United
States. When one of these air masses moves over an area, it can bring
a change in the weather. To understand how the weather will change,
you need to know the different kinds of air masses.
Air masses that form over land are called continental air masses.
Where they form tells you a little about the air’s temperature and
moisture content. A continental tropical air mass has warm, dry air.
They form over the Sonora Desert in the southwest part of the U.S.
They are abbreviated as cT. They usually bring fair, dry weather.
Continental air masses that form over Canada and Alaska are called
continental polar. They are abbreviated cP. They bring cooler, dryer air
to the south. In the winter, they bring freezing temperatures.
If an air mass forms over an ocean, it is called a maritime mass. If
it formed over the warm waters of the Caribbean Sea or the Gulf of
Mexico, it is called tropical. It would be abbreviated as mT. It would
bring warm, humid weather with it. You might expect it to rain if one of
these air masses moved into your area.
Maritime polar air masses form over the cold waters of the North
Pacific. Abbreviated mP, they bring heavy rain in the winter to the west
coast.
An arctic air mass is like a continental polar air mass. It is much
colder, though. Arctic air masses form very far north; above 60º
latitude where the air is very cold. In the winter, they bring severely
cold temperatures.
Air Masses Questions
Matching: Match the name of the air mass to the places it forms.
1._____ continental polar (cP)
a. North Pacific ocean
2._____ continental tropical (cT)
b. Alaska or Canada, above 60º lat.
3._____ arctic
c. Alaska or Canada, below 60º lat.
4._____ maritime polar (mP)
d. Caribbean Sea or Gulf of Mexico
5._____ maritime tropical (mT)
e. Sonora Desert
Fill in the blank:
1. Air masses that form over land are called __________________.
2. Air masses that form over water are called_________________.
3. Air masses that form at very high latitudes (above 60º) are called
__________________.
4. Maritime air masses usually bring ____________________.
5. Two kinds of air masses are alike except that one is colder. They
are ________________ and ____________________.