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N91
AIR MASSES
Earth Science
Instructions: Highlight, underline, or circle the answers to the below questions. Next
to each answer, write the number of the corresponding question.
1. What is an air mass?
2.
How do scientists classiff air masses?
a
J.
What do the characteristics of an air mass depend on?
4.
Where do the following air masses form: Tropical, Polar, Maritime, and Continental?
Listen to the evening news in the winter and you may hear a
weather forecast like this:'A huge mass of Arstic air is moving
our \ray' bringing free[rytemPeratures:' Today's weather can
be influenced by air from thousands of kilometers awayperhaps from Canada or the Pacific Ocean' A huge body of air
that has similar temPerature, humiditf, and air Pressure at any
given height is called an airmass. A single air mass may spread
onet *illions of square kilometers and be uP to 10 kilometers deep.
Types of Air Masses
to tvvo characterScientists classifi ait masses according
majortvpes of
ir,t*;.il;;"tit. *a humiditv' Four
America:
North
in
;;;ssel iono"""" the weather tropical' maritime
-"titi-"
tropical, continental
oolar. and continental -of
Polar'
* at mass depend on the
content of the region over
moisture
and
temperatures
*niifr tn. air mass forms' Remember that temPerature
pressure'
nit pt.ssure. Cold, dense air has atrigher
'*Th;;;acteristics
"*.* warm, less dense air has a lower Pressure'
while
and
ir.pd, ;*"r*, air masses form in the tropicsform
masses
air
cold'
or
Polar,
have low air pressure.
of 50" north latitude and south of
50o south
lati-
"ottn
tude. Polar air masses have high air pressure' on
Whether an air mass is humid or dry depends
air
whether it forms over water or land' Maritime
so
oceans'
the
from
evaPorates
Water
masses form over oceans.
form
masses
air
Continental
humid'
the air can become very
to large
fl"a.-Continental'air masses have less alposure
conti"".t
of moisture from bodies of water' Therefore'
"-o"rr.t"
nental air masses
are drier than maritime air masses'
Air Masses that Affect North America
Maritime Polar
Maritime Tropical
What characteristics do these air masses
What characteristics do these air masses
have?
have?
Where do these air masses form?
Where do these air masses form?
What kind of weather do these air masses
bring?
What kind of weather do these air masses
bring?
Which areas of the United States do these
air masses affect?
Which areas of the United States do these
Draw how these
air masses affect
the United States:
Draw how these
air masses affect
the United States:
air masses affect?
Continentt I Tropical
Continental Polar
What characteristics do these air masses
have?
What characteristics do these air masses
have?
Where do these air r nasses form?
Where do these air masses form?
Whatkind of weatht :r do these air masses
What kind of weather do these air masses
bring?
bring?
nited States do these
Which areas of the
air masses affect?
Which areas of the United States do these
air masses affect?
Draw how these
air masses affect
the United States:
Draw how these
air masses affect
the United States:
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