Air Masses and Fronts
Chapter 16 section 2
S6E4.b – Relate unequal heating of
land and water surfaces to form large
global wind systems and weather.
S6E4.c – Relate how moisture
evaporating from the oceans affects
the weather patterns and the
weather events such as hurricanes.
Air Masses
Air mass – is a large body of air where
temperature and moisture content are
similar throughout.
 Moisture content and temp are determined
by the area over which the air mass forms
called source regions.
 Represented on maps by two-letter
symbols; first letter – moisture content,
second letter - temperature
Cold Air Masses (3)

Continental polar
(cP)-

air mass forms over
northern Canada,
brings extremely cold
winter weather to the
US, summer brings
cool, dry weather.
Cold Air Masses


Maritime polar (mP)
(Forms in 2 places)

Forms over the North
Pacific Ocean; cool and
very wet, brings rain
and snow to the Pacific
Coast in winter, foggy
weather in summer.
Forms over the North
Atlantic Ocean brings in
cool, cloudy weather
and precipitation to
New England in the
winter, cool weather in
the summer.
Warm Air Masses (4)

Maritime tropical (mT)

Develops over warm
areas in the Pacific
Ocean and Atlantic
Ocean. Winter they
bring mild, often
cloudy weather.
Summer, hot and
humid weather,
hurricanes, and
thunderstorms.
Warm Air Masses

Continental tropical
(cT)

Forms over the
deserts of northern
Mexico and the
southwestern United
States; moves
northward and brings
clear , dry, and hot
weather.
Air Masses of North America
Review
1.
2.
What are the major
air masses that
influence the
weather in the
United States?
What is one source
region of a maritime
polar air mass?
1.
2.
Continental polar,
maritime polar,
maritime tropical,
and continental
tropical.
The North Pacific
and the North
Atlantic Oceans.
Review
3. Why does the Pacific
Coast have cool, wet
winters and warm, dry
summers?
3. Cool, wet winters are
affected by a maritime
polar air mass.
Summers are affected
by a dry continental
air mass.