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Air masses get their characteristics based
on
The abbreviations used to classify air masses
use the following letters: c, m, T, P, and A.
For each letter, describe its property:
Word
c
continental
m maritime
T Tropical
P Polar
A Arctic
Means
dry
moist
warm
cold
very cold
warm and moist
cold and dry
http://www.classzone.com/books/earth_science/terc/content/visualizations/es2001/es2001page01.cfm?chapter_no=20
cP air mass
mT air mass
dry, cool air
warm, moist air
High Pressure
Area
Low Pressure
Center
cP air mass
mT air mass
dry, cool air
warm, moist air
High Pressure
Area
Low Pressure
Center
cP air mass
mT air mass
dry, cool air
warm, moist air
High Pressure
Area
Low Pressure
Center
cP air mass
mT air mass
dry, cool air
warm, moist air
High Pressure
Area
Low Pressure
Center
cP air mass
mT air mass
dry, cool air
warm, moist air
High Pressure
Area
Low Pressure
Center
Air Masses
Facts:
• Air mass is a region of air with similar properties in the atmosphere
• Air mass typically move from the west to the east in the Northern Hemisphere under the influence of
the prevailing westerlies.
• Example: Hot, dry air from the continental tropical air mass will bring hot, dry weather to Texas when
it moves in from Arizona.
• Masses of air that stay in place for some length of time take on the characteristics of temperature
and humidity from the surface of the earth over which the air stands.
• Masses of air that originate over the ocean tend to be moist
• There are four major types of air masses that affect the weather in the United States:
Maritime Tropical
Maritime Polar
Continental Tropical
Continental Polar
Characteristics
Name
Characteristics
Maritime Tropical
•Forms near the equator.
•Warm, moist air
•Summer- very hot, humid weather
•Winter - rain or snow
Maritime Polar
•Forms over the Pacific Ocean in both the
winter and the summer.
•Summer – cooler temperatures to the
eastern states and fog to California and
other western states.
•Winter- Heavy snow and very cold
temperatures
Continental Tropical
•Forms over land in Mexico.
•Brings dry, hot air to the southwestern
states.
Continental Polar
•Forms over land in northern Canada.
•Winter- very cold temperatures in the
United States
High and Low Pressure Systems
High Pressure Areas (H) – air
tends to sink, winds blow
outward from the center,
turning clockwise. High
pressure area usually brings
clear skies, dry weather, and
gentle winds.
Low Pressure Areas (L) – the
air tends to rise, and winds
spiral in toward the center in
a counterclockwise direction.
The low pressure areas
usually brings cloudy, wet
weather, often with strong,
gusty winds.
High and Low Pressure Systems
• Areas of high pressure can be caused when cool air is sinking
and pressing on the ground. When warm air rises, however, it
causes a region of low pressure.
• Regions of sinking air are called highs, high pressure regions, or
anticyclones. Clear skies and fair, dry weather usually occur in
these regions.
• Regions of rising air are called lows, low pressure regions,
depressions, or cyclones. Clouds, rain, and strong winds often
occur in these regions.