Download What is an air mass?

What is an air mass?
A large body of air having nearly
uniform conditions of temperature and
humidity at any given altitude.
• Warm air forms over tropical regions near the equator.
• T- Tropical
•
Cold air forms over polar regions. P- Polar
• Wet air masses form over water
m- maritime
• Dry air masses from over land.
c- continental
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• Moisture content is noted by the first
letter.
m – maritime – wet
c – continental – dry
• Temperature is noted by the second
letter.
P – polar – cool
T – tropical - warm
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• Continental Polar (cP) , “cold and dry”
– closer to the Poles over land-locked regions.
• Continental Tropical (cT), “warm and dry”
– closer to the Tropics over land-locked
regions.
• Maritime Polar (mP), “cold and damp”
– closer to the Poles over water.
• Maritime Tropical (mT), “warm and humid”
– closer to the Tropics over water.
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The advancing edge of a mass of cold or
warm air.
front- the area where two air masses meet
and do not mix (from military language
meaning a battle area where opposing
armies meet to fight)
A front always causes a change in weather because
the air masses that meet do not mix and their
different densities and air pressure produce wind,
clouds and temperature changes.
•
A front is a boundary between air masses.
Four types of fronts and map symbols
The directions that the bumps face is the direction the front is
moving.
1. Cold front
2. Warm front
3. Stationary front
4. Occluded front
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When a fast moving cold air mass runs into a
slow moving warm air mass and the thicker cold
air slides under the lighter warmer air.
• Bring thunderstorms, rain or snow.
• Most tornadoes develop from
thunderstorms on the edge of a cold
front.
• Cold front followed by sunny cooler drier
air.
• http://www.mesoscale.iastate.edu/agron
206/animations/05_cnWfronts.html
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What will happen if the warm air mass
contains only a little water vapor?
• Warm air with little water vapor may be
accompanied by ONLY cloudy skies.
• If there is a lot of water vapor in the warm
air, heavy rain(thunderstorms)or snow may
fall.
When a moving warm air mass collides with a
slowly moving cold air mass and the warm air
moves over the cold air.
If warm air is humid, showers and rain fall along
the front. In winter warm fronts can bring snow.
• If warm air is dry, scattered clouds form.
• Because warm fronts move more slowly
than cold fronts, weather may be more foggy
or rainy for several days.
• After a warm front passes, the weather is
likely to be warm and humid.
http://www.mesoscale.iastate.edu/agron206/animations/05_c
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nWfronts.html
When a cold air mass and warm air mass meet,
but neither air mass has enough force to move the
other air mass.
• Many days of cloudy, wet weather.
http://www.youtube.com/watch?v=VwI1NmESxss
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When a warm air mass is caught between two
cooler air masses and the thicker cold air masses
move underneath the thinner warm air mass and
push it upward.
• Brings cool temperatures with large amounts of
rain or snow
http://www.youtube.com/watch?v=4gc7puH279s
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Cold Front, Warm Front and
Occluded Front Animation
• http://www.phschool.com/atschool/phsciexp/active_art
/weather_fronts/
• http://www.classzone.com/books/earth_science/terc/c
ontent/visualizations/es2002/es2002page01.cfm?chap
ter_no=visualization
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Quiz
1.
Describe a maritime polar (mP) air mass, in terms of
moisture and temperature.
2. What is the name of an air mass that forms over water?
3. What is the name of an air mass that forms over land?
4. What is the name of an air mass that forms in a cold
region?
5. What is the name of an air mass that forms in a warm
region?
6. Describe a continental tropical (cT) air mass, Moisture and
temperature.
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Quiz
7. The boundary between two air masses is called a
______________________.
8. A cold air mass meets and pushes a warm air mass out of
the way. What type of front am I?
9. A warm air mass is trapped between to cold air masses.
What type of front am I?
10. A warm air mass meets and pushes a cold air mass out of
the way. What type of front am I?
11. I am a front that brings drizzly rain and am followed by
warm clear weather. Name me.
12. A cold air mass meets a warm air but neither is very
strong. They are separated and many days of wet ,
cloudy weather occur.
Which types of fronts can you
find on this map?