Air Masses and Fronts

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Air Masses and Fronts
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Air Masses

• All of the air within an air mass have similar
  temperature and humidity levels.
• An air mass takes the characteristics of the land
  or water that it forms over

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Air Masses

• The temperature of an air mass depends on where
  it forms
• Polar - P - forms over the poles
• Tropical - forms over the tropics

• Cold or cool air

• Warm or hot air

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Air Masses

• The amount of moisture in the air mass depends on
  where it forms
• Maritime - m - Forms over oceans
• Continental - c - Forms over land

• High moisture content

• Low moisture content

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Air Masses

• Depending on where the air mass forms, it can be
  one of four types
• 1. Maritime Tropical (mT)
• 2. Maritime Polar (mP)
• 3. Continental Tropical (cT)
• 4. Continental Polar (cP)

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cP
mP
mP
mT
mT
cT
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Fronts

• The area where air masses meet

Air masses collide, and dont tend to mix
because of differing densities.
Front
cP
mT
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Fronts
Air spins around low pressure in a
counter-clockwise rotation.
2. Warm Front
L
1. Cold Front
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Air flowing down from Canada replaces existing
warm air to create a cold front.
L
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Air flowing up from the South replaces cooler air
to create a warm front.
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Warm Front

• A warm front is created by warm air (less dense)
  glides over existing cold air, eventually
  replacing it. Warm fronts usually yield long
  steady precipitation.

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Cold Front A cold front is created as cold air
(more dense) plows through warm air. Cold fronts
are fast moving and can produce violent storms.
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A cP air mass moving through an area creating a
fast moving cold front
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Stationary Fronts
Stationary fronts occur as colliding air masses
fail to advance. The may result in on / off
precipitation for several days.
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Air masses colliding in the mid-section of the
U.S. create favorable conditions for tornado
development.
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Tornado alley is the name given to the region in
the U.S. that sees more tornadoes than anywhere
in the world.