Air masses

1
Air masses

• Characteristics
• Large body of _____with similar ____________,
  ___________, humidity, __________.
• Move and affect a large portion of a continent

2
Air masses

• Source region the area where an air mass
  acquires its properties
• Two criteria used to classify an air mass
• 1) By the latitude of the source region
• Polar (P)
• High ______________
• Cold
• Tropical (T)
• Low _______________
• Warm

3
Air masses

• 2) By the nature of the surface in the source
  region
• Continental (c)
• Form over _________
• Likely to be dry
• Maritime (m)
• Form over __________
• Humid air

4
Air masses

• Four basic types of air masses
• _______________ ____________(cP)
• _______________ ____________ (cT)
• _______________ ____________ (mP)
• _______________ ____________ (mT)

5
Fronts

• ________________ that separates air masses of
  different ___________.
• Air masses retain their identities
• Warmer, less dense air forced to move ___.
• Cooler, denser air acts as wedge, moving
  _____________.

6
Types of Fronts

• Warm front
• Warm air replaces cooler air
• Shown on a map by a line with semicircles
• Clouds become lower as the front nears
• Moves into an area _________.
• Light-to-moderate precipitation

7
Warm front
8
Types of Fronts

• Cold front
• Cold air replaces warm air
• Shown on a map by a line with triangles
• Twice as steep as warm fronts
• Advances _________ than a warm front.
• Associated weather is more violent than a warm
  front
• Intensity of precipitation is greater
• Duration of precipitation is shorter

9
Types of Fronts

• Cold front
• Weather behind the front is dominated by
• Cold air mass
• Subsiding air
• Clearing conditions

10
Cold front
11
Types of Fronts

• Stationary front
• Flow of air on both sides of the front is
  parallel to the line of the front
• Position of the front _______ _______ move.
• Occluded front
• Active cold front overtakes a warm front
• Cold air wedges the warm air upward
• Weather is often ___________ .
• Precipitation is associated with warm air being
  forced aloft

12
Formation of an occluded front