Download front - Issaquah Connect

4 Major Types of Air Masses
Affect US Weather
 Maritime tropical- warm and humid air
 Maritime polar- cool and humid air
 Continental tropical- warm and dry air
 Continental polar- cool and dry air
2
Major Air Masses Affecting
US Weather
http://www.geog.ucsb.edu/~joel/g110_w05/lecture_notes/midlat_surface/agburt09_01.jpg
3
YOU TRY IT! Label the Air Masses
4
When two air masses that
have different properties
meet, they do not easily
mix. A boundary called a
front forms between the
two air masses.
5
Boundaries in Air
• A front is the boundary between two air
masses of different densities.
• In the United States, air masses usually
travel west to east.
• As they move, they meet up with other air
masses.
• Individual air masses do not usually mix.
• Instead, a front forms between them.
• Fronts bring changes in the weather.
6
Cold Fronts
• A cold front is the forward edge of a cold
air mass.
• A cold front is formed when a cold air
mass pushes its way underneath a warm
air mass.
• Can form tall cumulonimubs clouds and
precipitation.
• Brief, heavy storms are likely.
7
A cold front forms when cold air pushes
warm air upward.
8
Warm Fronts
• A warm front is the forward edge of a warm air
mass.
• A warm front forms when a warm air mass pushes
over a cooler air mass.
• The warm air slowly moves up and over the cold air.
• As the warm air rises, it cools.
• Produces cloud-covered skies.
• Often brings many hours of steady rain or snow.
9
Warm Front
10
Stationary Fronts
• Sometimes cold and
warm air masses stay
put for a while.
• Clouds may cover the
sky for days.
11