Download Name: Ch 24.5 Weather Patterns (pgs 765 – 768) Part 1 AIR MASS

Name:
Ch 24.5 Weather Patterns (pgs 765 – 768)
Part 1
AIR MASSES:
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A body of air that has uniform properties (same temperature and moisture); Air masses take on the
properties of the surfaces they form over (over land = dry; over water = moist; tropical = warm; polar = cold)
Polar air masses move toward the poles; Tropical air masses move toward the poles.
Where air masses with different properties collide  fronts develop
North American Air Masses
Maritime Polar (mP):
Form over the N. Atlantic; brings cool, moist air to the N.West. Responsible for HEAVY PRECIP. In N. West
Continental Polar (cP):
Forms over Canada; brings cold, dry air to the mid-west
Maritime Tropical (mT):
Forms over warm ocean water (The Gulf of Mexico); Brings warm, moist air to the mid-west.
Continental Tropical (cT):
Forms over Mexico; brings hot, dry air to the S.West
Front = A boundary between 2 air masses with contrasting properties; Clouds and precipitation occur along front
boundaries.
Cold Fronts
Describe what happens in terms of the movement of air
masses, during a COLD FRONT.
Draw/ Map out what happens during a COLD
FRONT
Cold air collides with warm air mass; Cold air sinks
UNDER warm air (it’s denser) and warm air is pushed
straight up (aloft). This warm air (which has more room
in it for moisture) condenses to form clouds.
The boundary is steep due to the vertical movement of
warm air.
Cloud Type:
Cumulonimbus
Duration:
½ hour to a few
hours (Rapid)
Associated Weather:
Thunderstorms, winds, heavy precipitation, (tornadoes
and hail); After= cooler temps., drier (less humid), and
clear skies
Weather Map Symbol:
Warm Fronts
Describe what happens in terms of the movement of air
masses, during a WARM FRONT.
Draw/ Map out what happens during a
WARM FRONT
Warm air collides with cold air. Warm air gradually
climbs over the cold air (it’s lighter). Warm air with
moisture condenses and forms clouds.
Cloud Type:
Stratus/ Nimbostratus
Associated Weather:
Steady rain; warmer weather after
Duration:
A day
Weather Map Symbol:
Stationary Fronts
Describe what happens in terms of the movement of air
masses, during a STATIONARY FRONT.
Draw/ Map out what happens during a
STATIONARY FRONT
Cold and warm air push against one another in opposite
directions. Warm air gets pushed aloft; clouds form and
precipitation develop; Front line gets “stuck”
Cloud Type:
Mixed (a variety)
Duration:
DAYS (more than
one)
Associated Weather:
Clouds and rain for a prolonged period of time.
Weather Map Symbol:
Occluded Fronts
Describe what happens in terms of the movement of air
masses, during a OCCLUDED FRONT.
Draw/ Map out what happens during a
OCCLUDED FRONT
One cold air mass collides into a warm front. Warm air
gets pushed aloft and trapped between two cold air
masses. Acts like a cold front.
Cloud Type:
Cumulonimbus
Associated Weather:
See cold front
Duration:
Short (less than a
day)
Weather Map Symbol: