Download Air Masses and Fronts

Air Masses and Fronts
Air Mass
• A large body of air
• At least 1,000 miles
•
•
across
Uniform temperature
and humidity
Flows as one unit
Air Mass
• Four main types
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–
–
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Cold (polar)
Warm (tropical)
Water (maritime)
Land (continental)
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–
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Maritime tropical
Maritime polar
continental tropical
Continental polar
• Combinations
Fronts
• When two air masses
meet
Fronts
• Warm front—When a
warm air mass
overrides a cold area,
it rises slowly,
creating
nimbostratus,
altostratus or
cirrostratus clouds.
This can produce light
precipitation.
Fronts
• Cold front—When a
cold air mass
overrides a warm
area, it pushes the
warm air up forcefully,
creating cumulus and
cumulonimbus clouds.
Cold fronts often
produce
thunderstorms and
very bad weather.
Fronts
• Stationary front—
When a cold air mass
and warm air mass
flow side-by-side, and
neither mass invades
the other, weather
can by unpredictable.
It most often
resembles a warm
front, with light rain if
any precipitation
occurs.
Fronts
• Occluded front—When
two cold air masses
trap a warm air mass,
they push the warm
air up. The boundary
that exists is between
two similar air
masses: cold and
cooler air. Clouds and
precipitation are
likely.
Mid-latitude Cyclones
• Severe storms that
develop between
tropical and polar air
masses in midlatitude regions
around low-pressure
centers.