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How does an air mass form?
When a body of air remains
stationary over a region for some
time or as air moves over a large
uniform region.
What are four types of weather fronts
and their characteristics?
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Warm
Cold
Stationary
Occluded
What type of weather do cyclones and
anticyclones bring?
• Cyclones bring clouds, precipitation and
storms.
• Anticyclones have clear skies, little
precipitation, and calm conditions.
How do thunderstorms form?
• Strong rising movements of air within the
cumulonimbus cloud. This occurs when two
air masses collide.
How does a tornado form?
• When a vertical column of rotating air
develops an updraft of a thunderstorm.
Why do continental polar masses have
different properties than tropical
maritime air masses?
• Continental polar masses form in cold dry
regions.
• Tropical maritime masses form in humid,
warm regions.
• Properties are dependent of the region in
which they form.
Using static electricity, explain how a
lightening strike forms.
• Lightening is an example of static discharge.
During a thunderstorm, air swirls violently,
and a difference develops and lightening
strikes. Static electricity is the same way.
Charges are collected and a difference builds
up between the charges until a spark occurs.
Where is tornado alley?
Tornado alley
When do most tornados occur?
• March through May is when the weather
conditions are most probable for tornados.
A Hurricane
What are cold fronts?
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A cold air front is the place where a cold air mass replaces a warm air mass.
These different air masses do not mix because they have different temperatures
and densities. As the cold front develops the warm air behind the front is pushed
up over the top of the cold air. This happens because the warm air is lighter than
the cold air. You often see clouds forming at a cold front. This is because as the
warm air rises, it cools and condenses. Clouds are masses of cool condensed air.
Air mass
• Large body of air that has a fairly uniform
physical properties
Front
• Sharply defined boundary that forms of unlike
air masses
Cold Front
• When cold air overtakes warm air
Warm front
• When warm air overtakes cold air
Stationary front
• When two unlike air masses form a boundary
and do not move
Occluded front
• When a warm air mass is stuck between two
cooler air masses
Cyclone
• Weather system with a center of low air
pressure.
Anticyclone
• A weather system with a swirling center of
high air pressure.
Thunderstorm
• A small weather system that includes thunder
and lighting. It’s usually followed by strong
winds and heavy rain or hail.
Lightning
• A sudden electrical discharge in the
atmosphere.
Thunder
• The sound produced by rapidly expanding air
along the path of a lightning discharge.
Tornado
• A small but intense windstorm that takes the
form of a rotating column of air that touches
the ground. A common name for this is a
Twister.