Download air masses and fronts

AIR MASSES AND
FRONTS
By: Ms. Nail
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An air mass is a large body of air that develops over a particular region.
• Warm air forms over tropical regions near the equator. Has low air pressure.
T- Tropical
•
Cold air forms over polar regions. Has high air pressure
P- Polar
•
Wet air masses form over oceans.
m- maritime
•
Dry air masses from over land.
c- continental
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• Moisture content is noted by the first
letter.
m – maritime – wet
c – continental – dry
• Temperature is noted by the second
letter.
P – polar – cool
T – tropical - warm
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4
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• mP- maritime polar
• cP – continental polar
• mT – maritime tropical
• cT – continental tropical
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•
A front is a boundary between air
masses.
•
Four types of fronts and map symbols
1.
2.
3.
4.
Cold front
Warm front
Occluded front
Stationary front
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COLD FRONT
• What is a cold front? A cold front forms
when a cold air mass pushes under a warm
air mass.
• Bring thunderstorms, rain or snow.
• This produces cumulonimbus clouds.
• Cold front followed by cooler drier air.
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Cold Front
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WARM FRONT
• What is a warm front? A warm front forms
when a warm air mass moves up and over a
cold air mass.
• This produces stratus and cirrus clouds.
• Brings drizzly precipitation.
• Followed by clear warm weather.
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Warm Front
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STATIONARY FRONT
• What is a stationary front? A stationary
front forms when a warm air mass and
a cold air mass meets but neither
advances.
• Many days of cloudy, wet weather.
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Stationary Front
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OCCLUDED FRONT
• What is an occluded front? An
occluded front forms when a fast
moving cold air mass overtakes a
slower warm air mass. The warm air is
caught between two cooler air masses.
The cool dense air moves under the
warm less dense air and cuts the warm
air mass off.
• Brings cool temperatures with large
amounts of rain or snow
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Occluded Front
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Quiz: Take this on the paper provided.
1. Describe a maritime polar (mP) air mass, in terms of moisture and temperature.
2. What is the name of an air mass that forms over water?
3. What is the name of an air mass that forms over land?
4. What is the name of an air mass that forms in a cold region?
5. What is the name of an air mass that forms in a warm region?
6. Describe a continental tropical (cT) air mass, Moisture and temperature.
7. The boundary between two air masses is called a ______________________.
8. A cold air mass meets and pushes a warm air mass out of the way.
What type of front am I?
9. A warm air mass is trapped between to cold air masses.
What type of front am I?
10. A warm air mass meets and pushes a cold air mass out of the way.
What type of front am I?
11. I am a front that brings drizzly rain and am followed by warm clear weather. Name
me
12. A cold air mass meets a warm air but neither is very strong. They are separated
and many days of wet , cloudy weather occur.
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Pressure Systems
What is air pressure?
The force that a column of air applies ON the air
or a surface below it. Air flows from areas of:
HIGH pressure to areas of low pressure.
Air pressure is the same thing as saying
Barometric Pressure.
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What is a HIGH pressure system?
Circulating air with HIGH pressure at it’s center and lower
Pressure outside of the system.
In the center of a HIGH pressure system, what
happens to the density of the air?
It increases & thickens. The density of the air sinks and
move to areas of low pressure.
What does the level of density cause the air to do?
Move away from the center
What kind of weather does a high-pressure system
bring? Clear skies and fair weather. High pressure = Happy weather.
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What kind of air mass has a HIGH pressure?
Cool Air Masses
How do the air molecules circulate in a high-pressure system?
CLOCKWISE.
AND what does it cause the air to do in terms of the center of the system?
Move DOWN & AWAY from the center of the system.
What is the weather map symbol for a high-pressure system?
(USE YOUR colors)
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What is a LOW pressure system?
Circulating air with LOW pressure at it’s center and higher
Pressure outside of the system.
In the center of a LOW pressure system, what
happens to the density of the air?
It decreases & gets lighter; Rises and moves to areas
of high pressure.
What does the level of density cause the air to do?
Move toward the center
What kind of weather does a low-pressure system bring?
Clouds, rain or snow. Low pressure = Lousy weather.
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What kind of air mass has a LOW pressure?
Warm Air Masses
How do the air molecules circulate in a LOW-pressure system?
COUNTER CLOCK-WISE
AND what does it cause the air to do in terms of the center of the system?
Move UP & TOWARD the center of the system.
What is the weather map symbol for a low-pressure system?
(USE YOUR COLORS)
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What weather instrument is used to measure air pressure in
the atmosphere?
Barometer, Air pressure is the SAME thing as saying Barometric pressure.
What unit of measure is used when measuring air pressure?
MILLIBARS (mb) or INCHES OF MERCURY (in.HG)
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Compare/Contrast Chart
High and Low Pressure
Moving inward on
isobars…
Density of air
Representation on a map
Motion of air
Also known as…
Motion of air causes a
zone of…
Stability of atmosphere
High Pressure
Pressure Increases
Low Pressure
Pressure Decreases
Higher
H (typically blue)
Clockwise, air sinks
Anticyclone
Divergence
Lower
L (typically red)
Counterclockwise, air
rises
Cyclone
Convergence
Stable
Unstable
High Pressure
LOW PRESSURE