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Weather
Part 3
Why Do We Have
Weather?
The Green House Effect
Heat is trapped by our Atmosphere
The Sun’s
light shines on
the Earth
Some sunlight is
reflected back into
space from the
clouds
Atmosphere
The Green House Effect
Without this Green
House Effect the Earth
would lose all of its
heat. The Earth would
be a very cold place to
live.
Atmosphere
The Southern
Sun heatsHemisphere
Northern
the Earth
unevenly.
gets
is
getting
much most
less. of the
Sun’s light.
The Air
Because of this the air
around the Earth heats
unevenly, creating large
bodies of air at different
temperatures.
The Air
These massive bodies of air are known
as air masses.
An AIR MASS is a large body of air that
has similar temperature and moisture
properties throughout.
http://www.geography.hunter.cuny.edu/~tbw/wc.notes/8.air.masses/air_mass_source_regions.htm
There are two basic types of air
masses. A warm, moist air mass, and a
cool dry air mass.
A warm, moist air mass forms in the
tropical regions of our planet, close to
the equator, usually over the water.
Cool, dry air masses form closer to the
north or south poles and form over
land.
© 2003 - 2006 Michael Ritter ([email protected])
When these two types of air masses
meet they create weather. The
boundary between two air masses is
called a FRONT.
© 2003 - 2006 Michael Ritter ([email protected])
A COLD FRONT is defined as an area
where a cold air mass is replacing a
warmer air mass.
Cold fronts generally move from
northwest to southeast. The air behind
a cold front is noticeably colder and
drier than the air ahead of it.
A cold front is represented by a solid line
with triangles along the front pointing in
the direction of movement, and is colored
blue.
© 2003 - 2006 Michael Ritter ([email protected])
A WARM FRONT is defined as the
transition zone where a warm air mass
is replacing a cold air mass.
Warm fronts generally move from
southwest to northeast and the air behind
a warm front is warmer and more moist
than the air ahead of it.
When a warm front passes through, the
air becomes noticeably warmer and more
humid than it was before.
A warm front is represented by a solid
line with half circles pointing towards
the colder air and in the direction of
movement.
On colored weather maps, a warm
front is drawn with a solid red line.
1) True or False – With out the Green house Effect the earth
would be a very hot place?
False
2) True or False – A front is a large body of air that has similar
temperature and moisture properties throughout.
False
3) True or False – Where two air masses meet is called a front
True
4) True or False – Cold fronts form in the warm tropical
regions of the world like Florida.
False
5) True or False – When a warm air mass replaces a cold air
mass this is called a warm front.
True