Transcript Meteorology Part II

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3.
Why does it take a plane longer to travel
from NC to Russia than from Russia to NC?
How are air masses named?
What type of air is associated with a mT air
mass?
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3.
What type of weather is associated with a
low pressure system?
How does pressure change as you go
towards the center of a high pressure
system?
What direction do the winds blow in a high
pressure system in the Northern
hemisphere? Why does the direction
change in the Southern hemisphere
Recall:
 Warm Air RISES, and Cool Air SINKS.
 At low altitudes, air pressure is HIGH. At high
altitudes, air pressure is LOW.
At the equator, air becomes WARMER and RISES to an
area of LOWER pressure.
2. The LOW pressure causes the air to EXPAND, moving
it toward the POLES.
3. Next, the air COOLS and SINKS back to the earth.
4. Finally, the air will move toward the EQUATOR, where
the cycle begins again.
1.
THE EARTH ROTATES TOWARD THE EAST.
 The resulting wind movement is called the
CORIOLIS EFFECT.
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link
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Low Pressure = rain.
High Pressure = dry.
0° Tropical Rainforest
30° Desert
60° Temperate Rainforest
90° Polar Desert (Tundra)
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Wind speed is measured using an
ANEMOMETER (see p. 545)
Wind direction is measured using a
WEATHER VANE
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Wind caused by TEMPERATURE and
PRESSURE differences
Jet Stream: narrow bands of FAST, highALTITUDE, WESTERLY winds.
 Speed: up to 185 km/hr
 Altitude: 10.7 km to 12.2 km
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Resemble JETS of WATER
2 types:
POLAR = stronger of the two
SUBTROPICAL = controls much of the
weather in the US
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an immense body of air that is characterized
by similar temperature and moisture
can be 1,600 km or more across… take
several days to move over an area
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When an air mass moves out of the region
over which it formed, it carries its temp &
moisture
- The characteristics of an air mass change as
it moves and so does the weather in that area
- Air masses are classified according to the
surface over which they form
Front: narrow region separating 2 air
masses of different densities____
 Air masses collide forming _fronts_.
 Fronts can cause dramatic __changes__
in weather.
 4 Types: _cold , __warm__,
___stationary__, and __occluded___
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Cold, dense air displaces ___warm___ air,
forcing the warm air _up__ along a steep
front.
 Warm air _rises _, cools, and _condenses_
 Forms __clouds__, __showers__, and
sometimes __thunderstorms_____
 Fast temperature change: air gets colder.
 Advance more ___rapidly___ than a
warm front.
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SYMBOL: Color? Direction of movement?
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DIAGRAM:
 Advancing _warm___ air displaces
__cold___ air, and the warm air rises
above the cold air.
 Extensive _cloudiness__ and
___precipitation____
 Slow temperature change: air gets
warmer.
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SYMBOL: Color? Direction of movement?
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DIAGRAM:
 Warm and Cold air meet, but neither
moves into the other’s territory,
which __stalls__ the front.
 They stall because the
___temperature__ and
__pressure___ gradients are small.
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SYMBOL: Color? Direction of movement?
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DIAGRAM:
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A cold air mass moves so rapidly that it
__overtakes a warm front____.
The cold air masses collide, pushing the warm
air ___upward____.
Causes precipitation on both sides of the
front_______.
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SYMBOL: Color?
Direction of movement?
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DIAGRAM:
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Thunderstorms: Form when warm
humid air rises in an unstable
environment
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generates lightning and thunder and
frequently produces gusty winds, heavy
rain & hail
•Strong updrafts
•Supply moist air
•Cloud grows vertically
•Amount of precipitation
is too great for updrafts to
support
•Heavy precipitation
•Gust winds, lightning
•Downdrafts dominate
through the cloud
•Cooling effect of falling
rain and the flowing of
colder air from high above
calms the storm
Violent windstorms that take the form of a rotating
column of air called a vortex that extends
downward from a
cumulonimbus cloud.
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LIGHTNING: Electricity is discharged from a
thundercloud in the form of lightning. A bolt of
lightning can heat the air around it to a temperature
four times as hot as the sun.
The heated air expands
violently and sends out
a rumbling shock wave
that we hear as thunder
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Whirling tropical cyclones that produce winds
of at least 119 Km/hr
Cause high winds, huge waves, and extensive
flooding hundreds of miles away
Growing threat- >50% of the US population
lives within 75 km of the coast.
The north pacific has the greatest number of
storms (~20 per year)
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Late summer when temps are warm enough
to provide heat and moisture the air
Begins as a tropical disturbance- disorganized
clouds & thunderstorms w/ low pressure
Inward rush of warm moist air moves towards
the center
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Air turns upwards and rises in a
cumulonimbus cloud (eye wall)
 eye wall has the greatest wind speeds & heaviest
rain
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Rising air is carried away from the storm
center- provides room for more inward flow
At the very center of storm is the eye
 zone where precipitation ceases and winds
subside.
 air gradually descends in the eye and compressedwarmest part of the storm