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Meteorology:
The Science of
Weather (Part 2)
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Foldable Topics
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Jet Stream
Air Masses
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Winds
Gyres
Ocean Currents
Weather Tools &
Equipment
Jet Stream
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Jet Stream: “river” of air in the upper
troposphere with very high wind speed
The jet stream’s high winds are caused by the
difference of temperatures between two air
masses.
Jet streams usually form in the winter
Jet streams do not cause weather. They are the
result of weather conditions such as temperature
differences.
Air Masses
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Air Mass: a body of air over a large area that
develops and keeps characteristics of pressure,
temperature, and humidity of the area over
which it develops
Air Mass Types
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Types- Location
Maritime: develop over oceans, so they are moist
 Continental: develop over land, so they are dry
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Types- Temperature
Arctic: develop in the arctic region, so they are very
cold
 Polar: cold, but not as cold as arctic
 Tropical: develops in tropical regions near the
equator so they are very warm
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Air Masses
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Combine the location and temperature names to
get a description of the air mass
Continental Arctic (cA): extremely cold and dry
 Continental Polar (cP): cold and dry
 Maritime Polar (mP): cold and moist
 Maritime Tropical (mT): warm and moist
 Continental Tropical (cT): hot and dry
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Global Air Masses
Winds
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Wind: Movement of air caused by differences in
density and pressure of air
“High to Low makes the WIND BLOW!”
Winds & Coriolis Effect
Earth’s rotation or
“spin” causes winds
to be deflected or
“turned” to the
right in the
northern
hemisphere and left
in the southern
hemisphere.
Wind & Convection Cells
•Convection Cells: uneven
heating of the Earth’s surface
causes bands of wind that
blow in a certain direction.
•Winds are named for the
direction they come from
•Easterlies come from the east
•Westerlies come from the west
Doldrums: area near the Equator with little or no
wind
Gyres- “swirling vortex”
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Gyres: large areas of water that swirl due to the
Earth’s rotation
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Water swirls to the right in the Northern Hemisphere
Water swirls to the left in the Southern Hemisphere
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Major Gyres:
1.
2.
3.
4.
5.
North Pacific Ocean (clockwise)
South Pacific Ocean (counterclockwise)
Indian Ocean (counterclockwise)
South Atlantic Ocean (counterclockwise)
North Atlantic Ocean (clockwise)
Major Ocean Gyres
Ocean Currents
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Ocean Current: movement of ocean water in a
certain direction
Ocean currents result from heating from the sun
(produces wind) and Earth’s rotation (Coriolis
Effect)
Types:
Surface currents
 Deep Ocean Currents
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Surface Currents
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Surface Currents: ocean currents at the surface
or top of the ocean. Surface currents are caused
primarily by wind and the Coriolis Effect
Gulf Stream: surface current that starts in
southern Florida and flows along the eastern
U.S. coast.
The Gulf Stream’s warm water influences climate in
its path because it carries warm tropical water near
the equator to colder areas in the north.
 Hurricanes travel in its path.
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Ocean Currents
Deep Currents
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Deep Ocean Currents: ocean currents deeper in
the ocean caused by density differences due to
salinity (salt content).
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These currents involve 90% of the ocean’s water
The water that sinks in the North Atlantic flows all the way past the
equator into the Southern Hemisphere.
The water then flows past Antarctica and into the Pacific and Indian
Oceans. Here some of the deep waters are warmed and so rise again to
the surface.
This cycle of ocean water circulation from the surface to the deep ocean
and back to the surface again is called conveyor belt cycling.
Conveyor Belt Cycling
Tools of the Trade
Barometer
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A device used to
measure
atmospheric
pressure.
Common pressure
units include pounds
per square inch (psi)
Atmospheric
pressure at sea level
is about 14.7 pounds
per square inch
Anemometer
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Instrument used to
measure the speed of
airflow in the
atmosphere.
Revolving cups drive an
electric generator which
operates an electric
meter that is calibrated
in wind speed.
Common unit is km/h
Common unit over water
is “knot”, or one nautical
mile per hour. This
equals 1.15 mph over
land.
Hygrometer
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Instrument used to
measure the
humidity, or amount
of water vapor, in
the air
They make use of
the principle that
organic substances
contract and expand
in response to the
humidity
Psychrometer
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A hygrometer used to
determine the relative
humidity of the air.
The bulb of one
thermometer is kept
wet (by a thin, wet cloth
wick) so that the cooling
that results from
evaporation makes it
register a lower
temperature than the
dry-bulb thermometer
Relative humidity is
determined as a %
Weather Balloons
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A balloon with a
radiosonde attached to it
which measures weather
data.
The radiosonde measures
weather data. A
transmitter on the
radiosonde sends the data
back to tracking equipment
on the ground every one to
two seconds.
The balloon flights last for
around 2 hours, can drift as
far as 125 miles away, and
rise up to over 100,000 ft.
(about 20 miles) in the
atmosphere!
Weather balloons are the
primary source of data
above the ground.
Weather Maps
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TWC - Interactive Weather Map
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NOAA – Current Weather Forecast