Unit 9-2: Atmosphere 2

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Unit 9-2 Atmosphere 2

• Heat Transfer and Convection Currents.
• Global Distribution of Solar Radiation.
• Coriolis Effect.
• Global Wind Patterns.
• Jet Streams.
• Local Wind Systems.

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TAKS Practice Atmosphere 2

1. What layer of the atmosphere has the most
   water?(a) troposphere (b) stratosphere(c)
   mesosphere (d) thermosphere
2. Where is air pressure the lowest?(a) troposphere
   (b) stratosphere(c) mesosphere (d)
   thermosphere
3. What protects living things from too much
   ultraviolet radiation?(a) oxygen (b)
   nitrogen(c) argon (d) ozone

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TAKS Practice Atmosphere 2

1. What layer of the atmosphere has the most
   water?(a) troposphere (b) stratosphere(c)
   mesosphere (d) thermosphere
2. Where is air pressure the lowest?(a) troposphere
   (b) stratosphere(c) mesosphere (d)
   thermosphere
3. What protects living things from too much
   ultraviolet radiation?(a) oxygen (b)
   nitrogen(c) argon (d) ozone

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TAKS Practice Atmosphere 2

1. What layer of the atmosphere has the most
   water?(a) troposphere (b) stratosphere(c)
   mesosphere (d) thermosphere
2. Where is air pressure the lowest?(a) troposphere
   (b) stratosphere(c) mesosphere (d)
   thermosphere
3. What protects living things from too much
   ultraviolet radiation?(a) oxygen (b)
   nitrogen(c) argon (d) ozone

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TAKS Practice Atmosphere 2

1. What layer of the atmosphere has the most
   water?(a) troposphere (b) stratosphere(c)
   mesosphere (d) thermosphere
2. Where is air pressure the lowest?(a) troposphere
   (b) stratosphere(c) mesosphere (d)
   thermosphere
3. What protects living things from too much
   ultraviolet radiation?(a) oxygen (b)
   nitrogen(c) argon (d) ozone

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Guiding Questions Atmosphere 2

1. What are the three kinds of heat transfer in the
   atmosphere? (p.442)
2. What causes convection currents in the
   atmosphere? (p.442)
3. What parts of the Earth receive the most and
   least solar radiation? (p.445)
4. What is the Coriolis Effect? (p.446)
5. Describe how global wind patterns work. Name and
   give the direction of wind in each latitude band
   (0, 0-30, 30-60, 60-90). (p.447)
6. What is the jet stream? (p.448)
7. Describe land and sea breezes. (p.449)

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1. What are the three kinds of heat transfer in
the atmosphere?

• The three kinds of heat transfer present in the
  atmosphere are radiation, conduction and
  convection.
• Energy from the Sun comes to Earth as radiation,
  in the form of electromagnetic waves, including
  infrared radiation. This radiation primarily
  heats up the Earths surface, but also the
  greenhouse gases (CO2, CH4) and solid particles
  in the atmosphere.

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Heat Transfer (cont.)

• The surface transfers heat to adjoining air by
  conduction the direct contact of air molecules
  with the hot surface.
• As the air molecules heat up, they move faster
  and become spaced further apart, making the air
  less dense. The warmer, less dense rises, like a
  hot air balloon. This is convection.

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Heat Transfer (cont.)
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2. What causes convection currents in the
atmosphere?

• A convection current in the atmosphere is caused
  by the changing density of air as it is heated
  and cooled. Hot air is less dense than cold air.
  
• As the air molecules next to the ground heat up,
  making the air less dense. The warmer, less
  dense rises.
• As the air rises and moves away from the hot
  surface, it cools and sinks because it is now
  more dense. This completes the convection
  current.
• As the cool air reaches the surface, it is again
  heated, restarting the current.

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3. What parts of the Earth receive the most and
least solar radiation?

• Because of the Earths curved surface, the Suns
  energy strikes the poles at an angle, spreading
  out the energy over a wider area than near the
  equator.
• Generally, the Earths equator region receives
  the most solar radiation, and the Earths poles
  receive the least radiation.

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Distribution of Solar Radiation (cont.)

• Specifically, the Suns radiation strikes the
  Earth most directly at the Tropic of Capricorn
  (23.5 S latitude) on December 21, at the Equator
  (0 latitude) on March 21 and September 22, and
  at the Tropic of Cancer (23.5 N latitude) on
  June 21.
• The Suns radiation strikes the Earth least
  directly at the South Pole at June 21 and at the
  North Pole at December 21. Actually, on these
  dates, the Sun does not rise at all.

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Distribution of Solar Radiation (cont.)
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4. What is the Coriolis Effect?

• The Coriolis effect causes moving air to turn to
  the right in the northern hemisphere and to the
  left in the southern hemisphere.

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5. Describe how global wind patterns work. Name
and give the direction of wind in each latitude
band(0, 0-30, 30-60, 60-90).

• The Suns uneven heating of earths surface forms
  giant loops, or cells, of moving air. The
  Coriolis effect deflects the surface winds to the
  west or east, setting up belts of prevailing
  winds that distribute heat and moisture around
  the globe.

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Global Wind Patterns (cont.)
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Global Wind Patterns (cont.)

• Doldrums At the equator (0 latitude), heating
  causes air to expand and rise, creating a zone of
  low pressure. Cloudy, rainy weather develops
  almost every afternoon.
• Trade Winds From the equator to 30 N and 30 S
  latitude, warm air heated at the surface near the
  equator rises high in the atmosphere, travels
  towards the poles to about 30, and then cools
  and sinks back to the surface. As this air
  travels back towards the low pressure area at the
  equator, it is deflected by the Coriolis effect
  to the west.

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Global Wind Patterns (cont.)

• Westerlies Near 30 N and S latitude, Earths
  rotation deflects air from west to east as air
  moves towards the polar regions (from SW to NE in
  the United States, moving weather systems from
  west to east). At about 60 N and S latitude,
  the air rises and flows in the upper troposphere
  back to 30 N and S latitude, where it sinks to
  the surface again.
• Polar Easterlies Near the poles, cold air sinks
  and moves away from the poles. Earths rotation
  deflects the wind from east to west.

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6. What is the jet stream?

• The jet stream is a narrow band of strong winds
  that flow near the top of the troposphere. In
  the northern hemisphere, the polar jet stream
  forms at the boundary between cold, dry polar air
  to the north and moist tropical air to the south.
  The jet stream moves faster in the winter. It
  helps move storms from west to east across the
  United States.

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7. Describe land and sea breezes.

• A sea breeze is created during the day because
  solar radiation warms the land faster than the
  water. Air over the land is heated by conduction.
  The heated air is less dense and has lower
  pressure. Cooler, denser air over the water has
  higher pressure and flows onto the land, creating
  a convection current.
• A land breeze is created at night, because the
  land cools more rapidly than the water. Air over
  the land becomes cooler than air over the water.
  As warm air over the ocean rises, cool dense air
  from land flows towards the water to replace it.

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Land and Sea Breezes (cont.)
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Land and Sea Breezes (cont.)