Earth Science

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Just Another Windy Day

• Earth Science
• High School

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To slide show
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What is wind?

• The movement of air from an area of higher
  pressure to an area of lower pressure
• Hot air is less dense than cool air, causing air
  pressure to be lower where air is heated

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• The sun heats the troposphere unevenly,
  activating a system of winds that move energy
  from one area of Earth to another.
• Earths curved surface causes solar energy to
  strike earth at different angles. The more
  direct the angle the greater the energy received.

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• Whenever air pressure increases or decreases
  rapidly in relation to nearby areas, winds
  increase in velocity.
• Winds can be either horizontal or vertical in
  direction.

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The Coriolis Effect

• The rotation of the Earth causes moving air and
  water to appear to turn to the right or north of
  the equator and to the left or south of the
  equator.

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Visualizing Global Winds
Back to show
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• 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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Polar easterlies

• In the polar regions, cold, dense air sinks and
  moves away from the poles. Earths rotation
  deflects this wind from east to west.
• Refer to handout

To visual
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Westerlies

• Near 30º north and south latitude, Earths
  rotation deflects air from west to east as air
  moves towards the polar region. In the United
  States, the westerlies move weather systems from
  west to east.
• Refer to handout

To visual
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Trade winds

• Air warmed near the equator travels toward the
  poles, but gradually cools and sinks. As the air
  flows back toward the low pressure of the
  doldrums, the Coriolis effect deflects the
  surface wind to the west. Early sailors relied
  on these winds to navigate global trade routes.
• Refer to handout

To visual
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Doldrums

• Along the equator, heating causes air to expand,
  creating a zone of low pressure. Cloudy, rainy
  weather develops almost ever afternoon.
• Refer to handout

To visual
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Jet Stream

• Narrow belts of strong wind that blow near the
  top of the troposphere
• Form at the boundary of cold, dry polar air to
  the north and warm, moist tropical air to the
  south
• Moves faster in the winter because the difference
  between cold and warm air is greater
• Helps move storms across the country

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Lets check for understanding

• Why do some parts of the Earths surface receive
  more of the suns heat than other regions?
• How does the Coriolis effect influence wind
  circulation on Earth?
• Why does little wind and lots of afternoon rain
  occur at the doldrums?
• Which wind system helped early sailors navigate
  Earths oceans?

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Teacher Page

• Content Earth Science
• Grade Level High School
• Creator Lisa Boulden
• IBD describe the pattern and relationships in
  the circulation of air around the Earth.
• Students will need a journal and pencil or pen
• Print slide number 15, 16, and 17 for student
  handout
• Answers to questions
• Earths curved surface causes solar energy to
  strike Earth at different angles. The more
  direct the angle, the greater the energy
  received.
• Air masses in the northern hemisphere are
  deflected to the right, while those in the
  southern hemisphere are deflected to the left.
• As air at the equator is warmed it is lifted and
  cooled. This causes clouds and precipitation
  most afternoons.
• Trade winds.

To slide show
15
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16
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17
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