Warm-up discussion

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Warm-up discussion

• Imagine that you are at the beach, and you get
  into the water and begin swimming. Describe what
  happens if you stop swimming.
• What does the water feel like?
• What does the water do to your body?
• Do you stay in the same spot? If not what
  happens?
• Discuss at table and elect one speaker to share
  out.

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CURRENTS
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What is an ocean current?

• Streamlike movements of water.

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Currents are Important Because.

• They help to move boats and ships
• They mix nutrients around the oceans
• They bring up small organisms and plants to the
  surface so that animals like birds can feed on
  them.

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There are two types of ocean currents

• Surface Currents
• Deep Currents

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Surface Currents

• Streamlike movements of water that occur at or
  near the surface of the ocean.

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Surface currents are caused by the following

• Winds
• The Earths Rotation (Coriolis Effect)
• Temperature differences in ocean water
• Continents (continental Deflection)

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2. The Coriolis Effect

• The Earths rotation causes wind and surface
  currents to move in curved paths rather than in
  straight lines.

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3. Temperature Differences

• There are warm currents and cold currents.
• Warm water wants to moves from the equator to the
  poles
• Cold water wants to move from the poles to the
  equator
• This creates a consistent movement of water.
• The cold water sinks to the bottom and moves
  towards the equator WHILE
• The warm water floats and moves towards the
  poles.

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Deep Currents

• Streamlike movements of ocean water far below the
  surface.

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What causes Currents

• Currents are caused by Winds and
• Temperature differences of the water
• REMEMBER
• Heat up- rise up
• Cool down- go down

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How does temperature affect currents?

• Cold-water currents occur as the cold water at
  the poles sinks and slowly moves toward the
  equator.
• Warm-water currents travel out from the equator
  along the surface, flowing toward the poles to
  replace the sinking cold water.

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How does temperature affect currents?

• - Some currents carry warm water- warm currents
• some currents carry cold water- cold currents
• Where do you think the warmest and coldest oceans
  on Earth are? (Discussion)

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• Warm currents start at the equator
• Cold currents start at the north and south poles
• Therefore warm currents flow from the equator to
  poles
• Cold currents go from poles to equator
• Table Discussion

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• - currents in the 2 hemispheres move in different
  directions.
• - Currents in the northern hemisphere move in a
  clockwise direction.
• (from 12- 6 oclock, OR from East to West)
• Currents in the southern hemisphere move in a
• counter clockwise direction (like going
  backwards on a clock OR from West to East).

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The Gulf Stream

• The Gulf Stream is one of the most famous WARM
  currents.

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• What do you know?
• 1. What is a current?
• 2. What are the 2 types of currents AND how are
  they different?
• 3a. how do currents in the north hemisphere of
  the earth differ from the movement of currents in
  the southern hemisphere?
• b. Illustrate this difference on the globe below.
• 4. How do warm currents on earth move around the
  earth?
• 5. How do cold currents move around the earth?
• 6. Why do you think warm and cold currents move
  in the way that they do around the earth?

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Understanding the causes of currentsWorking
with a Partner

• Using the chapter section and your notes answer
  the following questions on your handout with a
  partner
• List the three factors that cause surface
  currents.
• List the three factors that cause deep currents.
• How are surface currents and deep currents
  different?

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3 factors that cause Surface Currents

• (1) Global winds
• (2) The Coriolis Effect
• (3) Continental deflections
• These three factors keep surface currents flowing
  in distinct patterns around the Earth.

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3 factors that causeDeep Currents

• (1) Decreasing temperature
• (2) Increasing salinity through freezing
• (3) Increasing salinity through evaporation