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Published byJanis Bennett Modified over 6 years ago
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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 Earth’s Rotation (Coriolis Effect) Temperature differences in ocean water Continents (continental Deflection)
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2. The Coriolis Effect The Earth’s 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 Thermohaline *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 o’clock, 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 currents: Working 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 cause Deep Currents
(1) Decreasing temperature (2) Increasing salinity through freezing (3) Increasing salinity through evaporation
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