Ocean Currents, Part IV: Polar vs. Tropical Water

For this experiment, you will need 2-6 to 8 oz. Styrofoam cups, 2 push pins, a clear rectangular 6-qt. container such as a small aquarium, 20 marbles, red and blue food coloring, hot, cold and room temperature water.


Place marbles in the cups to keep them from floating or tipping. Pour icy-cold water in one of the cups and add 6 drops of blue food coloring. Stir. Pour very hot water in the other cup and add 6 drops of red food coloring. Stir.
Stick a push pin in each cup at the level where the hole will be just below the surface of the water in the large container. The pins should be at the same level in both cups. Leave the pins in the cup. Place white paper or cloth behind the container so that any water movement is easily seen. Carefully place the cups in the container of water with the push pins facing away from each other. Pull out the push pins in each cup. Bend down so that you are eye level with the experiment.

Continue to add the appropriate temperature water to the two cups to keep the water level in each cup almost to the top.
Where does the clear (room temperature) blue (cold) and red (hot) water start and where do they end up?

You may also notice a phenomenon called upwelling. It is when cold water hits a solid such as land, or in this case, the side of the aquarium, the water goes up and ends up just under the layer of hot water. You can see how this would create additional currents.

 Based on your observations, what generalizations can you could make about what happens when water of different temperatures meet?
Alex's science journal page

Sources::
GEMS: Ocean Currents
Grades 5-8
7 Activities
Students gain fascinating insights into our ocean planet through these innovative activities. They learn how wind, temperature, salinity, and density set water into motion, and they make an “in-depth” investigation of the key physical science concept of density. They model how pollution dumped in one location can spread throughout the ocean. Learning is placed in a real-world context as students predict and analyze routes taken by shipwrecked sailors, the 1990 Nike shoe spill, the raft Kon Tiki, and other voyages. In “Message in a Bottle,” students create stories to show what they've learned over the course of the unit.

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