Deep-Sea Circulation

Background Information

The Betty Crocker Ocean Fudge Swirl


To visualize and understand the relationship between temperature, salinity and the density of seawater, and the important role these factors play in the circulation of the deep-sea.

What you will need:

1. At least two colors of food dye. Any color will do but blue and red are best.

2. A large clear container, like an aquarium. A clear pitcher will work okay, a jar won't. You need to be able to put your hand inside it and you need to be able to see inside it.

3. Salt

4. Ice cube trays and some way to freeze water

5. The rubber part of a turkey baster

The Experiments:

1. 1. Fill an ice cube tray with water. Add (yellow) food dye. Freeze the water.

2. Fill another ice cube tray with water and add a few pinches (10-15 grains) of salt into each cube receptacle. Dissolve the salt by stirring. Add a different color (blue) food dye. Freeze the salt water.

3. Fill your aquarium or receptable with water.

4. Place one frozen freshwater ice cube in the container of tap water.

5. Describe what you see. How does the food dye move in the container? Up? Down? Swirling?

6. Repeat the experiment using a saltwater ice cube in a fresh container of water.

7. Again, describe what you see. How does the food dye move in the container?  Up? Down? Swirling?

7. Repeat the experiment placing both cubes in the receptacle at the same time.

8.  Compare the movement of the meltwater from the two ice cubes. What happens? Which meltwater moves fastest? Which moves deepest?

Part Two

1. Fill your aquarium with fresh tap water.

2. Remove the rubber end of a turkey baster.

3. Fill the rubber end of the turkey baser with hot (near boiling) water. Be careful!!!!

4. Add (red) food dye to the turkey-baster-rubber-thingy filled with hot water.

5. Carefully place the turkey baster rubber thingy with hot water in the bottom of your water-filled receptacle.

6. What happens to the water in the turkey baster? Describe how and where it moves.

Thought Questions

1. What did you learn about temperature, salinity and water density from your observations?

2.  Do your observations agree with scientific theory?

3.  How do the results of this experiment support the idea that temperature and salinity are the driving force behind movement of water in the deep-sea?