Density Currents Activity

The ocean has two main types of currents.  We have studied surface currents.  Another type of current is the density current.  Density currents are caused by differences in density.  In the following activity, we will discover which types of water are more dense or less dense than other types of water.

We will use these four types of water:

Room temperature tap water -clear

Sample 1 - ½ cup of Room temperature salt water- red

Sample 2 - ½ cup of Cold tap water-blue

Sample 3 - ½ cup of Hot tap water-green

Get a plastic box and prop one end up on a science book.  You will need to carefully add each type of water in the order listed above.   Before you add each type of water make a prediction about what will happen.

Begin by putting  800 ml of room temperature water in the container.  Now answer the first question before you get the next water sample.

1.  What do you think will happen when you add the room temperature salt water?

CAUTION!!! You should hold the top of the cup next to the end of the box AWAY from the water.  SLOWLY, VERY SLOWLY, use a funnel or the plastic baster to pour the water sample down the side of the box.   Now, look into the box from the side.  Get down low to look carefully.

2.  Get your first sample and add to container- What did happen?

3.  What do you think will happen when you add the cold water?

4. Get your second sample and add to container- What did happen?

5.  What do you think will happen when you add the hot water?

6.  Get your third sample and add to container- What did happen?

7.  Which type of water was the most dense?

8.  Which type of water was the least dense?

9.  Based on your findings, explain how density can cause currents.