Convection Current Lab

Introduction:

Convection, it is the force that drives all of our planet's motion. From the deepest magma to the slightest breeze in the air brushing our skin, the force behind the movement is convection. Convection is one of the ways that heat moves in a fluid.
In the ocean, convection currents are responsible for the mixing and movement of the waters around the globe. In this lab we will be observing convection currents modeled with hot and cold water and food coloring.

Objectives:

Model and observe convection currents.
Observe how temperature differentials effect the movement of water in a shallow pan.
Observe the effect of seafloor shape and manmade structures on the movement of convection currents.

Materials:

Each group or team will receive one set of materials.

1. One plastic pan to hold water.
2. 4 styrofoam cups to support pan and to contain the warm water.
3. Red and Blue food coloring.
4. Water.
5. Test tubes and droppers.
6. White paper.
7. Data recording sheets.
8. Small rocks or rubber stoppers for the seafloor features.

Procedure:

General notes:

You will be handling HOT water in this lab, you MUST wear the safety aprons at all times during the lab.

You will be completing five trials in this experiment, each time you begin a new trial you will
want to get a new pan of water and refresh your heat source if it has cooled.

Handle the pans carefully they break easily. Use two hands!!

You will be placing the drop of food coloring in different locations and carefully observing its pattern of movement. You will record your observations in detailed sketches done with colored pencils and including directional arrows.

Be careful not to bump the tables or you will disturb your currents.

Be frugal with the food coloring. Using only a few drops will allow you to see the currents most clearly.

Basic diagram of pan and cups.

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Trial A. No heat source

Place the drop of food coloring in the still water with no heat source.
The drop of color should be placed at the center of the pan, right on the bottom.
Draw what happens to the food coloring as you look at it from the side and top views. Be sure to include arrows.
Write a brief description of what you see.

Trial B. Heat in Center /Drop in Center

Place the drop of food coloring in the still water with heat source under the center.
The drop of color should be placed at the center of the pan, right on the bottom.
Draw what happens to the food coloring as you look at it from the side and top views. Be sure to include arrows.
Write a brief description of what you see.

Trial C . Heat in Center /Drop close to side / bottom of pan

Place the drop of food coloring in the still water with heat source under the center.
The drop of color should be placed near the side of the pan, right on the bottom.
Draw what happens to the food coloring as you look at it from the side and top views. Be sure to include arrows.
Write a brief description of what you see.

Trial D . Heat in Center /Drop on top of pan

Place the drop of food coloring in the still water with heat source under the center.
The drop of color should be placed near the top of the pan.
Draw what happens to the food coloring as you look at it from the side and top views. Be sure to include arrows.
Write a brief description of what you see.

Trial E . Heat on one side / ice on other side

Place two drops of food coloring in the still water with heat source under the side of the pan and a baggie of ice near one edge.
One drop of color should be placed near the side of the pan, right on the bottom over the heat source. The second near the ice bag.
Draw what happens to the food coloring as you look at it from the side and top views. Be sure to include arrows.
Write a brief description of what you see.

recording sheet for data here

Discussion Questions.

Write out complete sentences to the following questions. Use lined paper. You may need to consult outside resources such as your book or the internet to answer these questions.

Describe how the currents moved in the pans. Did the color mix with the water? Why?

In the case of the real ocean what is the heat source?

What kind of current is the Gulf Stream?

How might currents help the fishing industry?

How does the Coriolis effect influence the currents on a global scale?

How did Ben Franklin's Understanding of the Gulf stream help 18th century sailing ships move efficiently across the Atlantic Ocean?

Describe two other places you might have seen or can expect to find density currents other than in the ocean?


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