The Gulf Stream and Warming

Subject Area

Physical Science

Age or Grade

7th – 8th grade

Estimated Length

40 minutes

Prerequisite knowledge/skills

Heat Convection

Description of New Content

Real World Application of Convection

Goals

Learning that uneven distribution of heat causes the world ocean currents to move from low latitudes to high latitudes, carrying heat from the tropics to the poles, and providing wild winters to some countries on the eastern sides of the oceans.

Materials Needed

Fish Tank, Food Coloring, small glass or beaker, hot water, tap water, and “blue ice” pack.

Power point provided

Procedure

Opener.

Heat Transfer occurs in three ways, convection, conduction, and radiation. Today we will be learning how convection drives the world’s ocean currents, often called the ocean conveyor belt.

Development

Use PowerPoint to show how the worlds oceans are partially driven by cold saltier water at the high latitudes sinking, pulling currents like the Gulf Stream North toward the poles. Explain how reduction in global arctic sea ice is reducing the salinity of the surface water near the poles, and thus decreasing the rate of sinking, and thus the Northward pull of the current.

Closure

Real world convection in the classroom. Fill a small fish tank (6”x12”) with about 4” of water, enough that the small glass or beaker will be covered. At one end of the tank place the cold “blue ice” pack (this can also be done with a bag of ice if cold pack is not available). Fill the beaker with very hot water, add a few drops of food coloring, dark colors work better, blues especially well. Gently place the glass with the hot water into the tank at the opposite end, away from the ice pack. In a few seconds the blue dye will begin to “flow” from the glass to the surface, and toward the blue ice pack. It is very important to not bump the tank, so as to avoid mixing. In a few minutes, the dye will begin to sink near the ice pack, and will form a convection cell in your tank.

Evaluation

Extensions

References

Files: GulfStream.pdf

Movies:

All about ARGO Floats:

World Ocean Circulation:

North Atlantic Ocean Circulation: