User's Manual
®
ME-6816 012-12254A Theory
3
Theory
• Water density is affected by temperature and salinity, resulting in deep water currents in the ocean.
Procedure
Temperature Differences
Prepare the water
You will need a hot plate, two containers (one-liter or larger), water, ice cubes, a stirring rod, and food coloring.
• Fill one of the containers with one liter of cool water and add six ice cubes. Stir the water until all of the ice melts.
• At the same time, fill the other container with one liter of water and place the container on the hot plate. Stir the water as it
warms up to at least 10 ° C above room temperature.
Prepare the chambers
• Start with the top and bottom valves closed on the Density Circulation Model.
• Add one liter of the ice cold water to one reservoir and add one liter of warm water to the other reservoir. Stir the water in each
chamber to make sure they are homogeneous.
• Add a few drops of food coloring to each reservoir. Stir if necessary.
• Allow the model to sit very still for a few minutes.
Observe and Record
1. Open the top and bottom valves to allow circulation.
2. Observe the movement of the more dense, cooler water and the less dense, warmer water.
3. Record what happens in both reservoirs.
Salinity Differences
• Start with the top and bottom valves open. Add cool tap water to each reservoir until the water level is at 1 liter for both. Close
the top and bottom valves after you add the water.
• Instead of ice, add about 200 g of salt to one of the reservoirs. Use a stirring rod or long handle spoon to stir the salt and water
until all of the salt is dissolved. Follow the same procedure as for water.
1. Allow the model to sit very still for a few minutes. Add a few drops of food coloring to each reservoir.
2. Open the top and bottom valves to allow circulation.
3. Observe the movement of the more dense, saltier water and the less dense, fresh water.
4. Record what happens in both reservoirs.
Using the Model with a Temperature Sensor
Equipment Setup
1. If you are using a computer, connect a PASCO interface to the computer, turn on the interface, and turn on the computer.
If you are using a stand alone interface, turn on the PASCO interface.