Salinity and temperature differences create masses of water with different densities. Gravity causes more dense water to sink below less dense water As a result, the less dense water rises. These factors create currents.
For the next few experiments, we will explore how water of different salinity levels and of different temperatures react. Our first experiment will be with water of different salinity levels.
You will need:
- 2 identical plastic bottles (about 12-16 ounces) with straight sides and threaded mouths (water bottles are good)
- a tornado tube
- a white dish towel
- salt, Kosher preferred because it leaves the water more clear
- food coloring (any color but yellow)
- a yogurt or small container of sour cream lid with the rim cut off
- room temperature water
- a tablespoon
Fill two bottles with room temperature tap water. Fill one bottle to the very top and leave about an inch of space at the top of the second bottle. Add approximately 4 Tablespoons of salt (preferably Kosher salt as it leaves the water clear) and six drops of food coloring to the bottle with the space at the top and shake well. This is the salty water bottle. Screw a tornado tube tightly onto the salty water bottle. Finish filling the salty water bottle to the very top on the tornado tube with tap water.
If you continue to watch the bottles for at least 5 minutes, you will see that the bottles pretty evenly divide, with the colored water on the bottom and the clear water on the top.
What do you think this tells you about when waters of different salinity levels come in contact with each other?
|The water with the most salt and therefore the most density, will move to below the water with less salt and therefore less density. This movement can create a current.|