# Lesson 5: Turnover and Upwelling

## Day 2

### Activity 2: Turnover and Upwelling

Materials: desk lamp, small fan, thermometers (kit)
For this activity, you will use the container from the previous activity and choose one of two options. The first option deals with turnover, and the second explores upwelling. (Although upwelling occurs in a saline environment, it is not necessary to use saline water for the activity).

Note: After you have completed this activity (either option), put the lid on the container and then set the container and its contents aside for use in Lesson 9.
While turnover and upwelling are caused by different factors (turnover is the result of cooling water and upwelling is the result of winds) time restraints require that your child focus on one of the activities. Allow your child to choose the option that most interests him. Note: After your child has completed this activity (either option), remind him to put the lid on the container and then set the container and its contents aside for use in Lesson 9.

#### Option 1: Turnover

Follow the steps below to observe how turnover works:
1. Place the water and sediment container from Activity 1 in a location so that it can reach room temperature (about 64-77(degrees) F or 18-25(degrees)C).
2. Next, place the container in a cooler environment (a refrigerator or freezer) -- the temperature difference should be at least thirty degrees Fahrenheit or sixteen degrees Celsius.
3. Do not allow the sample to freeze. Use your thermometer to periodically check the water's temperature until it is at least thirty degrees (or sixteen degrees Celsius) below room temperature. NOTE: You do not need to record the temperatures -- just keep track until the temperature has changed by at least 30(degrees)F (16(degrees)C).
4. Once the container temperature has dropped, remove it from its cooling location and place a lamp so that it is shining on the side of the bottle. (Remove the top so that you can take temperature readings.)
5. Take the temperature of the container's contents and make an initial observation of the sediment and record these on the "Turnover" activity page.
6. Take temperature readings and observe the container every fifteen minutes for the next hour. Record the temperature and any observations about the sediment.
Make the connection: Based on what you observed, what happened? How is this significant for a lake or other large body of fresh water that is not moving?
Student Activity Page
For this activity, your child is taking the container and its contents from Activity 1 and seeing what will occur as the water temperature changes. Although there will be some challenges because of the size of the container, the sample should exhibit signs of turnover — warmer water rising and cooler water sinking and causing the sediment to be disturbed. If this did not occur, your child will need to think about something very important for scientific investigations — limiting factors. The limiting factors in this experiment are the container and time — in a lake, the changes occur in very large volumes of water over the course of days and even weeks. If your child does not see turnover in his experiment, have him think about what would happen in a lake. The goal is to have your child think more deeply about processes such as turnover.

Make the connection:
Based on what you observed, what happened?
As the water warmed up, the warmer water in the container should have risen and the cooler water should have sunk to the bottom of the container. As this continued, the sediment in the container should be disturbed.

How is this significant for a lake or other large body of freshwater that is not moving?
If the container were a lake, the movement of the sediment should have led to nutrients on the bottom being spread throughout the lake, which would be beneficial to various organisms living in the lake's waters.

#### Option 2: Upwelling

Follow the instructions below to observe the effects of upwelling:
1. Place the water and sediment container from Activity 1 in a location so that it can reach room temperature (about 64-77(degrees)F or 18-25(degrees)C).
2. Next, place the container in a cooler environment (a refrigerator or freezer) -- the temperature difference should be at least thirty degrees Fahrenheit or sixteen degrees Celsius.
3. Do not allow the sample to freeze. Use your thermometer to periodically check the water's temperature until it is at least thirty degrees (or sixteen degrees Celsius) below room temperature. NOTE: You do not need to record the temperatures as the water is cooling - just keep track until the temperature has changed by at least 30(degrees)F (16(degrees)C).
4. Once the container temperature has dropped, remove it from its cooling location. There is a possibility that the container will tip over in this experiment, so choose a surface where you could easily clean up the water and sediment, if needed.
5. Remove the lid from the container.
6. Take the temperature of the container's contents and make an initial observation of the sediment and record these on the "Upwelling" activity page.
7. Set up a fan so that it is blowing over the mouth of the container.
8. Take temperature readings and observe the container every fifteen minutes for the next hour. Record the temperature and any observations about the sediment.
Student Activity Page
For this activity, your child is taking the container and its contents from Activity 1 and looking to see what will occur as the water temperature changes due to wind. Though there will be some challenges because of the size of the container, the sample should exhibit signs of upwelling — winds causing cooler waters to rise from the bottom and carry the sediment along with it. If this did not occur, your child will need to think about something very important for scientific investigations — limiting factors. The limiting factor in this experiment is the size of the container. The container mouth may be too small or too large to actually reflect the surface of a large body of water. Also, the depth of the container may actually be significant enough to impact the results (too shallow by scale). A second limiting factor is the fan. While it represents surface winds, the fan's blowing does not accurately reflect the strength of surface winds. This lack of scale with regards to windspeed does not necessarily represent the types of surface winds that generally cause upwelling. Continue to challenge and encourage your child with the goal not being about the limiting factors, but rather having your child better able to conceptualize processes such as upwelling.

If upwelling does not occur in the experiment, still have your child think about what should happen in an ocean. The goal is to have your child think more deeply about processes such as upwelling and how these processes are beneficial for organisms that live in the oceans.

Make the connection:
Based on what you observed, what happened?
As the winds blew on the surface of the water in the container, they should have caused the denser, cooler waters from the bottom of the container to rise.

How is this significant for the ocean?
The winds blow surface waters elsewhere, which leads to the cooler waters rising to the surface and carrying the nutrients that have settled on the bottom.