How does the temperature of the
Great Lakes change over time?

In the spring the water is very cold and only a few brave (or crazy) people will go swimming in a lake, but by July and August many people will go swimming. The Great Lakes even with their huge size, have temperature changes. In this activity you will examine how they change and compare the five lakes to each other to see how they are the same and how they might be different.

Student Materials Needed:
Access to a web browser (Netscape, Explorer).
Computer with CD-Rom or with the file loaded onto the hard drive.
Student Handout to record information. Graph paper.

Earth Systems Understandings: This activity deals with Understandings # 1, 3, 4 (Aesthetics, Scientific Study, and Interacting Subsystems).

Objectives:
- Students will use satellite image movies to make observations about temperature changes in the Great Lakes.
- Students will hypothesize the causes of some of their observations and then use more data to support or reject their hypothesis.

Procedure:
1. Make predictions about the following before beginning to explore the movies. Record your predictions on your answer sheet. The answer sheet is numbered to match the procedure instructions.

• a. Which lake is the coldest, warmest?
• b. What lake will warm up the fastest, slowest?
• c. What conditions affect the temperature of the lakes change?

2. In this activity you will be looking at satellite images that have been color coded to show surface temperatures. Use the introductory material about these types of images to answer the questions on your handout. The images described in the introductory material have been further modified and standardized to make the movies.

3. Select five locations on the lake that you have been assigned. At least two of the locations should be near land and at least two should be in open water. Sketch the outline of your lake and mark the locations that you are going to collect data at. Label them A, B, C, D and E. Your teacher may have a large map available, or you can use the location map to help you pick locations and know what they are located near.

4. Make predictions about your five locations.

• a. Which of the five sites will warm up the fastest, slowest?
• b. Which of the five sites will get the warmest? How warm do you predict (0-30 degrees Celsius)?
• c. Where will the lake change the fastest, slowest? (north, south, shore, bays, deep, open areas,....)

5. Pick a starting date for collecting your data between Jan 1st and Jan 14th. Record it in the date column for row 1. Click on the link and then download or view the 1996 quicktime movie. Movies (If the version of browser does not recognize and play the movie, you may have to edit the application settings (under preferences) to recognize the suffix (qt) used by these movies.)(source page - http://www.glerl.noaa.gov/data/data.html ) and advance to your starting date (use the forward and back arrows on the keyboard.) Record the temperatures for your five selected locations (A-E) on this beginning date. Record the temperatures on the data table. Advance two weeks in the movie and record the temperatures for this date. Continue recording data at two week intervals until you reach the end of the movie.

6. Graph the temperature data that you have collected. Use a different color or symbol for each site (A-E).

7. What observations can you make from your graphs? What predictions in # 4 were correct? Incorrect? Record your observations.

8. Compare the temperature changes to the bathymetry (bottom depth) data for your lake. Approximately how deep was each of your sites? Did this appear to affect the temperature changes?

9. Did you observe any anomalies (data that did not fit the pattern)? Describe any observed anomalies.

10. Take a look at the weather map for any dates that you have anomalies. Does the weather map help you come up with a possible explanation of the anomaly? What is your explanation? Online link to Archived Weather Data 1996 on. Now locate the data for 1996 and the particular dates / maps that you are interested in. If you do not have online access to the Internet select , from the dates below, near any anomalies and see if you can come up with any explanations / hypothesis.

11. Decide as a group what is the most important information to share with your base groups (1 person from each lake). You will be the expert on your lake.

12. What are some other questions that you might investigate about the Great Lakes using the type of data in this activity?

Meet in base groups as assigned.

• Share what you learned about your lake with each other. Discuss the following:
• 13. How were the lakes alike?
• 14. How were they different from each other?
• 15. What were the conditions that affected the temperature on all of the lakes?

Extension:

What do you predict the temperatures will be like in other years? Pick one of your locations (A-E) and then graph the temperature data for that site in the 1996 and 1997 years. What do you think the current temperatures might be? Current