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)
Computer with CD-Rom or with the file loaded onto the hard drive.
Student Handout to record information.
Earth Systems Understandings: This activity deals with Understandings # 1, 3, 4 (Aesthetics, Scientific Study, and Interacting Subsystems).
Objectives:
- Students will use satellite images 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 images.
Record your predictions on your handout.
2. In this activity you will be looking at satellite images that have been color coded to show surface temperatures. Read the introductory material about these images so that you know what they show. Look at a couple of water surface temperature images so that you have an idea about the information that they contain. Answer the questions on your handout.
3. Select five locations on the lake that you have been assigned. Select locations that you can describe and find. At least two of the locations should be near land and at least two should be in open water. Describe your selections on your handout. Give a verbal description (site x = most western end of the lake, just off shore of city y) and the latitude and longitude of each of the sites. Your teacher may have a large map available, or you can use the location map.
4. Examine ten of the satellite images and use the temperature scale at the top right of the image to estimate the temperature for each of your sites. Record the temperature for each site on your handout. Make sure that you look at the scale. Each map has its own scale. If your lake is cloud covered, use a different image.
5. Graph the temperature data that you have collected. Use a different color or symbol for each site.
6. What observations can you make from your graphs? What predictions were correct? Incorrect? Record your observations.
7. What information would be helpful in understanding the changes in temperature?
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 days that you have anomalies. Does the weather map help you come up with a possible explanation of the anomaly? What is your explanation?
July 13 / August 19 / September 10, 18, 28 / October 13, 17, 26
11. Based on what you have learned, predict how you think the Great Lakes would freeze over. Which would be first, last, fastest, slowest? Compare your predictions to the chart about the Great Lakes and ice conditions. You do not need to record your predictions.
12. 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.
Meet in base groups as assigned.
Extension:
Make predictions of the current temperatures of your sites. Go on-line and locate current temperature maps and compare them to your predictions. Report to the class your results and possible explanations of any differences between your predictions and the actual temperatures.
