Infrared Yellowstone Lesson 1
The Invisible Yellowstone National Park

IV. DAY 2: INFRARED OLD FAITHFUL

Activity Time: 30-60 minutes

In this section your learners will be using their "observation skills" to determine what kinds of information can be gathered from visible light images as compared to infrared images. So far they have had unanswered questions and curiosities about Old Faithful and have learned that the infrared images (with an appropriate false color temperature map) can give information on the relative temperature of an object. In this activity they will discover that they can determine a relative temperature of the water from the geyser and also get a sense of the temperatures of the nearby landscape as compared to the geyser water. Please note that the infrared images of the geothermal features in Yellowstone National Park were taken from quite a distance away and the temperatures described by the false color mapping do not represent actual temperatures since the heat reaching the infrared camera drops off with distance from the source. However, the infrared images are very useful for describing objects in the scene relative to each other, as in warmer or cooler, hotter or colder, etc. using the false color map as a guide.

You will be using the Old Faithful visible images (Image 1a, Image 2a, Image 3a) and the Old Faithful infrared images (Image 1b, Image 2b, Image 3b) from Image Set 1 of the Image Appendix (Section VII.A):

1. Begin the activity by dividing your learners into small learning groups of 3-4 learners each. Be sure the groups have enough space to spread the images out and discuss without disturbing other groups.

2. Refresh the topic from Day 1 by showing the video clip/still image of Old Faithful and reviewing the main questions and curiosities from the previous day.

3. To each group, hand out the visible light image set of Old Faithful (Image Appendix - Image Set 1: Images 1a, 2a, 3a). Make note that the three images are sequential: Image 1a is near the beginning of an eruption, Image 2a is near the middle of an eruption, and Image 3a is near the end of an eruption.

4. To each group, hand out Section VI. Worksheets - Observation Log A. Assign one person in each group to be "note taker".

5. Discuss the task and scenario with your learners. The ultimate task is for each group to "observe" the images and record their observations and questions about what they see. Sample scenario: They are to take on the roles of explorers and have come upon this interesting geothermal feature. Their sponsoring company wants detailed observation logs to accompany any images they take. It is their goal to describe in detail what they are observing and note questions they are having about what they see.

The below sample observations are some of the main observations of the images and are not all of the observations one could make.

Sample Observation statements on Image 3a:

6. It should not take very long for the basic observations to be made. Through a brief discussion, revisit the limitations of the visible light images and their prior questions. Discuss any new questions that have come up during their first observation session. End the discussion by asking a very open-ended question, "How can we find the answers to your questions?" Entertain your learners' ideas and guide them towards their newfound understanding of infrared images from Day 1's activity, Exploring Infrared Imaging.

7. It just so happens that you have infrared images to accompany the visible images! If you are using the sample scenario of an exploration team, you can tell them that their sponsoring company gave them an infrared camera. They took pictures using a regular camera and the infrared camera simultaneously and are now comparing the visible light images to the infrared images to see if they can obtain more information about the mysterious geothermal feature. Hand out the infrared image sets of Old Faithful (Image Appendix - Image Set 1: Images 1b, 2b, 3b) and Section VI. Worksheets - Observation Log B to each group. Again, assign a "note taker".

8. First instruct them to complete the top portion of Observation Log B. Depending on the skill level of your learners, you may want or need to pause the activity and review the answers to the questions before they proceed with their observations and comparing of the infrared images. The questions help them reflect on Day 1's activity, Exploring Infrared Imaging.

*Note that this is *reverse* from what learners may experience when learning about light. The students may be confused by the fact that the color blue is representing a cooler color than the color red. Explain to the students that in false-color images, any color can be chosen to represent the different temperature ranges in the images and that this just happens to be the colors which were assigned to represent the temperatures for the infrared images used in this lesson.

  • How can you use the infrared image and visible light image together to learn about an object?

    Answer: A visible light image can help us see the specific features of an object (like hair, leaves, the colors that our eyes see) that we normally will observe with our own eyes. An infrared image will tell us which areas are cooler or warmer. Together, we can compare and contrast the images to determine which areas are cooler and warmer (infrared image) and then use the visible light image to help us discover clues as to why those areas are cooler or warmer. In essence, the visible light image helps observers determine the context and what objects are in the image. The infrared image offers us a new perspective and new information on those objects in the image and help form a more complete picture of what was happening the image was taken.

    9. The next step is for your learners to compare and contrast the visible light images and the infrared images. This is the heart of the activity. They will soon realize that they can answer one of their original curiosities: Is the water hot, warm, cool, or cold? Additionally, they can determine a relative temperature of the surrounding area and realize that the water is not the only thing that is hot! The ground, as compared to the tree line, is relatively warm as well.

    The below sample observations are some of the main observations of the images and are not all of the observations one could make.

    Sample Observation statements on Image 2a and Image 2b:

    • The water in the center (directly spraying upwards) is very hot as compared to the rest of the image.
    • The steam seen in Image 2a can be seen in the infrared image. It is cooler than the water that is directly spraying upward in the center.
    • The ground is not black or purple, it is blue. It's cooler than the water, but warmer than the trees. Is all the ground warm in this area? Can we walk on it or is it too hot like lava?
    • The steam nearest the spraying hot water is warmer than the steam that is farther away. The farther away steam looks more wispy.
    • There looks to be a puddle of water near the bottom of the picture and you can see it in the infrared image as a small green area. Since green is warmer than blue, we know it's not ice but warm water.

    10. To conclude this activity, ask your learners to prepare their observations to present to the class. Hold a class discussion/presentation forum where they can discuss their observations, what they learned about the geothermal feature, and questions they have about the feature. We suggest you use color overhead transparencies or a computer presentation to have the images available to the entire class for reference during the presentations/discussion. The main goal of this lesson was to compare and contrast the visible light image versus the infrared image. If you have other curriculum goals that deal with the geology content, this will serve as a nice segway into talking about the geothermal hotspot of Yellowstone National Park!

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