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ctivities
Warm-up:
Place a visible-infrared APT image pair on the screen for the entire class to view. The
pair should contain at least two of the differences between the types listed in the
Teacher Background, which can be readily pointed out to the students. Explain, using
specific examples, some of the differences between infrared (IR) and visible imagery.
Procedure:
Pass out the visible-IR image pairs (listed under materials) to each cooperative group.
Hand out worksheets. Ask students to examine the images and determine which are IR
and which are visible. After students confer, you may wish to check with each group
before allowing them to proceed.
As you walk about the room to monitor the students’ success, the following points
about the images will be helpful:
1 The warmer waters of the Gulf Stream will be readily distinguishable from the
colder waters of the North Atlantic on the IR image. This differentiation will not be
noticeable on the visible image.
- Clouds will look white on the visible image because they show reflected sunlight.
Shadows will be readily apparent. If the shadows point westward, it is a morning
image (sun in the eastern sky). If the shadows point eastward, it is an evening
image (sun in the western sky). Clouds on the IR image will appear in differing
shades of gray depending upon their temperature (related to their height).
- A July IR image of a hot day will easily distinguish cities from their surroundings.
The warm asphalt and concrete are radiating more infrared energy than the sur-
rounding vegetation. The following are some of the cities that should be easily dis-
tinguished by students—with the help of a student gazetteer (a book containing
geographical names and descriptions). This list is applicable when using imagery of
the Southern Great Lakes region.
- Detroit, Michigan
- Milwaukee, Wisconsin
- Toledo, Ohio
- Indianapolis, Indiana
- Dayton, Ohio
- Columbus, Ohio
- Fort Wayne, Indiana
- On the following day, you may wish to give your students an assessment of their
individual ability to identify visible and infrared images. Student instructions are on
page 218. Using additional image pairs and practice will help ensure their success.
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