Classification of Cloud Types
Through Infrared APT Imagery
Day 1 - Warm-up
Explain to the students that you will be assessing their prior knowledge of the characteristics
of cloud types. To do this, you will show them slides of illustrations of various
types of clouds. Be sure not to present the clouds in any sort of order. Describe each
cloud as you present them with phrases such as "puffy or heap-like" for cumuliform or "layered or sheet-like" for stratiform clouds.
Display one infrared APT image - large enough for the entire class to see - that contains
examples of all three cloud types as classified by height.
- After all slides have been viewed, assign each cooperative group to a workstation
and distribute the set of index cards with the cloud information. Instruct students to
classify the cards into two or more groups, based upon criteria they choose.
- After each group has completed their classification, have them share their classification criteria with the class.
- Have students answer the first two questions on the worksheet. Classifying Cloud Types Through Infrared APT Imagery. After they have answered questions (1) and
(2), explain to students that they will classify clouds on the basis of their cloud
height because the imagery provides temperature information which is directly
related to cloud height. (Cloud temperature decreases as the altitude increases.)
- To see how the temperature varies with cloud height, ask students to use the standard
atmosphere data provided on their worksheets to make a graph of the
decrease in temperature with altitude. These temperature differences can be
detected on infrared photographs. They should sketch the different cloud types
found in each of the three layers, described as simply low, medium, or high on
their Cloud Type Survey. Their completed work should resemble figure 1.
Point out the relatively dark and warmer surfaces along with the familiar geographic
feature you've included (such as the Great Lakes, Chesapeake Bay estuary, or the Baja
peninsula). If you are working on an image at an active ground station, use the
imaging software to reveal surface temperatures at various points on the image. Then point out the low, middle, and high cloud types and their resulting appearance on APT infrared imagery.
Day 2 - Classifying clouds on infrared APT images
For procedure, see student worksheet entitled Cloud Classification. For the answer to question 1, see 1st paragraph of Background: Clouds
Reference: "Earth's Mysterious Atmosphere - ATLAS 1 Teacher's Guide with Activities." (For use with Middle-School students.) NASA EP-282/11-91, pp. 193-201.