Classification of Cloud Types
Through Infrared APT Imagery

Activities

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.

• 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