When a large body of air remains over an area for
several days or weeks, the body of air may change its thermal and moisture
properties according to the land or water under it. The air exchanges
heat with the land or water, either warming or cooling, until its temperature
closely matches that of the surface below it. The body of air also
gains or loses moisture depending on the temperature and moisture content
of the surface. A body of air that resembles the characteristics of
the surface under it is called an air mass.
In this exercise, students will examine the physical characteristics of several types of air masses. Students will discover that air masses can be identified and defined by their temperature and moisture content.
Objectives
In this exercise, students will examine the physical characteristics of several types of air masses. Students will discover that air masses can be identified and defined by their temperature and moisture content.
Objectives
- Given maps depicting two or more air masses, the student will be able to categorize bodies of air by temperature and moisture characteristics.
- Given maps depicting two or more air masses, the student will be able to recognize large regions of similar type air.
- Given a map of air temperatures, the student will be able to describe similarities and differences between temperatures on the map.
- Given a map of dewpoint temperatures, the student will be able to describe similarities and differences between dewpoint temperatures on the map.
- Maps should show two different air masses within the state. A good example is when a cold front is moving across the state, preferably with continental polar and maritime tropical air masses.
- Divide the class into groups of 3 or 4 students.
- When the students circle the warm, cool, moist, and dry regions, be sure they do not use small circles around only a few stations. Try to get them to see a large region (e.g., 1/2 or 1/4 of the state) as warm or cool, moist or dry.
- Students may need to be reminded that dewpoint temperature is an indication of the amount of moisture in the air.
- This lesson consists of oral questions. You may want each group of students to write their answers before discussing the answers with the class.
| PROCEDURE 1. Obtain one temperature map and one dewpoint temperature map for each student in your group. 2. Contour the temperature map every 10 degrees. 3. Contour the dew point map every 10 degrees. 4. Circle the region on your map that contains the warmest temperature readings. Use a red pencil. 5. Circle the region on your map that contains the coolest temperature readings. Use a blue pencil. 6. Circle the region on your map that contains the highest dewpoint temperatures. Use a green pencil. 7. Circle the region on your map that contains the lowest dew point temperatures. Use a brown pencil. QUESTIONS 1. Where are the warmest temperatures? Are the dew points high or low in this region? Label this region A. 2. Where are the coolest temperatures? Are the dew points high or low in this region? Label this region B. 3. If you were to describe the regions as "warm and dry", "warm and moist", "cool and dry", or "cool and moist", how would your describe region A? Region B? 4. The Northern Hemisphere can be divided into three "latitudinal" regions: (a) the polar region, between 60°N and 90°N, (b) the middle latitudes, between 30°N and 60°N, and (c) the tropics, between 0°N and 30°N. Where do you think the air in region A came from? Why? Region B? Why? 5. What do you think causes air to be moist or dry? Why? 6. How specific do you think you can get predicting where a region of air is from originally? 7. Why do you think you can predict these regions? What does this say about how "air masses" are formed? 8. Based on our class data and discussions, what can you say about the source and characteristics of the air that covers large regions of the state? |
PREREQUISITES
(Per person):
Air Mass Continental Air Mass Continental Polar Continental Tropical Maritime Air Mass Maritime Polar Maritime Tropical Polar Air Mass Tropical Air Mass CORE CURRICULUM SKILLS APPLIED IN THIS LESSON
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