Catastrophic Events
Part 1
Lesson 4
Focus Question: How do surface temperatures on earth affect the air above it?
Learning Target:
· I understand warm surfaces radiate heat energy and warm the air above them.
· I understand warm air is less dense than cool air and has a tendency to rise, creating an unstable air mass.
· I understand cool surfaces absorb heat energy and cool the air above them.
· I understand cool air is more dense than warm air and has a tendency to sink, creating a stable air mass.
· I understand water evaporates from heated surfaces, and the rising water vapor cools, condenses, and forms clouds
Student Objectives:
· Investigate the effect of surface temperature on the temperature of the air above the surface.
· Hypothesize how heat is transferred between the earth’s surface and the air above it.
· Observe and describe the effect of surface temperature on the movement of air above the surface.
· Determine the basic conditions under which water moves through the air.
· Develop working definitions for the terms “stable air mass” and “unstable air mass”.
Getting Started:
1. Go over your homework from Lesson 3, Student Sheet 3.1b: Interpreting a Data Table, with your teacher. As you do, think about the following:
a. What was the temperature of Portland Parklands at 2:00 p.m.?
b. How do you think this temperature might compare with the temperature of the Atlantic Ocean near Portland, Maine, at 2:00 p.m.?
c. How do you think the temperature of the earth’s surface affects the temperature of air above it?
d. How do you think the temperature of the air affects how air moves?
Discuss your ideas with the class.
2. In this lesson, you will investigate how the temperature of a surface affects air temperature, air movement, and the formation of clouds. Your teacher will show you a Convection tube. Brainstorm with your class ways in which you might use the tube to explore this interaction.
Inquiry 4.1: Investigating the Temperature of Air
1. Look over Student Sheet 4.1: Investigating the Temperature of Air as your teacher discusses it. Read the question at the top of the student sheet. You will complete the student sheet as you conduct Inquiry 4.1
2. Observe as your teacher demonstrates the setup and Steps 5 through 12 of the Procedure. Review Figures 4.1 and 4.2 with your teacher at this time.
3. How would you make this investigation a fair test? List your ideas under Question 1 on Student Sheet 4.1.
4. Make a prediction, then record it under Question 2 on the student sheet. Discuss your prediction with your class.
5. Collect your materials. With your group, practice reading the thermometers inside the cylinders. The number on the thermometer highlighted with green is the correct temperature. If two numbers that are not green are highlighted, you can average them.
6. If it has not been done for you, fill one plastic container with hot water and one with ice water (crushed ice).
7. Use the digital thermometer to measure the temperature of the hot water. Also measure the temperature of the crushed ice. Write the temperature for cold and hot water in Table 1 on the student sheet.
8. Before you place each container of water (without its lid) under a Convection Tube record the starting temperatures of both thermometers in both cylinders on Table 1 of the student sheet. Write them across from Time 0:00. (Thermometer A is the top thermometer.)
9. Set your stopwatch at zero. Place the container of hot water under one Convection Tube. Place the container of cold water under the other Convection Tube, as show in Figure 4.1. Then start the stopwatch.
10. Record the changes in temperature in each Convection Tube every minute for 3 minutes in Table 1. If the temperature goes higher than the thermometer’s highest temperature, you can record 30+ C on your data table. (Do not touch the outside of the cylinder. Your hand may affect the temperature readings.)
11. If it gets difficult to see inside the Convection Tube, use a paper towel to remove moisture from the base. Attach a paper towel to a ruler with a rubber band and use this device to clear the cylinder and base, as shown in Figure 4.2. After clearing the convection Tube, you can cover your containers of water or ice with plastic wrap and secure the wrap with a rubber band.
12. Clean up.
Reflecting on What You’ve Done
1. Answer these questions; then discuss your results with the class.
a. How did the temperature of each container of water affect the temperature of the air above it?
b. The movement of heat is called heat transfer. Describe the heat transfer between the container of hot water and the air. Describe the heat transfer between the container of cold water and the air.
c. Under what conditions was it difficult to see through a cylinder? Why do you think this happened?
d. Why do you think covering the container helped to keep the cylinder clear?
2. Read “What’s the Forecast?” on pages 50-53 before Inquiry 4.2 begins.
Inquiry 4.2: Investigating How Warm Air and Cool Air Move
1. Record the purpose of this investigation in your notebook. Write it in the form of a question. Then share it with your group or class. Also share with the class your ideas on how to test this question.
2. Your teacher will demonstrate how to do this investigation. Follow along using Procedure Steps 4 through 9.
3. Make a prediction. How do you think air will move above a hot surface? How do you think air will move above a cold surface? Record your prediction in your notebook. Discuss your ideas with your group or class.
4. Pick up your materials. Set up the Convection Tubes with hot and cold water, as you did in Inquiry 4.1. You will not be recording temperature changes in this investigation. Use the ruler and paper towel to clear the cylinder or cover the containers with plastic wrap.
5. Attach a funnel and tubing to the Convection tube with cold water. (It is very important that you begin with the cold water.)
6. When you are ready, ask your teacher to light your group’s punk stick. Immediately blow it out and hold the smoking punk over the aluminum pan, as shown in Figure 4.3. Hold the funnel at an angle over the punk so the smoke goes inside. Do not touch the funnel with the burning punk.
7. Your teacher will turn off the classroom lights. Use your flashlight to see the smoke particles moving. Hold the flashlight behind the Convection Tube and then at the top of it. Do not cover the opening of the Convection Tube. (See Figure 4.4 [A] and [B].) Kneel down so you can see the smoke at eye level as it enters the Convection Tube. Talk to your partners about how the smoke moves.
8. Move the tubing and funnel to the Convection Tube with hot water. (One member of your group should carefully continue to hold the burning punk.) Clear the cylinder with the ruler and paper towel if needed. Place the punk under the funnel to add smoke to the Convection Tube with hot water. Observe. Use the flashlight to view the smoke.
9. When you have finished observing the Convection Tube with hot water, clean up. Carefully dip just the tip of the punk into a container of water. This will stop the tip from smoldering. Then cut off the wet tip.
Reflecting on What You’ve Done
1. Answer these questions in your science notebook; then discuss them with the class:
a. On the basis of your temperature readings in Inquiry 4.1, how does the temperature of a surface affect the temperature of the air above it?
b. How did the air, which was visible because of the smoke, move in the Convection Tube when the water under it was cold? Explain why you think this happened.
c. What happened to the air inside the Convection Tube when the water was hot? Explain why you think this happened.
d. Why do you think moisture formed on the inside of the Convection Tube with hot water? How do you think this relates to cloud formation on the earth?
e. Apply what you observed in Lesson 4 to the earth. If the earth’s surface is cold, what will happen to the air above it? If the surface is hot, what will happen to the air above it?
2. Read Air Masses,” on page 49.
3. With your teacher’s help, develop working definitions for the terms “stable air mass” and “unstable air mass.” Record your definitions in your science notebook. Apply what you observed in this lesson to cloud formation. When do you think clouds are more likely to form: when stable air remains close to the earth’s surface or when unstable air rises and moves quickly to high altitudes?
4. Look ahead to Lesson 5, in which you will connect two Convection Tubes to investigate what happens when air masses meet.