By Susan M. Frack and Scott Prickett
The change in air masses of the atmosphere results in the “weather”. There is no place on earth that is exempt from such changes. The sun is the source of energy that is responsible for these changes. As the earth revolves around the sun and rotates on its own axis, the intensity of the sun’s energy varies. Although the tilt of the earth ‘s axis is constant, the position of this axis is constant, the position of this axis in relationship to the sun is what varies the intensity of the energy to create the seasons. When the axis is tilted toward the sun, the hemisphere experiences summer. When tilted away, the hemisphere experiences winter. The daily rotation is responsible for smaller scale unequal heating causing small scale variations in weather such as land/sea breezes or thunderstorms.
By studying these changes in the atmosphere one can hope to earn how to predict these changes and thus make life more comfortable. One tool used for this study is a thermometers. It is essential to understand its use to be able to keep track of heat transfers over the planet. Processes involved in heat transfer include: conduction, convection, and evaporation and condensation. It is important to understand these processes because it is not the sun that directly heats the atmosphere but rather the transformation of solar energy by the earth itself that heats the atmosphere.
Knowing how and in what quantities solar energy reaches the earth as well as how solar energy changes after it reaches the earth’s surface will allow weather to be more understandable and less mysterious!!
- 2 lab pans
- very warm water
- black paper
- white paper
- hot plate
- battery powered fan
- foil pans
- food color
- foam cups
- eye droppers
- heat lamp
- clear plastic shoe boxes
- Nat. Sci. Obj.
- 1. Compare heat and temperature
- 2. Name and describe 3 methods of heat transfer; conduction, convection, evaporation-condensation.
- 3. Explain what happens to solar energy after it travels through the atmosphere and reaches the earth.
- 4. Demonstrate use of max/min thermometers and use it to keep record of local temps for 2 weeks.
Nebraska Frameworks Obj.: I-1, I-3, I-5
1. Set up the following 3 pans of water:
- a. ice/water mixture
- b. tap water
- c. hottest water you can put your hands in
Have the students put 1 hand in pan “a” and 1 hand in pan “c” for 1 minute. Remove hands and dry quickly. Then put both hand in pan “b”. Have them discuss how each hand now feels.
2. After their hands have returned to “normal”, have students record the room temperature. Then have them move about the room and touch a variety of objects--metal, plastic, wood, etc.--to get an idea of these items temperature/heat. They should record their observations--feels warm, cold, neither, etc. Then they should try to rank the way the items felt from warmest to coldest. Theoretically, all the items should feel the same because they are all in the same room with the same air temperature. Discuss their differences and lead them to question the differences in the way the objects felt and why.
3. Through their questions and discussions as well as needed research, lead the students to an understanding of heat, temperature, and how they relate to each other. Students should then write an essay/paper comparing heat and temperature.
Use the ice/hot water demonstration to lead into a discussion of methods of heat transfer in the atmosphere and on earth. Define conduction, convection, and the evaportion-condensation cycle if necessary. Divide the class into 3 groups and assign each group one of the 3 transfer methods. Have them develop a demonstration/experiment that shows their method of heat transfer. Use the “Mission Impossible--Heat Transfer” worksheet. Have the groups present their experiment/demo to the other groups. Each student will need to watch them closely s they will need to come up with three questions about each of the demos they have watched. The questions should be conclusion-type that can be answered by observing what happened in the demonstrations they watched.
1. Set up demonstration to illustrate that the earth only receives 1/2 of 1 billionth of the sun’s energy every second: (you may need to go into the gym for this)
- set up a fake fire in the center of the room (sun)
- arrange the students in a circle that is 30 meters away from the fire.
- tell the students that they are mosquitoes ( earths). Ask them to estimate how much of the fire light they are receiving and write it down.
- collect the slips and have students tabulate them from largest to smallest Post results.
2. Return to the classroom for discussion. Have students do research to find out how much energy the earth actually receives or just tell them: 1/2 of 1 billionth is actually 180 quadrillion watts or as much as 1.8 quadrillion 100-watt light bulbs all shining at the same time!! YIKES!! Use this to talk about just how powerful the sun is. Talk about the accuracy of their guesses as well.
3. Lead into a discussion of exactly what does the earth and atmosphere do with these 180 quadrillion watts of energy every second:
- 30% is reflected before it ever reaches the earth’s surface--by clouds and other particles in the atmosphere.
- 20 % is absorbed by the clouds and other particles in the atmosphere
- 50 % is absorbed by the surfaces of the earth.
Ask what types of surfaces do they feel would make good absorbers and which surfaces would make good reflectors. Make lists, rank the contents from best to worst and save them to use after the investigation. Complete the investigation, “Radiant Energy and Temperature’--Appendix A.
4. Process the investigation and lead into a discussion of “albedo”--percentage of radiant energy reflected back into space. Discuss why some surfaces are better reflectors than absorbers. Have students write answers to the following questions:
- Ice and clouds have high albedos and the lowest temperatures. Explain.
- Plowed land, grass and forests have low albedos, also lower temperatures. Why?
- Concrete, sand, asphalt roads have medium to low albedos, but high temperatures. Why?
1. Have students research the history of thermometers as well as the different types of thermometers, thermostats, thermocouples, and thermisistors. Use Internet as well as more traditional resources. Parameters of research:
- What is a thermometer?
- development of a thermometer and temperature scales
- explain why different types of thermometers are necessary
- explain the primary uses of each type of thermometer
Have students prepare either oral or written reports or any other type of project you like.
2. Review/teach how to use the max/min thermometer, using the directions that come with it. Have students record data for 2 weeks.
lab on “Water Thermometers”--Appendix B
A. Students produce a 1-2 page newspaper detailing:
- heat transfer
- solar radiation
- heat/temperature and how to measure them
B. Create a hyper-studio project detailing the same topics listed above.
C. Put a page on the Web that details the same topics.
You and your fellow Impossible Weather Forces have been assigned the concept of “Heat Transfer in the Atmosphere”. You must design and carry out a demonstration/experiment that illustrates this concept. You may use any or all of the materials on your list to carry out your project. As you show your experiment to the remainder of the forces, you must also orally explain what is going on and be able to try to answer any of their questions. BEWARE!! You must also be able to defend your choice of materials, method, and observations to your instructor. Take care as “saboteurs” are lurking in the shadows where you least expect them.
As always, should you or any of your Impossible Weather forces fail,or be caught with incorrect information, this office and your instructor will disavow any knowledge of your existence. Thank-you and Good Luck! This paper will self-destruct in 5 seconds--
MATERIALS AVAILABLE FOR YOUR USE:
|funnels||clear plastic shoe boxes*|
|black paper||white paper|
|beakers||battery powered fan|
|food color||foam cups|
|personal safety goggles|
OUTLINE YOUR PLAN:
RADIANT ENERGY AND SURFACE TEMPERATURE
ADAPTED FROM: Prentice Hall Earth Science, Prentice Hall, Inc., 1991
Do different earth surfaces reflect/absorb energy from the sun equally well?
- 12 thermometers per group
- stop watches
- container for water--flat plastic pan works well
- graph paper
- colored pencils
- Place a thermometer on the grass in the sun. Place a second thermometer on the grass in the shade. Follow this same procedure for the remaining surfaces listed on the chart.
- Begin timing. After 2 minutes, record the temperature of each surface. Leave the thermometers sit for 18 more minutes. Then record the final temperature.
- Graph each surface on the same graph. Use a different color for each of the 6 surfaces.
- Compare results and answer conclusions.
- Which surface Was the warmest? Why?
- Which surface was the coolest? Why?
- Compare the temperatures in the shade to the temperatures in the sun for each surface:
- What conclusions can you reach about the amount of heat energy different surfaces absorb in the sun?
- In what ways does the relationship between type of surface and amount of heat absorbed affect peoples lives?
- A glider is a kind of plane that flies without an engine. In order for it to stay in the air, the glider pilot looks for large, paved areas or plowed fields to fly over. Why?
- How could a large, light-colored area of land and a nearby dark-colored area of land create wind on a sunny day?
- Water in a lake feels cool during the day but warm at night. Explain.
WATER THERMOMETERS BACKGROUND:
A thermometer measures the average speed of all moving molecules at particular moment. This measurement indicates a change in temperature when a body adds or loses heat energy. Fast moving molecules increase the temperature reading, and slow moving molecules lower it. The expansion and contraction of molecules greatly influences weather conditions.
To build and test a colored-water thermometer.
- Erlenmeyer flask
- food coloring
- Bunsen burner
- glass tubing, 2 pieces--2 feet long, each piece
- one-hole stopper
- ringstand and clamp
- masking tape
- safety goggles
- Fill a flask with water and add food coloring.
- Heat a 15”-18” piece of glass tubing until it can be bent into a U-shape.
- Insert one end of the tubing into the hole of the stopper. The tubing should slide through the stopper until the end barely protrudes the other end.
- Press the stopper into the flask, invert and support with the clamp to the ring stand
5. Observe the water level in the tube. Place a thin strip of masking tape on the tube at the water level.
- Put your hand over the bottom of the flask:
- What happens to the water level?
- What caused the water level to move?
- Take your had off the flask.
- What happens to the water level?
- What causes the water level to move?
- Does the activity measure the average speed of all moving molecules?_______ Why or why not?
- Does the activity indicate a change in temperature when a body adds or loses heat energy? _______________ Why or why not/
- What does the activity show regarding the water level in the tube?
- Place the flask with colored water inside it in a large empty beaker.
- Insert a 2-foot piece of glass tubing into the a one-hole stopper. Place the stopper on the flask.
- Now test what effect, if any, the following conditions have on the water leverl in the tube:
- Add ice water to the beaker. Be sure to keep the neck of the flask above the waterline. Effect?
- Remove ice water and add hot tap water to the beaker. Effect?
- Using warm, colored water in the flask, add the ice water to the beaker. Effect?
- Using warm. colored water in the flask, add hot tap water to the beaker. Effect?