The Greenhouse Effect (page 2)
Try New Approaches
- What effect do surface materials have on the greenhouse effect? Repeat the original experiment, preparing boxes with different surfaces by covering the soil with different materials, such as sand, rocks, and grass. A surface of water could be prepared by lining the box with plastic and filling it with about 2 inches (5 cm) of water instead of soil. Science Fair Hint: Display photographs of the various boxes with the results of the experiment. Include a display, such as the one shown in Figure 42.2, indicating the percentage of radiant energy reflected back into space. For information about reflected radiant energy, see radiation in Jack Williams's The Weather Book, second edition (New York: Vintage Books, 1997).
- What is the relationship between the greenhouse effect and surface temperatures at night, in the absence of the Sun's radiant energy? Repeat the original experiment, taking temperature readings while the boxes are in direct sunlight outdoors. Then after dark, again take readings from both thermometers every 15 minutes for 1 hour.
- Could the composition of the atmosphere affect its ability to trap infrared energy? Compare different materials for their ability to trap infrared energy. Repeat the original experiment using plastic wrap and other materials, such as waxed paper, clear Plexiglas, and glass. Science Fair Hint: Display samples of the box covers with the results of the experiment.
- Density is the mass of a substance per unit volume. The greater the density of a substance, the closer together its particles. How does the density of the atmosphere affect its ability to trap infrared energy? Repeat the previous experiment twice, first using two layers of covering material, then using three layers. Science Fair Hint: Compare the results of the experiment to surface environments on celestial bodies with little or no atmosphere, such as the Moon and Mars, and those with a dense atmosphere, such as Venus. Use an astronomy text to find out about the atmosphere of the different celestial bodies. Make charts showing the composition and density of their atmosphere and surface environment.
Design Your Own Experiment
- Design a way to determine how the Earth's atmosphere affects the surface air temperature at night. One way is to record air temperature at sunset and again at sunrise for one or more weeks in a Day and Night Temperature Data table similar to Table 42.1. Calculate the difference between the two temperatures each day, and determine an average by adding the differences and dividing by the total number of days. Note: Your temperature measurements should be taken during a time of a constant weather pattern.
- Repeat the previous experiment during a onemonth time span to determine how cloud cover affects surface temperature during the night. Do this by recording air temperature during cloudy and noncloudy periods. On four or more days on which the weather forecast calls for the same amount of nighttime cloud cover, record the temperature at sunset and again at sunrise. Repeat by recording the day and night temperatures on four or more days with little or no nighttime cloud cover. Use the results to determine how the presence or absence of clouds in the troposphere leads to more heat escaping to space, thus causing a greater decrease in nighttime temperature.
Get the Facts
Carbon dioxide, one of the greenhouse gases, is responsible for much of the warming of the Earth. Some scientists predict a rise in the average temperature of the Earth if the amount of carbon dioxide in the atmosphere continues to increase. Find out more about the production of carbon dioxide. How do fossil fuel emissions and deforestation affect the level of carbon dioxide in the atmosphere? What is insolation and how does it affect global warming? For information about the greenhouse effect and greenhouse gases, see Janice VanCleave's Ecology for Every Kid (New York: Wiley, 1996), pp. 139–146.
Warning is hereby given that not all Project Ideas are appropriate for all individuals or in all circumstances. Implementation of any Science Project Idea should be undertaken only in appropriate settings and with appropriate parental or other supervision. Reading and following the safety precautions of all materials used in a project is the sole responsibility of each individual. For further information, consult your state’s handbook of Science Safety.