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How Greenhouse Gases Work
Before beginning an experiment on the greenhouse effect, it is important to discuss the vital role greenhouse gases play in global climate. Greenhouse gases work by trapping heat reflected from the sun in Earth's atmosphere. Without the greenhouse effect, Earth's temperature would be too cold to sustain life, but scientists contend that an overabundance of these gases (carbon dioxide, methane, nitrous oxide, ozone and water vapor) could cause the Earth's temperature to rise to levels unbearable to life as we know it.
Supplies
To demonstrate the greenhouse effect, you will need a large glass bowl, a dark cloth large enough to cover the inside of the bowl, a thermometer, plastic wrap and a small block of wood. You also will need access to a heat source. The experiment can be conducted outside on a sunny day or using a heat lamp in the classroom.
Method
Cover the inside of the bowl with the cloth, then set the wooden block in the center of the bowl. Rest the thermometer on top of the wooden block, and place the bowl under your heat source for one hour. Record the temperature readings, then tightly seal the opening of the bowl with plastic wrap, and place it back under your heat source. Remain with the bowl this time, and watch as the temperature in the bowl rises in a matter of only minutes. Remove the thermometer from the bowl when its reaches capacity, record the temperature and discuss your findings.
Results
In this experiment the bowl represents Earth, and the dark cloth represents Earth's surface. The first measurement represents the temperature of the air inside the bowl. The plastic wrap represents the greenhouse effect. When the bowl is sealed, the plastic wrap acts in much the same way as greenhouses gases do. The sun reflects off the surface of the Earth (dark cloth) and bounces back up. Greenhouse gases (plastic wrap) trap the heat, and keep it inside the atmosphere (the bowl), drastically raising the temperature.