Friday, June 08, 2001
Understanding global warming
By USA Today
Earth needs the greenhouse effect
Greenhouse gasess are those in the air that absorb some of the infrared radiation the Earth gives off. This warms the gases and the surrounding air. The gases also radiate infrared energy back to the Earth. The greenhouse gases help control the Earth's temperature.
The air near the surface of the earth is a mixture of gases with nitrogen being the most common and oxygen the second most common. Nitrogen accounts for 78.08% of the volume of the gas in the air and oxygen for 20.95%. The remaining 0.97% is accounted for by several other gases including carbon dioxide and water vapor, the two most important greenhouse gases.
Enhanced greenhouse effect
The greenhouse effect that could cause climate change is the "enhanced greenhouse effect". It works the same way as the natural greenhouse effect, but the extra carbon dioxide and other gases that we release into the atmosphere help increase the amount of energy that becomes trapped.
To understand how the natural greenhouse effect can impact the climate of a planet, we can look to our two heavenly neighbors, Venus and Mars. Venus, with a thick atmosphere of carbon dioxide and a "runaway greenhouse effect", has an average surface temperature of 900 degrees Fahrenheit. Mars, with a thin atmosphere of carbon dioxide and virtually no greenhouse effect, has a mean surface temperature of -80 degrees Fahrenheit. Earth seems to have an atmosphere and greenhouse effect that are just right for creating prime conditions for life.
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