Greenhouse gases
| The atmosphere of the Earth acts in a very similar way to a greenhouse. Sunlight penetrates the transparent air and causes the ground to warm. The atmosphere then acts as a blanket, keeping the warmth of the Earth from escaping back into space. This effect is due to certain gases in the atmosphere which are very good at absorbing and re-radiating the heat energy before it is lost to space. These gases, called "greenhouse gases", include carbon dioxide, water vapor, and methane. Without the greenhouse effect, the entire planet would be much colder, by about 63 degrees Fahrenheit (35 degrees Celsius), than it presently is. |
Credit: NASA
For more info: http://asd-www.larc.nasa.gov/Outreach/greenhouse/greenhouse.html