Many chemical compounds in the atmosphere act as greenhouse gases These gases allow sunlight (shortwave radiation) to freely pass through the Earth's atmosphere and heat the land and oceans The warmed Earth releases this heat in the form of infrared light (longwave radiation), invisible to human eyes1 Some of theMuch like the glass of a greenhouse, gases in Earth's atmosphere sustain life by trapping the sun's heat These "greenhouse gases" allow the sun's rays to pass through and warm the planet but prevent this warmth from escaping the atmosphere into space Without them, Earth would be too cold to sustain life as we know it greenhouse gas, any gas that has the property of absorbing infrared radiation (net heat energy) emitted from Earth's surface and reradiating it back to Earth's surface, thus contributing to the greenhouse effect Carbon dioxide, methane, and water vapour are the most important greenhouse gases Esrl Global Monitoring Laboratory Educ...