Phenomenon whereby the surface and the lower atmosphere of a planet are maintained at a relatively high temperature owing to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation from the planet. It is so-called because the heating of Earth's atmosphere is loosely analogous to the glass of a greenhouse letting light in but not letting heat out. The term is often used to refer specifically to the increased magnitude of this effect occurring in the modern age in the context of global warming: Gases from the burning of fossil fuels and other sources, including water vapor, carbon dioxide, methane, and chlorofluorocarbons, absorb infrared radiation and prevent its energy from leaving the Earth, resulting in the increasing mean global surface temperature.
