greenhouse effect

noun

1. an atmospheric heating phenomenon, caused by short-wave solar radiation being readily transmitted inward through the earth’s atmosphere but longer-wavelength heat radiation less readily transmitted outward, owing to its absorption by atmospheric carbon dioxide, water vapor, methane, and other gases; thus, the rising level of carbon dioxide is viewed with concern.
2. such a phenomenon on another planet.

noun

1. an effect occurring in greenhouses, etc, in which radiant heat from the sun passes through the glass warming the contents, the radiant heat from inside being trapped by the glass
2. the application of this effect to a planet’s atmosphere; carbon dioxide and some other gases in the planet’s atmosphere can absorb the infrared radiation emitted by the planet’s surface as a result of exposure to solar radiation, thus increasing the mean temperature of the planet

1. The retention of part of the Sun’s energy in the Earth’s atmosphere in the form of heat as a result of the presence of greenhouse gases. Solar energy, mostly in the form of short-wavelength visible radiation, penetrates the atmosphere and is absorbed by the Earth’s surface. The heated surface then radiates some of that energy into the atmosphere in the form of longer-wavelength infrared radiation. Although some of this radiation escapes into space, much of it is absorbed by greenhouse gases in the lower atmosphere, which in turn re-radiate a portion back to the Earth’s surface. The atmosphere thus acts in a manner roughly analagous to the glass in a greenhouse, which allows sunlight to penetrate and warm the plants and soil but which traps most of the resulting heat energy inside. The greenhouse effect is essential to life on Earth; however, the intensification of its effect due to increased levels of greenhouse gases in the atmosphere is considered to be the main contributing factor to global warming.