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The greenhouse effect on Earth is defined as: "The infrared radiative effect of all infrared absorbing constituents in the atmosphere.Greenhouse gases (GHGs), clouds, and some aerosols absorb terrestrial radiation emitted by the Earth’s surface and elsewhere in the atmosphere."
Greenhouse gases are infrared active, meaning that they absorb and emit infrared radiation in the same long wavelength range as what is emitted by the Earth's surface, clouds and atmosphere. [19]: 2233 99% of the Earth's dry atmosphere (excluding water vapor) is made up of nitrogen (N 2) (78%) and oxygen (O 2) (21%).
Carbon dioxide is a greenhouse gas. It absorbs and emits infrared radiation at its two infrared-active vibrational frequencies. The two wavelengths are 4.26 μm (2,347 cm −1 ) (asymmetric stretching vibrational mode ) and 14.99 μm (667 cm −1 ) (bending vibrational mode).
A few examples of the major greenhouse gases are water, carbon dioxide, methane, nitrous oxide, ozone, and CFCs. These gases can absorb infrared radiation from the Earth's surface as it passes through the atmosphere. The most influential greenhouse gas is water vapor. It frequently occurs in high concentrations, may transition to and from an ...
An exact calculation using the MODTRAN model, over all wavelengths and including methane and ozone greenhouse gasses, as shown in the plot above, gives, for tropical latitudes, an outgoing flux = 298.645 W/m 2 for current CO 2 levels and = 295.286 W/m 2 after CO 2 doubling, i.e. a radiative forcing of 1.1%, under clear sky conditions, as well ...
The atmosphere envelops the earth and extends hundreds of kilometres from the surface. It consists mostly of inert nitrogen (78%), oxygen (21%) and argon (0.9%). [4] Some trace gases in the atmosphere, such as water vapour and carbon dioxide, are the gases most important for the workings of the climate system, as they are greenhouse gases which allow visible light from the Sun to penetrate to ...
Greenhouse gases in the atmosphere are responsible for a majority of the absorption of longwave radiation in the atmosphere. The most important of these gases are water vapor, carbon dioxide, methane, and ozone. [22] The absorption of longwave radiation by gases depends on the specific absorption bands of the gases in the atmosphere. [19]
On Earth, carbon dioxide is the most relevant, direct greenhouse gas that is influenced by human activities. Water is responsible for most (about 36–70%) of the total greenhouse effect, and the role of water vapor as a greenhouse gas depends on temperature. Carbon dioxide is often mentioned in the context of its increased influence as a ...