Editing Greenhouse effect (section)

=== Outgoing longwave radiation ===
[[File:Spectral Greenhouse Effect.png|thumb|upright=1.35|The greenhouse effect is a reduction in the flux of outgoing longwave radiation, which affects the planet's radiative balance. The spectrum of outgoing radiation shows the effects of different greenhouse gases.]]
The Earth and its atmosphere emit ''longwave radiation'', also known as ''thermal infrared'' or ''terrestrial radiation''.<ref name="IPCC" />{{rp|2251}} Informally, longwave radiation is sometimes called ''thermal radiation''. [[Outgoing longwave radiation]] (OLR) is the radiation from Earth and its atmosphere that passes through the atmosphere and into space.

The greenhouse effect can be directly seen in graphs of Earth's outgoing longwave radiation as a function of frequency (or wavelength). The area between the curve for longwave radiation emitted by Earth's surface and the curve for outgoing longwave radiation indicates the size of the greenhouse effect.<ref name="Schmidt2010"/>

Different substances are responsible for reducing the radiation energy reaching space at different frequencies; for some frequencies, multiple substances play a role.<ref name="Schmidt2010paper">{{cite journal |last1=Schmidt |first1=G. A. |last2=Ruedy |first2=R. A. |last3=Miller |first3=R. L. |last4=Lacis |first4=A. A. |title=Attribution of the present-day total greenhouse effect |journal=Journal of Geophysical Research |date=2010 |volume=115 |issue=D20 |doi=10.1029/2010JD014287 |bibcode=2010JGRD..11520106S |url=https://pubs.giss.nasa.gov/docs/2010/2010_Schmidt_sc05400j.pdf |access-date=14 June 2023}}</ref> Carbon dioxide is understood to be responsible for the dip in outgoing radiation (and associated rise in the greenhouse effect) at around 667&nbsp;cm<sup>−1</sup> (equivalent to a wavelength of 15 microns).<ref name="wijng">{{cite journal |last1=van Wijngaarden |first1=W. A. |last2=Happer |first2=W. |title=Dependence of Earth's Thermal Radiation on Five Most Abundant Greenhouse Gases |journal=Atmospheric and Oceanic Physics |date=2020 |arxiv=2006.03098 |url=https://wvanwijngaarden.info.yorku.ca/files/2020/12/WThermal-Radiationf.pdf?x45936 |url-status=live |archive-url= https://web.archive.org/web/20230508080935/https://wvanwijngaarden.info.yorku.ca/files/2020/12/WThermal-Radiationf.pdf?x45936 |archive-date= 8 May 2023 }}</ref>

Each layer of the atmosphere with greenhouse gases absorbs some of the longwave radiation being radiated upwards from lower layers. It also emits longwave radiation in all directions, both upwards and downwards, in equilibrium with the amount it has absorbed. This results in less radiative heat loss and more warmth below. Increasing the concentration of the gases increases the amount of absorption and emission, and thereby causing more heat to be retained at the surface and in the layers below.<ref name="IPCC4_ch012" />