English: This chart shows the intensity as a function of frequency for longwave (LW) radiation emitted by Earth’s surface (SLR) and outgoing LW radiation emitted to space (OLR). The difference between these, the intensity of radiation emitted by the surface but not reaching space, is referred to as the greenhouse effect (GHE).

The strength of the greenhouse effect varies with frequency (or wavelength). The greenhouse effect at different frequencies is associated with different greenhouse gases.

The particular version of the figure is base on modeling the propagation of longwave thermal radiation through Earth’s atmosphere. However, observation data looks quite similar.

Quantities

• The X-axis plots frequency divided by the speed of light, a quantity conventionally called “wavenumber.”

• The value plotted on the Y-axis goes by various names, including spectral irradiance

Similar figures This work was inspired by similar figures such as these:

• NASA Taking the Measure of the Greenhouse Effect Gavin Schmid
• Greenhouse Effect Basics: Warm Earth, Cold Atmosphere Tom Curtis
• Dependence of Earth’s Thermal Radiation on Five Most Abundant Greenhouse Gases by W. A. van Wijngaarden and W. Happer

Similar observational data

• FIRST (Far-Infrared Spectroscopy of the Troposphere)

Additional references

An early reference defining the GHE as surface longwave emissions minus outgoing longwave emissions was:

• Raval, A.; Ramanathan, V. (1990). “Observational determination of the greenhouse effect“. Proceedings of the Brookhaven National Laboratory Workshop: 5–16.

This definition is also alluded to in IPCC AR6 WG1 p. 968.

Credit

This is a derived word based on File:Spectral OLR.png by Lukas Kluft, CC BY-SA 4.0, via Wikimedia Commons.