Editing Infrared (section)

== Nature ==

[[Sunlight]], at an effective temperature of 5,780&nbsp;[[Kelvin|K]] (5,510&nbsp;°C, 9,940&nbsp;°F), is composed of near-thermal-spectrum radiation that is slightly more than half infrared. At [[zenith]], sunlight provides an [[irradiance]] of just over 1&nbsp;[[kW]] per square meter at sea level. Of this energy, 527 W is infrared radiation, 445 W is visible light, and 32 W is [[ultraviolet]] radiation.<ref>{{Cite web |title=Reference Solar Spectral Irradiance: Air Mass 1.5 |url=http://rredc.nrel.gov/solar/spectra/am1.5/ |url-status=live |archive-url=https://web.archive.org/web/20190512190812/https://rredc.nrel.gov/solar//spectra/am1.5/ |archive-date=2019-05-12 |access-date=2009-11-12}}</ref> Nearly all the infrared radiation in sunlight is near infrared, shorter than 4 μm.

On the surface of Earth, at far lower temperatures than the surface of the Sun, some thermal radiation consists of infrared in the mid-infrared region, much longer than in sunlight. Black-body, or thermal, radiation is continuous: it radiates at all wavelengths.  Of these natural thermal radiation processes, only lightning and natural fires are hot enough to produce much visible energy, and fires produce far more infrared than visible-light energy.<ref>{{Cite web |title=Blackbody Radiation &#124; Astronomy 801: Planets, Stars, Galaxies, and the Universe |url=https://www.e-education.psu.edu/astro801/content/l3_p5.html |url-status=live |archive-url=https://web.archive.org/web/20190501191803/https://www.e-education.psu.edu/astro801/content/l3_p5.html |archive-date=2019-05-01 |access-date=2019-02-12}}</ref>