A false-color image of 2 ppl in long-wavelength infrared (body-temperature thermal) radiation
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Infrared radiation
Infrared radiation
[1] Infrared radiation/Infrared light or just infrared (IR) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves.
Note: Infrared radiation and infrared light are almost the same, both referring to electromagnetic waves of the spectrum's infrared portion.
"Infrared radiation" is often for scientific contexts.
"Infrared light" is often daily used.
Infrared spectral band starts with the waves longer than those of red light (longest waves in the visible spectrum), so we cannot see IR and often (according to ISO, CIE) understood to have wavelengths of ~780 nm (380 THz) to 1 mm (300 GHz, often divided between longer-wavelength thermal IR, emitted from terrestrial sources, and shorter-wavelength IR or near-IR, part of the solar spectrum. Longer IR wavelengths (30–100 μm) are at time included as part of the terahertz radiation band. Almost all black-body radiation from objects near room temperature is in the IR band. As a form of EMR, IR carries energy and momentum, exerts radiation pressure, and has properties corresponding to both those of a wave and of a particle, the photon.
Edme Mariotte
History
History
Fire emits invisible heat; 1681, pioneer experimenter Edme Mariotte shows that glass, by transparent to sunlight, obstructs radiant heat. 1800, astronomer Sir William Herschel found infrared radiation is a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer. A bit more than half of the Sun's energy iseventually found, byHerschel's studies, to come to Earth in form of infrared. Balance between absorbed and emitted infrared radiation has crucial effect on Earth's climate.
References
References
[1] Wikipedia
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