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  2. Infrared - Wikipedia

    en.wikipedia.org/wiki/Infrared

    Infrared radiation is popularly known as "heat radiation", [31] but light and electromagnetic waves of any frequency will heat surfaces that absorb them. Infrared light from the Sun accounts for 49% [32] of the heating of Earth, with the rest being caused by visible light that is absorbed then re-radiated at longer wavelengths. Visible light or ...

  3. Visible spectrum - Wikipedia

    en.wikipedia.org/wiki/Visible_spectrum

    Electromagnetic radiation in this range of wavelengths is called visible light (or simply light). The optical spectrum is sometimes considered to be the same as the visible spectrum, but some authors define the term more broadly, to include the ultraviolet and infrared parts of the electromagnetic spectrum as well, known collectively as optical ...

  4. Electromagnetic spectrum - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_spectrum

    Above infrared in frequency comes visible light. The Sun emits its peak power in the visible region, although integrating the entire emission power spectrum through all wavelengths shows that the Sun emits slightly more infrared than visible light. [15] By definition, visible light is the part of the EM spectrum the human eye is the most ...

  5. Optical window - Wikipedia

    en.wikipedia.org/wiki/Optical_window

    The optical atmospheric window is the optical portion of the electromagnetic spectrum that passes through the Earth's atmosphere, excluding its infrared part; [10] although, as mentioned before, the optical spectrum also includes the IR spectrum and thus the optical window could include the infrared window (8 – 14 μm), the latter is ...

  6. Light - Wikipedia

    en.wikipedia.org/wiki/Light

    Another example is incandescent light bulbs, which emit only around 10% of their energy as visible light and the remainder as infrared. A common thermal light source in history is the glowing solid particles in flames, but these also emit most of their radiation in the infrared and only a fraction in the visible spectrum.

  7. Optical radiation - Wikipedia

    en.wikipedia.org/wiki/Optical_radiation

    Optical radiation is the part of the electromagnetic spectrum with wavelengths between 100 nm and 1 mm. [1] [2] This range includes visible light, infrared light, and part of the ultraviolet spectrum. [3] Optical radiation is non-ionizing, [4] and can be focused with lenses and manipulated by other optical elements.

  8. Sunlight - Wikipedia

    en.wikipedia.org/wiki/Sunlight

    Sunlight is a portion of the electromagnetic radiation given off by the Sun, in particular infrared, visible, and ultraviolet light. On Earth, sunlight is scattered and filtered through Earth's atmosphere as daylight when the Sun is above the horizon.

  9. Photometry (optics) - Wikipedia

    en.wikipedia.org/wiki/Photometry_(optics)

    Infrared and ultraviolet radiation, for example, are invisible and do not count. One watt of infrared radiation (which is where most of the radiation from an incandescent bulb falls) is worth zero lumens. Within the visible spectrum, wavelengths of light are weighted according to a function called the "photopic spectral luminous efficiency."