An incandescent lamp's light is thermal radiation, and the bulb approximates an ideal black-body radiator, so its color temperature is essentially the temperature of the filament. To the extent that a hot surface emits thermal radiation but is not an ideal black-body radiator, the color temperature of the light is not the actual temperature of the surface. This permits the definition of a standard by which light sources are compared. The color temperature of the electromagnetic radiation emitted from an ideal black body is defined as its surface temperature in kelvins, or alternatively in micro reciprocal degrees (mired). K indicates the color temperature in kelvins, and M indicates the color temperature in micro reciprocal degrees. The vertical axes of Planck's law plots building this animation were proportionally transformed to keep equal areas between functions and horizontal axis for wavelengths 380–780 nm. wavelength (λ) curves for the visible spectrum. Tubular fluorescent lamps or cool white/daylight Warm white compact fluorescent and LED lamps "Soft white" compact fluorescent and LED lamps Match flame, low pressure sodium lamps (LPS/SOX) The fact that "warm" lighting in this sense actually has a "cooler" color temperature often leads to confusion. The spectral peak of warm-colored light is closer to infrared, and most natural warm-colored light sources emit significant infrared radiation. The hue-heat hypothesis states that low color temperatures will feel warmer while higher color temperatures will feel cooler. "Warm" in this context is with respect to a traditional categorization of colors, not a reference to black body temperature. Color temperature is conventionally expressed in kelvins, using the symbol K, a unit for absolute temperature.Ĭolor temperatures over 5000 K are called "cool colors" (bluish), while lower color temperatures (2700–3000 K) are called "warm colors" (yellowish). Although the concept of correlated color temperature extends the definition to any visible light, the color temperature of a green or a purple light rarely is useful information. In practice, color temperature is most meaningful for light sources that correspond somewhat closely to the color of some black body, i.e., light in a range going from red to orange to yellow to white to bluish white. The color temperature scale describes only the color of light emitted by a light source, which may actually be at a different (and often much lower) temperature.Ĭolor temperature has applications in lighting, photography, videography, publishing, manufacturing, astrophysics and other fields. Color temperature is usually measured in kelvins. The temperature of the ideal emitter that matches the color most closely is defined as the color temperature of the original visible light source. The CIE 1931 x,y chromaticity space, also showing the chromaticities of black-body light sources of various temperatures ( Planckian locus), and lines of constant correlated color temperature.Ĭolor temperature is a parameter describing the color of a visible light source by comparing it to the color of light emitted by an idealized opaque, non-reflective body. JSTOR ( June 2012) ( Learn how and when to remove this template message). Unsourced material may be challenged and removed.įind sources: "Color temperature" – news Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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