Definition and Measurement of Color Temperature
– Color temperature is a parameter describing the color of a visible light source.
– It compares the color of light emitted by a light source to that of an idealized opaque, non-reflective body.
– The color temperature of the closest matching ideal emitter is defined as the color temperature of the light source.
– Color temperature is usually measured in kelvins.
– The color temperature scale describes only the color of light emitted by a light source.
Applications of Color Temperature
– Color temperature has applications in lighting, photography, videography, publishing, manufacturing, astrophysics, and other fields.
– It is most meaningful for light sources that correspond to the color of a black body.
– The concept of correlated color temperature extends the definition to any visible light.
– Color temperature is conventionally expressed in kelvins.
– Color temperatures over 5000K are called cool colors, while lower color temperatures are called warm colors.
The Sun
– The Sun closely approximates a black-body radiator.
– The effective temperature of the Sun is 5772K.
– The color temperature of sunlight above the atmosphere is about 5900K.
– The changing color of the Sun during the day is mainly due to the scattering of sunlight.
– Daylight has a spectrum similar to that of a black body with a correlated color temperature of 6500K or 5500K.
Lighting
– Color temperature is important to consider for lighting building interiors.
– A lower color temperature light is often used in public areas to promote relaxation.
– A higher color temperature light is used to enhance concentration, for example in schools and offices.
– CCT dimming for LED technology is regarded as a difficult task.
– Feedback loop systems are used to actively monitor and control the color output of multiple color mixing LEDs.
Aquaculture
– Color temperature is of concern in fishkeeping, particularly in freshwater and saltwater/reef aquariums.
– In freshwater aquaria, color temperature is important for producing an attractive display.
– In saltwater/reef aquariums, color temperature is essential for tank health and sustaining coral.
– Light of shorter wavelength can penetrate deeper into water, providing essential energy sources to algae and coral.
– Simulating the natural color temperature of tropical sunlight (around 6500K) is often desired in reef aquariums. Source: https://en.wikipedia.org/wiki/Color_temperature
This article needs additional citations for verification. (June 2012) |
Color 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. The temperature of the ideal emitter that matches the color most closely is defined as the color temperature of the original visible light source. Color temperature is usually measured in kelvins. 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.
Color temperature has applications in lighting, photography, videography, publishing, manufacturing, astrophysics and other fields. 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. 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. Color temperature is conventionally expressed in kelvins, using the symbol K, a unit for absolute temperature.
Color temperatures over 5000 K are called "cool colors" (bluish), while lower color temperatures (2700–3000 K) are called "warm colors" (yellowish). "Warm" in this context is with respect to a traditional categorization of colors, not a reference to black body temperature. The hue-heat hypothesis states that low color temperatures will feel warmer while higher color temperatures will feel cooler. The spectral peak of warm-colored light is closer to infrared, and most natural warm-colored light sources emit significant infrared radiation. The fact that "warm" lighting in this sense actually has a "cooler" color temperature often leads to confusion.
