Color temperature
From The Glossary of Digital Photography
Describes the color of a light source by measuring the temperature in kelvins. Note that this is not degrees kelvin. Although there are many references to degrees kelvin, or 0K, the proper terminology is simply K. Daylight has a color temperature of 5500 K, and tungsten bulbs can produce light with a temperature of either 3200 K or 3400 K, depending on the type of bulb. Temperatures above 5500 K have a bluish tint, those below have more of a reddish look. By adjusting the white balance of the camera to a temperature close to that of the light source, the colors in the scene remain natural looking. There are special meters available that can measure the color temperature of a scene or light source. See also Kelvin
