It is a measurement of the color of white light, expressed in degrees Kelvin. (The Kelvin scale is a measure of temperature, starting from absolute zero.) The color temperature is the color of light a perfect black-body radiator emits when heated to the temperature. Computer monitors typically have a color temperature of 5000-9300 Kelvins : 5000 Kelvins is a yellow-white, 9300 Kelvins is a blue-white. A color temperature of 6500 Kelvin stands for daylight at noon.