The
color temperature of a light source is the
temperature of an ideal
black-body radiator that radiates light of comparable
hue to that of the light source. Color temperature is a characteristic of
visible light that has important applications in
lighting,
photography,
videography,
publishing,
manufacturing,
astrophysics,
horticulture, and other fields. In practice, color temperature is only meaningful for light sources that do in fact correspond somewhat closely to the radiation of some black body, i.e., those on a line from reddish/orange via yellow and more or less white to blueish white; it does not make sense to speak of the color temperature of, e.g., a green or a purple light. Color temperature is conventionally stated in the unit of absolute temperature, the
Kelvin, having the unit symbol K.