What is color temperature?

Color temperature is a characteristic of visible light used to describe the relative “warmness” and “coolness” of the light.  Incandescent lights are considered warm because they have a lower color temperate.  Color temperatures range from a low red on up to yellow, then white, then blue and then purple.  Lights with a high color temperature have a tendency to bu more luminous.  In HID Xenon lights start at 3000K (Kelvin) for fog lamps.  Most HID lights are about 5000K to 6000K which is basically white or a white-bluish color.