Color temperature describes the actual spectrum of white light. It is comparable to light radiated from a so-called blackbody that is heated up. With the heating the body becomes red hot and with further increasing temperature white hot. With different temperatures the emitted white light differs. The white light don't necessarily contains an even distribution over the entire light spectrum but can be combined by different spectral parts.

blackbody color temperatures

A low color temperature shifts light toward red, a high color temperature shifts light toward blue, with increasing color temperature it shifts more to higher frequencies (shorter wave lengths) containing higher energy.

The color emitted from a tungsten lamp is comparable to the yellow-white glow of a blackbody radiator with a temperature is approximately 3200 degrees Kelvin. With a temperature of about 5500 kelvin the white light is identical to the white light of the sun at midday. The evening twilight just before dark is similar to about 12.000 kelvin.

The standard color temperature for TV lighting is 3.200 kelvin. This is considerably lower than average daylight.