What is the relationship between light source spectrum and color temperature?

Color temperature is an index of spectral energy distribution, with high color temperature and slightly more spectral energy components distributed in short wave and blue. The color temperature is low, the spectral energy is slightly distributed in the long wave, and the color is yellow. So the color temperature does not represent the color of light, but the spectral energy distribution of mixed light, which is mostly used for white light. Color light is pure color light, which has its characteristic spectrum and wavelength, and its energy is concentrated in a specific spectrum.

Lumen is the unit of luminous flux, which is often used to characterize the luminous intensity of light source.

Related to it are the illumination unit (lux) and the brightness unit (Cantera).