The term color temperature is widely used – and often misused in illumination work. It relates to the color of a completely radiating (black body) source at a particular temperature and of light sources that color-match such a body. The color temperature of a light source is the absolute temperature of a blackbody radiator having a color equal to that of the light source. Its correlated color temperature is the absolute temperature of a blackbody whose color most nearly resembles that of the light source.
If you would insert an iron rod, (a theoretical black body, or a perfect radiator) into a fire, the iron rod begins to heat up. As the rod heats up, the rod begins to change color. As the rod gets hotter and hotter the rod begins to glow. The hotter the rod, the brighter and the lighter the color appears. When this rod reaches the exact color of a common household incandescent light bulb, it is said to give off all its energy at 2700 degrees Kelvin.
If you leave the rod in the fire, and the fire is made hotter, the color of the rod leaves the warm glow of incandescence and brightens to a point higher up the Kelvin level. When the rod reaches a color of a cool white lamp, it is said to give off all its energy at 4,000 degrees Kelvin, etc. If you continue to heat the rod, what happens? The rod will finally reach a white color equal to 5,000 degrees Kelvin and higher.
The blue sky you see on a normal clear day is approximately 7,500 degrees Kelvin.
Vi-Tek 93® Plus, at 6700 degrees Kelvin, is the brightest fluorescent lamp on the market with a high color rendering of 93. Experts agree that the higher lumen output, higher color rendering and the higher Kelvin temperature allows people to see color almost as it would be outside in the daylight. Better to determine contrast, and affords a much more comfortable work environment.