Color temperature is the technical term for measuring the color of light. The Kelvin Temperature scale is used. The term “temperature” is a touch misleading because it is not referring to the degree of hot or cold, but rather the color of the light. The higher the number the “colder,” or bluer, the light is. The lower the number, the “warmer” or more orange the light.

Standard sunlight is about 5,400 degrees Kelvin. Shadowy sunlight is “colder,” about 7,400 degrees. Tungsten halogen TV lights are orange and come in at 3200 degrees kelvin. Compact florescent is blue, similar to sunlight, but standard florescent light found in schools and offices is green. The kind of lights often used in street lights, high pressure sodium, are extremely orange and actually look orange to the eye.

Kelvin color temperature scale