Consider a bulb's Kelvin temperature. There are two major ways to differentiate between types of light: The Kelvin temperature (this measures the warmness or the coldness of the white light spectrum) ...

The color temperature of a light, measured in kelvins, is its most noticeable characteristic. A candle, at 1900 K, appears orange. Daylight, at 5500 K, is much whiter and bluer. A 5500-K bulb, however ...