What is Kelvin temperature on fluorescent lamps/lightbulbs?

The color temperature refers to the color of light. This temperature is measured in Kelvins. The Kelvin scale ranges from 1500 to 9000. The lower the Kelvin scale number, the warmer the color temperature, resulting in a warmer (more oranges and reds) light source. The higher the Kelvin scale number, the cooler (more blues or greens) the color temperature, or light source. For example, a 3000 Kelvin bulb will emit a warmer light than a 4000 Kelvin. The Kelvin temperature listed on the product package may be referred to as K (e.g. 3500K), or may be listed as “warm white,” or “cool white.” Therefore, if you desire a color rendition from a CFL that is similar to an incandescent lamp, utilize bulbs that have a color temperature no higher than 3000K. Natural daylight is listed at 6000K.
For more information, visit the visit the Energy Savers web site.