LED Lights At Home

Color temperature has a specific scientific meaning. If you use the term “warm glow of light” to describe a typical incandescent bulb, a color scientist will correct your naive description. Similarly, the description “warm white” for a particular type of LED that mimics incandescent light closely is a misnomer.

Wikipedia, of course, has a full discussion of color temperature and several nice diagrams. I’ll summarize here.

Some LED products provide their color temperature. Some are labeled simply “warm white” because we lay persons think of the yellowish glow of an incandescent light as “warm”, though they have a color temperature close to the relatively cool incandescent lights.

Natural daylight is around 5000 degrees, while incandescent lights are around 3800 degrees.

Oddly, reds and oranges are at the cooler end of the scale (under about 2000 degrees K) while the hottest temperatures (16,000) are blue.

Thoroughly confused now? It is probably best to divorce in your mind the concept of temperature as a measure of heat/cold from any color associations.

The idea of color temperature originated with Lord Kelvin in the 19th century and relates to “absolute zero”, the temperature at which nothing can be colder.

Because colors look different under different lights sources (which have different color temperatures), this concept is often used in photography and printing, with a 5000 degree K light source used as a standard to ensure that whoever looks at a photograph or proof is seeing it under controlled conditions.

Lord Kelvin’s scale involves heating a “black body radiator” to different temperatures and measuring the light emitted.