Have you ever been driving on the freeway, late at night and all of the sudden you feel you're about to be abducted by an alien spacecraft? The brilliant, unearthly blue-white lights sweep over you, reflect off your side and rearview mirrors and sear your eyeballs. The colors inside of your car literally come alive as your shadow on the dashboard creates a sharply contrasted 2D image of yourself. Just when you think that maybe Steven Spielberg got it right, the blonde in the Audi zooms around you with her high beams on.

If that has ever happened to you (or something possibly less dramatic), you've noticed color temperature in lighting. Color Temperature is a measurement that indicates the hue of a specific type of light source. It is measured in Degrees Kelvin which don't have anything to do with how hot the bulb actually gets. Low color temperature implies warmer (more yellow/red) light while high color temperature implies a colder (more blue) light. In between the yellow and blue is a whiter light.

So, why do we measure the hue of the light as a "temperature"? This was started in the late 1800s, when the British physicist William Kelvin heated a block of carbon. It glowed in the heat, producing a range of different colors at different temperatures. The black cube first produced a dim red light, increasing to a brighter yellow as the temperature went up, and eventually produced a bright blue-white glow at the highest temperatures. 

With compact fluorescent bulbs, we deal mainly in three color temperatures.  2700K lamps are for people who want the warm, yellow look of incandescent bulbs.  4100K bulbs are aimed at persons who require a bit more usable light in the whiter spectrum. Full spectrum lights (around 5500K) are for those who need very bright light, exceptional color rendering and relief from the winter blues. Watch future newsletters for articles dedicated to full spectrum benefits. The easiest way to get an idea of what the Kelvin temperatures relate to in real life is to check out the chart below.  The actual light produced by a given lamp can vary by manufacturer.

Temperature (Kelvin)	Type of Light
1700K	Candlelight
2700K	Incandescent lamp
3000-3500K	Warm White
3200K	Sunrise/sunset
3400K	1 hour from dusk/dawn
4100-4200K	Cool White
5000-5500K	Full Spectrum light
5500K	Sunny daylight around noon
6000-7000K	Daylight
6500-7500K	Overcast sky
9000-12000K	Blue sky

 

You may also notice that some manufacturers offer colored party bulbs. These specialized compact fluorescent bulbs utilize a mix of phosphors and specially tinted glass to enhance or reduce different segments of the light spectrum and end up with the desired color. Usually discrete colors are measured in nanometers. Red-658nm, Yellow-626nm (Bug Light), Green-546nm and Blue-450nm. Blacklights are generally less than 300nm.

Now back to our Audi-Spaceship. I've found that the low beams are around 3800K and high beams are approximately 5000K. That compares to a stock halogen headlight at 3200K. There are even 'upgrades' for the headlights that are rated at 5900K! It makes me wonder what's next. Maybe headlights so bright that they vaporize bugs before they collide with the windshield? Ah, there's an idea...