Color Temperature Reference Chart

Color Temperature Reference Chart

Digital cameras and film are sensitive to the temperature of light and are measured in Kelvin (K).  Daylight temperatures are about 5,000 to 5,500 degrees K and at this temperature, the light appears 'white.'  Warmer light sources, such as incandescent filament-light, is colored at a longer wavelength, usually about 3,000K.

Warmer Colors (Red)
2700K Sodium-Vapor

3000K Incandescent and Warm-white Fluorescent

3700K White fluorescent

5000K Day-white fluorescent

5200K Direct Sunlight (white)

5400K Electronic Flash

6000K Cloudy/overcast (trending Blue)

7200K Mercury Vapor, high-temp)

8000K Deep Shade (under a bright blue sky)

Cooler Colors (Blue)

In photography, color temperatures can be seen in the final prints.  For example, photographing under deep shade can give the photographs a distinct blue tint.  This can be corrected by using the digital camera's built-in white-balance (with film, use a warming filter).  Photographs can also be corrected in post-processing, using a photo-editor.

Note: Color temperature is not the wavelength of a specific color (measured in nanometers 600nm, etc.).

See this imageLiner.blogspot.com article on DSLR White Balancing / Color Correction
White Balance

In practice, older fluorescent lighting displays an unpredictable color spectrum that is hard to color-correct; often with simultaneous greens, yellows and blues.  Newer fluorescent lighting has a more predictable color spectrum and are often advertised with their color temperature.  However, some brands mistakenly show the color temperature as "Lumens"  (e.g. GE branded lamps report 2700 Lumens; should be 2700K).

Related articles:
White Balance
Setting Exposure with an 18% Grey Card