What is color temperature in photography?

The color temperature one of the most important things in photography. I would say it also part of photography multiplication table, something all photographers know and use all the time.

Definition of the color temperature
Well, technically speaking color temperature is one of the many characteristics of the visible light. Each light source has it own color temperature.  Take a look at this table:
Temperature Source
1,700 K Match flame, low-pressure sodium lamps (LPS/SOX)
1,850 K Candle flame, sunset/sunrise
2,700–3,300 K Incandescent lamps
3,000 K Soft (or Warm) White compact fluorescent lamps
3,200 K Studio lamps, photofloods, etc.
3,350 K Studio “CP” light
4,100–4,150 K Moonlight
5,000 K Horizon daylight
5,000 K Tubular fluorescent lamps orcool white/daylight compact fluorescent lamps (CFL)
5,500–6,000 K Vertical daylight, electronic flash
6,200 K Xenon short-arc lamp
6,500 K Daylight, overcast
6,500–10,500 K LCD or CRT screen
15,000–27,000 K Clear blue poleward sky

The color temperature measured in Kelvin (K). As it visible from the current table the light temperature varies from reddish to bluish tints. Natural daylight is usually between 5500 to 6000 K but in the “magic hours” it became as warm as 2000K as well. Light below 5000 K (1,700 – 5000K) considered as warm colors and the light above  daylight (5000-27000K) referred to cool colors.

Color temperature and White Balance

In photography, the color temperature is always used along with term “white balance”. To create correct white balance photographer need to understand with what color temperature he deal with and adjust camera settings accordingly.

Find more about White Balance Here