Colour temperature spectrum. Illustration of a range of colour temperatures on a spectrum, with values expressed in Kelvin. This spectrum shows how the overall hue of light can vary in terms of a calculated characteristic known as colour temperature. The light produced by a source such as the Sun, a candle, or particular kinds of lighting will include a range of colours, depending upon its temperature, but this can be averaged out to obtain its colour temperature. The colour temperature of sunlight appears to vary as a result of light scattering by the atmosphere.