2.4.7.11 Atmospheric Attenuation

Normally light coming from light sources is not influenced by fog or atmospheric media. This can be changed by turning the media_attenuation on for a given light source on. All light coming from this light source will now be diminished as it travels through the fog or media. This results in an distance-based, exponential intensity falloff ruled by the used fog or media. If there is no fog or media no change will be seen.

Note:in POV-Ray 3.0 this feature was turned off and on with the atmospheric_attenuation keyword.