real life attenuation factors

What are the real life factors of light attenuation. Say in normal atmospheric conditions.

There’s haze, but the primary reason for point sources is that as light radiates, it disperses – the same energy is flowing through a larger area.

For point light in void (clear air is almost like void), the lighting is l=L/(r*r) with L being the color/intensity of the light and r the distance to the light. Think about the surface of a sphere centered on the light.