What is the maximum distance at which a light may be seen under existing visibility known as?

The maximum distance at which a light can be seen under existing visibility conditions is referred to as the luminous range. This term specifically describes the effective reach of a light source based on its intensity and the atmospheric conditions at the time. Luminous range takes into account factors such as haze, fog, and precipitation that may impact visibility, which is why it emphasizes the distance a light can be perceived rather than any other operational distances associated with a vessel or navigation.

Cruising range would refer to the distance a vessel can travel on a specific amount of fuel, while visibility range generally pertains to how far one can see in specific conditions without specifically focusing on light sources. Signal range could refer to the distance over which signals (like sound signals) can be effectively communicated but does not specifically pertain to the visibility of lights. Thus, luminous range is the precise terminology used to capture the concept of light visibility under varying atmospheric conditions.