Geographic and Nominal Range of Lights

Nominal Range Visibility Lights

Using the range of a light as a means of judging distance off depends on which of its four ranges you are using (see Figure 12.2). A light's geographical range is the distance it can be seen in conditions of perfect visibility and usually equates to its dipping distance. Its visual range is the distance it can be made out against its background. This varies with atmospheric conditions and sometimes is increased by using binoculars. A light's luminous range is the distance it can be seen...