How to Use the Luminous Range Diagram
How to Use the
The diagram is entered from the top or bottom border, using nominal
range obtained from the Light List. The figures along the curves
represent the estimated meteorological visibility at the time of
observation, and those along the left-hand border represent the luminous
range under those conditions.
Example: A light has a nominal range of 20 miles. If the
meteorological visibility is 20 miles, the light would be sighted at about
33 miles. If the meteorological visibility is only 5 miles, the luminous
range of the light is about 12 miles.
When using this diagram, you must remembered that:
the range obtained is approximate.
atmospheric conditions may not be consistent between the observer
and the light.
the glare of background lighting will reduce the range at which light