- Luminous Range: The visibility of a light in various degrees of restricted visibility; or meteorological visibility.
|Nominal Range: The visibility of a light in optimal conditions; visibility listed on the chart and on the bottom of the Luminous Range Diagram (Light List, page vii).
||Curved lines with circled numbers on Luminous Range diagram represent ranges of visibility and are defined on the right margin:
- 3 = Light Fog; .27 to .54 mi visibility
- 4 = Thin Fog; .54 to 1.1 mi visibility
- 5 = Haze; 1.1 to 2.2 mi visibility
- 6 = Light Haze; 2.2 to 5.4 mi visibility
- 7 = Clear; 5.4 to 11 mi visibility
- 8 = Very Clear; 11 to 27 mi visibility
- 9 = Exceptionally Clear; over 27 mi visibility
|Locate nominal range of light from chart on the bottom of diagram.
||Follow up the grid lines to middle of restricted visibility range.
||Follow grid line to left margin of diagram for nominal range.
||Example: a light with nominal (charted) range of 13 mi. should only be visible for about 6.5 miles in light haze.