Navigation General · Aids to Navigation — Light Visibility
The 'luminous range' of a light differs from its 'nominal range' because luminous range depends on:
- AThe vessel's speed
- BThe light's color only
- CThe day of the week
- DThe prevailing visibility/atmospheric conditions at the time✓ Correct
Explanation
Nominal range is the stated range in a standard atmosphere (meteorological visibility of 10 nm). Luminous range is the actual range for the existing visibility—reduced in haze/fog, possibly greater in exceptionally clear air. Both differ from the geographic range set by heights of light and eye.
Authority: Light List; Bowditch
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