How is the intensity of a light expressed in...

🔍 Key Concepts

• Meaning of intensity in navigation lights (candlepower/brightness, not distance seen in actual weather) • Difference between nominal range and ranges that depend on conditions like visibility and height of eye • How the Light Lists standardize a light’s strength so mariners can combine it with visibility tables and geographic range diagrams

💭 Think About

• Which of these options describes an inherent property of the light itself, rather than how far you can see it under specific conditions? • Which range is defined for a standard meteorological visibility (like 10 nautical miles) so it can be used as a reference value in tables? • If the weather gets worse or your height of eye changes, which of these listed ranges would stay the same in the book while the others would effectively change in practice?

✅ Before You Answer

• Identify which term is tied to standard clear-weather visibility, not actual current conditions • Eliminate any term that depends on observer height of eye or local weather at the moment • Pick the option that is used as a reference brightness value printed in the Light Lists, from which other ranges can be derived

How is the intensity of a light expressed in the Light Lists?

Geographic range

Meteorological range

Luminous range

Nominal range