nautical twilight"The twilight stage during which the sun's unrefracted center is at elevation angles −6° > h0 > −12°. During a clear evening's nautical twilight, horizontal illuminance decreases from ∼3.
NAUTICAL TWILIGHT
The time after civil twilight, when the brighter stars used for celestial navigation have appeared and the horizon may still be seen.
nautical twilight—See twilight.
negative vorticity—See vorticity.
Nautical twilight refers to the interval of incomplete darkness that occurs when the sun's center is approximately 12 degrees below the horizon.
2) Nautical Twilight: The period of time before sunrise and after sunset when the sun is not more than 12 degrees below the horizon.
The time after nautical twilight has commenced and when the sky is dark enough, away from the sun's location, to allow astronomical work to proceed. It ends when the center of the sun is 18° below the horizon.
Related term: twilight ...
ASTRONOMICAL TWILIGHT The time after nautical twilight has commenced and when the sky is dark enough, away from the sun's location, to allow astronomical work to proceed. It ends when the center of the sun is 18° below the horizon.
At this time, objects are no longer distinguishable.
NOAA National Weather Service - Cite This Source - This Definition
Browse Related Terms: Astronomical Dusk, Civil Dusk, Dusk, EVE, Horizon, Nautical Twilight, Sunrise, Sunset ...
Nation Weather Service Office:NWS: National Weather Service Offices located in many cities throughout the United States.
Nautical Mile: A nautical mile is about 1.15 statute mile.
Nautical Twilight: When the sun is no more than 12 Degs.
 See also: Light, Twilight, Weather, Meteor, Horizon
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