nautical twilight

nautical twilight
That period before sunrise and after sunset when the upper limb of the sun is below the visible horizon and the center of the sun is not more than 12° below the celestial or sensible horizon. During this interval of incomplete darkness, the degree of illumination is such that general outlines are still discernible, although detailed operations become impossible. All the bright stars are visible at this time. It is the time when the navigational stars are visible and the sea horizon is still sufficiently visible to permit celestial observations with a sextant.

Aviation dictionary. 2014.

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  • nautical twilight — navigacinė prieblanda statusas T sritis Gynyba atitikmenys: angl. nautical twilight pranc. crépuscule nautique ryšiai: platesnis terminas – prieblanda …   NATO terminų aiškinamasis žodynas

  • nautical twilight — noun The period in which the sun is between 6° 12° below the horizon in the morning and evening …   Wiktionary

  • nautical twilight — noun : the period before sunrise or after sunset during which the sun is not more than 12 degrees below the horizon …   Useful english dictionary

  • end of evening nautical twilight — Occurs when the sun has dropped 12 degrees below the western horizon, and is the instant of last available daylight for the visual control of limited ground operations. At end of evening nautical twilight there is no further sunlight available.… …   Military dictionary

  • Twilight — For other uses, see Twilight (disambiguation). Twilight at Riga Bridge …   Wikipedia

  • Nautical Almanac (band) — Nautical Almanac are a noise music group based out of Baltimore Maryland with a rotating membership based around Carly Ptak and Twig Harper.[citation needed] Contents 1 History 2 Select discography 2.1 …   Wikipedia

  • begin morning nautical twilight — The start of that period where, in good conditions and in the absence of other illumination, enough light is available to identify the general outlines of ground objects and conduct limited military operations. Light intensification devices are… …   Military dictionary

  • twilight — The period of incomplete darkness following sunset and preceding sunrise. Twilight is designated as civil, nautical, or astronomical, as the darker limit occurs when the center of the sun is 6°, 12°, and 18°, respectively, below the celestial… …   Aviation dictionary

  • observation twilight — That part of the twilight period during which the horizon may be observed as a sharply defined line and the navigational stars may be seen. The light diffused during this period. For computation purposes, this twilight begins or ends when the… …   Aviation dictionary

  • begin morning civil twilight — The period of time at which the sun is halfway between beginning morning and nautical twilight and sunrise, when there is enough light to see objects clearly with the unaided eye. At this time, light intensification devices are no longer… …   Military dictionary

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