local horizon


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horizon

horizon
horizon
i. In general, the apparent or visible junction of the earth and sky, as seen from any specific position. Also called a visible or local horizon.
ii. When an apparent boundary is modified by refraction, terrain, or other factors, it is called an apparent horizon.
iii. A small circle on the celestial sphere, the plane of which passes through the observer's eye and is parallel to the observer's rational horizon, is called a sensible horizon.
iv. A path followed by a radar beam when it is tangential to earth is a radar horizon.
v. The locus of the point at which direct rays from a terrestrial radio transmitter become tangential to the earth is a radio horizon.
vi. A line resembling the visible horizon but above or below it is called a false horizon.
vii. An artificial horizon is a gyroscopic instrument for indicating the attitude of an aircraft with respect to the horizontal. See artificial horizon.
References in periodicals archive ?
The method allows directly specifying the attitude of the vehicle with respect to the relative wind velocity vector and local horizon, which makes it very suitable for trajectory computations even with a limited aerodynamic database available.
The Navajo do not live in villages; they were a nomadic people with no single fixed center from which the sun could be observed against familiar landmarks on the local horizon and at which they could gather for large communal celebrations.
The Moon did finally clear the local horizon, and a bright moonbow did eventually appear, but not until the early hours of the next morning!
The by-now familiar data-entry menus appear at the top of the Java window, while the upper portion of the display features a Mercator view of the local horizon with the positions of the Sun and Moon depicted for various times throughout their periods of visibility.
One sailor likened the meteor's appearance to "the center of an electrode welding on iron." A brilliant flash occurred after the object dipped below the local horizon.
Moore's challenge to view all the objects that rise 5 [degrees] above one's local horizon makes Caldwell-hunting a global game.

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