Half of a sphere
Related Terms |
INTERSECT
To cut or cross. For example, two non parallel lines in a plane intersect in a point, and a plane intersects a sphere in a circle
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JUNE SOLSTICE
Summer solstice in the Northern Hemisphere
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MAGNETIC CIRCLE
A sphere of specified radius about the magnetic compass location to be kept free of any magnetic or electrical equipment which would interfere with the compass.
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LUNE
The part of the surface of a sphere bounded by halves of two great circles.
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ALMUCANTAR
A small circle on the celestial sphere paralleled to the horizon. Also called CIRCLE OF EQUAL ALTITUDE, PARALLEL OF ALTITUDE.
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ANTICYCLONE
An approximately circular portion of the atmosphere, having relatively high atmospheric pressure and winds which blow clockwise around the center in the Northern Hemisphere and counterclockwise in the Southern Hemisphere. An anticyclone is characterized by good weather.
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APPARENT PLACE
The position on the celestial sphere at which a celestial body would be seen if the effects of refraction, diurnal aberration, and geocentric parallax were removed; the position at which the object would actually be seen from the center of the earth. Also called APPARENT POSITION.
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NADIR
The point on the celestial sphere vertically below the observer, or 180° from the zenith.
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AURORA AUSTRALIS
The aurora in the Southern Hemisphere
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NAVIGABLE SEMICIRCLE
The half of a cyclonic storm area in which the rotary and forward motions of the storm tend to counteract each other and the winds are in such a direction as to tend to blow a vessel away from the storm track. In the Northern Hemisphere this is to the left of the storm center and in the Southern Hemisphere it is to the right.
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