Online Encyclopedia
Search over 40,000 articles from the original, classic Encyclopedia Britannica, 11th Edition.
LATITUDE (Lat. latitudo, latus, broad)
Online EncyclopediaEncyclopedia Home :: LAP-LEO
del.icio.us it!
|
See also:LATITUDE (See also:Lat. latitudo, latus, broad) , a word meaning breadth or width, hence, figuratively, freedom from restriction, but more generally used in the See also:geographical and astronomical sense here treated. The latitude of a point on the See also:earth's See also:surface is its angular distance from the See also:equator, measured on the curved surface of the earth. The See also:direct measure of this distance being impracticable, it has to be determined by astronomical observations. As thus determined it is the See also:angle between the direction of the plumb-See also:line at the See also:place and the See also:plane of the equator. This is identical with the angle between the See also:horizontal planes at the place and at the equator, and also with the See also:elevation of the See also:celestial See also:pole above the See also:horizon (see See also:ASTRONOMY). Latitude thus determined by the plumb-line is termed astronomical. The See also:geocentric latitude of a place is the angle which the line from the earth's centre to the place makes with the plane of the equator. Geographical latitude, which is used in mapping, is based on the supposition that the earth is an elliptic spheroidthe plumb-line. The latitude of a celestial See also:object is the angle which the line See also:drawn from some fixed point of reference to the object makes with the plane of the See also:ecliptic. Variability of Terrestrial Latitudes.—The latitude of a point on the earth's surface, as above defined, is measured from the equator. The latter is defined by the See also:condition that its plane makes a right angle with the earth's See also:axis of rotation. It follows that if the points in which this axis intersects the earth's surface, i.e. the poles of the earth, See also:change their positions on the earth's surface, the position of the equator will also change, and there-fore the latitudes of places will change also. About the end of the 19th See also:century See also:research showed that there actually was a very See also:minute but measurable periodic change of this See also:kind. The See also:north and See also:south poles, instead of being fixed points on the earth's surface, wander See also:round within a circle about 50 ft. in See also:diameter. The result is a variability of terrestrial latitudes generally. To show the cause of this See also:motion, let BQ represent a See also:section of an oblate See also:spheroid through its shortest axis, PP. We may consider this spheroid to be that of the earth, the See also:ellipticity being greatly exaggerated. If set in rotation around its axis of figure PP, it will continue to rotate around that axis for an indefinite See also:time. Additional information and CommentsThere are no comments yet for this article.
» Add information or comments to this article.
Please link directly to this article:
Highlight the code below, right click, and select "copy." Then paste it into your website, email, or other HTML. Site content, images, and layout Copyright © 2006 - Net Industries, worldwide. |
|
|
[back] LATINUS |
[next] LATIUM |