Obliquity of the ecliptic: Difference between revisions
From Glossary of Meteorology
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<div class="definition"><div class="short_definition">The angle between the [[plane of the ecliptic]] (or the plane of the earth's [[orbit]]) and the plane of the earth's [[equator]]; the | <div class="definition"><div class="short_definition">The angle between the [[plane of the ecliptic]] (or the plane of the earth's [[orbit]]) and the plane of the earth's [[equator]]; the "tilt" of the earth.</div><br/> <div class="paragraph">The obliquity of the ecliptic is computed from the following formula: <div class="display-formula"><blockquote>[[File:ams2001glos-Oe2.gif|link=|center|ams2001glos-Oe2]]</blockquote></div> where ''t'' is the year for which the obliquity is desired. For 1999, the value was 23°26′21.89″. It is the oblique orientation of the earth's axis relative to its orbit that accounts for the seasons, for, in the period of a year, the [[angle of incidence]] of [[incoming solar radiation]] varies by nearly 47° at any one place. Particularly at high latitudes, this results in a great seasonal [[temperature]] contrast. M. Milankovitch has calculated that the obliquity of the ecliptic varies between 24.5° and 22° in the course of 40 000 years. This [[variation]] may be considered as a long-period [[climatic control]] and is included in the astronomical theory of [[ice ages]].</div><br/> </div> | ||
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Latest revision as of 14:46, 20 February 2012
obliquity of the ecliptic
The angle between the plane of the ecliptic (or the plane of the earth's orbit) and the plane of the earth's equator; the "tilt" of the earth.
The obliquity of the ecliptic is computed from the following formula: where t is the year for which the obliquity is desired. For 1999, the value was 23°26′21.89″. It is the oblique orientation of the earth's axis relative to its orbit that accounts for the seasons, for, in the period of a year, the angle of incidence of incoming solar radiation varies by nearly 47° at any one place. Particularly at high latitudes, this results in a great seasonal temperature contrast. M. Milankovitch has calculated that the obliquity of the ecliptic varies between 24.5° and 22° in the course of 40 000 years. This variation may be considered as a long-period climatic control and is included in the astronomical theory of ice ages.
