Milankovitch cycles: Difference between revisions
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'''Milankovitch cycles''' are cycles in the Earth's orbit that effect the amount of solar radiation striking the Earth at different times of the year. They are named after [[Milutin Milanković]]. These cycles include the [[precession]], [[eccentricity]], and [[axial tilt]] of Earth's orbit. All three processes occurring simultaneously produce 100,000 year [[ice age]] cycles. Frequency modulation [[(FM)]] of the approximate 100,000-year eccentricity cycles by the 413,000-year component accounts for the variable duration of the ice ages.<ref>J. A. Rial Science 23 July 1999 285: 564-568 [DOI: 10.1126/science.285.5427.564]</ref> The precession is Earth's wobble caused by our daily rotation while orbiting the Sun. It is the same physics as a top's wobble: the Earth's axis currently points towards the star [[Polaris]], but after 21,000 years our axis will have made a complete circle. At 10,500 years our North will be 180 degrees away from where it points now, essentially South from the current perspective. The study of paleomagnetism has demonstrated that the Earth's magnetic field varies in both orientation and intensity through time. "Evidence from high-sedimentation-rate South Atlantic deep-sea cores indicates that global and Southern Ocean carbon budget shifts preceded thermohaline circulation changes during the last ice age initiation and termination and that these were preceded by ice-sheet growth and retreat, respectively."<ref>Alexander M. Piotrowski, Steven L. Goldstein, Sidney R. Hemming, and Richard G. Fairbanks Science 25 March 2005 307: 1933-1938 [DOI: 10.1126/science.1104883] </ref> | '''Milankovitch cycles''' are cycles in the Earth's orbit that effect the amount of solar radiation striking the Earth at different times of the year. They are named after [[Milutin Milanković]]. These cycles include the [[precession]], [[eccentricity]], and [[axial tilt]] of Earth's orbit. All three processes occurring simultaneously produce 100,000 year [[ice age]] cycles. Frequency modulation [[(FM)]] of the approximate 100,000-year eccentricity cycles by the 413,000-year component accounts for the variable duration of the ice ages.<ref>J. A. Rial Science 23 July 1999 285: 564-568 [DOI: 10.1126/science.285.5427.564]</ref> The precession is Earth's wobble caused by our daily rotation while orbiting the Sun. It is the same physics as a top's wobble: the Earth's axis currently points towards the star [[Polaris]], but after 21,000 years our axis will have made a complete circle. At 10,500 years our North will be 180 degrees away from where it points now, essentially South from the current perspective. The study of paleomagnetism has demonstrated that the Earth's magnetic field varies in both orientation and intensity through time. "Evidence from high-sedimentation-rate South Atlantic deep-sea cores indicates that global and Southern Ocean carbon budget shifts preceded thermohaline circulation changes during the last ice age initiation and termination and that these were preceded by ice-sheet growth and retreat, respectively."<ref>Alexander M. Piotrowski, Steven L. Goldstein, Sidney R. Hemming, and Richard G. Fairbanks Science 25 March 2005 307: 1933-1938 [DOI: 10.1126/science.1104883] </ref> | ||
Revision as of 15:59, 29 February 2008
Milankovitch cycles are cycles in the Earth's orbit that effect the amount of solar radiation striking the Earth at different times of the year. They are named after Milutin Milanković. These cycles include the precession, eccentricity, and axial tilt of Earth's orbit. All three processes occurring simultaneously produce 100,000 year ice age cycles. Frequency modulation (FM) of the approximate 100,000-year eccentricity cycles by the 413,000-year component accounts for the variable duration of the ice ages.[1] The precession is Earth's wobble caused by our daily rotation while orbiting the Sun. It is the same physics as a top's wobble: the Earth's axis currently points towards the star Polaris, but after 21,000 years our axis will have made a complete circle. At 10,500 years our North will be 180 degrees away from where it points now, essentially South from the current perspective. The study of paleomagnetism has demonstrated that the Earth's magnetic field varies in both orientation and intensity through time. "Evidence from high-sedimentation-rate South Atlantic deep-sea cores indicates that global and Southern Ocean carbon budget shifts preceded thermohaline circulation changes during the last ice age initiation and termination and that these were preceded by ice-sheet growth and retreat, respectively."[2]
- Precession
- Eccentricity
- Axial tilt