@prefix qx8: . @prefix skos: . qx8:-JKFDT9CX-H skos:exactMatch , , ; skos:altLabel "Milankovic theory"@en, "théorie de Milankovic"@fr ; skos:definition "Les cycles de Milankovitch sont des variations cycliques des paramètres de l'orbite de la Terre (les paramètres de Milankovitch) qui engendrent des variations du climat terrestre. Les principaux cycles sont les suivants. Le cycle de l'excentricité, il s'agit de la variation de la forme de l'orbite terrestre, qui oscille entre une forme plus circulaire et une forme plus elliptique. Le cycle principal a une période d'environ 400 000 ans et des cycles secondaires de l'ordre de 100 000 ans. Le cycle de l'obliquité, il s'agit de la variation de l'inclinaison de l'axe de rotation de la Terre par rapport à son orbite. Ce cycle a une période d'environ 41 000 ans. Le cycle de la précession des équinoxes, il s'agit de la variation de l'orientation de l'axe de rotation de la Terre. Ce cycle a une période d'environ 26 000 ans. Les cycles de Milankovitch sont notamment utilisés dans le cadre de la théorie astronomique des paléoclimats. Ces changements climatiques naturels ont pour principale conséquence la succession de périodes glaciaires et interglaciaires. Leur étude en termes de phénomènes périodiques est du ressort de la cyclostratigraphie. (Adapté de : https://fr.wikipedia.org/wiki/Cycles_de_Milankovitch)"@fr, "Milankovitch cycles describe the collective effects of changes in the Earth's movements on its climate over thousands of years. The term was coined and named after the Serbian geophysicist and astronomer Milutin Milanković. In the 1920s, he hypothesized that variations in eccentricity, axial tilt, and precession combined to result in cyclical variations in the intra-annual and latitudinal distribution of solar radiation at the Earth's surface, and that this orbital forcing strongly influenced the Earth's climatic patterns. The Earth's rotation around its axis, and revolution around the Sun, evolve over time due to gravitational interactions with other bodies in the Solar System. The variations are complex, but a few cycles are dominant. The Earth's orbit varies between nearly circular and mildly elliptical (its eccentricity varies). When the orbit is more elongated, there is more variation in the distance between the Earth and the Sun, and in the amount of solar radiation, at different times in the year. In addition, the rotational tilt of the Earth (its obliquity) changes slightly. A greater tilt makes the seasons more extreme. Finally, the direction in the fixed stars pointed to by the Earth's axis changes (axial precession), while the Earth's elliptical orbit around the Sun rotates (apsidal precession). The combined effect of precession with eccentricity is that proximity to the Sun occurs during different astronomical seasons. Milankovitch studied changes in these movements of the Earth, which alter the amount and location of solar radiation reaching the Earth. This is known as solar forcing (an example of radiative forcing). Milankovitch emphasized the changes experienced at 65° north due to the great amount of land at that latitude. Land masses change temperature more quickly than oceans, because of the mixing of surface and deep water and the fact that soil has a lower volumetric heat capacity than water. (Adapted from: https://en.wikipedia.org/wiki/Milankovitch_cycles)"@en ; a skos:Concept ; skos:prefLabel "Milankovitch theory"@en, "théorie de Milankovitch"@fr ; skos:inScheme qx8: ; skos:broader qx8:-16D1PHWR-Z . qx8: a skos:ConceptScheme . qx8:-16D1PHWR-Z skos:prefLabel "astronomical theory"@en, "théorie astronomique"@fr ; a skos:Concept ; skos:narrower qx8:-JKFDT9CX-H .