How does eccentricity affect seasons

There are hundreds of different types of cycles in our world and in the universe. Some are natural, such as the change of the seasons, annual animal migrations or the circadian rhythms that govern our sleep patterns. Others are human-produced, like growing and harvesting crops, musical rhythms or economic cycles.

These variations affect the distance between Earth and the Sun. Eccentricity is the reason why our seasons are slightly different lengths, with summers in the Northern Hemisphere currently about 4. As eccentricity decreases, the length of our seasons gradually evens out. That means each January, about 6. The total change in global annual insolation due to the eccentricity cycle is very small.

Obliquity is why Earth has seasons. Over the last million years, it has varied between Larger tilt angles favor periods of deglaciation the melting and retreat of glaciers and ice sheets. Foraminifera : A large and diverse group of, single-celled aquatic organisms mainly marine that construct their shells from calcium carbonate. Intertropical Convergence Zone ITCZ : The equatorial region where the trade winds of both hemispheres come together and are associated with high precipitation.

As the ITCZ is tethered to the zone of maximum solar insolation, its location migrates north and south of the equator with the seasons. Isotope : Variants of a particular element that have the same number of protons, but different number of neutrons. Milankovitch : Milutin Milankovitch — , a Serbian mathematician who proposed that climatic changes, particularly ice ages, were the result of variations in the Earth's orbital elements.

Monsoon : A wind system whose direction changes with the seasons. Often associated with seasonal precipitation. Radiolaria : A large and diverse group of single-celled marine organisms that construct their shells from silica. Seasonality : Changes in timing, duration, or intensity of the within-year distribution of climatic elements, but not in total annual amounts e. Speleothem : A mineral deposit, typically calcium carbonate, that precipitates from solution in a cave e.

Uranium-thorium dating : An absolute dating technique based on the natural radioactive decay of uranium to thorium. An, Z. The history and variability of the East Asian paleomonsoon climate. Quaternary Science Reviews 19, Bar-Matthews, M.

Sea-land oxygen isotopic relationships from planktonic foraminifera and speleothems in the Eastern Mediterranean region and their implication for paleorainfall during interglacial intervals.

Geochimica et Cosmochimica Acta 67, A high resolution and continuous isotopic speleothem record of paleoclimate and paleoenvironment from 90 to 53 ka from Pinnacle Point on the south coast of South Africa. Quaternary Science Reviews 29, Bartholomew, G. Ecology and the protohominids.

American Anthropologist 55, Behrensmeyer, A. Science , Bobe et al. Dordrecht, Netherlands: Springer, Bender, M. Climate correlations between Greenland and Antarctica during the past , years.

Nature , Cohen, A. Understanding paleoclimate and human evolution through the hominin sites and paleolakes drillng project. Scientific Drilling 8, Couchoud, I. Millennial-scale climate variability during the Last Interglacial recorded in a speleothem from south-western France. Quaternary Science Reviews 28, Darwin, C. London, UK: John Murray, African climate change and faunal evolution during the Pliocene-Pleistocene. Earth and Planetary Science Letters , Hays, J.

Variations in the Earth's orbit: Pacemaker of the ice ages. Johnson, T. Amsterdam, Netherlands: Gordon and Breach Publishers, Kingston, J. Shifting adaptive landscapes: Progress and challenges in reconstructing early hominid environments. Yearbook of Physical Anthropology 50, Isotopic evidence for Neogene hominid paleoenvironments in the Kenya Rift Valley.

Astronomically forced climate change in the Kenyan Rift Valley 2. Journal of Human Evolution 53, Koeberl, C. Lambert, F. Laskar, J. A long-term numerical solution for the isolation quantities of the Earth. Astronomy and Astrophysics , Potts, R. Variability selection in hominid evolution. Evolutionary Anthropology 7, Scholz, C. East African megadroughts between and 75 thousand years ago and bearing on early-modern human origins.

Stein, M. Deep drilling at the Dead Sea. Scientific Drilling 11, Trauth, M. Late Cenozoic moisture history of East Africa. High- and low-latitude forcing of Plio-Pleistocene East African climate and human evolution. Vrba, E. Vrba et al. Wang, Y. A continuous ka paleoclimatic record from stalagmite in Tangshan Cave, Janjing. Milankovitch's calculations and charts, which were published in the s and are still used today to understand past and future climate, led him to conclude that there are three different positional cycles, each with its own cycle length, that influence the climate on Earth: the eccentricity of Earth's orbit, the planet's axial tilt and the wobble of its axis.

The Earth orbits the sun in an oval shape called an ellipse, with the sun at one of the two focal points foci. Ellipticity is a measure of the shape of the oval and is defined by the ratio of the semiminor axis the length of the short axis of the ellipse to the semimajor axis the length of the long axis of the ellipse , according to Swinburne University.

A perfect circle, where the two foci meet in the center, has an ellipticity of 0 low eccentricity , and an ellipse that is being squished to almost a straight line has an eccentricity of nearly 1 high eccentricity. The Earth's orbit slightly changes its eccentricity over the course of , years from nearly 0 to 0.

When the Earth's orbit has a higher eccentricity, the planet's surface receives 20 to 30 percent more solar radiation when it's at perihelion the shortest distance between the Earth and sun each orbit than when it is at aphelion the largest distance between the Earth and sun each orbit.

When the Earth's orbit has a low eccentricity, there is very little difference in the amount of solar radiation that is received between perihelion and aphelion. Today, the eccentricity of Earth's orbit is 0.

At perihelion, which occurs on or around Jan. The tilt of the Earth's axis relative to the plane of its orbit is the reason that we experience seasons. Slight changes in the tilt changes the amount of solar radiation falling on certain locations of Earth, according to Indiana University Bloomington.