Sentences with phrase «by precession»

In a linear version of the Milankovitch theory, the two shorter cycles can be explained as responses to insolation cycles driven by precession and obliquity.

During periods of low eccentricity, such as about 400,000 years ago and during the next 100,000 years, seasonal insolation changes induced by precession are not as large as during periods of larger eccentricity (Box TS.6, Figure 1).

Hominin expansion and diversification seem to be associated with climate pulses characterized by the precession - forced appearance and disappearance of deep EARS lakes.

That this seems controlled by precession is indicated that around 41 kya the Amazon basin was also savanna but also see the presentation on this matter 2 — 3 years ago at the AGU fall meeting.

[25] Also the observed position angles of the stars are also subject to small cumulative changes (additional to position angle changes caused by the Precession of the Equinoxes), as first determined by W. H. van den Bos in 1926.

During this time, rainfall was affected by the African monsoon which strengthened and weakened on a 23,000 year cycle driven by the precession of the equinoxes.

Not exact matches

Buckminster Fuller's law of precession is exemplified by a honeybee flying from flower to flower, gathering pollen to make honey.

The resulting theory, though founded on quite different principles and developed in an independent fashion from Einstein's theory, nevertheless gives predictions that are identical to the latter's, within observable limits, for each of the four classic tests of gravitational theories (i.e., precession of the perihelion of Mercury, redshift of light emitted by a massive body, the bending of light - beams in a strong gravitational field, and the apparent slowing of the speed of light propagation near massive bodies).

The precession of the equinoxes is caused by the differential gravitational forces of the Sun and the Moon on the Earth.

Their paths shift slightly from one orbit to the next — a phenomenon known as precession — but when astronomers use general relativity to predict the amount of this shift, their answers are off by a factor of four.

By his new calculations, the predicted precession agrees almost exactly with observations.

In particular, there was no sign of climate change in Indonesia associated with Earth's orbital precession, a wobble caused by Earth's axis tilt that generates differences in sunlight in a 21,000 - year cycle.

The researchers determined that the precession of the pulsar's orbital axis advances by 4.77 degrees per year, plus or minus 0.66 degrees.

Our measured relativistic spin precession rate of per year (68 % confidence level) is consistent with that predicted by general relativity within an uncertainty of 13 %.

By assuming that the sun was spherical, Albert Einstein (father of the Theory of General Relativity) explained with precision a variation in the orbit of Mercury, the so - called precession of the perihelion — a phenomenon that Newton's theory of gravity could not explain.

The moment of inertia was determined from Viking lander and Pathfinder Doppler data, by measuring the precession rate of Mars.

Precession: difference between the longitude (along our orbit) toward which the axis is tilted, and the longitude of perihelion, multiplied by earth's eccentricity.

In addition, they could track the jets» precession, the movement caused by the disk's wobble.

It is believed that the PETM was likely initiated by changes of the orbital parameters of the Earth (eccentricity, obliquity and precession of axis) causing an increase in the intensity and distribution of solar radiation reaching the earth (Sexton et al, 2011).

Hence over the Plio - Pleistocene, East African climate is best characterised as a long - term trend towards increasing aridity punctuated by periods of precession - forced high rainfall leading to the periodic appearance of deep freshwater lakes.

According to NASA, precession occurs when the curvature of space - time is warped by the gravity and rotation of a celestial body.

Presenting two inter-related projects, Celestial Sphere and Precession, Rachel Garrard has been inspired by the geometric patterns and movements of stars and planets.

This may also help explain why, before about 800 ky ago, glacial cycles were dominated by the 41 ky obliquity cycle, while precession had very little effect.

Citing a speech by a retired TV weatherman who could no more construct a climate model than a television camera, and the philosophical authority of one «Thomas Eddington» (the inventor of the supernova light bulb, perhaps — surely not the Sir Arthur who confirmed the relativistic precession of the orbit of Mercury?)

But eccentricity modulates the effect of precession (the alignment of perihelion and aphelion with solstices or equinoxes)(actually, obliquity does modulate this too, but while obliquity variations have significant effect by themselves, they are relatively small in proportion to the difference with zero obliquity, whereas Earth's eccentricity variations include getting near zero, where aphelion and perihelion would have no effect as they wouldn't exist.

Vetoretti and Peltier (2004) found that glacial inceptions can be caused either by a strong obliquity forcing or by a combination of eccentricity - precession forcing and low CO2 values, which is in line with results from Berger and Loutre (2001) who found that CO2 is important during times like the MIS - 11, when the insolation variations are too small to drive glacial - interglacial cycles.

If the Earth were completely symmetrical across the equator, the effect of precession would by a ~ 20,000 (I'm rounding) year cycle, but with two cycles of the global average in that time (with perihelion going from solstice to equinox to solstice completing one such global average cycle).

However, changes in eccentricity interact with seasonal effects induced by obliquity and precession of the equinoxes.

From Peru: You've complimented me by sharing my project (the vostok viewer) on this blog, but I should add that that project began here a couple years ago when I asked Tamino to define climatic precession.

While it is possible that the less significant, and originally overlooked, inclination variability has a deep effect on climate, [11] the eccentricity only modifies insolation by a small amount: 1 — 2 % of the shift caused by the 21,000 - year precession and 41,000 - year obliquity cycles.

Other mechanisms, both oceanic and terrestrial, that depend on the precession amplitude modulated by eccentricity, can be evoked together with the variation of dust influx in the western Tethys to explain the detected eccentricity periodicity in the δ13C record.

Marine and terrestrial sediment sequences demonstrate that subtropical African climate periodically oscillated between markedly wetter and drier conditions, paced by earth orbital precession cycles recurring roughly every 20 kyr (Lourens et al., 1996).

Those forces and motions are driven by the following: First, the motions of the Earth relative to the Sun: the periodic changes in its elliptical orbit, its rotation about its polar axis, changes in the tilt of that axis, and the precession of that axis.

For a completely carbon - dioxide - free reconstruction of the Vostok temperatures since 450 000 years refer to O. G. Sorokhtin (references on card n ° 7) chapter 4.4 pp. 180 - 190 Precession Cycles and the Earth Climate: it explains in detail and computes the quick de-glaciations observed by G.Roe and by Lisiecki & Raymo, with all the «saw - teeth».

It points out that if your paleo data is dominated by the NH summer, you will exaggerate the Milankovitch effect of NH summers cooling due to the precession cycle that affects the perihelion season.

Only 1 of the past 8 interglacials has lasted longer than about half a precession cycle, which we are now past by 2 centuries.....

In hip nomenclature, I would be a near perfect «flat - earther» in the blatant perfect pretzel logic that would make such an assignation applicable to one that comprehends the pacing of our climate by the 3 orbital variables of precession, obliquity and eccentricity.

An obliquity peak — thermally lagged by 6,500 years, coinciding with a peak of precession modulation / eccentricity, causes an interglacial.

Vegetation changes suggest that they constitute distinctive climatic states established by insolation conditions from the obliquity and precession cycles (figure 47).

The Laurentide ice sheet that stretched as far south as New York State and Ohio some 20,000 years ago had retreated to eastern Canada, just across the water from Greenland, by roughly 11,000 years ago thanks to increased sunlight (due to the periodic wobble in Earth's axis known as precession).

Precession: difference between the longitude (along our orbit) toward which the axis is tilted, and the longitude of perihelion, multiplied by earth's eccentricity.

Might the «weather» of orbital cycles be impacted by K / T but not the «climate» — perhaps the trajectories of obliquity, precession and eccentricity would become completely different given sufficient time, but maybe with the same general character — periods and amplitudes and average values being similar enough that a casual glance at any given time segment (on the necessary scale to characterize the orbital cycle «climate») wouldn't look like anything different.

The 23,000 - year and 41,000 - year cycles are driven ultimately by two components of Earth's orbital geometry: the equinoctial precession cycle (23,000 years) and the axial - tilt cycle (41,000 years).

During the Early Triassic, Milankovitch cycles were dominated by 405 kyr, 125 kyr, and 95 kyr eccentricity cycles, 33 kyr obliquity cycles, and 21 kyr, 20 kyr, and 17 kyr precession cycles19, 31,49.

Obliquity and precession variations arise due to the torque exerted by gravity (i.e., a force that acts perpendicular to he spin axis of the top) which ultimately comes from the pull of the Sun and Moon on Earth's equatorial bulge.