If you can't explain the 'pause', you can't explain the cause
Variations in the Earth's Orbital Characteristics The Milankovitch theory suggests that normal cyclical variations in three of the Earth's orbital characteristics is probably responsible for some past climatic change.
The basic idea behind this theory assumes that over time these three cyclic events vary the amount of solar radiation that is received on the Earth's surface.
The first cyclical variation, known as eccentricitycontrols the shape of the Earth's orbit around the Sun. The orbit gradually changes from being elliptical to being nearly circular and then back to elliptical in a period of aboutyears.
The greater the eccentricity of the orbit i. Currently, the Earth is experiencing a period of low eccentricity. The second cyclical variation results from the fact that, as the Earth rotates on its polar axisit wobbles like a spinning top changing the orbital timing of the equinoxes and solstices see Figure 7y-2 below.
This effect is known as the precession of the equinox. The precession of the equinox has a cycle of approximately 26, years.
According to illustration A, the Earth is closer to the Sun in January perihelion and farther away in July aphelion at the present time. Because of precession, the reverse will be true in 13, years and the Earth will then be closer to the Sun in July illustration B.
This means, of course, that if everything else remains constant, 13, years from now seasonal variations in the Northern Hemisphere should be greater than at present colder winters and warmer summers because of the closer proximity of the Earth to the Sun.
The third cyclical variation is related to the changes in the tilt obliquity of the Earth's axis of rotation over a 41, year period. During the 41, year cycle the tilt can deviate from approximately At the present time, the tilt of the Earth's axis is When the tilt is small there is less climatic variation between the summer and winter seasons in the middle and high latitudes.
Winters tend to be milder and summers cooler. Warmer winters allow for more snow to fall in the high latitude regions.
When the atmosphere is warmer it has a greater ability to hold water vapor and therefore more snow is produced at areas of frontal or orographic uplift. Cooler summers cause snow and ice to accumulate on the Earth's surface because less of this frozen water is melted. Thus, the net effect of a smaller tilt would be more extensive formation of glaciers in the polar latitudes.
Periods of a larger tilt result in greater seasonal climatic variation in the middle and high latitudes. At these times, winters tend to be colder and summers warmer.
Colder winters produce less snow because of lower atmospheric temperatures. As a result, less snow and ice accumulates on the ground surface.
Moreover, the warmer summers produced by the larger tilt provide additional energy to melt and evaporate the snow that fell and accumulated during the winter months. In conclusion, glaciers in the polar regions should be generally receding, with other contributing factors constant, during this part of the obliquity cycle.
Computer models and historical evidence suggest that the Milankovitch cycles exert their greatest cooling and warming influence when the troughs and peaks of all three cycles coincide with each other.
Atmospheric Carbon Dioxide Variations Studies of long term climate change have discovered a connection between the concentration of carbon dioxide in the atmosphere and mean global temperature.
Carbon dioxide is one of the more important gases responsible for the greenhouse effect. Certain atmospheric gases, like carbon dioxide, water vapor and methaneare able to alter the energy balance of the Earth by being able to absorb longwave radiation emitted from the Earth's surface.
The net result of this process and the re-emission of longwave back to the Earth's surface increases the quantity of heat energy in the Earth's climatic system.
Researchers of the s CLIMAP project found strong evidence in deep-ocean sediments of variations in the Earth's global temperature during the past several hundred thousand years of the Earth's history. Other subsequent studies have confirmed these findings and have discovered that these temperature variations were closely correlated to the concentration of carbon dioxide in the atmosphere and variations in solar radiation received by the planet as controlled by the Milankovitch cycles.
It was also theorized that the oceans were a major store of carbon dioxide and that they controlled the movement of this gas to and from the atmosphere. The amount of carbon dioxide that can be held in oceans is a function of temperature.
Carbon dioxide is released from the oceans when global temperatures become warmer and diffuses into the ocean when temperatures are cooler.
Initial changes in global temperature were triggered by changes in received solar radiation by the Earth through the Milankovitch cycles.We would like to propose a catastrophic plate tectonics theory as a framework for Earth history.
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The Pomeroy essay focuses on theories in the field of psychology and describes stages through which they rise, become accepted, challenged and discarded. Demystifying Plot Points and the Inciting Incident () Many confuse the Inciting Incident with the 2nd major plot point of a narrative.
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