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Degree: Geography (Bachelors) - Oxford, St Catherine's College University
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Over the past 2 million years, climate has oscillated between periods of warm climate (glacials) and periods of cooler climate (interglacials). Changes in the shape of earth's orbit help explain these changes. These are known as 'Milankovitch cycles'.
There are three such ‘Milankovitch cycles’:
1. Axial precession
The angle of tilt on earth's axis changes over a 41,000 year cycle. This causes more or less sunlight to reach the ice caps at the poles.
Earth's orbit around the sun varies between being a perfect sphere and an ellipse. When this orbit is an ellipse, less sunlight reaches the earth at certain points in its orbit, cooling the climate.
3. Precession of the equinoxes
Earth does not stay entirely still when it orbits the sun, but rather 'wobbles' slowly on its axis, much like a child’s spinning top. This causes the amount of sunlight hitting the earth to vary.
Combined, these three ‘Milankovitch cycles’ cause the amount of sunlight hitting the earth to change in complex ways over long timescales. They can be seen as the ‘trigger’ for glacials and interglacials operating over the Quaternary period.see more
Energy is transferred throughout the food chain as animals at lower trophic levels are consumed by those at higher trophic levels. In every living organism, energy is taken in as food. But when one organism eats another, only around 10% of this energy is transferred to the higher organism. So…where does this surplus energy go?
There are three main ways in which energy is output in every organism. These are:
RESPIRATION to generate energy for movement and organ functioning
EXCRETION as faeces, urine or gas
TISSUE (biomass) generation
When organisms are consumed in the foodchain, only energy stored as TISSUE is transferred. Therefore, at each stage of the food chain, less energy and biomass is transferred between organisms than at the previous trophic level.see more