GGR377 questions 1.docx

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Adrien Djomo

•How was the universe before the big bang? Nothing, a single spot subatomic •What are the main explanations of the big bang theory and how did it expanded? According to the standard theory, our universe sprang into existence as "singularity" around 13.7 billion years ago. Our universe is thought to have begun as an infinitesimally small, infinitely hot, infinitely dense, something - a singularity. After its initial appearance, it apparently inflated (the "Big Bang"), expanded and cooled, going from very, very small and very, very hot, to the size and temperature of our current universe. It continues to expand and cool to this day and we are inside of it •Explain the main changes which have occurred since the big bang. Solar system formation: Moon’s formation: Earth’s moon has been created from debris of a collision of Earth with another body as big as Mars First continents: Initial crust formed when Earth's surface first solidified from a combination of tectonic plates and intense impacts of the heavy bombardment Atmosphere and Oceans: •How the solar system was formed? The solar system was formed from a large, rotating cloud of interstellar dust and gas called the solar nebula •At about 4.5 Ga, the nebula began a contraction •Center of nebula collapsed rapidly until nuclear fusion of hydrogen into helium began •Outer part of nebula gravity caused matter to condense around density perturbations and dust particles, and the rest of the protoplanetary disk began separating into rings •One of the important elements in the Earth formation are the atmosphere and oxygen formations. Explain how this happened and how it has affected the life on earth. •The first atmosphere captured the solar nebula and was composed mostly of hydrogen and some helium •After impact molten Earth released volatile gases which in combination with gases from volcanoes formed the second atmosphere rich in greenhouse gases but poor in oxygen •The third atmosphere rich in oxygen emerged when bacteria began to produce oxygen about 2.8 Ga Atmosphere >protected Earth from radiation, meteors, asteroids. warms the planet, reduce temperature extremes day and night. Oxygen > organisms evolve and diversified, increase global productivity. Explain the chronological terms used to describe the Geological Time scale •Supereon: It divides the Earth’s history into several eons of the geological time and two supereons (Precambrian and Phanerozoic) •Eon: is a geochronology unit that divides the Earth’s history in 04 periods of about half a billion years •Era: is a geochronology unit that divides the Earth’s history in 10 periods of several hundred million years •Epoch: is a geochronology unit that divides the Earth’s history in tens of millions of years •Age: is a geochronology unit that divides the Earth’s history in millions of years What are the main characteristics of each eon of the Earth? Hadean: Solar system formed Archean: Continental plates formed, magnetic field Proterozoic Eon: Glaciation, snowball earth Phanerozoic Eon: Pangea, continents drift about When and how the human life evolved and how the expansion has occurred? By about 2 Ma, the first animal classified Homo human appeared in Africa from Apes (6 Ma), (Chimpanzees) Africa > Asia& Europe > Americas Describe the Milankovitch cycle Orbital shape (eccentricity): 100,000 years, elipse>circular, perihelion-closest to sun, aphelion-furthest to sun Axial tilt (obliquity): These slow 2.4° obliquity variations are roughly periodic, taking approximately 41,000 years to shift between a tilt of 22.1° and 24.5° and back again. Axial precession: Precession is the trend in the direction of the Earth's axis of rotation relative to the fixed stars, with a period of roughly 26,000 years. This gyroscopic motion is due to the tidal forces exerted by the Sun and the Moon on the solid Earth, which has the shape of an oblate spheroid rather than a sphere. The Sun and Moon contribute roughly equally to this effect. Compare the climate during the quaternary and the present climate Quaternary: During the quaternary glaciation, about 2.6 million years ago, the earth experienced a regular series of cold glacial periods approximately every 100,000 years •At the beginning of the Holocene about 11,700 years ago, the earth became warmed to approximately its present-day mean temperature, •Warm period continued until approximately 5,500 years BP and was followed by a colder period known as the Neoglacial period •The climate analysis of the last 2,000 years show that there has been very little variation up the years 1850 at the beginning of the industrial revolution. •During this period, there was the Medieval Warm period approximately 800 to 1200 AD and the Little Ice Age approximately 1400 to 1800 AD •The present warm period started at the beginning of the pre-industrialized period about 1850 years ago with the conversion of forest lands to crop lands and plantation What is the distinction between the carbon cycle and the carbon budget? Carbon Cycle: Biogeochemical cycle by which carbon is exchanged among the biosphere, pedosphere, geosphere, hydrosphere and atmosphere of the Earth Global carbon budget: balance of the exchanges of carbon between the carbon reservoirs of the carbon cycle What is the composition of the air in per cent or millions of dry air by volume? Nitrogen>78.084%, Oxygen>20.946%, Argon>0.934%, Carbon Dioxide>0.035%, Other>0.002% Why carbon dioxide is the most relevant greenhouse gas in the atmosphere? Sustain life: Carbon-based molecules is the main component of biological compounds Greenhouse effect: CO2 is the most human
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