Chapter 6 Book Notes

Chapter 6 Book Notes - Astronomy 180 Chapter 6 Earth and...

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Astronomy 180 Chapter 6: Earth and Moon (Pages 137-165) I. Earth: A Dynamic, Vital World The earth’s albedo of 0.37 indicates that there are large quantities of liquid water as well as dry land (water = 71%) II. Earth: A Dynamic, Vital World: The Earth’s atmosphere has evolved over billions of years Nitrogen and oxygen are found rarely in the atmospheres of other planets First atmosphere was comprised of hydrogen and helium which eventually escaped the gravitational pull Second atmosphere primarily carbon dioxide and water with some nitrogen; prevented earth from freezing ( greenhouse effect ) Photosynthesis in early plants helped to remove the excess CO 2 in the atmosphere Because the air has mass, it is pulled toward the earth by gravity and creates pressure [ = (force) / (area)] 1 atmosphere (atm) = a pressure of 14.7 lbs / sq inch (pressure at sea level) This pressure decreases with increasing altitude, divided by 2 with every 5.5km of altitude Troposphere – the lowest level of the Earth’s atmosphere; all of earth’s weather occurs in this lowest layer Stratosphere – the second layer in the Earth’s atmosphere, directly above the troposphere The stratosphere is the realm of the ozone layer – the lower stratosphere, where most of the ozone in the air exists Ozone molecules = O 3 ; this absorbs intermediate wavelength solar UV rays; sunlight creates ozone The troposphere is heated primarily by the earth Mesosphere – the layer in the Earth’s atmosphere above the stratosphere Ionosphere – Region of the Earth’s atmosphere, above the mesosphere, in which sunlight ionizes many atoms III. Earth: A Dynamic, Vital World: Plate tectonics produce major changes on the Earth’s surface Crust – the solid surface layer of some astronomical bodies, including the terrestrial planets, the moons, the asteroids, and some stellar remnants. The segmented appearance of the Earth’s crust reveals that the planet is constantly changing & earthquakes & volcanoes hint at activity below the Earth’s crust Continental drift – the gradual movement of the continents over the surface of the Earth due to plate tectonics Pangaea (“all lands”) – the “super continent” that broke up into today’s current continents Seafloor spreading – the process whereby magma upwelling along rifts in the ocean floor causes adjacent segments of the Earth’s crust to separate. Plate tectonics – the motions of large segments (plates) of the Earth’s surface caused by convective motions in the underlying mantle Supercontinent – the merge of plates into a single mass; every 500 million years is when a supercontinent appears Earthquakes tend to occur at the boundaries of the crustal plates where they collide (convergent boundaries),
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This note was uploaded on 04/18/2008 for the course AST 180 taught by Professor Barlow during the Fall '08 term at N. Arizona.

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Chapter 6 Book Notes - Astronomy 180 Chapter 6 Earth and...

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