NOTES: Earth: Age--4.6 billion years by radioactive isotope dating. Atmosphere--80% Nitrogen, 20% Oxygen, trace of Carbon Dioxide. Pressure = 14.7 lbs/sq in. Originally lots of CO2, but oceans absorbed it, plankton and plant life converted it to O2. Troposphere--0-10 km--weather here. Planes must go above. Stratosphere--11-50 km--ozone layer (helped life move to land) Mesosphere--50-90 km --temperature decrease Ionosphere--above 90 km--aurora generated here--temp. rises History--earth was once molten, radioactivity provided heat to keep the core molten, substances segregated. We know core is denser iron and nickel because density of earth = 5.5 g/cm3, but surface rocks have a lower density than that. Layers of the earth: (see overlay) In addition part of the mantle and the whole crust make up the lithosphere, the rolling crustal plates. Wegener's theory of continental drift. (See map.) Magnetosphere: the realm of the earth's magnetic field extending into space. Electrons in the solar wind are trapped in the Van Allen Belts (overlay). Aurora (northern and southern lights) caused by electrons in solar wind whirling around magnetic field lines and radiating. Weather: earth's rotation yields Coriolis force--winds counter- clockwise in northern hemisphere, clockwise in southern.

Age (from oldest rocks): 4.6 Billion Years

Atmospheric Layers

History--earth was once molten, radioactivity provided heat to keep the core molten, substances segregated, heavier ones drawn to center by gravity. Earth’s core is mostly iron and nickel.

Layers of the Earth How do we know? Seismology—earthquake waves. We also know core is denser iron and nickel because density of earth = 5.5 g/cm3, but surface rocks have a lower density than that.

A lesson in Geology that really ROCKS! Three major types of rock.

Igneous rocks form when molten rock cools and becomes solid. Molten rock is called magma when it is below the Earth’s surface and lava when it is above.

Sedimentary rock For thousands, even millions of years, little pieces of our earth have been eroded--broken down and worn away by wind and water. These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each. These layers are pressed down more and more through time, until the bottom layers slowly turn into rock.

Metamorphic rocks are rocks that have "morphed" into another kind of rock. These rocks were once igneous or sedimentary rocks. How do sedimentary and igneous rocks change? The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change. If you examine metamorphic rock samples closely, you'll discover how flattened some of the grains in the rock are.

Part of the mantle and the crust make up the lithosphere, the rolling crustal plates.

In about 1911, Alfred Wegener learned a dance called the Continental Drift  Heat makes lower mantle flow in circular patterns, Breaking up lithosphere and moving the continents.

Modern reconstruction of Pangaea, ca. 255 million years ago

Compass points in direction of magnetic field lines. The north magnetic pole really is in the north (not south).

Aurora: northern and southern lights-- Aurora Borealis and Australialis Caused by solar wind hitting earth’s magnetic field.

Auroras result from emissions of photons in the Earth's upper atmosphere, above 80 km (50 miles), from ionized nitrogen atoms regaining an electron, and oxygen and nitrogen atoms returning from an excited state to ground state. They are ionized or excited by the collision of solar wind particles being funneled down and accelerated along the Earth's magnetic field lines; excitation energy is lost by the emission of a photon of light, or by collision with another atom or molecule: oxygen emissions Green or brownish-red, depending on the amount of energy absorbed. nitrogen emissions Blue or red. Blue if the atom regains an electron after it has been ionized. Red if returning to ground state from an excited state. From Wikipedia on ‘Aurora (Astronomy)’

Composed of electrons ‘boiling’ off the sun.

The Van Allen Belts: trapped charged particles between magnetic field lines. A third belt has been found.

Gaspard-Gustave de Coriolis An engineer and physicist, He introduced the terms 'work' and 'kinetic energy' with their present scientific meaning, and studied flow on a rotating body like the Earth.

The Coriolis effect causes wind flowing from high pressure to low pressure regions to curve as the wind moves. This creates the trade winds. In the Northern Hemisphere, the Coriolis effect causes flow to curve to the Right In the Southern Hemisphere, the Coriolis effect causes flow to curve to the Left