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    Earth part 1 Earth part 1 Presentation Transcript

    • Earth Part 1 The Habitability of Earth
    • Outline I. The Early History of Earth A. Four Stages of Planetary Development B. Earth as a Planet II. The Solid Earth A. Earth's Interior B. The Magnetic Field C. Earth's Active Crust III. The Atmosphere A. Origin of the Atmosphere B. Human Effects on Earth's Atmosphere
    • The Early History of Earth Earth formed 4.6 billion years ago from the inner solar nebula. Four main stages of evolution: Most traces of bombardment (impact craters) now destroyed by later geological activity Two sources of heat in Earth’s interior:
      • Potential energy of infalling material
      • Decay of radioactive material
    • Earth’s Interior Direct exploration of Earth’s interior (e.g. drilling) is impossible. Earth’s interior can be explored through seismology: earthquakes produce seismic waves . Two types of seismic waves: P ressure waves: Particles vibrate back and forth S hear waves: Particles vibrate up and down
    • Seismology Seismic waves do not travel through Earth in straight lines or at constant speed. They are bent by or bounce off transitions between different materials or different densities or temperatures. Such information can be analyzed to infer the structure of Earth’s interior.
    • Earth’s Interior (2) Basic structure : Earth’s interior gets hotter towards the center. Earth’s core is as hot as the sun’s surface; metals are liquid. Melting point = temperature at which an element melts (transition from solid to liquid) Melting point increases with increasing pressure towards the center => Inner core becomes solid Solid crust Solid mantle Liquid core Solid inner core
    • Question
      • Which of the diagram represents the MANTLE of the Earth?
      • A
      • B
      • C
      • D
      • E None of the above.
    • Question
      • Which of the diagrammed sections of the Earth's interior represents the Outer Core?
      • A
      • B
      • C
      • D
      • E None of the above.
    • Question
      • Which of the diagrammed sections of the Earth represents the CRUST?
      • A
      • B
      • C
      • D
      • E None of the above.
    • Earth’s Magnetic Field
      • Convective motions and rotation of the core generate a dipole magnetic field
      • Earth’s core consists mostly of iron + nickel: high electrical conductivity
    • The Role of Earth’s Magnetic Field Earth’s magnetic field protects Earth from high-energy particles coming from the sun (solar wind). Surface of first interaction of solar wind with Earth’s magnetic field = Bow shock Region where Earth’s magnetic field dominates = magnetosphere Some high-energy particles leak through the magnetic field and produce a belt of high-energy particles around Earth: Van Allen belts
    • The Aurora (Polar Light) As high-energy particles leak into the lower magnetosphere, they excite molecules near the Earth’s magnetic poles, causing the aurora
    • Question
      • The presence of Earth’s magnetic field is a good indication that
      • A there is a large amount of magnetic material buried near the North Pole.
      • B there is a quantity of liquid metal swirling around in the Earth's core.
      • C the Earth is composed largely of iron.
      • D the Earth is completely solid.
      • E there are condensed gasses in the core of the Earth.
    • The Active Earth About 2/3 of Earth’s surface is covered by water. Mountains are relatively rapidly eroded away by the forces of water.
    • Tectonic Plates Earth’s crust is composed of several distinct tectonic plates, which are in constant motion with respect to each other  Plate tectonics Evidence for plate tectonics can be found on the ocean floor … and in geologically active regions all around the Pacific
    • Plate Tectonics Tectonic plates move with respect to each other. Where plates move toward each other, plates can be pushed upward and downward  formation of mountain ranges, some with volcanic activity, earthquakes Where plates move away from each other, molten lava can rise up from below  volcanic activity
    • Active Zones Resulting from Plate Tectonics Volcanic hot spots due to molten lava rising up at plate boundaries or through holes in tectonic plates
    • Earth’s Tectonic History
    • History of Geological Activity Surface formations visible today have emerged only very recently compared to the age of Earth.
    • The Rock Cycle
      • Plate tectonics is involved in the formation of the three major categories of rocks
        • Igneous Rock
          • cooled from molten material
        • Sedimentary Rock
          • Layered eroded material formed by the action of wind, water, or ice
        • Metamorphic Rock
          • Rock that has been altered in the solid state by extreme heat and pressure
    • Geology of Earth
      • Telling Rocks Apart
      • How geologists tell apart different minerals and rocks
        • color, luster, texture
        • hardness test
          • scratching one against another
            • diamond is hardest
        • acid test
          • using weak hydrochloric acid to
        • streak test
          • form a streak across a ceramic tile
    • Question
      • Rocks formed from other rocks that are heated and placed under great pressures are called
      • A igneous rocks
      • B sedimentary rocks
      • C metamorphic rocks
      • D fault rocks
      • E scarp rocks
    • Question
      • Rocks formed from layers of fine material that have been compressed under water are called
      • A igneous rocks
      • B sedimentary rocks
      • C metamorphic rocks
      • D fault rocks
      • E scarp rocks
    • Question
      • The greenhouse effect occurs largely because
      • A a gas is transparent to visible light and opaque to infrared radiation.
      • B a gas is transparent to infrared radiation and opaque to ultraviolet radiation.
      • C ozone is transparent to ultraviolet radiation and opaque to infrared radiation.
      • D methane is transparent to infrared radiation and opaque to visible light.
      • E the sun emits more infrared radiation than ultraviolet radiation.
    • Question
      • Rocks formed when molten material cools and solidifies are called
      • A igneous rocks
      • B sedimentary rocks
      • C metamorphic rocks
      • D fault rocks
      • E scarp rocks
    • Question
      • Which of the following are not used to identify rocks:
      • A crystalline shape
      • B acid test
      • C streak test
      • D hardness test
      • E all of the above can be used to identify a rock
    • Earth’s Atmosphere
      • Composition
        • Nitrogen (78%), Oxygen (21%), Argon, Water Vapor, CO 2 , Methane, other
      • Atmospheric Pressure
        • pressure exerted by atmosphere
      • Warming
        • Sun - solar constant is not really constant
        • greenhouse effect
          • warming due to the transparency of a substance to radiation at visible wavelengths and opacity to infrared radiation
    • The Atmosphere Atmospheric composition severely altered (  secondary atmosphere) through a combination of two processes: 1) Outgassing: Release of gasses bound in compounds in the Earth’s interior through volcanic activity Earth had a primeval atmosphere from remaining gasses captured during formation of Earth 2) Later bombardment with icy meteoroids and comets
    • The Structure of Earth’s Atmosphere The ozone layer is essential for life on Earth since it protects the atmosphere from UV radiation Composition of Earth’s atmosphere is further influenced by:
      • Chemical reactions in the oceans,
      • Energetic radiation from space (in particular, UV)
      • Presence of life on Earth
      The temperature of the atmosphere depends critically on its albedo = percentage of sun light that it reflects back into space Depends on many factors, e.g., abundance of water vapor in the atmosphere
    • Question
      • The greenhouse effect occurs largely because
      • A a gas is transparent to visible light and opaque to infrared radiation.
      • B a gas is transparent to infrared radiation and opaque to ultraviolet radiation.
      • C ozone is transparent to ultraviolet radiation and opaque to infrared radiation.
      • D methane is transparent to infrared radiation and opaque to visible light.
      • E the sun emits more infrared radiation than ultraviolet radiation.
    • Structure of the Atmosphere
    • Circulation in our atmosphere results from convection and the Earth’s rotation
      • Because of the Earth’s rapid rotation, the circulation in its atmosphere is complex, with three circulation cells in each hemisphere
    • Winds
      • Local winds
        • wind chill factor
      • Global wind patterns
    • Weather Producers
      • Air Masses
      • Evaporation
        • Absolute humidity
        • Relative humidity
      • Fronts
      • Waves and cyclones
      • Storms
        • thunderstorms, tornadoes, hurricanes
    • An idealized cold front
    • An idealized warm front
    • Weather Forecasting
      • Predictions based upon
        • “ characteristics, location, and rate of movement of air masses and associated fronts and pressure systems”
        • Complex computer models
      • Led to science of “chaos”
        • chaotic dynamic systems
    • Climate
      • “ general pattern of the weather that occurs for a region over a number of years”
      • Major climate regions
        • tropical
        • temperate
        • polar
    • The principal climate zones
    • Question
      • Which of the following layers of the atmosphere is highest above the surface of the Earth?
      • A troposphere.
      • B stratosphere.
      • C thermosphere.
      • D mesosphere.
      • E ozone layer.
    • Question
      • What is the primary ingredient of the Earth's atmosphere?
      • A Nitrogen
      • B Oxygen
      • C Nitrogen and oxygen in equal parts
      • D Hydrogen
      • E Carbon dioxide
    • Question
      • Earth possesses few visible craters and the Moon possesses many. This is largely because
      • A Earth formed later than the Moon and, therefore hasn't encountered as many meteoroids.
      • B the Moon doesn't have an atmosphere that could burn up meteorites before impacting.
      • C erosion and plate tectonics have slowly removed evidence of past cratering on Earth.
      • D A, B and C.
      • E Only B and C above.
    • Ocean currents influence temperatures and climates
    • The hydrologic cycle Tidal forces help power the motion of the oceans
      • Most of the hydrologic cycle and weather on the
      • Earth occurs in the troposphere
    • Distribution of the Water
    • Watersheds of three rivers
    • The path of groundwater
    • Oceanography
      • Waves and tides
        • changes coastal structure
          • transport of material
        • long term and short term changes
      • A Climate control mechanism
        • ocean conveyor belt
          • major control of climate
    • A wave passing in the open ocean
    • A wave becoming breaking onshore
    • Ocean Conveyor Belt - Major Climate Control
    • Human Effects on Earth’s Atmosphere 1) The Greenhouse Effect Earth’s surface is heated by the sun’s radiation. Heat energy is re-radiated from Earth’s surface as infrared radiation. CO 2 , but also other gases in the atmosphere, absorb infrared light  Heat is trapped in the atmosphere. This is the Greenhouse Effect. The Greenhouse Effect occurs naturally and is essential to maintain a comfortable temperature on Earth, but human activity, in particular CO 2 emissions from cars and industrial plants, is drastically increasing the concentration of greenhouse gases.
    • Global Warming
      • Human activity (CO 2 emissions + deforestation) is drastically increasing the concentration of greenhouse gases.
      • As a consequence, beyond any reasonable doubt, the average temperature on Earth is increasing.
      • This is called Global Warming
      • Leads to melting of glaciers and polar ice caps (  rising sea water levels) and global climate changes, which could ultimately make Earth unfit for human life!
    • The Greenhouse Effect
      • Solar energy is the energy source for the atmosphere
      • In the greenhouse effect, some of this energy is trapped by infrared absorbing gases in the atmosphere, raising the Earth’s surface temperature above what it would be if there was no greenhouse effect
    •  
    • Rising Carbon Dioxide
    • Human Effects on the Atmosphere (2) 2) Destruction of the Ozone Layer Ozone (= O 3 ) absorbs UV radiation, (which has damaging effects on human and animal tissue). Chlorofluorocarbons (CFCs) (used, e.g., in industrial processes, refrigeration and air conditioning) destroy the Ozone layer. Destruction of the ozone layer as a consequence of human activity is proven (e.g., growing ozone hole above the Antarctic); Must be stopped and reversed by reducing CFC use, especially in developed countries!
    • Industrial chemicals released into the atmosphere have damaged the ozone layer in the stratosphere
    • Question
      • The greenhouse effect occurs largely because
      • A a gas is transparent to visible light and opaque to infrared radiation.
      • B a gas is transparent to infrared radiation and opaque to ultraviolet radiation.
      • C ozone is transparent to ultraviolet radiation and opaque to infrared radiation.
      • D methane is transparent to infrared radiation and opaque to visible light.
      • E the sun emits more infrared radiation than ultraviolet radiation.