Lecture2 systems
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Lecture2 systems






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    Lecture2 systems Lecture2 systems Presentation Transcript

    • Announcements Please turn in Quiz #1 Math review, Mon. & Weds. 4-4:45 pm, in McG-S 230
    • The Tools of Geography
      • maps
      • GIS
      • remote sensing
      • statistics
      • numerical models
      • LOGIC!
      Which object best approximates the shape of the Earth? Frisbee Beachball
      • Not only did the ancient Greeks know the Earth was round, Eratosthenes estimated its diameter within 1% of actual size in 200 BC!
      • Columbus wasn’t such a rebel after all.
    • Sun Aswan Alexandria 7.2 ° Circ. = 2 π r Circumference = 805 km ∙ 50 805 km Circ. = 40,250 km r = 6400 km 7.2 ° 1 50 r = Circ. 2 π = 7.2° 360° 805 km Circumference = 1 50
    • 6378.16 km
    • 6378.16 km 6356.8 km
    • The 4 Spheres of Geography
    • Lithosphere Hydrosphere Atmosphere Biosphere
    • Lithosphere Hydrosphere Atmosphere Biosphere
    • Lithosphere Hydrosphere Atmosphere Biosphere Soil
    • Systems
      • An ordered, interrelated set of “ things ” & their “ attributes ”
      • linked by “ flows ” of energy and/or matter
      thing 1 thing 2 flow
    • Systems
      • Systems thinking is vital for all the observational sciences...
      • We can’t run experiments big enough!
      • Examples of Systems:
      • Ecosystem
      • River Channel
      • Weather
      • Plate Tectonics
    • Systems A systems approach to Earth’s energy balance From: Strahler & Strahler Where and how does the energy flow in this global-scale natural system?
    • Open Systems
      • Matter or energy flows in and out
      Input Output e.g., Crim Dell
    • Open Systems
      • Systems can be in
      • equilibrium (inputs = outputs)
      • or disequilibrium (inputs ≠ outputs)
      Input Output e.g., Crim Dell
    • Open Systems
      • If Crim Dell is in equilibrium, storage stays constant: Steady State
      • What does this mean for the water level through time? It is stable.
      Add 500 gallons per week Lose 500 gallons per week Input Output e.g., Crim Dell
    • Open Systems
      • If there is a drought and inflow is reduced, what would you expect to happen?
      • To outflow?
      • To storage?
      Add 200 gallons per week Lose ??? gallons per week ??? Input Output e.g., Crim Dell
      • Open
      Closed input output
      • inputs and/or outputs of energy or matter in a system
      • no inputs or outputs
      • matter/energy moves endlessly in series of interconnected paths
      • = CYCLES
      Closed Systems
    • Closed Systems
      • Whether a system is open or closed depends on scale .
      • Scales range from:
      • local regional global universal
      • If we expand the frame of reference to a global scale , most Earth systems become closed ; we live on a finite planet
      • Examples? Exceptions?
    • Closed Systems
      • Examples of closed systems:
      • Rock cycle
      • Water cycle
      • Food web*
      • Carbon cycle
      • * If you include death and decay…
      (Lithosphere) (Hydrosphere) (Biosphere) (All four!)
    • Closed Systems
      • Exception:
      Solar Inputs Radiation output to space Energy
    • Energy as a System
      • Used by Lord Kelvin to estimate the age of the Earth in 1863 (first extra-Biblical estimate): Given an initial temperature and a present temperature, we know the rate of heat loss, so can calculate an age.
      Energy on Earth is not quite in equilibrium 2 nd Law of Thermodynamics: Heat flows from warmer bodies (Earth) to cooler bodies (Space) Led to a huge conflict with Darwin et al. His age: 20-100 million years; not enough time for evolution or some observed geological phenomena.
    • Energy as a System But a scientist’s results are only as good as the data and the assumptions. What did Kelvin not know about? Convection in the mantle Heat from the radioactive decay of atomic nuclei