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Earth Science

Earth Science. Coach Williams Room 310B. Chapter 15. Physical Oceanography. Section 15.1: The Oceans. Objectives: Identify methods used by scientists to study Earth’s oceans Discuss the origin and composition of the oceans Describe the distribution of oceans and major seas.

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Earth Science

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  1. Earth Science Coach Williams Room 310B

  2. Chapter15 • Physical Oceanography

  3. Section15.1: The Oceans • Objectives: • Identify methods used by scientists to study Earth’s oceans • Discuss the origin and composition of the oceans • Describe the distribution of oceans and major seas

  4. Oceanography • The study of Earth’s oceans

  5. Modern Oceanography • Sonar: SOundNAvigation and Ranging” • Mapping ocean floors • Side-scan sonar: angles • Satellites: monitor water temp/ waves

  6. Origins of Oceans • Earth: 4.6 billion years old • Ocean sedimentary rock • Igneous rock- lava chilled quickly = water • Where did ocean water come from? • Meteorites colliding release water • 0.05% of meteorites are water • Volcanism: water vapor

  7. Distribution of Earth’s Water • Oceans: 97% of Earth’s water • Freshwater/glaciers: 3% • Sea Level: level of the ocean • Ice makes sea levels vary • Sea floor rising/falling • 71% of planet is covered by oceans • Major Oceans: Pacific, Atlantic, Indian • Other oceans: Arctic & Antarctic • Seas: smaller than oceans and usually land-locked

  8. Oceans

  9. Section15.2: Seawater • Objectives: • Compare/contrast the physical and chemical properties of seawater • Explain ocean layering • Describe the formation of deep-water masses

  10. Chemical Properties of Seawater • 96.5% water & 3.5% dissolved salt (NaCl) • Salt is metal & group17 on periodic table • Salinity: amount of dissolved salt • Average: 35ppt (parts per thousand) • Lower: polar regions, river/ocean, high precipitation • Higher: low precipitation/high evaporation • Salt: Volcanism, weathering/rivers • Dissolved gasses: O, N, CO2 • Salt balance: precipitate, ocean spray, animals

  11. Physical Properties of Seawater • Density: more dense than pure water >1 • Salinity, temperature • Freezing point lowered (-2°C) • Darkness: ocean water absorbs light (100m)

  12. Ocean Layering • Range of surface temp.: -2°C through 30°C (Avg=15°C) • Depth & temp.: deeper = colder • Temp. Profile: plots temp. with depth • 3 Layers (based on temp./density) • Surface layer • Thermocline: rapidly decreasing temp. • Bottom layer

  13. Ocean Layering

  14. Water Masses • Warm tropic water rises • Polar waters sink • 3 Ocean Masses: • Antarctic Bottom Water • North Atlantic Deep Water • Antarctic Intermediate Water

  15. Water Masses

  16. Section15.3: Ocean Movements • Objectives: • Describe the physical properties of waves • Explain how tides form • Compare/contrast various ocean currents

  17. Waves • Wave: movement that carries energy • Caused by wind • Water moves up and down; energy moves forward

  18. Wave Characteristics • Crest: tallest part • Trough: lowest part • Wavelength: distance between wave • Wave base: how deep water is disturbed • ½ of wavelength • Speed of wave affected by wavelength • Speed = wavelength x frequency • Wave height: distance from crest to trough • Wind speed • Wind duration • Fetch: how much open water

  19. Wave Characteristics

  20. Breaking Waves • Breakers: collapsing waves • Friction with bottom slows water down • Faster waves catch slower moving water • Faster water at top • Shapes shoreline

  21. Tides • Periodic rise/fall of sea level • High Tide: highest level • Low Tide: lowest level • Tidal range: difference between two levels

  22. Causes of Tides • Gravitational pull: Earth, Moon, Sun • Gravity depends on mass and distance • Sun: larger mass (Solar Tides) • Moon: closer (Lunar Tides) • Spring tides: Sun/Moon/Earth aligned • Tides are higher/lower than normal

  23. Causes of Tides

  24. Ocean Currents • Density currents: • Caused by density differences (salinity/temp.) • Slow moving • Surface currents: • Wind driven currents • Top 100m • Faster • Predictable patterns • Gyres: circular current systems

  25. Ocean Currents

  26. Gyres

  27. Upwelling • Movement of water up and down • Brings nutrients from deep

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