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Chapter 15

Chapter 15. Earth’s Oceans. The Global Ocean. One vast body of water covering more than two thirds of Earth’s surface Oceans contain 97% of the water on Earth Oceanographers study the oceans: Water chemistry Wave action Marine organisms Sediments. Data Collection. Surface

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Chapter 15

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  1. Chapter 15 Earth’s Oceans

  2. The Global Ocean • One vast body of water covering more than two thirds of Earth’s surface • Oceans contain 97% of the water on Earth • Oceanographers study the oceans: • Water chemistry • Wave action • Marine organisms • Sediments

  3. Data Collection • Surface • Sonar—find the depth of the ocean, map undersea mountain ranges • Floats and Satellites (TOPEX/Poseidon)—map temperature, salinity, wave motion • Deep water—unmanned and manned submersibles (Alvin) • Computers—model information about tides, tsunamis, pollution, climate change

  4. Research Ships Sentry and Alvin HMS Challenger

  5. Origin of the Oceans • Oceans have existed almost since the beginning of Earth’s geologic history. • Evidence indicates that the source of the water on Earth was • volcanic eruptions (water vapor) • impacts with comets and meteorites

  6. Distribution of Earth’s Water • The southern hemisphere has much more water than the northern hemisphere.

  7. Sea level changes (due to melting glaciers and thermal expansion)

  8. Major Oceans • Pacific • Atlantic • Indian • Arctic • Southern

  9. Chemical Composition of Seawater • Water • NaCl • MgCl2 • KCl • CaCl2 • Average salt concentration is 3.5% (varies from 3.2% to 3.7%) • Salt added and removed is in equilibrium

  10. Ocean Stratification (Layering) • Ocean water forms layers based on density, caused by temperature and salinity differences

  11. Water Masses • AABW: Antarctic Bottom Water—coldest and most dense • NADW: North Atlantic Deep Water—less dense than AABW

  12. Ocean Movements: Waves

  13. Waves • Shallow water causes waves to slow down

  14. Ocean Movements: Tides • Tides are caused by gravitational effect of both the Moon and the Sun • Spring Tides: higher tidal range • Neap tides: lower tidal ranges

  15. Ocean Movements: Currents • Gyres (horizontal surface currents) transfer heat from equator to poles

  16. Ocean Movements: Currents • Density currents (ocean conveyor belt) move vertically as well as horizontally

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