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Chapter 13

Chapter 13. Ocean Systems. I. Oceans are connected. Cover most of Earth (3/4) 7 continents divide ocean into sections Contain salts and gases from rain & rivers and from elements underground/undersea. Salinity and Density. Salinity is the measurement of dissolved salt

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Chapter 13

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  1. Chapter 13 Ocean Systems

  2. I. Oceans are connected • Cover most of Earth (3/4) • 7 continents divide ocean into sections • Contain salts and gases from rain & rivers and from elements underground/undersea

  3. Salinity and Density • Salinity is the measurement of dissolved salt • Density is the measurement of matter in a given space • Water that contains salt is heavier therefore has a greater density than fresh water • The more dense water is, the easier it is to float (Dead Sea near Israel p. 429) • When water evaporates from ocean, salt is left behind increasing the salinity of remaining water • Salinity is also high in cold areas (glaciers)

  4. Gases • Ocean water has same gases as air (oxygen, nitrogen and carbon dioxide) which is essential to ocean life • Oxygen increases with plants and algae that live near the surface of the ocean where the sun shines

  5. Temperature Varies • Layer 1-Surface- heated by sun so is the warmest and less dense • Layer 2-Thermocline-below surface with temp dropping as depth drops (graph p. 431) • Layer 3-Deep Water-cold all year all over the globe (near freezing temps) • Location and season does change the temp (pic p. 431)

  6. Ocean Floor • Continental shelf-sloping land going into ocean on the • Continental slope –steep slope into ocean • Trenches-narrow steep cliffs in ocean floor Mariana Trench is deepest place in world (11,000+ meters below sea level) • Abyssal plane-wide flat area of ocean floor • Mid ocean ridge-chain of mountains under ocean Molten rock rises up within Earth to form ridges (p. 432-33)

  7. Ocean Exploration • Water pressure makes it difficult to explore depths • Other obstacles: Dark, lack or air, cold waters • Scuba, submarines and robots help explore the ocean floor • Sonar is a system that uses sound waves to measure distances, give detailed pics and locate objects. A fast echo return means shallow and a slow echo return means deep.

  8. Review p. 434 • What substances are contained in ocean water? • Draw and label/describe 5 features of the ocean floor. • Describe 3 kinds of technology or equipment used to explore the ocean. • Where in the ocean do you think water pressure is greatest and why? • What are 2 problems in ocean exploration? • Where does oxygen in the ocean come from? • Why doesn’t warm surface water sink to the bottom?

  9. II. Oceans move in currents • Ocean current is a large amount of moving water. • Surface currents are caused by strong winds blowing across globe due to uneven heating of Earth. They are curled into giant clockwise whirlpools in Northern hemisphere-spreading heat. They move warm water away from equator and cool water away from poles. (pic p. 437) • Gulf Stream-surface current that moves warm water NE towards Europe • Deep currents are caused by differences in density.

  10. Downwelling/Upwelling • Deep currents involve both down and up welling • Downwelling-from surface to depths carrying oxygen down allowing animals to live in depths • Upwelling-from depths to surface carrying nutrients from floor for sea life near surface • Cycle and a symbiotic relationship – goes on continuous and one depends on the other

  11. Climate and Weather • Weather is daily conditions and climate is patterns of weather in an area over a long period of time. • Ocean and atmosphere interact in unpredictable ways • Change in one current can result in huge changes • El Nino is when global weather changes for 12-18 months (more/less snow, warmer/cooler)

  12. Review p. 440 • What are 2 causes of currents in the ocean? • How do currents distribute heat around the globe? • How are climate & weather related to currents? • Describe how upwelled water differs from the water around it. • How do surface currents occur? • What is the Gulf Stream and how does it affect Europe? • What would happen if all ocean currents halted?

  13. III.Waves • Wave is an up & down motion along surface of water due to winds, earthquakes, landslides, any movement • Shape of wave includes: crest/high point, trough/low point, height/vertical distance between crest and trough, wavelength/distance between one crest to the next crest (pic p. 443) • Waves move energy-not water.

  14. Waves cause currents near shore • Longshore current- moves water parallel to the shore where waves meet land and angle – zigzag motion moves and piles sand along beach-can produce sand bars out in ocean • Rip current- narrow streams of water that break through sandbars and drain rapidly back to deep sea-occur when high winds or waves cause large amount of water to wash back from shore/beach-very dangerous-swimmers should swim parallel to shore to escape it

  15. Review p. 445 What can cause waves in the ocean? What happens to waves near the shore? Name and describe 2 kinds of currents that waves cause. Describe the shape of all waves. Why are rip currents formed near sandbars? How should swimmers respond if caught in a rip current?

  16. IV. Tides • Tide is the periodic rising and falling of the water level of the ocean • High tide is when the water level along a beach is high-exposing little beach/sand. • Low tide is when the water level along a beach is low-exposing more beach/sand. • There are 2 high and 2 low tide per day (totaling 4)

  17. Gravity causes tides • Gravity of sun and moon pull on Earth causing oceans to bulge on the side facing the moon and the opposite side-high tide • Between the two bulges are dips-low tide (pic p. 449) • As Earth rotates, different parts of Earth pass through the bulges and dips • Tidal range is difference in height of high and low tide and it depends on the shape of land above and below ocean

  18. Monthly Tides • Spring tide – an extra high tide and an extra low tide – occurs when both gravity of sun and moon pull at the same time • Neap tide- a smaller high tide and a smaller low tide (less extreme between) – occurs when sun and moon are not lined up with Earth so gravity pulls in different directions (pic p. 451)

  19. Generate Electricity • Energy of tides generates electricity • Dam built near path of water, water flows and is trapped in dam during high tide, when tide is low dam gates open and water rushes out. Water spins turbines that power electric generators. • Benefit of hydroelectricity – less pollution and water is a renewable resource

  20. Review p. 452 • Describe the appearance of tidal changes at the beach. • Explain the difference between sun and moon and creating tides. • How are tides used to generate electricity? • Compare & contrast neap and spring tides. • How would tides differ if the moon revolved around the Earth twice a month? • What are the benefits of hydroelectricity?

  21. Test Time • Review the power point and complete Chapter review on page 455 (#1-14). • Complete graph for # 1-3 • Use testing strategies and notes to answer #4-10. Use ALL CAPS • Answer in thorough complete sentences for #11-14. • On any drawings, be sure to label and describe.

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