Chapter 20 Directed Reading, continued. 29. During an El Nino event, surface water temperatures along South America's western coast

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1 28. What is upwelling? 29. During an El Nino event, surface water temperatures along South America's western coast Mark each of the following statements True or False. 30. El Nitio affects both surface water and weather patterns. 31. El Nirio can occur as often as every 2 years. 32. El Nino does not alter weather patterns enough to cause disasters. Section Review (p. 541) Now that you've finished Section 1, review what you learned by answering the Section Review questions in your ScienceLog. Section 2: Waves (p. 542) 1. Winds and earthquakes are two possible causes of ocean waves. Anatomy of a Wave (p. 542) 2. Which part of a wave is represented by each letter on the following diagram? a. c. b. d. Wave Formation and Movement (p. 542) 3. Water remains in the same place as waves travel through it. TEXAS EDITION, GRADE 8, UNIT 6 RESOURCES 161 A A

2 4. Surface wave energy reaches all the way to the bottom of the ocean. Specifics of Wave Movement (p. 543) 5. Using Figure 12 on page 543 as a reference, explain how you determine a wave period. 6. What is the equation for wave speed? Types of Waves (p. 543) 7. Waves can form by all of the following EXCEPT a. wind. d. impact by cosmic bodies. b. landslides. e. earthquakes. c. the phases of the moon. 8. What is the difference between shallow-water waves and deepwater waves? Read pages Then choose the type of wave or current in Column B that best matches the description in Column A, and write the corresponding letter in the space provided. Column A Column B 9. when waves hit the shore at an angle a. longshore current 10. move steadily across the ocean b. undertoe 11. break in open ocean c. whitecaps 12. moves below and opposite to incoming waves d. swells 162 HOLT SCIENCE AND TECHNOLOGY

3 13. How do tsunamis form? 14. Explain how a storm surge forms. Section Review (p. 547) Now that you've finished Section 2, review what you learned by answering the Section Review questions in your ScienceLog. cn Section 3: Tides (p. 548) 1. Which of the following influence tides? (Circle all that apply.) a. Venus c. the moon b. the sun d. Mercury _0 The Lure of the Moon (p. 548) 2. The sun's gravity is the dominant force affecting the Earth's tides. 3. Which of the following people developed theories on the principle of gravitation? (Circle one.) a. Lord Kelvin c. Sir Isaac Newton b. Marie Curie d. Pytheas 4. The pull of the moon's gravity is more noticeable in liquids 0_ Q.) 0 than in solids because liquids are lighter than solids. 5. Where on Earth do high tides occur? (Circle all that apply.) a. the part of the Earth that is facing the moon b. the part of the Earth that is directly opposite the part facing the moon c. the part of the Earth that is facing the sun d. any part of the ocean TEXAS EDITION, GRADE 8, UNIT 6 RESOURCES 163 A

4 Name Date Class 6. What two factors determine when tides occur? 7. Tides do not occur at the same spots on Earth because a. the Earth rotates more quickly than the moon revolves around the Earth. b. the moon revolves around the Earth more quickly than the Earth rotates. c. the Earth rotates at the same speed that the moon revolves around the Earth. d. none of the above 8. How long does it take for a point on the Earth that is facing the moon to rotate so that it is facing the moon again? a. 24 hours and 5 minutes b. 12 hours and 50 minutes c. 12 hours and 5 minutes d. 24 hours and 50 minutes 9. Read the Brain Food on page 549 of your textbook. How are dry land tides different from ocean tides? E1 Tt C 9.; C rt3 The Lunar Cycle (p. 550) 10. Why does the moon appear to change shape when we view it from the Earth?,to C 0 _C).c HOLT SCIENCE AND TECHNOLOGY

5 11. Look at Figure 22 on page 550 of your textbook. Then number the following phases of the moon to show the order in which they occur. Start with the new moon. waxing gibbous last quarter new moon waning gibbous first quarter waning crescent full moon waxing crescent 12. When the moon is, the sunlit part that we see from the Earth grows smaller. When the moon is, the sunlit part grows larger. Tidal Variations (p. 551) 13. Since the sun is much larger than the moon, why is the sun's influence on tides less powerful than the moon's influence? The difference between the levels of ocean water at high tide and low tide is called a tidal variation. Read page 551 to determine whether the statements below are true for spring tides or neap tides. Write ST for spring tides and NT for neap tides in the space provided. 15. occur during the first and third quarters of the moon 16. have the largest daily tidal range 17 occur when the sun, Earth, and moon line up with one another 18 occur when the sun, Earth, and moon form a 90 angle 19. occur when the sun's and moon's gravitational forces pull on the Earth in the same direction occur when the sun's and moon's gravitational forces pull on the Earth in opposite directions TEXAS EDITION, GRADE 8, UNIT 6 RESOURCES 165

6 Name Tidal Energy (p. 552) 21. What are two advantages of using tidal energy to generate electricity? 22. Tidal power plants are built in areas with small tidal ranges. 23. Why do some people oppose tidal power plants? Tides and Topography (p. 553) 24. Tides can be accurately predicted once the has been measured at a certain point over a period of time. 25. Where do tidal bores occur? (Circle all that apply.) a. narrow bays c. oceans b. inland rivers d. estuaries Section Review (p. 553) Now that you've finished Section 3, review what you learned by answering the Section Review questions in your ScienceLog. 166 HOLT SCIENCE AND TECHNOLOGY