1. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides Bellringer If the moon had the mass of a golf ball, the sun would have the mass of about 110 school buses! This analogy shows the difference in mass of the moon and the sun. Although the moon is much smaller than the sun is, the moon exerts more influence on Earth’s tides than the sun does. Why do you think this happens? Chapter 14

2. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides Objectives Explain tides and their relationship with the Earth, sun, and moon. Describe four different types of tides. Analyze the relationship between tides and coastal land. Chapter 14

3. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides The Lure of the Moon The daily changes in the level of ocean water are called tides. Tides are influenced by the sun and the moon and occur in a variety of cycles. High Tide and Low Tide How often tides occur and the difference in tidal levels depend on the position of the moon as it revolves around the Earth. Chapter 14

4. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides The Lure of the Moon, continued Battle of the Bulge When part of the ocean is directly facing the moon, the water there and the water on the opposite side of Earth bulges toward the moon. The bulges are called high tides. Water is drawn away from the areas between the high tides, which causes low tides to form. Chapter 14

5. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides The Lure of the Moon, continued The figure below shows how the position of the moon affects where high and low tides form. Chapter 14

6. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides The Lure of the Moon, continued Timing the Tides Tides occur at different times each day because the Earth rotates more quickly than the moon revolves around the Earth. Chapter 14

7. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides Tidal Variations The sun also affects tides. The combined forces of the sun and the moon on Earth result in tidal ranges that vary based on the positions of the three bodies. A tidal range is the difference between levels of ocean water at high tide and low tide. Chapter 14

8. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides Tidal Variations, continued Spring Tides are tides with the larges daily tidal range and occur during new and full moons. During these times, the sun, Earth, and moon are aligned. Neap Tides are tides with the smallest daily tidal range and occur during the first and third quarters of the moon. During these times, the sun, Earth and moon form a 90º angle. Chapter 14

9. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides Chapter 14

10. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Section 4 Tides Tides and Topography In some coastal areas that have narrow inlets, movements of water called tidal bores occur. A tidal bore is a body of water that rushes up through a narrow bay, estuary, or river channel during the rise of high tide and causes a very sudden tidal rise. Chapter 14

11. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu

12. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu End of Chapter 14 Show

13. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu Interpreting Graphics The diagram below shows the possible positions of the moon relative to the Earth and sun during different tidal ranges. Use the diagram below to answer the questions that follow. Chapter 14 Standardized Test Preparation

14. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. At which position would the moon be during a neap tide? A 1 B 2 C 3 D 4 Chapter 14 Standardized Test Preparation

15. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 1. At which position would the moon be during a neap tide? A 1 B 2 C 3 D 4 Chapter 14 Standardized Test Preparation

16. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. At which position would the moon be during a spring tide? F 1 G 2 H 3 I 4 Chapter 14 Standardized Test Preparation

17. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 2. At which position would the moon be during a spring tide? F 1 G 2 H 3 I 4 Chapter 14 Standardized Test Preparation

18. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. The tidal range would be greater when the moon is at position 3 than when the moon is at position 4 because Chapter 14 Standardized Test Preparation A position 4 forms a 90° angle with the sun and the Earth. B position 3 is very near a neap-tide position. C position 3 is very near a spring-tide position. D position 4 is very near a spring-tide position.

19. Copyright © by Holt, Rinehart and Winston. All rights reserved. ResourcesChapter menu 3. The tidal range would be greater when the moon is at position 3 than when the moon is at position 4 because Chapter 14 Standardized Test Preparation A position 4 forms a 90° angle with the sun and the Earth. B position 3 is very near a neap-tide position. C position 3 is very near a spring-tide position. D position 4 is very near a spring-tide position.