The Dynamic Ocean

1. The Dynamic Ocean Ch. 16

2. 16.1 Ocean Circulation SC.912.N.1.1, SC.912.N.2.5 SC.912.E.6.5, SC.912.E.7.2, SC.912.E.7.3 , SC.912.E.7.4 , SC.912.E.7.9

3. Objectives • Explain how surface currents develop. • Describe how ocean currents affect climate. • State the importance of upwelling. • Describe the formation of density currents.

4. Vocabulary • Ocean current • Surface current • Gyre • Coriolis Effect • Upwelling • Density current

5. Essential Questions • How do surface currents develop? • How do ocean currents affect climate? • Why is upwelling important? • How are density currents formed?

6. 16.1 The Composition of Seawater

7. Ocean Currents 1 min video http://www.cleanvideosearch.com/media/action/yt/watch?videoId=3niR_-Kv4SM

8. Surface Circulation • Ocean current is the mass of ocean water that flows from one place to another. • Surface currents are movements of water that flow horizontally in the upper part of the ocean’s surface. • Surface currents develop from friction between the ocean and the wind that blows across its surface.

9. Ocean Surface Currents

10. Gyers • • Gyres are huge circular-moving current systems that dominate the surfaces of the oceans. • TheCoriolis effect is the deflection of currents away from their original course as a result of Earth’s rotation.

11. Ocean Current & Climate • When currents from low-latitude regions move into higher latitudes, they transfer heat from warmer to cooler areas on Earth. • As cold water currents travel toward the equator, they help moderate the warm temperatures of adjacent land areas.

12. False-Colored Satellite Image of the Gulf Stream

13. Upwelling • Upwelling is the rise of cold water from deeper layers to replace warmer surface water. • Upwelling brings greater concentrations of dissolved nutrients, such as nitrates and phosphates, to the ocean surface.

14. Effects of Upwelling

15. Deep Ocean Circulation • Densitycurrents are vertical currents of ocean water that result from density differences among water masses. • An increase in seawater density can be caused by a decrease in temperature or an increase in salinity.

16. Deep Ocean Circulation • High Latitudes • Most water involved in deep-ocean currents begins in high latitudes at the surface. • Evaporation • Density currents can also result from increased salinity of ocean water due to evaporation.

17. Cross Section of the Arctic Ocean

18. A Conveyor Belt • In a simplified model, ocean circulation is similar to a conveyor belt that travels from the Atlantic Ocean, through the Indian and Pacific Oceans, and back again.

20. Ocean Current Video 15 min. http://www.cleanvideosearch.com/media/action/yt/watch?videoId=Ca4eRt2wwg8

21. Essential Questions You have 15 minutes to answer the questions from this section. Be prepared to discuss your answers.

22. How do surface currents develop? Surface currents develop from friction between the ocean and the wind that blows across its surface.

23. How do ocean currents affect climate? Warm water currents that come from equatorial regions transfer heat to cooler areas of Earth; for example the Gulf Stream and North Atlantic currents warm northwestern Europe in the winter months. Cold water currents from the poles moderate warm temperatures of adjacent land areas.

24. Why is upwelling important? Upwelling brings dissolved nutrients to the ocean surface, providing the necessary nutrients for phytoplankton to undergo photosynthesis. This productivity supports the extensive populations of fish and other organisms.

25. How are density currents formed? They are formed when the density of water changes due to a change in salinity and temperature.

26. 16.2 Waves & Tides

28. Objectives • Describe how ocean waves get energy. • State three factors that determine characteristics of a wave. • Describe how energy moves through a wave. • Explain the forces that produce tides.

29. Vocabulary • Wave height • Wave length • Wave period • Fetch • Tide • Tidal range • Spring tide • Neap tide

30. Waves and Tides 9 min video http://www.cleanvideosearch.com/media/action/yt/watch?videoId=l1WF8b6HZLM

31. Wave Motion Demo • Purpose – Students will see that wave energy travels without causing individual particles of the medium to move very much. • Materials – Slinky toy • Procedure – Have a student hold one end of a slinky without moving it. Stretch the slinky out, gather a few rings together, release them all at once while still holding the end of the slinky in your hand.

32. Essential Questions • From where do ocean waves obtain energy? • What three quantities are used to describe a wave? • How does energy move by means of a wave? • What force produces tides? • What are three typical tidal patterns?

34. Wave Characteristics • Most ocean waves obtain their energy and motion from the wind. • The wave height is the vertical distance between the trough and crest. • The wavelength is the horizontal distance between two successive crests or two successive troughs.

35. Anatomy of a Wave

36. Wave Characteristic • The wave period is the time it takes one full wave—one wavelength—to pass a fixed position. • Fetch is the distance that the wind has traveled across open water. • The height, length, and period that are eventually achieved by a wave depend on three factors: (1) wind speed, (2) length of time the wind has blown, and (3) fetch.

37. Wave Motion • Circular orbital motion allows energy to move forward through the water while the individual water particles that transmit the wave move around in a circle.

38. Breaking Waves • Changes occur as a wave moves onto shore. • As the waves touch bottom, wave speed decreases. The decrease in wave speed results in a decrease in wavelength and an increase in wave height.

39. Breaking Waves

40. Tides • Tides are daily changes in the elevation of the ocean surface. • Ocean tides result from the gravitational attraction exerted upon Earth by the moon and, to a lesser extent, by the sun. • Tide-Causing Forces • The force that produces tides is gravity.

41. Tide Bulges on Earth Caused by the Moon

42. Tides • Tidal range is the difference in height between successive high and low tides. • Spring tides are tides that have the greatest tidal range due to the alignment of the Earth–moon–sun system. • Neap tides are tides that have the lowest tidal range, occurring near the times of the first-quarter and third-quarter phases of the moon.

43. Tides Spring Tides Neap tides • When the Earth, Moon, and Sun are aligned we experience Spring Tides. • New Moon & Full Moon • When Earth, Moon, and Sun are at right angles to each other, we experience Neap Tides. • First Quarter & Third Quarter

44. Earth–Moon–Sun Positionsand the Tides

45. Tidal Patterns • Three main tidal patterns exist worldwide: diurnal tides, semidiurnal tides, and mixed tides.

46. Essential Questions You have 15 minutes to answer the questions from this section. Be prepared to discuss your answers.

47. From where do ocean waves obtain energy? Waves obtain their energy from wind.

48. What three quantities are used to describe a wave? Three qualities used to describe waves are: wind speed, the length of time the wind has blown, and fetch.

49. How does energy move by means of a wave? Circular motion allows energy to move forward through a wave, while the individual water particles that transmit the wave move around in a circle.

50. What force produces tides? Gravity is the force that produces tides.