Ocean Unit

1. Ocean Unit • Ocean Waves, Currents & Tides

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3. Georgia Standards: S6E3: Students will recognize the significant role of water in earth processes. d. Explain the causes of waves, currents, and tides.

4. Waves: Essential Questions: How does a wave form? How do waves change near the shore? How do waves affect shorelines and beaches?

5. Wave Formation: • Wave: the movement of energy through a body of water. (Only energy moves through the wave until close to the shoreline). • Most waves form when wind blowing across the water’s surface transmit their energy to the water. • Wave size is determined by: • 1) strength of wind • 2) lengthof time wind blows • 3) distance over which the wind blows.

6. Parts of a Wave

7. Waves at the shoreline • As waves come into shore, water washes up the beach at an angle, carrying sand grains. The water and sand then runs straight back down the beach. • As a wave approaches shore and touches the bottom of the ocean, the shallower water slows the shoreward side of the wave first. Then, the rows of waves gradually turn and becomes more nearly parallel to the shore. (The wavelength decreases & wave height increases.)

8. Wave effect on shorelines • Waves shape a beach by eroding the shore in some places and building it up in others. • Some features created: • Barrier beaches • Sand dunes • Groins (See text pages 364-365 for pictures)

10. Ocean Waves Most waves in the ocean are created by wind. The wind blows across the surface of the water and transfers energy into the water, creating waves. Three things that affect the height of a wave are: strength of the wind, length of time the wind blows, and distance that the wind blows. Tsunami Energy

12. Tsunami • A type of wave usually created by an earthquake beneath the ocean floor. • The abrupt movement of the ocean floor sends pulses of energy through the water above it. When tsunamis reach the coast, they can be devastating as an earthquake on land, smashing buildings and bridges. • Most common in the Pacific Ocean, but have also occurred in the Indian Ocean. • See figure 7 p 362.

13. Waves • A wave is the movement of energy through a body of water. • What causes waves? Winds blowing across the water’s surface transmits their energy to the water. • Wave size is affected by a) strength of the wind • b) length of time the wind blows • c) distance over which the wind blows. • Causes: STRENGTH TIME DISTANCE

14. 4. Waves move energy toward the shore, not water. • 5. 2. 1. 4. 3.

15. 6. What is a tsunami? A type of wave created mainly by an earthquake beneath the ocean floor. • Challenge Question: How does a wave change when it enters shallow water near shore? Wave height increases & wavelength decreases due to friction with the bottom of the ocean and more shallow water.

16. Ocean Tides: Essential Questions: • What causes tides? • What affects the heights of tides? • How are tides a source of energy?

17. Ocean Currents: large stream of moving water through the ocean. Essential questions: What causes surface currents and how do they affect climate? What causes deep currents and what effects do they have? How does upwelling affect the distribution of nutrients in the ocean?

18. Ocean Currents (see p 381)

20. Surface Ocean Currents Text p 381 • Affects water to a depth of several hundred meters and driven mainly by winds. • Winds move in a pattern, causing currents to move in a predictable pattern. • Cause of wind/current patterns = Coriolis effect. • Coriolis Effect – because Earth rotates on its axis, the paths of the winds and currents turn.In the Northern Hemisphere –turns right, in the Southern Hemisphere, turns left.

21. How do currents affect climate?Text page 382 Read • Climate – the pattern of temperature and precipitation typical of an area over a long period of time. • Currents move cold and warm water around the world. • Cold (more dense) water from the poles is carried towards the equator. • Warm (less dense) water from the equator is carried toward the poles. Ocean currents

22. El Nino see p 383 • An abnormal climate event that occurs every two to seven years in the Pacific Ocean. El Nino Complete packet “currents” page.

23. SURFACE CURRENTS: • 1. A large stream of moving water that flows through the oceans is a(n) current. (p380) • 2. The effect of Earth’s rotation on the direction of winds and currents is called the _coriolis effect_. (p 381) • 3. Surface currents in the Northern Hemisphere curve to the _right_.(p381) • 4. Surface currents in the Southern Hemisphere curve to the left.(p381)

24. 5. The largest and most powerful surface current in the North Atlantic Ocean is the Gulf Stream. ( p 381) • 6. The Gulf Stream is caused by strong wind from the west. It carries more / less (circle one) water than the Mississippi River. It is a warm (temp) water current and carries water from the Gulf of Mexico to the Carribean Sea. (p381) • 7. The pattern of temperature and precipitation typical of an area over a long period of time is called climate_. (p 382 bold)

25. 8. A surface current warms or cools the air above it, influencing the climate of the land near the coast. (p 382 bold) • 9. How does the Gulf stream influence the climate along the western coast of Norway? • Warm currents (Gulf Stream & North Atlantic Drift) brings Norway a mild climate. • 10. How do cold-water currents affect weather on land near a coast? • Cold water cools air above—causing the air to hold less moisture ---brings cool dry weather to an area along its path.

26. 11. An abnormal climate event that occurs every 2 to 7 years in the Pacific Ocean is called El Nino. (p 383) • 12. How does El Nino begin?(p 383) Unusual winds over Western Pacific Ocean—causing warm water to move eastward toward South America’s coast. Can cause shifts in weather patterns & possible severe weather. 1997-98, warm winds in USA caused a warm winter in most of the country and flooding/mudslides in California.

27. Deep Ocean Currents • Occur deep below the water’s surface • Caused by differences in the density of ocean water. • Density of water depends on two things: • Salinity • Temperature Observe demonstration on how this movement occurs. • Deep currents move and mix water around the world. They also carry cold water from the poles toward the equator.

28. Upwelling • The movement of cold water upward from the deep ocean. • Occurs when winds blow away the warm surface water, allowing cold water to rise & replace it. • Brings up tiny ocean organisms, minerals, and other nutrients from deep in the ocean towards the surface. Without this motion, the surface waters of the open ocean would be very scarce in nutrients. • Many people depend on this—brings fish/food/and jobs to areas that would otherwise not be available.

29. Ocean Unit Packet P. 10 • Complete for a grade. • Use Text p. 384-385.

30. Currents • Why Rip Currents Form • As waves travel from deep to shallow water, they will break near the shoreline. When waves break strongly in some locations and weakly in others, this can cause circulation cells which are seen as rip currents: narrow, fast-moving belts of water traveling offshore.  Rip Current:

31. Why Rip Currents are Dangerous Rip currents are the leading surf hazard for all beachgoers. They are particularly dangerous for weak or non-swimmers. Rip current speeds are typically 1-2 feet per second. However, speeds as high as 8 feet per second have been measured--this is faster than an Olympic swimmer can sprint! Thus, rip currents can sweep even the strongest swimmer out to sea.Over 100 drownings due to rip currents occur every year in the United States. More than 80% of water rescues on surf beaches are due to rip currents.Rip currents can occur at any surf beach with breaking waves, including the Great Lakes.

32. Currents • Why Rip Currents Form • As waves travel from deep to shallow water, they will break near the shoreline. When waves break strongly in some locations and weakly in others, this can cause circulation cells which are seen as rip currents: narrow, fast-moving belts of water traveling offshore.  Rip Current:

33. Currents • Why Rip Currents Form • As waves travel from deep to shallow water, they will break near the shoreline. When waves break strongly in some locations and weakly in others, this can cause circulation cells which are seen as rip currents: narrow, fast-moving belts of water traveling offshore.  Rip Current:

34. Why Rip Currents are Dangerous Rip currents are the leading surf hazard for all beachgoers. They are particularly dangerous for weak or non-swimmers. Rip current speeds are typically 1-2 feet per second. However, speeds as high as 8 feet per second have been measured--this is faster than an Olympic swimmer can sprint! Thus, rip currents can sweep even the strongest swimmer out to sea.Over 100 drownings due to rip currents occur every year in the United States. More than 80% of water rescues on surf beaches are due to rip currents.Rip currents can occur at any surf beach with breaking waves, including the Great Lakes.

35. When Rip Currents Form Rip currents can be found on many surf beaches every day. Under most tide and sea conditions the speeds are relatively slow. However, under certain wave, tide, and beach profile conditions the speeds can quickly increase to become dangerous to anyone entering the surf. The strength and speed of a rip current will likely increase as wave height and wave period increase. They are most likely to be dangerous during high surf conditions as the wave height and wave period increase.

36. Where Rip Currents Form Rip currents most typically form at low spots or breaks in sandbars, and also near structures such as groins, jetties and piers. Rip currents can be very narrow or extend in widths to hundreds of yards. The seaward pull of rip currents varies: sometimes the rip current ends just beyond the line of breaking waves, but sometimes rip currents continue to push hundreds of yards offshore.

37. How to Identify Rip CurrentsLook for any of these clues: • a channel of churning, choppy water • an area having a notable difference in water color • a line of foam, seaweed, or debris moving steadily seaward • a break in the incoming wave pattern • None, one, or more of the above clues may indicate the presence of rip currents. Rip currents are often not readily or easily identifiable to the average beachgoer. For your safety, be aware of this major surf zone hazard. Polarized sunglasses make it easier to see the rip current clues provided above.

38. How to Avoid and Survive Rip Currents (#1 Learn how to swim!) • Never swim alone. • Be cautious at all times, especially when swimming at unguarded beaches. If in doubt, don’t go out! • Whenever possible, swim at a lifeguard protected beach. • Obey all instructions and orders from lifeguards. • If caught in a rip current, remain calm to conserve energy and think clearly. • Don’t fight the current. Swim out of the current in a direction following the shoreline. When out of the current, swim towards shore. • If you are unable to swim out of the rip current, float or calmly tread water. When out of the current, swim towards shore. • If you are still unable to reach shore, draw attention to yourself:  face the shore, wave your arms, and yell for help. • If you see someone in trouble, get help from a lifeguard. If a lifeguard is not available, have someone call 9-1-1 . Throw the rip current victim something that floats and yell instructions on how to escape. Remember, many people drown while trying to save someone else from a rip current.

39. How to Avoid and Survive Rip Currents (#1 Learn how to swim!) • Never swim alone. • Be cautious at all times, especially when swimming at unguarded beaches. If in doubt, don’t go out! • Whenever possible, swim at a lifeguard protected beach. • Obey all instructions and orders from lifeguards. • If caught in a rip current, remain calm to conserve energy and think clearly. • Don’t fight the current. Swim out of the current in a direction following the shoreline. When out of the current, swim towards shore. • If you are unable to swim out of the rip current, float or calmly tread water. When out of the current, swim towards shore. • If you are still unable to reach shore, draw attention to yourself:  face the shore, wave your arms, and yell for help. • If you see someone in trouble, get help from a lifeguard. If a lifeguard is not available, have someone call 9-1-1 . Throw the rip current victim something that floats and yell instructions on how to escape. Remember, many people drown while trying to save someone else from a rip current.

40. Currents • Why Rip Currents Form • As waves travel from deep to shallow water, they will break near the shoreline. When waves break strongly in some locations and weakly in others, this can cause circulation cells which are seen as rip currents: narrow, fast-moving belts of water traveling offshore.  Rip Current:

41. Why Rip Currents are Dangerous Rip currents are the leading surf hazard for all beachgoers. They are particularly dangerous for weak or non-swimmers. Rip current speeds are typically 1-2 feet per second. However, speeds as high as 8 feet per second have been measured--this is faster than an Olympic swimmer can sprint! Thus, rip currents can sweep even the strongest swimmer out to sea.Over 100 drownings due to rip currents occur every year in the United States. More than 80% of water rescues on surf beaches are due to rip currents.Rip currents can occur at any surf beach with breaking waves, including the Great Lakes.

42. When Rip Currents Form Rip currents can be found on many surf beaches every day. Under most tide and sea conditions the speeds are relatively slow. However, under certain wave, tide, and beach profile conditions the speeds can quickly increase to become dangerous to anyone entering the surf. The strength and speed of a rip current will likely increase as wave height and wave period increase. They are most likely to be dangerous during high surf conditions as the wave height and wave period increase.

43. When Rip Currents Form Rip currents can be found on many surf beaches every day. Under most tide and sea conditions the speeds are relatively slow. However, under certain wave, tide, and beach profile conditions the speeds can quickly increase to become dangerous to anyone entering the surf. The strength and speed of a rip current will likely increase as wave height and wave period increase. They are most likely to be dangerous during high surf conditions as the wave height and wave period increase.

44. Where Rip Currents Form Rip currents most typically form at low spots or breaks in sandbars, and also near structures such as groins, jetties and piers. Rip currents can be very narrow or extend in widths to hundreds of yards. The seaward pull of rip currents varies: sometimes the rip current ends just beyond the line of breaking waves, but sometimes rip currents continue to push hundreds of yards offshore.

45. How to Identify Rip CurrentsLook for any of these clues: • a channel of churning, choppy water • an area having a notable difference in water color • a line of foam, seaweed, or debris moving steadily seaward • a break in the incoming wave pattern • None, one, or more of the above clues may indicate the presence of rip currents. Rip currents are often not readily or easily identifiable to the average beachgoer. For your safety, be aware of this major surf zone hazard. Polarized sunglasses make it easier to see the rip current clues provided above.

46. How to Avoid and Survive Rip Currents (#1 Learn how to swim!) • Never swim alone. • Be cautious at all times, especially when swimming at unguarded beaches. If in doubt, don’t go out! • Whenever possible, swim at a lifeguard protected beach. • Obey all instructions and orders from lifeguards. • If caught in a rip current, remain calm to conserve energy and think clearly. • Don’t fight the current. Swim out of the current in a direction following the shoreline. When out of the current, swim towards shore. • If you are unable to swim out of the rip current, float or calmly tread water. When out of the current, swim towards shore. • If you are still unable to reach shore, draw attention to yourself:  face the shore, wave your arms, and yell for help. • If you see someone in trouble, get help from a lifeguard. If a lifeguard is not available, have someone call 9-1-1 . Throw the rip current victim something that floats and yell instructions on how to escape. Remember, many people drown while trying to save someone else from a rip current.

47. Why Rip Currents are Dangerous Rip currents are the leading surf hazard for all beachgoers. They are particularly dangerous for weak or non-swimmers. Rip current speeds are typically 1-2 feet per second. However, speeds as high as 8 feet per second have been measured--this is faster than an Olympic swimmer can sprint! Thus, rip currents can sweep even the strongest swimmer out to sea.Over 100 drownings due to rip currents occur every year in the United States. More than 80% of water rescues on surf beaches are due to rip currents.Rip currents can occur at any surf beach with breaking waves, including the Great Lakes.

48. When Rip Currents Form Rip currents can be found on many surf beaches every day. Under most tide and sea conditions the speeds are relatively slow. However, under certain wave, tide, and beach profile conditions the speeds can quickly increase to become dangerous to anyone entering the surf. The strength and speed of a rip current will likely increase as wave height and wave period increase. They are most likely to be dangerous during high surf conditions as the wave height and wave period increase.

49. Where Rip Currents Form Rip currents most typically form at low spots or breaks in sandbars, and also near structures such as groins, jetties and piers. Rip currents can be very narrow or extend in widths to hundreds of yards. The seaward pull of rip currents varies: sometimes the rip current ends just beyond the line of breaking waves, but sometimes rip currents continue to push hundreds of yards offshore.

50. How to Identify Rip CurrentsLook for any of these clues: • a channel of churning, choppy water • an area having a notable difference in water color • a line of foam, seaweed, or debris moving steadily seaward • a break in the incoming wave pattern • None, one, or more of the above clues may indicate the presence of rip currents. Rip currents are often not readily or easily identifiable to the average beachgoer. For your safety, be aware of this major surf zone hazard. Polarized sunglasses make it easier to see the rip current clues provided above.