1. Unit 3: Waves and tides

2. Part 1 - Lesson 23: Waves

3. Teauhuapo

4. Intro to waves and tides
Prezi wave comparison
Wave demonstration

5. Wave basics Where do ocean waves come from?
Anything through which energy flows is called a medium.
Ex: metal, string, water, land, air

6. Wave basics Where do ocean waves come from?
A disturbance caused by the transfer of energy through a medium is called a wave.
Source of energy for most waves is wind.

7. Wave Structure Crest – highest part of a wave
Trough – lowest part of a wave
Wave Height

8. Wave structure
Wave height – vertical distance between a crest and its nearest trough.
Amplitude – half of the wave height
Wavelength – horizontal distance between two crests or troughs
Wave Height

9. WAVELENGTH= horizontal distance (crest to crest)
WAVE HEIGHT = vertical distance (crest to trough)

10. Wave basics
If you look at the ocean in a cross section, surface wave would like a transverse wave.
Transverse wave – motion of water is perpendicular to direction of wave

11. Wave basics
It’s actually an orbital wave – water is moving a circular motion

12. Orbital motion
The size of the orbit of the water particles increases with wavelength
The orbit size decreases rapidly with depth
Only "feel" waves to a depth of 1/2 of their wavelength

14. Wave basics
Longitudinal wave – Motion of the water moves parallel to the flow of energy.
Think slinky!

15. Longitudinal
Transverse

16. 𝑝𝑒𝑟𝑖𝑜𝑑= 1 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 𝑂𝑅 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦= 1 𝑝𝑒𝑟𝑖𝑜𝑑
Wave calculations
Period = time for wave to move 1 wavelength
Frequency = number of waves passing fixed point
Inverse relationship:
𝑝𝑒𝑟𝑖𝑜𝑑= 1 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦 𝑂𝑅 𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦= 1 𝑝𝑒𝑟𝑖𝑜𝑑

17. Parts of a wave 20 seconds Period = time for wave to move 1 wavelength
What is the period for the graph? a. b.
20 seconds

18. Parts of a wave
Frequency = # of waves passing fixed point
What is the frequency for the graph?
𝟏 𝟐𝟎 or 0.05 sec
In 1 second, 1/20th of wave will pass point or takes 20 seconds for complete wave to pass point (typical wind driven ocean wave is 20 seconds or less)

19. What affects wave height?
a. Wind speed b. Wind duration c. Fetch
WAVE HEIGHT = vertical distance (crest to trough)

20. What affects wave height?
1. Wind speed
How hard wind blows changes energy transfer & therefore wave height
WAVE HEIGHT = vertical distance (crest to trough)

21. What affects wave height?
2. Wind duration
How long wind blows changes energy transfer & therefore wave height

22. What affects wave height?
c. Fetch
Amount of ocean surface area affected by wind blowing in the same direction.

23. What causes a wave to break?

24. What affects how a wave breaks?
Type of swell
Wind direction
Slope of sea bed
Sea floor features

25. How does a wave break?
Wave train approaches shore "feels" bottom at depth = 1/2 wavelength
Bottom of wave slows even more as gets shallower, wave crest moves ahead of base of wave
When depth of water is ½ of wave height, it will break.

26. Deep water vs. shallow water waves
Deep Water waves
The wave occurs in water deeper than half the wavelength.
Not affected by seafloor
Shallow Water waves
Waves enter water that is equal to or less than 1/20 the wavelength

27. Types of Waves Spilling breaker: Found at gently sloping bottom.
Plunging breaker: Found at moderate sloping bottom.
Surging breaker: So steep that wave doesn’t break until right at shoreline. S

28. Training to survive big waves

29. More Types of waves
Tsunami – caused by plate shift on seafloor causing a major displacement of water
Malaysia tsunami
Click

30. Tsunami

31. tsunami

32. tsunami

33. More Types of waves
Rogue waves – Waves come together in positive interference

34. Rogue waves often involve more than two wave crests combining
Rogue waves often involve more than two wave crests combining. In some cases, rogue waves seem to be generated when waves interact with strong surface water currents. Researchers model rogue waves as a non-linear process, meaning they do not involve simple wave crest addition, but more complex interactions of wave energy

36. Lesson 24: Tides

37. Tides
Causes
Moon’s gravity
Centrifugal force
Sun’s gravity

38. The Sun affects the Earth because it is so large, while the Moon's proximity to Earth is the main reason for its role in the tidal cycle.

39. High and low tide High Tide: Low Tide:
Occurs when the body of water is in line with the moon.
Highest point water reaches onto shore.
Low Tide:
Occurs when the body of water in perpendicular to the moon.
Lowest point water reaches onto shore.

40. Tidal range: Distance between high and low tide.
Affected by moon phase.

41. Organisms must adapt to tidal range.
Ex: Sea turtles lay their eggs above the highest high tide.

42. Largest tidal range in the world – bay of fundy
Tidal range = 16m or 52 feet

43. Tidal range
This photo is a double exposure (a photographic technique where a film is exposed twice, thus superimposing one image on top of another) of the NOAA Ship Fairweather docked at a pier in Anchorage, Alaska. The two photos were taken from the same location, capturing the ship at both high tide and low tide. The tidal range was between 9 and 11 meters (~30– 36 feet).

44. Tidal movement Flood tide: Water moving onshore from low to high tide.
“Tide is coming in”

45. Tidal movement Ebb tide: Water moving offshore from high to low tide.
“Tide is going out”

47. Flood tide
Ebb tide

48. 3 basic patterns of tides
Semidiurnal tide pattern
Most areas on Earth experience this type
Two high tides and two low tides per day

49. 3 basic patterns of tides
Diurnal tide cycle
One high and one low tide per day

50. 3 basic patterns of tides
Mixed Tide pattern
Two highs and two lows per day but one set of tides is more dramatic than the other.

51. 2 types of tides 1) Spring Tide
Sun and moon line up and pull in the same direction
Greatest tidal variation between high and low
Occurs twice a month
New and full moon

52. tides
2) Neap Tide
Sun and Moon are lined up perpendicular (partially cancelling each other out)
Least tidal variation