1. Ocean Waves and Tides

2. Waves
A Wave is a rhythmic movement that carries energy through matter or space.
In oceans, waves move through seawater

4. Waves Caused by: Wind Earthquakes
Gravitational force of the Moon and Sun.

5. Parts of a Wave Crest – highest point of a wave
Trough – lowest point of a wave
Wave Height – vertical distance between the crest and the trough
Wavelength – horizontal distance between two crests or two troughs

6. Wavelength
Crest
Wave Height
Still Water
Trough
Wave Parts

7. Wave Movement
When a wave passes through the ocean, individual water molecules move up and down but they do not move forward or backward.

9. Wave Movement
When a wave breaks against the shore, the crest outruns the trough and the crest collapses.
Called a breaker.
In this case, water does move forward and backward.

11. Cause of Waves
Wind
When wind blows across a body of water, friction causes the water to move along with the wind.
Wave Height depends on –
Wind speed
Distance over which the wind blows
Length of time the wind blows

14. Tides The rise and fall in sea level is called a tide.
Caused by a giant wave.
One low-tide/high-tide cycle takes about 12 hrs and 25 min.
Tidal range is the difference in ocean level between high-tide and low-tide

15. What is the Tidal Range? HT = 30 ft, LT = 20 ft HT = 20 ft, LT = 12 ft

16. Gravitational Effect of the Moon
Two big bulges of water form on the Earth:
one directly under the moon
another on the exact opposite side
As the Earth spins, the bulges follow the moon.

18. The Cause of Tides
The primary body that influences the tides is the moon
The gravitational pull is greatest on the side of Earth closest to the moon, causing Earth to be stretched slightly
On the side of Earth closest to the moon, the pull of the moon’s gravity on the oceans is greater than it is on solid Earth
Water will flow towards this tidal “bulge”, creating a high tide
As Earth rotates, it will go “through” the tidal bulges, resulting in alternating high and low tides

19. Cause of Tides

20. Tidal Cycle
The sun also produces tidal bulges, slightly smaller than those produced by the moon
The influence is most noticeable during new and full moon phases (Earth-moon-sun are aligned), causing larger tidal bulges
Tidal Range – the difference in height between successive high and low tides
Spring Tides – have the greatest tidal range due to the alignment of the Earth-moon-sun system (new and full moons)
Neap Tides – daily tidal range is less due to the sun and moon acting against each other

21. Gravitational Effect of the Sun
Spring Tides
Earth, Moon, and Sun are lined up
High Tides are higher and Low Tides are lower than normal

22. Spring Tides

23. Gravitational Effect of the Sun
Neap Tides
Earth, Moon, and Sun form right angles
High Tides are lower and Low Tides are higher than normal

24. Neap Tides

25. Tidal Patterns
Tides at various locations respond differently to the tide-producing forces
Three main tidal patterns exist worldwide: diurnal tides, semidiurnal tides, and mixed tides
Diurnal Tidal Pattern – characterized by a single high tide and a single low tide each tidal day
Semidiurnal Tidal Pattern – characterized by two high tides and two low tides each tidal day
Mixed Tidal Pattern – characterized by a large inequality in high water heights, low water heights, or both

26. Tidal Patterns

27. Tides explained in 10 minutes

28. Hopewell Rocks near Bay of Fundy

29. b. Earthquakes- Waves caused by earthquakes are called Tsunamis
Tsunamis were once called Tidal waves, but they have nothing to do with the tides.
They are produced by earthquakes and other seismic disturbances. That’s why they’re also called seismic sea waves.
Sudden outflow of water then it returns much higher

30. Pools and Earthquakes

31. iii. Tsunamis are very long, fast moving waves!
They can have wavelengths of 150 miles, wave heights of 100 ft and move as fast as 450 mph (jet speed!).

32. Japan’s Tsunami from a Car

33. The End