526. Q U I Z NO. 25

Q U I Z    NO. 25

OCEANS

1. In the following illustration what do you call the land that borders the oceans?

The shore is the land bordering the oceans

2. In the following illustration what is the name of the line separating the shore from the ocean?

Shoreline

3. As shown in the following illustration, what do you call the strip of land lying between low and high tide?

All of the landmass to the left of this line lies adjacent to the ocean and forms it border

This line separates the shore from the ocean, i.e., it represents the contact between water and land

A = high tide

B = low tide

The beach or shore face.

4. What do call the flat-topped ridge illustrated in the following image? Note that sand or

gravel is only deposited there during high tide.

Berm

5. What is the name of the feature that is defined as the area along the shore extending from the seaward position where sand particles are moved by waves to the landward edge of the permanent coast?

This is the technical definition of a beach.

6. What is the name of the feature illustrated below?

6. crest or crest line

7. What is the name of the feature illustrated below?

trough or trough line

8. What is the name of the feature illustrated by the length of the red arrow below?

Wavelength

9. What is the period of an ocean wave?

This is a flat-topped ridge

This red line represents the locus of the highest points on a wave

This red line represents the locus of the lowest points on a wave

Seabed

The period is the time it takes successive crests or troughs to pass a stationary point

10. What do you call the vertical distance from trough to crest?

wave height

11. If a typical wave had a wavelength of say 40 meters, and a period of 8 seconds, then what is its speed?

The magnitude of the velocity or speed is wavelength divided by time; hence, the velocity is 40 meters/8 seconds or 5 meters/sec.

12. In the following illustration what do you call the region over which wind blows

continuously?

Fetch is the maximum distance over which a given wind blows.

13. Please review the wave profile shown in the illustration for question 12. As waves

generated within a storm move outward away from the storm center and begin their travels

to distant shorelines what happens to their crest lines?

They become lower, more rounded, symmetrical, and sinusoidal in form.

14. The range of the period of common swell is __6__ to __16__ seconds.

15. The range of the wavelengths of common swell varies from__56__ to ___400___ meters

16. There is a mathematical relationship between wavelength and wave base for deep water ocean waves. What is that relationship?

Wave base is the limiting depth of particle motion as swell passes through a volume of seawater. It is equal to ½ the wavelength, i.e., wave base = (1/2) * where  is wavelength.

17. Particles lying above wave base follow what kinds of paths as swell pass through a given volume of seawater?

They follow a circular path.

18. Does the diameter of the circular path followed by particles above wave base increase or decrease with depth?

18. The diameter decreases with depth.

19. If you were in a submarine approaching a swell with a wavelength of 800 meters, then at what depth would you have to dive to in order to escape the effects of the oncoming swell?

The wind blows continuously over this region and

in the direction of the purple arrow

19. The answer is 800 meters/2 = 400 meters

20. Please review the following illustration, and then describe the condition under which a deep-water wave becomes a shallow-water wave?

20. When the seabed rises above wave base, then a deep water wave becomes a shallow water wave.

21. What happens to wavelength as deep water waves become shallow water waves?

21. Wavelength decreases

22. What happens to wave height as deep water waves become shallow water waves?

22. Wave height increases

23. What happens to wave period as deep water waves become shallow water waves?

23. Wave period remains unchanged

24. When the water depth is one-half the wavelength of a deep-water wave, water particles just above the bottom follow what kind of a path?

24. They begin to follow an elliptical rather than circular path.

25. Because water particles in a shallow-water wave follow a back-and-forth elliptical path it takes longer for water particles to complete their circuits than do water particles higher in the water column. As a result the seabed is said to exert what on the advancing wave?

25. traction or resistance to forward movement

26. When does an advancing shallow-water wave become unstable and start to break?

26. When the water depth reaches about 1.3 times its height it will break.

27. What is the name of the feature shown in the following illustration?

27. swash zone

28. What is the name given to surf rushing up the shore face?

28. swash

29. What is the name given to surf running back down the shoreface?

Within this zone surf runs up and then down this surface

29. backwash

30. Grains of sand caught in the swash zone will be dragged, pushed, and carried up the shore face in the direction of the swash, and then will be dragged, pushed, and carried down the shore face by the backwash acting under the influence of gravity. This process results in grains of sand being slowly translated down the beach. What is this overall process called?

30. long shore drift

31. Please review the following illustration. Note that as the swell approaches the shore the crests are even and parallel but at an angle to the shoreline. When this geometry occurs, the end of the approaching wave that is closest to the shoreline will feel the drag created by the seabed before the deeper water end does. Hence, it slows down and eventually breaks while the end furthest from the shoreline maintains its deep-water form and speed. As shown in the illustration what is the ultimate result of this overall process?

31. wave refraction – the bending of crestlines into parallelism with the shore line

32. The velocity of a wave is a vector as it has both magnitude and direction. In the following illustration the general vector showing the direction and magnitude of the approaching swell is broken down into components that are perpendicular and parallel to the shoreline. Which of these two components is responsible for long shore currents?

32. The component of wave motion that is parallel to the shoreline.

33. Along a coast line long shore currents traveling in opposite directions commonly meet. When this happens they turn and flow back out to sea. What are these seaward flowing currents called?

33. rip currents

34. How many tides occur in every 24 hour day?

34. 4 – 2 high and 2 low

35. What is the common center of mass of the Earth-Moon pair called?

Deep water swell – crests are parallel and

at angle to shoreline

End closest to shoreline

End furthest from shoreline

35. barycenter

36. Where is the common center of mass of the Earth-Moon pair located?

36. The barycenter lies along a line connecting the centers of the Earth and Moon, at a point about 1707 km (~1068 miles) below the surface of the Earth that faces the moon.

37. Inertial forces acting within the Earth-Moon pair are sometimes referred to as "outward" or "center" fleeing or “centrifugal” forces. After reviewing the above illustration are they everywhere the same on and within the Earth?

Yes

38. According to Sir Issac Newton, the gravitational pull of the Moon on any point on the Earth will vary inversely as the second power of the distance of that point from the Moon. After reviewing the above illustration is the gravitational attraction of the Moon everywhere the same on the Earth?

No

39. After reviewing the above illustration is the gravitational force of the Moon on the surface of the Earth facing the Moon greater or less than the inertial force?

The gravitation force is greater than the inertial or centrifugal force.

40. After reviewing the above illustration is the gravitational force of the Moon on the surface of the Earth facing away from the Moon greater or less than the inertial force?

The gravitation force is less than the inertial or centrifugal force.

41. What effect do your answers to the two previous questions imply about the world’s oceans or hydrosphere?

The hydrosphere (e.g., oceans) bulges toward the moon on the side of the Earth facing the moon, and away from the moon on the side of the Earth facing away from the moon. The Earth spins beneath these bulges resulting in two low and two high tides every 24 hours.

42. Please review the above illustration. As shown in (A) twice a month the centers of the Sun, Moon, and Earth are aligned in a straight line? During these events the gravitational field of the Sun works in concert with the gravity field of the Moon resulting in a tidal range higher than normal. What are these tides called?

Spring

43. As shown in (B) twice a month the centers of the Moon and Earth are aligned in a straight line at a right angle to the center of the Sun. During these events the gravity field of the Sun counteracts that of the Moon resulting in tidal ranges that are less than normal. What are these tides called?

Neap