Tides, Waves, and Currents Test Review
1. Using the tide table from the “Tide Graph” assignment, calculate the tidal range for the following days:
2. Distinguish between a diurnal tide and a semidiurnal tide.
Diurnal tide patterns consist of 1 high tide and 1 low tide; semidiurnal patterns consist of 2 high tides and 2 low tides
3. What are mixed tide patterns and where can they be found?
Mixed tide patterns consist of some days having diurnal patterns and some days having semidiurnal patterns
4. What is the difference between spring tides and neap tides?
Spring tides occur during new and full moons when the earth, moon, and sun are aligned; they have larger tidal ranges.
Neap tides occur when the moon is at a 90 degree angle from the earth so there is no alignment; these tides typically have
smaller tidal ranges.
5. Draw a picture of how the planets are aligned for a spring tide and a neap tide.
6. Using the Galveston Bay Tides Graph, identify the day of the spring tide and neap tide.
Spring Tide: 14
7. In what direction is the tide flowing for ebb tides and flood tides?
Flood tides: low to high; Ebb: high to low
8. What causes waves to occur?
Winds blowing on the ocean surface
9. Draw and label the parts of a wave.
10. Calculate the following
Wavelength is 21m, period is 7 s, what is the wave’s velocity?
Velocity = wavelength x frequency or Velocity = wavelength / period
V= 21 / 7 = 3
Wavelength is 15m, period is 30 s, what is the wave’s velocity?
V= 15/30= 0.5
Wave velocity is 6m/s, period is 9 s, what is the wavelength?
Wavelength=velocity / frequency or Wavelength=velocity x period
W= 6 x 9 = 54
Wave velocity is 5 m/s, period is 10 s, what is the wavelength?
W=5 x 10 = 50
11. How are breakers different from whitecaps? Breakers occur on the shore whereas whitecaps occur on the open ocean when
winds blow off the waves’ crests.
12. What is the difference between a rogue wave and a tsunami?
Tsunamis happen when there is seismic activity whereas rogue waves are a result from constructive interference.
13. When surfing, what direction must you move in order for you to move forward? According to Newton’s Law, the surfer
should push backward in order to move the surfboard forward.
14. Using your waves foldable, explain the differences between the movement of a seiche wave and a wind wave.
Seiche waves are standing waves so they move up and down. Wind waves are progressive waves so they “roll”.
15. Using the “Wave’s Type” Chart from your waves foldable, what are the characteristics for each of the following types of
16. Which current is primarily responsible for bringing warmer water to Europe and the British Isles?
The Gulf Stream
17. Which current did Marlin (Nemo’s dad) use to get to Sydney, Australia?
The East Australian Current
18. What does the Coriolis Effect state?
Earth’s rotation causes winds and currents to move in a clockwise direction in the Northern Hemisphere and in a
counter-clockwise direction in the Southern Hemisphere.
19. What are gyres and how are they formed?Gyres are ocean currents that move in giant circles. They are made from the
combination of the westerly winds pushing water eastward along the upper Atlantic, the trade winds pushing it westward
near the equator, and the Coriolis Effect
20. Identify the five major ocean gyres and which way does each spin?
The North Atlantic and North Pacific Gyres spin clockwise and the South Atlantic, South Pacific, and Indian spin
21. What characteristics define each type of the currents and give an example?
Western boundary currents: fastest. Narrow, deepest currents that move warm water away from the equator. Ex:
Gulf Stream & EAC
Eastern boundary: wide and slower currents that move cooler water towards the equator; Ex; California
Currents, Canary Current
Transverse Current: Link western and Eastern Currents; Ex Antarctic Circumpolar Current
22. Using your map of the world ocean currents, which currents form
Gulf Stream , East Australian Current, Brazilian Current
California Current, Canary Current
AntArctic Circumpolar Current
23. What does Ekman’s transport basically explain?
That when a wind is blowing, ships will drift the right of it.
24. How are vertical ocean currents formed?
Usually by a convection current (difference in temperature) or by gradient pressure
25. What is the difference between upwellings and downwellings. Which of the two is more biologically productive? Upwellings
bring nutrient-rich deep ocean water back to the surface; this increases biological productivity. Downwellings bring
surface waters to the deep ocean; there is no significant biological impact.
26. When observing wave and tide induced currents, which two are caused by waves? Describe each.
Rip currents and undertows are caused by waves. Undertows are the returning currents or backwash from a wave
breaking on shore. Ripcurrents are the returning currents or backwash from a wave breaking on shore
27. When observing wave and tide induced currents, which two are caused by tides? Describe each.
Tidal currents and whirlpools (eddies) are caused by tides.
28. What are “eddies” (whirlpools) and how are they important?
29. How does thermohaline circulation occur in the ocean? Warm salty surface water is chilled and sinks in the North Atlantic
to flow towards Antarctica. Then the cooled water flows to the bottom of the Atlantic, Indian and Pacific basins where
upwellings return the water back up as surface flow to the Atlantic Ocean.
30. What are the different parts of the oceanic conveyor belt? Warm,salty water; upwellings