Waves Focus Questions

1. What moves in a wave?

   water particles/energy

2. Describe how the particles move in a typical wave.

   water particles move in a circular path (orbit)

3. Parts of a Wave

   crest - highest part of a wave above sea level

   trough - valley below average sea level

   height - vertical distance between crest and trough

   wavelength - horizontal distance between crests/troughs

   period - time it takes for a wave to move a distance of one wavelength

   frequency - number of waves that pass a fixed point per second

4. What causes waves?

   wind, atmospheric pressure (seiche), volcanic eruptions, tsunami, changes in gravitational forces and Earth’s rotation (tides)

5. Contrast “deep-water” and “shallow-water” waves

   deep water - deeper than ½ wavelength, water travels in orbits, capillary waves & wind waves only, small

   shallow water - shallower than 1/20th original wavelength, only moves forward & backward, seiches, seismic sea waves, and tides, big

6. What is the relationship between wavelength and wave velocity?

   the longer the wavelength, the faster the wave energy will move through the water

7. Which waves have the longest wavelengths?

   Seismic Sea Waves/Tsunami & Tides (caused by an earthquake)

8. What is the average height, period, and speed of a wind wave?

   height: 600 m, period: 20 seconds, speed: 70 mph

9. Describe how a wind wave (capillary wave) forms - include 3 factors involved in the wave height?

   grows from capillary waves, grows larger if it remains in deep water and wind continues to blow, wind strength, wind duration, fetch (uninterrupted distance over which wind blows without changing direction)

10. How does the swell develop?

    dispersion; where waves separate/waves with longer wavelengths are faster and outrun smaller waves

11. What can cause consecutive waves to be different heights?

    interference - wind waves from different storm systems add (constructive interference) or subtract (destructive interference) from each other/ surf beat - sets of big waves; big then small again, then big (continuous pattern like that)

12. What is a rogue wave?

    many waves of different length and height converge at one spot; wave larger than before or after

13. Describe how a wave breaks.

    wave train reaches shore; less than half wavelength, orbitals near bottom flatten and wave crests become peaked instead of rounded, waves slow due to interaction with the bottom and wavelength decreases, crest moves ahead of supporting base and breaks when it gets in shallow water

14. Contrast plunging and spilling waves.

    plunging waves are violent, leaving an air-filled tube between crest and foot of wave due to steep sloping bottom while spilling waves, crest slides down face of the wave; gently sloping bottom (are in SC)/ contour and composition of bottom can also affect breaking waves)

15. Describe Tsunami waves.

    period: 20 mins, speed: 470 mph, height: 200km

Tides

1. Who first developed an understanding of the tides?

   Isaac Newton

2. What are the primary forces that cause the tides?

   gravitational forces of the moon and sun, motion of the earth

3. Which celestial body has the most profound influence on ocean tides? Why?

   Moon; it’s closer to the Earth so it has a stronger pull

4. How long is a tidal day?

   24 hours and 50 minutes

5. How much time passes between low tide and the next high tide?

   6 hours and 12.5 minutes

6. What is a spring tide? When do they occur? Are the tides stronger or weaker?

   when the earth, sun & moon are in a line (higher high tide and lower low tide), occur every 2 weeks during new and full moons, stronger tides

7. What is a neap tide? When do they occur? Are the tides stronger or weaker?

   when the earth, sun & moon form a right angle (opposite) (not very high tides and not very low tides), occur every 2 weeks, occur 1 week after spring tide, weaker tides

8. What is a King Tide?

   extra high tide; when the earth is closer to the sun and the moon tides will be stronger

9. What role does climate change play in tidal impacts?

   sea level rises since the ocean absorbs heat and expands, tide is higher than normal

10. What if a hurricane hit at high tide and/or during King Tides?

    more flooding; much worse weather with storm surges (way higher w/different tides)

11. What conditions created the greatest tide variation?

    January, new or full tide, perigee

12. Contrast Semidiurnal, Diurnal, and Mixed tidal patterns?

    semi - 2 high tides, 2 low tides/day (not at the same high) : diurnal - 1 high tide, 1 low tide : mixed - successive high or low tides have different heights throughout cycle

13. What is the tidal pattern here in Myrtle Beach?

    semidiurnal

14. What is an amphidromic point?

    node near center of an ocean basin where there is NO tide, 12 areas in the world

15. What are several factors that affect the tide at any one locality?

    position of sun & moon relative to earth, rotation of earth, shape of coastlines, elliptical orbits of the moon

16. What is a tidal bore? Where do they usually occur?

    tidal wave; wave moving upstream in an estuary or river, predictable

17. Define the following.

    tidal range: high to low difference; varies greatest in bays or inlets

    flood current: water rushing in an enclosed area due to tidal crest

    ebb current: water rushing out due to tidal trough

    slack water: time of no current, at high and low tide when current changes direction

18. What is an effect of tidal friction?

    the number of days in a year has decreased (days have grown longer)

19. How does the tide impact marine organisms?

    some organisms can tolerate more exposure than others, animals and plants sort themselves into 3 or more horizontal bands (subzones) within the intertidal zone, organisms time arrival and departure times with tides

20. Describe tidal zonation

    different zones for life where ocean meets the land, different levels of life, out of or in water, more life in deeper zones

21. What adaptations do organisms that live in the intertidal zone process?

    not drying out by closing their shell (muscles), holding onto rocks with suction cups, burrowing, flexible bodies, dealing with extreme temperature and salinity changes, predation, timing of reproduction (sea turtles)

22. What are the advantages and disadvantages of tidal power?

    advantages - low operating costs; power source is free; no pollution

    disadvantages - few appropriate sites; parts of plant damaged by storms and corroded by seawater; alter height of wave; disrupts organisms; increases tidal friction

23. What impact can the tides have on you personally?

    weather (hurricanes) and shipping of products overseas