1. Waves

2. What is a wave?  a transmission of energy through matter.

3. What travels in waves?  Sound  Light (electromagnetic NRG)  Energy through water

4. Basic Wave Info

5.  Wavelength is measured from crest to crest  Wave height is the distance from a wave's trough to its crest (i.e. amplitude). The crest is the top of an unbroken wave, the trough is at the bottom of the front of the wave  period: time it takes for one wavelength to go past a point  If 5 wave crests pass a point in 10 seconds, then the period would be 2 sec.  You may hear waves described like, " It's 5 ft at 13 seconds". What this means is that the average height of the largest 33% of the waves are 5 ft and that the average period (time between wave crests) of the most prevalent swell is 13 seconds

6.  frequency: number of wavelengths that pass a point during a time interval  One cycle per second is called 1 Hertz  Speed = wavelength/period  Therefore, the longer the wavelength, the faster it travels!  wave height (amplitude) has no effect on speed

8. Types of waves  Transverse  Motion of matter is perpendicular to the direction in which the wave is moving  Longitudinal  Matter moves back and forth in the same direction that the energy travels  sound  Orbital  Only transmit through fluids  Energy moves the fluid in a circular motion as it passes  Ocean waves  http://www.learningdemo.com/noaa/lesson09.html

10. What makes ocean waves?  A disturbance  wind- from storms  undersea earthquakes = tsunami  effect of moon and tides

12. What causes wave size?  how strong the wind is (velocity)  how long it blows for (time)  the distance that wind blows over water (fetch)

13. water waves  swells have varied velocities  change speed with depth- shallower = slower  Breakers form when water depth is about ½ the wavelength

16. 3 basic types of breaking waves  Depends on the type of shoreline  Spilling breakers occur on gently sloping coasts where the waves break slowly and over a long distance, with the crest spilling gently down the front of the wave  Plunging breakers occur when the coast is steeper, the waves slow down more quickly and the crest curls way over the front of the wave and plunges down towards the base---in other words it curls  = a good surf wave  Surging breakers occur where the coastline is very steep and the wave builds up very suddenly and breaks right onto the beach  Sometimes called a shore break

18. 3 things that happen to waves:  reflection  refraction (bending)  diffraction

19. Reflection of waves  180 phase shift with a rigid boundary  No phase shift with a non-rigid boundary  interference

20. Wave interference  Constructive-  When waves are “in phase”  the troughs and crests coincide and make the wave height greater  Destructive-  When the waves are out of phase  Crests of one wave train coincide with the troughs of another  Waves cancel each other out  Since neither of these happen very often, wave trains are both destructive and constructive  Leads to “mixed seas”

23. Refraction of waves  different velocities at different depths  bends around barriers  reduces the energy of the waves in a bay, concentrates the energy on a point (headland)

26. Diffraction  opening in barrier smaller than wavelength  semicircular waves produced  energy decreases