1. Waves

2. Pre-Survey Draw your best wave. How do waves form? How can they be good? Bad?

3. Types of Waves 1. Plunging Breakers form tubes or curls that cascade water down into the trough and break with a forceful crash form on steep sloping bottoms “surfing” waves

5. 2. Spilling Breakers form where bottom slopes gradually advance to shore with a line of foam tumbling down the front break slowly

6. 3. Surging Breakers Steep slope, deeper water look like wall of water advancing to shore Powerful, turns into plunging

7. Parts of a Wave crest – the highest point of a wave trough – the lowest point of a wave

8. Wave Properties height (H)– vertical distance from crest to trough wavelength (L) – the horizontal distance from crest to crest period (T)– the length of time it take one complete wave (crest to crest) to pass a fixed point frequency (F) – the number of wave crests that pass a fixed point during a certain amount of time (usually in seconds) speed (C) – the speed of a wave in a certain direction expressed as distance per unit of time

9. Important Equations Speed = wavelength / period Frequency = 1 / period Period = seconds/ wave Sample problems:  What is the speed if the length of a wave is 12 meters and it takes 2 seconds to pass a point?  What is the period of a wave with a frequency of 2 waves/sec?

10. Longshore Currents Current that moves parallel to shore

11. Rip Currents http://www.weather.com/activities/recreation/boatandbe ach/ripcurrents_identify.html http://www.weather.com/activities/recreation/boatandbe ach/ripcurrents_identify.html What is a rip current? Strong channel of water flowing seaward from shore

12. What should you do when…

13. Words of wisdom … “When in doubt, don’t go out”