1. WAVES

2. WAVES ARE WAVES, BUT WE WILL TALK ABOUT THEM AS TWO TYPES 1.Waves away from shore. a.These waves aren’t interacting with the bottom. b.What you would see from a boat. 2. Waves that hit the beach a.Wave type #1 and what it does when it reaches the shore. b.These waves interact with the bottom. c.The ones you play in and surfers surf on.

3. WHY ARE SOME WAVES SO BIG? Remember, there is friction between wind and water; this pushes the water. Size depends on three things. 1.Time duration wind is in contact with water. 2.Strength or speed of the wind 3.The fetch, or distance over water across which the wind blows.

4. WAVE FORMATION 1.Small ripples form as wind blows across surface. 2.The longer the wind blows, the higher the wind speed, and the greater the fetch, the bigger the waves will be. 3.The biggest waves form in from storms that last the longest with the most energetic winds that are in contact with water for hundreds of miles. 4.Sort of like rolling a snowball to make a snow man: the longer and farther you roll, the larger the ball will be.

5. HOW CAN THE BEACH AFFECT THE SIZE OF THE WAVE? The three important factors apply here, but the sea floor or lake bottom near shore is important, too. 1) Beach must be in area that receives waves from storms. A. Beach must be exposed to winds with a long fetch. 2) Waves will be larger if the bottom “rises up” quickly or steeply. A. Some sort of underwater protrusion like a reef or rocky ledge, etc. B. This causes wave to be pushed up and to rise out of the water higher. C. Like “Mavericks” in California. D. With gradual bottom, wave not as tall or high.

6. WHAT MAKES WAVES “BREAK” AT THE SHORE? Imagine walking up to your waist in Jello. You would have a harder time moving your legs than your upper body. This is what happens when a wave reaches a shoreline. The sand or rock bottom is like the Jello, it slows down the bottom portion of the wave, but the top part keeps going at the original speed and gets ahead of the lower part, sometimes to the point of “breaking”

7. WHAT MAKES WAVES “BREAK” AT THE SHORE? From: http://oceanexplorer.noaa.gov/edu/learning/9_ocean_waves/ocean_waves.html#slidehttp://oceanexplorer.noaa.gov/edu/learning/9_ocean_waves/ocean_waves.html#slide

8. WHY DO SOME WAVES FORM BARRELS FOR SURFERS? 1.When the wave bottom touches the ocean or lake bottom, the wave is... 1. pushed up 2. slowed down due to friction with the bottom 2.The lower part of the wave slows down the most while the upper part keeps going fast. 3.The upper part of the wave can then push and curl forward, ahead of the lower part of the wave, forming a barrel. 4.This is where the surfer wants to be.

9. WHAT IS A ROGUE WAVE? A wave that is much larger than the other waves around it. These occur when waves from different sources align perfectly, to make a wave that is sort of the sum of the two waves.

10. WHAT CAUSES WAVES? WIND FEATURES Friction: with the water surface. Duration: length of time wind is in contact with water. Fetch: the distance the wind is in contact with the water. Speed: speed of the wind GRAVITY Wave crests fall Wave troughs are pushed up Like a rope between two people

11. MAKING WAVES WITH ROPES

12. WATER WAVES TRANSFER ENERGY 1.The energy originally transferred from wind to water. 2.Waves in water are like all types of energy waves: the energy moves through a substance rather than moving the substance itself.* 3.Take sound waves for example. Does screaming push air across the room? No. Air molecules move in place as sound wave passes by. 4.Examples of “moving in place.: Boats, people, objects all “bob” up and down; water molecules move in circles below surface wave. * the water “moves in place” or in a circle and doesn’t move forward with the wave.

13. WHAT IS AN UNDERTOW? A RIPTIDE?

14. WAVE TERMINOLOGY The distance between one wave crest and the next wave crest is the wavelength The lower part of the wave is called the trough The amplitude is the height from sea level w ave “height” is from trough to crest and is what surfers care about. Wave height

15. WAVE FREQUENCY Wave frequency is the rate at which the waves are moving across the ocean/lake/puddle Imagine standing in the ocean up to your knees with waves coming in How often the crests are hitting your knees is the wave frequency Frequency is inversely related to wavelength, since high frequency means short distance between adjacent wave crests

16. Beach slope angle has a big effect on waves: http://oceanexplorer.noaa.gov/edu/learning/9_o cean_waves/activities/breaking_waves.html http://oceanexplorer.noaa.gov/edu/learning/9_o cean_waves/activities/breaking_waves.html How to animate a wave using perfect circles and a blue dot on each, showing the motion of water molecules at the surface of deep water: http://www.abc.net.au/science/video/2011/11/ 01/3353059.htm http://www.abc.net.au/science/video/2011/11/ 01/3353059.htm Above and below view of moving dots: http://www.acs.psu.edu/drussell/Demos/waves/ wavemotion.html http://www.acs.psu.edu/drussell/Demos/waves/ wavemotion.html

17. OTHER INFO AND SOME VIDEO LINKS There are lots of kinds of waves: shore break, surf break, barrel, spilling breakers, surging breakers, plunging breakers, The physics of waves can be very complicated, you may study the basics in US Physics Energy from wind and gravity is transferred to energy on the shore, eroding, shaping beaches, making sand, tossing logs up onto shore, giving surfers a great ride! Good resource: http://kingfish.coastal.edu/biology/sgilman/770Oceansinmotion.htmhttp://kingfish.coastal.edu/biology/sgilman/770Oceansinmotion.htm Videos: Gentle medium-sized breakers rolling in on California coast: http://www.youtube.com/watch?v=zmPzbZVUp3g http://www.youtube.com/watch?v=zmPzbZVUp3g Big storm last month in Ireland, with waves pounding against a breakwater and town: http://www.youtube.com/watch?v=sd_oMQ-GKAg#t=40 http://www.youtube.com/watch?v=sd_oMQ-GKAg#t=40 View from cliffs above Oregon coast at Port Orford: http://www.youtube.com/watch?v=BSKVlPFtgiA http://www.youtube.com/watch?v=BSKVlPFtgiA Grip of the Rip: on Haiku site: noaa_oceantoday_ripcurrents.mov APL studying waves with Go-Pro cams in straight of Juan de Fuca: http://www.apl.washington.edu/project/project.php?id=wavecams http://www.apl.washington.edu/project/project.php?id=wavecams

18. WHAT CAUSES WAVES? Determined by: Wind (duration and strength/speed), Fetch (distance), Water depth Gravity is key – pulls crest water down, which pushes trough upward, propagation of energy