Eva+Gershovich

Dado Beach in Haifa, Israel **The** //waves // **may not be so impressive, but the** //science // **behind them is!** Let's look at __3 important ideas__ in this picture:  Waves are caused by wind driving against water. When breezes of two knots or less blows over calm water, small ripples form and grow as the wind speed increases until whitecaps, comprised of millions of tiny air bubbles, appear in the breaking waves. Wave motion is influenced by water depth and shape of the shoreline. Typically, the shoreline is flatter and at a short distance from the water level, which means that the shoreline is much shallower. This influences the speed of the //**orbit of the waves**//. When waves reach surf zone, the speed of the waves decrease and so the waves slows down and build up. They build up because the shoreline “bumps” the wave higher and higher and eventually causes it to turn over. A wave will bend and change direction when one part of it goes slower or faster than another part. **//Wave refraction//** is the bending of waves in shallow water. Because the shoreline is shallower, the wave bends an changes direction, thus exhibiting wave refraction. And when wave refraction occurs, the speed of the orbit of the waves decline because the shallow shoreline impedes their way. It's like running an obstacle course: you start strong, and once you hit an obstacle, you slow down. So speed is greatly influenced by depth and shape of the shoreline, where a flatter shoreline would hinder its path much faster than a more uneven shoreline (water disperses easily, so an uneven shoreline would allow it to maintain its speed a bit longer).

Waves transport energy, not matter! Wind waves transmit energy, not water mass, across the ocean’s surface. And wind waves form when energy is transferred from wind to water. Energy is transported through means of the medium, not through water molecules. The medium is the substance that caries of the wave, and in this case wind. So in a water wave, energy is transported without the transport of water. In the wide, open ocean, energy is generated by friction moving the waves. Then, this energy is passed throughout water molecules in ripples. When the water molecules retain the energy, they begin to move in all directions. At this time, the molecules movement in all directions is called **//interference//**. Remember when we talked about the speed of waves being related to the shape of the shoreline? Well, the shape of the shoreline also has an impact on energy transmission. Uneven shorelines cause waves to bend around whatever gets in their way, like rocks. When this happens, wave's energy is spread out over different areas of the shoreline and therefore shapes the shoreline/coastline. Ripples appear on smooth water when the wind blows, but will die quickly if the wind stops. The restoring force that allows them to spread is //**surface tension.**//Wind waves are mechanical waves that spread between __air__ and __water__, where the restoring force is provided by gravity. As wind blows, pressure and friction forces perturb the equilibrium of the water surface. These forces transfer energy from the air to the water, forming waves. Wind, being the predominant force in wave motion, causes the waves to eventually "crash" when they reach shoreline, where you are able to see white water, Which is water molecules moving in all directions (as described under "Energy"). Now, let's examine the force of the wave in terms of strength. In the picture above, you can see that the wave amplitude is smaller than that of a tidal wave, but if we were to get caught in a rip current of splashing white water, we would be able to feel a significant impact. The ratio between human resistance and force of a wave is huge. Ever read about the safety precautions in getting out of a rip current, "swim parallel to the shoreline!" they tell us. Well, it's true. It is very unlikely for a person to defy the force of a rip current because they pull you straight out into the ocean. And a greater force of wind will increase the force of the rip current. A rip current is just an example of wave power caused by wind and fast moving water molecules generated from the transfer of energy during interference.



__Works Cited:__  Nave, R. "Wave Motion." //Ocean Waves//. Web. 20 Dec. 2011. . "Oceans in Motion: Waves and Tides." //NEW Science at Coastal Carolina University//. Web. 20 Dec. 2011. .

Klappenbach, Laura. "Tides and Waves - How Do Tides and Waves Work." //About.com//. The New York Times Company. Web. 20 Dec. 2011. .

Briney, Amanda. "Ocean Waves - Learn About Ocean Waves." //About.com//. New York Times Company. Web. 20 Dec. 2011. <http://geography.about.com/od/physicalgeography/a/waves.htm>. "Oceans Alive! | Oceans in Motion | Wind and Waves." //Www.mos.org//. 1998. Web. 20 Dec. 2011. <http://www.mos.org/oceans/motion/wind.html>.