This means that if you have less sand to walk on before the ocean's floor drops off steeply, like a cliff. On the East Coast, the shelf is broader -- there is more sand to walk on as the shelf drops gradually, like a really long ramp. Underneath the surface of the water, particles are spinning in the direction that the wind is moving in. The particles are largest at the surface of the water. The deeper you go in the water, the smaller the spinning particles.
As the wave moves inland and hits the upward slope of the continental shelf on the East Coast, the friction causes the particles to slow down, so the wave gradually collapses on itself. On the West Coast, the shelf rises suddenly near the coast, so the waves are much larger when they crash into the coastline -- the particles and thus the wave haven't been slowed down by extended friction with the shelf.
This means that the fetch the distance over which the wind blows is greater on the West Coast than on the East Coast. In this case, you can think of wave as a snowball: The farther you roll your snowball along in the snow, the bigger it gets. West-coast waves tend to start way out in the Pacific Ocean, so they have a greater distance to travel before they hit the shore -- more time to grow in size and length. Ernie Knowles, associate professor of oceanography at NC State University , can help us put all of this together: "The steep shelf on the West Coast would cause a more abrupt buildup of the shoaling wave so waves would be 'steeper' when they break.
But the much longer fetch in the Pacific Ocean allows the waves to receive more wind energy, and so they grow larger. The swell arriving on the West Coast has periods in the range of 10 to 17 seconds quite long waves , while the East Coast swell is more in the six- to second range. As you blow, the Styrofoam water particle doesn't move very much as the wave passes over it.
You've just created a small wave in your kitchen! Download image jpg, 77 KB. Looking out at the ocean, one often sees a seemingly infinite series of waves, transporting water from one place to the next. Though waves do cause the surface water to move, the idea that waves are travelling bodies of water is misleading. Waves are actually energy passing through the water, causing it to move in a circular motion. When a wave encounters a surface object, the object appears to lurch forward and upward with the wave, but then falls down and back in an orbital rotation as the wave continues by, ending up in the same position as before the wave came by.
If one imagines wave water itself following this same pattern, it is easier to understand ocean waves as simply the outward manifestation of kinetic energy propagating through seawater. Here's what you need to know in less than a minute. The ocean is never still. Whether observing from the beach or a boat, we expect to see waves on the horizon. Waves are created by energy passing through water, causing it to move in a circular motion. However, water does not actually travel in waves.
Waves transmit energy, not water, across the ocean and if not obstructed by anything, they have the potential to travel across an entire ocean basin. Waves are most commonly caused by wind. Wind-driven waves , or surface waves , are created by the friction between wind and surface water. As wind blows across the surface of the ocean or a lake, the continual disturbance creates a wave crest.
These types of waves are found globally across the open ocean and along the coast.
0コメント