Welcome to Brainstuff from house stuff Works dot com where smart happens. Hi'm Marshall Brain with today's question, why are the waves on the West coast of the United States bigger and better than the waves on the East coast of the United States. Some of the best surfing spots in the world are located along the United States West coast and in Hawaii, and the reason is simple. It's the waves. But why are the waves on the West
coast bigger than those on the East coast. There are three primary factors that determine a wave's height, First, the prevailing winds, second, the continental shelf, and third, something called the ocean fetch wind plays a big factor in wave height. The important thing to remember about waves is that the water isn't moving. The energy from the wind is moving through the water. On the West coast, the prevailing winds
are behind the waves, which increases the waves energy. On the East coast, the prevailing winds tend to blow against the incoming waves, decreasing the waves energy. So obviously this alone is gonna tend to make West Coast waves bigger and better. Then there's the continental shelf on each coast of the United states there is a continental shelf. To understand the continental shelf, let's imagine that the ocean dried up. The land under the water looks a bit like the
Grand Canyon, with cliffs and valleys, plateaus and ridges. On the west coast, if you walked out onto the continental shelf, you would notice that the shelf, the area between the beach and where the drop off begins, is narrower. This means that 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 much broader. There's more sand to walk on. As the shelf drops gradually like a really long ramp that you might see it an airport,
parking lot or something like that. As the wave moves inland, it hits the upward slope of the continental shelf. On the east coast, the friction causes the water 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 water, and thus the wave hasn't been slowed down by the extended friction of the ramp of the East coast shelf.
Then there's this fetch thing. The Pacific Ocean on the West coast has a greater expanse than the Atlantic Ocean on the East coast. This means that the fetch, or 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 a 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 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. Dr Ernie Knowles, who's an associate professor of oceanography at NC State University, can help us put all this together. He says the steep shelf on the West coast would cause a more abrupt build up 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 ten to seventeen seconds. Those are quite long waves, while the East Coast swell is more like six to ten seconds. What this all means is that if you're looking for good, consistent waves, you need to be on the West coast
or on the East coast. You can wait for a good hurricane to come along and really juice things up. For more on this and thousands of other top visit how stuff works dot com.