Waves are everywhere! They come in many different mediums and on different scales: electromagnetic waves (radio waves, visible light, Xrays), sound waves, vibrations on a guitar string and – ocean waves!
I’ve been thinking about ocean waves after I started taking a surfing class. So far, thinking about the physics of surfing has been much more pleasant than thinking about its dangers, like stepping on a sting-ray, getting hit by a surfboard, or getting pulled out to see by a rip current and drowning. These things scare me. I like to think that being scared of everything is just the tradeoff for having a vivid imagination, but anyways, I digress.
How do ocean waves work? To start a wave you need an initial energy source, and for the ocean that is the wind. A wind that blows in the same direction over a long distance at high speed can generate massive waves. The wind pulls against the surface of the water and transfers energy that builds up into waves.
They travel across the ocean and break where the ocean floor rises towards the shore. The rising ocean floor will slow down the water moving beneath the wave due to friction. The top of the wave will not slow down as much because it doesn’t come into direct contact with the ocean floor. The result is that the top of the wave travels faster than the water moving beneath it, causing the wave to rise up and curl forward. Eventually the wave becomes unstable and breaks on the shore.
 |
| *one step above a napkin doodle |
This is the area where the wave smashes into you in sprays of salty sea water unless you jump the wave or ride over it on your surfboard. If you are like me this is also the area where you get stuck when you see a big wave rolling towards you and think, "I don't need to go out any further."
Actually catching a wave is much more fun than trying to get over them unscathed. They tell me that in order to do that, you have to paddle a lot! You can catch a wave when you are paddling at the same speed as the wave (you need momentum to ride a wave).
That’s a very basic overview (no Laplacians here). There is more physics involved including tides, but for now, it’s about time I posted something already!
