Wave Refraction

[geoffschultz]

I've been studying the Mexican coastline/anchorages via satellite images and just saw a great image showing wave refraction. In a wider view of this area, the wind/waves are out of the due north (going top to bottom). As the waves get close to the coastline, they refract and end up coming in parallel to the shore, so despite having a piece of land providing "protection", you still have waves coming ashore. I always knew that this occurred, but didn't have any idea as to the extent.

-- Geoff

 

[Bill Roosa]

Look closer

You can also see wave reflection. A good way to tell when there is land nearby but can't see it.

 

[richk]

diffraction

diffraction also takes place. See attached image.

A good reference on these processes is the bible for these physical phenomena, the U.S. Army Corps of Engineers Shore Protection Manual, online at http://www.archive.org/stream/shoreprotectionm01unit#page/n1/mode/2up

(this is a copy from Woods Hole)

This pub gives analytic tools for performing your own analyses, which are typically dependent upon an adequate chart of bottom contours and some ideas of incoming swell properties.

Rich

 

[geoffschultz]

So is this diffraction or refraction? I'm guessing the former and suspect that I've been calling it the wrong thing for years!

-- Geoff

 

[Bill Roosa]

deffraction or refraction

diffraction is the interference of two wave trains producing a completely different wave pattern. Like when the wind starts to blow from a different direction and you get a confused sea
refraction is the slowing and consequent bending of waves as they pass through a changing media. Like when the waves slow as they move into shallow water.
Reflection is when a wave hits a solid object and "bounces" back
In this case you are seeing refraction and reflection but not diffraction

 

[Ross]

The complex ripple pattern in the near ground of this picture shows multiple refraction and reflection effects.

 

[Joe]

Remember how we used wave tanks in high school physics to show us the properties of light? Pretty cool to see it so dramatically in nature.