Ripples in the Sand.

JohnFP · Post by **JohnFP** » Tue Jan 04, 2005 5:52 pm

I thought I would start a new thread as I did not want to hijact the subject of the original post.

It is amazing how much research has gone into explaining why and how the ripples are formed in sand from wind and water. To me they look exactly like holographic fringes.

I thought I might inquire about what causes the ripples in the sand under waves and the studies carried out are simply fascinating. Most research indicates these ripple are from but a single wave train traveling in a single direction and contributed to friction, wave energy and gravity. But, is seems all the research tanks and hypothesis' are not of a single wave moving in a single direction. A closed tank must produce a reflected wave and research shows in shallow grades the wave action does not decease with depth. Even studies in long tanks where the wave dies at the end would surely have secondary waves bouncing off the sides at an angle due to friction of the water against the wall. Also, the studies of ripples in the sand surely do not take into account the true nature of wind, and that is that is would not move linearly like a light wave but would be crossing itself with gusts from different directions thus providing and interference pattern. I would be very interested in research that took into account two wave moving in opposite (or close to opposite) directions and the effects this has on the ripples.

Wave-formed sand ripples at Duck, North Carolina
http://chinacat.coastal.udel.edu/~kirby ... -jgr01.pdf

The Origin and Growth of Ripple-mark.
http://cwp.library.ucla.edu/articles/ay ... ipple.html

Oceanography: waves
http://www.seafriends.org.nz/oceano/waves.htm#shallow

A Computer Simulation of Sand Ripple Formation
http://www.math.hmc.edu/~hosoi/M164/sanddunes.doc

Colin Kaminski · Post by **Colin Kaminski** » Wed Jan 05, 2005 3:08 am

I have been to a beach in Kawai that has waves coming from both sides. It is a small spit of land that is formed by the waves coming in from both sides. It is porportedly the only place like it in the world. I did not notice any difference in the sand ripples. I was able to snorkle there. Next time I go there I will look more closely.

JohnFP · Post by **JohnFP** » Wed Jan 05, 2005 12:34 pm

You know Colin, I can't help it. I look at everything as a set of holographic fringes. Even when I drive by the city and I see all the different building jutting upward, randomly spaced and at different heights. I wonder what that city looks like from space when the correct "Illumination" wavelengh (radio waves) bouces off of it.