Wikipedia

My first wikipedia post.  On googling, there was only a sad inaccurate stub in place for wave setup.  A rather encyclopedic entry today, I think:


   In fluid dynamics, wave setup is the change in mean water level due to the presence of waves. This setup is present in and near the coastal surf zone, and is evidenced by a rise in mean sea level above the still water line.
   Wave setup can be mathematically modeled by considering the variation in radiation stress (Longuet-Higgins & Stewart 1962) in the longshore and cross shore directions. As a progressive wave approaches shore and the water height decreases, there is additional flux of horizontal momentum due to the bottom pressure, but the energy remains constant. The additional flux is balanced by a decrease in the mean water level before the waves break, called a "set down".
   After the waves break (see breaking wave), the energy is no longer constant, but decreasing due to energy dissipation after the break point. The radiation stress therefore decreases, and the free surface height increases to balance, causing wave setup. Both of the above descriptions are specifically for beaches with low slope. As the wave approaches shore, the higher mean sea level may lead to wave run-up on the beach.
   Wave setup and wave run-up are particularly of concern during storm events, when the effects of big waves generated by wind from the storm are able to do damage to coastal infrastructure because of wave setup and a corresponding increase in mean sea level.

Sand ripples

On a clear day, off of Makapu'u beach in Waimanalo, you can easily see the ripples in the sand.  I've often wondered about the physics of those ripples - so evenly spaced, and always perpendicular to the direction of the waves.  Coastal engineers think about them, too.  Understanding ripples is important for understanding how much friction, or bottom roughness there is on a beach.  The physics of the ripples gives tell-tale signs about the prevailing currents and waves, and you can tell, to a rough degree, whether or not the sand is being taken from the beach or added to the beach.

There are two different types of ripples - one that is most often seen in the lab, called 'orbital' ripples, and another that is common on real beaches, called 'anorbital' ripples.  These ripples get their names from the fact that in orbital ripples, there is a tiny eddy that forms behind the peak of the ripple that determines the shape and height of the ripple. An anorbital ripple - which is the kind you have likely seen - does not have this feature.  The height of its ripple is determined solely by the grain size - how big the sand is.

Of these sand patches, ripples, can move - and are moving.  This is called 'bedform dynamics'.

Some fun facts: 1)  geologists can use ripples to see what the ocean or bay was likely millions of years ago - since the ripples sometimes become ingrained as sedimentary rocks.   2) Einstein's son became interested in this problem and, of course, tried to solve the problem of bedform motion from a statistical perspective.  Einstein supposedly said it was too hard a problem, and he should do something else.

The flight from conversation

this article by an MIT professor is very interesting

http://www.nytimes.com/2012/04/22/opinion/sunday/the-flight-from-conversation.html?pagewanted=3&ref=general&src=me&pagewanted=all

I'm interested in this idea that by shifting to digital communication, humans are changing their entire way of dealing with the outside world.  The punch line is that there is no longer a conversation - but I don't think this is true.  There is still conversation, in another form.  What I do think is interesting is the idea that digital communication is addictive (my word, not hers) because it allows you to feel connected without having to actually engage in the sometimes frustrating, unpredictable and sometimes complicated existence that is another human in physical form.  It sets up such a comfortable barrier, that everyone can be alone and together at the same time.  

I wonder - have humans for all time been waiting for this? a way to be together and alone at the same time?  when I see micronesians here with their huge families, I wonder how they can live like that - so many people and personalities in the same small apartment.  it seems to take a skill that I don't have at all.  at the same time, i am rarely alone in my place, even if I'm physically alone.  i gave up facebook, but now find myself calling people more, and have started making far-away acquaintances on a site called Livemocha.com (for learning languages).  It's as if even my friends were too much responsibility, and finding a site that allows me to be with other users anonymously is the new "just right" for me. 

This has been a week of realizing that everyone is always in their own bubble, struggling their own struggle.  And everyone must eventually decide what life is about, what gives your particular life meaning.  Some seem to be more comfortable with this question than others - some seem to solve it by having children.  I think everyone has to deal with it eventually.