
A Wave-Tracking Experiment - srikar
http://www.npr.org/blogs/krulwich/2014/07/11/330748781/the-most-astonishing-wave-tracking-experiment-ever
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rcthompson
Anyone familiar with standard wave mechanics will expect that crossing waves
will pass right through each other. The part that confuses me is why the waves
don't spread out laterally. For instance, take the waves in the article that
went from the Indian ocean to the Mexican coast. Wouldn't they fan out across
the entirety of the Pacific ocean after passing between Australia and
Antarctica? Or maybe they do, but they're so big to begin with that even after
they do so, they're still big enough to crash on the entire west coast of the
Americas? Would the same storm have caused gigantic waves to crash on the much
closer southern Australian shore?

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dj-wonk
It may not answer your question directly, but the following is a nice write-
up:
[http://www.acs.psu.edu/drussell/Demos/waves/wavemotion.html](http://www.acs.psu.edu/drussell/Demos/waves/wavemotion.html)

"Water waves are an example of waves that involve a combination of both
longitudinal and transverse motions. As a wave travels through the waver, the
particles travel in clockwise circles. The radius of the circles decreases as
the depth into the water increases."

The animation is mesmerizing.

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rcthompson
That's a cool animation, and I've seen it before, but I'm talking about the
waves spreading out in the 3rd dimension, horizontally along the length of the
wave (i.e. perpendicular to the screen in that animation).

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ovis
You mean like ripples in a pond? Yes, that does happen for both deep and
shallow water waves. And yes, the wave power would be expected to spread
laterally, causing the amplitudes observed at a point to be smaller further
from the source.

Here's a model visualization of the tsunami set off by the 2004 Sumatran
earthquake. [http://youtu.be/46ovp1rZeL4](http://youtu.be/46ovp1rZeL4)

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omegant
Flying you can see when strong winds blow from land. The sea is flat at the
beach. But just 3 or 5 miles inland waves can be 1 meter high or more. It's
amazing how fast they go from milimeters to meters.

It's also possible to see how the wind blows differently, when guided by hills
and valleys. Just like pointing a huge hair dryer to a bathtub.

Edit: typos

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rcthompson
I'm having trouble visualizing what you're talking about here. What do you
mean by inland waves?

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satori99
I think he mean't offshore waves

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ajuc
So, what's the bandwidth and latency?

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zafka
Who is doing the work tracking waves today? This reminds me of the butterfly
flapping his wings of fractal fame. In this case though, they are tracking the
whole path.

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niels_olson
NOAA and a lot of secondaries using their data: surfline, magicseaweed,
swell3d, etc.

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carbocation
This is so broken on mobile that I cannot scroll down to read the article on
latest Chrome on iOS.

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montibbalt
Works fine in mobile IE

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scotchmi_st
> "The astonishing thing is, you'd think it would bump into a million other
> waves that are coming at it from every direction; that it would pass through
> other storms, spreading, bumping, traveling, that all this travel would sap
> its momentum. But, as Walter Munk would discover, that's not what happens."

Kinda weird that the article spends so long explaining high-school physics,
and in such astonished terms. Zomg! Waves pass through each other! The
Superposition principle! If they think that's cool, they should see some of
the stuff you can do with light and sound.

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javert
Many Americans don't take physics in high school. I didn't and I'm a computer
science phd student (so it's not that I wasn't intelligent enough to take it).
I was surprised to learn that waves coming from different directions just pass
through each other. I did take physics in college, from a guy who could barely
speak English.

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scoot
If this is true (and I have no evidence one way or the other), then surely
this is the bigger surprise (coming from an environment where science is
mandatory to middle-school equivalent, and at least one science subject almost
un avoidable before university level.

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learc83
>coming from an environment where science is mandatory to middle-school
equivalent, and at least one science subject almost un avoidable before
university level.

School districts are ran locally and the curriculum is usually set at the
state level, so there are differences, but 3 years of science is mandatory in
middle school in every state I've ever heard of. In addition, almost all
American high schools require 3 or 4 years of science for university bound
students (maybe a bit less for non college bound students but usually not less
than 3 years).

At my high school, in a not very big town in Georgia, everyone took physical
science, chemistry, and biology. However, you had choices for senior year--
physics, AP physics, AP chemistry, ecology or anatomy (you could take more
than one if you wanted).

