Message from discussion mysterious ripples... surface tension?
From: Kenny Tilton <ktil...@nyc.rr.com>
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Subject: mysterious ripples... surface tension?
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Date: Mon, 15 Aug 2005 22:14:10 GMT
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Organization: Road Runner - NYC
Background: In a park on a hot summer's day in an area tiled with 6-inch
hexagonal stones, a girl dumps most of a bottle of water on the tiled
ground. A puddle forms, which because of a very slight grade starts
extending in several directions.
I am puzzled by occasional bursts of concentric ripples appearing here
and there, as if a very light rain was just starting, or as if gas was
occasionally bubbling up from the bottom of a pond. But there was no
rain, and there was no mucky bottom, just tightly-fit stone tiles.
I squatted down close to the water and watched closely. The ripples
seemed to be forming spontaneously. I felt no rain or anything else
falling, nor did I see bubbles.
My guess -- and I am here seeking confirmation or better ideas -- was
that the surface of the puddle was being stretched by the slowly
extending arms of easing downhill, and that periodically the surface
"broke" at random points producing a shock of some sort at such a point
which got manifested as a ripple. Perhaps water pushed up through the
rupture starting a wave?