Open Thread: Ripples and Light

Light going through ripply/wavy water creates an effect on the bottom that we never quite figured out a name for* when some light is concentrated into brighter areas† which naturally makes other areas darker.  This . . . doesn't look like that very much.  I think that the reason is twofold.

First, the waves are large enough to be visible in themselves, thus distorting the view of the play of light and shadow on the bottom.  Second and, I believe, more importantly is where the picture was taken from.  Basically, if I hadn't cropped the image, my shadow would be in it.  (The bottom of the picture is level with the top of my shadow's head.)

Unless you happen to be a light source, this is as close as one can come to seeing what it looks like when the light coming out of the water is altered in the exact reverse way of the light going into the water.


* The reverse effect, the play of light and shadow created when the sun reflects off of a rippled surface (which is usually seen on ceilings) has a name in Italian, though it also applies to light from mirrors, which doesn't look the same at all.

WanderingUndine calls it "lakelight" when it's off a lake, which suggests a decent formula (pool-light when off a pool, sealight when off the sea, so forth.

† The technical term for an instance of any such phenomenon is "caustic", on the grounds that such manipulation of light is the means by which sunlight can be transformed into a death ray by, say, a magnifying glass.  Thus the bright areas are known as "caustics" or a "caustic network".

The noun "caustic" means "thingy that burns", with the adjective from which it is derived meaning "burny".  Most optical caustics do not burn; I feel that this technical term was badly chosen.


We have special open threads set aside for discussing various movies and shows, said discussions including plain text spoilers.  These are the current ones:
   ● Game of Thrones
   ● Avengers: Endgame
   ● Captain Marvel


Friday Sunday Recommendations!  What have you been reading/writing/listening to/playing/watching lately?  Shamelessly self-promote or boost the signal on something you think we should know about - the weekend’s ahead of us almost over, so give us something new to explore!

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