Shadows in the water

[Moontanman]

I noticed today as I was drifting around my pool on a floating raft that i was leaving traces of shadows on the bottom. The shadows seemed to swirl around on the bottom every bit as dark as my shadow on the bottom, these swirling shadows would get bigger break up go into orbit around a bigger shadow, grow bigger break up and merge. Some of them lasted 3 minutes after they formed. You could only see them well at high noon. I was amazed at how much they resembled pictures of deep space where nebula and galaxies swirled around each other. I found that the best shadows were made with the least effort. Moving fast seemed to break up the effect but very gently moving caused the biggest longest lasting swirl shadows. They continued even after all visible surface effects stopped. The swirl shadows were independent of the glitter effect of the surface waves, a very neat effect, i am sure others have seen this but what is it called?

[J.C.MacSwell]

I noticed today as I was drifting around my pool on a floating raft that i was leaving traces of shadows on the bottom. The shadows seemed to swirl around on the bottom every bit as dark as my shadow on the bottom, these swirling shadows would get bigger break up go into orbit around a bigger shadow, grow bigger break up and merge. Some of them lasted 3 minutes after they formed. You could only see them well at high noon. I was amazed at how much they resembled pictures of deep space where nebula and galaxies swirled around each other. I found that the best shadows were made with the least effort. Moving fast seemed to break up the effect but very gently moving caused the biggest longest lasting swirl shadows. They continued even after all visible surface effects stopped. The swirl shadows were independent of the glitter effect of the surface waves, a very neat effect, i am sure others have seen this but what is it called?

 

Just a guess: (surface effects aside)

 

If you stare at variable light intensities, your eye will produce a negative affect superimposed on what you look at next.

[swansont]

Water has a higher index than air, so light will refract when t enters. If the surface is curved, it will act as a lens and deflect light away from its original path. Density changes in the water could also be present, and give you interference effects. I don't know if it has a name.

 

 

Water striders doing this, in slo-mo

http://blogs.scienceforums.net/swansont/archives/3194

[Moontanman]

The really interesting part was how they interacted with each other, orbiting around, merging, breaking up and coming back together. It was facinating for sure...

[Jacques]

I think that you saw shadow of soliton

Check that http://www22.pair.com/csdc/pdf/falaco97.pdf

[Moontanman]

I think that you saw shadow of soliton

 

Check that http://www22.pair.com/csdc/pdf/falaco97.pdf

 

 

That was really great, thanks for the link, the soliton shadow is exactly what I saw!

[Jacques]

I found that on a search on soliton and after I read that I did the experiment in my swimming pool ! So when I read you I knew it was it.

I no longer have a swimming pool but I would like to see the experiment with some dye to vizualise the string joining the 2 vortex.

[insane_alien]

a bathtub should work too, or failing that a sink.

[Jacques]

Yes! I would need something to replace the sun. Maybe a flashlight.

[Moontanman]

Probably needs to be a point source of light strong enough to cause glitter lines, it works best at high noon in my back yard pool.