What causes spontaneous patterns on surface of my hot tea?

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Offline jkforde

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Hi,

I've noticed rapid surface fracturing & wave-like transition patterns on the surface of very hot black tea when the surface of the tea is viewed in direct reflected light.

There seems to be a layer of rapidly cooling & evaporating liquid on the surface that changes pattern & fractures with a rapid wave-like transition. It reminds me of the beautiful BZ reaction. Is there any link at the physics level?

Thanks a lot,
John
« Last Edit: 13/04/2012 20:43:23 by chris »

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Offline RD

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Re: Patterns on surface of hot tea...
« Reply #1 on: 10/04/2012 23:48:16 »
I don’t drink black tea, but I have noticed black coffee has a oil film floating on it.
Convection in the hot liquid could cause Bénard convection cells made visible by changes in the oil film.


[attachment=16292]
https://upload.wikimedia.org/wikipedia/commons/3/37/B%C3%A9nard_cells_convection.ogv


Bénard convection cells are a somewhat similar to Belousov-Zhabotinsky patterns ...

[attachment=16294]
https://www.youtube.com/watch?v=IBa4kgXI4Cg#t=44s
« Last Edit: 11/04/2012 00:41:29 by RD »

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Offline jkforde

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thanks a lot for the replies folks but I don't reckon it's convection cells that I'm seeing, I'll try to get a pic or vid of what I'm talking about..... tbc!

.... update... see a vid here: http://db.tt/78og8m6R
« Last Edit: 18/04/2012 10:05:22 by jkforde »

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Offline RD

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.... update... see a vid here: http://db.tt/78og8m6R

[attachment=16319]

looks like vapour vortexes (mini whirlwinds ) are breaking through the oil film, which then heals up rapidly erasing their trail, unlike the dust devil trails on mars which last a bit longer ...

« Last Edit: 23/04/2012 02:10:58 by RD »