Why are ice cubes grey in the middle?

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SUMMARY

The grey appearance of ice cubes in the center is primarily due to the formation of larger ice crystals and the presence of gas bubbles that develop during the freezing process. As the outer layers freeze rapidly, the inner layers take longer, leading to a denser structure with varying refractive indices. This causes light to scatter and reflect internally, resulting in reduced transparency and a greyish hue. The phenomenon is explained through principles of classical physics, particularly regarding light behavior in materials with differing refractive indices.

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This discussion is beneficial for physics students, materials scientists, and anyone interested in the optical properties of ice and the science behind crystallization processes.

bobsmith76
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Do you see how the ice-cube is less transparent in the center in this image?

http://p.lefux.com/61/20091013/A10470000C/Crystal-LED-Ice-Cube-1-Gallay.jpg

This image doesn't capture exactly what I see in my cup but it gets my point across. Why is an ice cube less transparent in the center? I'm guess it's because the atoms are more tight bonded in the center. But if that's true then

1. why does that make them less transparent?
2. why are they more tightly bonded in the first place?

I put this question in general physics because it doesn't seem to deal with anyone area of physics except maybe classical physics.
 
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Good question.
The outside freezes much faster than the inside and, the longer the freezing process, the larger the crystals that form. Also, any gas that comes out of the water near the outside will end up as bubbles near the centre, along with ice crystals.
So we have large crystals and possible bubbles in the middle.
Light gets internally reflected when it goes through a (nominally) transparent material if there are changes in refractive index. Light will be scattered and take a longer path on its way through this central part. It will be attenuated and images, seen through it will be diffused, giving a grey appearance..
 
sophiecentaur said:
Good question.
The outside freezes much faster than the inside and, the longer the freezing process, the larger the crystals that form. Also, any gas that comes out of the water near the outside will end up as bubbles near the centre, along with ice crystals.
So we have large crystals and possible bubbles in the middle.
Light gets internally reflected when it goes through a (nominally) transparent material if there are changes in refractive index. Light will be scattered and take a longer path on its way through this central part. It will be attenuated and images, seen through it will be diffused, giving a grey appearance..

Thanks for the explanation, I feel more knowledgeable in this forum..:smile::smile::smile: thanks,,,
 
It's just like a 'grey' cloud. Less light gets through.
 
good question but even better answer. thanks for the help.
 

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