Why do ice cubes form strange icicles on top when frozen?

[JabberWalkie]

So, I've noticed that when I freeze ice cubes these strange icicles appear on the top of the ice. I took a picture, included as an attachment.

Not really sure how something like this forms. Please no speculation.

 

[turbo]

That is formed by deposition from above. Drip, drip, drip. Think stalagmite.

 

[JabberWalkie]

I don't see how, its a freezer...every thing is frozen, so nothing drips from above. Also, its not formed vertically, it is at an angle to the normal.

 

[turbo]

If you can come up with an alternate answer (one that does not violate the laws of physics) please feel free. There is only one way that a stalagmite-type extension can form on an ice cube. There could be a number of causes for the dripping, but the method of formation (deposition of liquid water from above and freezing into a column) is not negotiable.

 

[russ_watters]

All freezers have defrost cycles, JabberWalkie. There most certainly is liquid water on the walls and ceiling from time to time.

 

[DaveC426913]

Not "negotiable"? Holy Jeez Turbo...

They are not stalagmites. Just because it walks like a duck doesn't mean it's a duck!


They are called Ice Spikes. They are formed as the top layer of water freezes over, leaving a smaller and smaller hole. The expansion of freezing water below this thin layer of ice causes water to bulge up through the hole, where it freezes in a ring.


Physically, if they can be compared to anything, they are more akin to deep sea volcanic vents.


(And I knew this before I looked on Wiki)

 

[Gokul43201]

Dave is exactly right. This is just the inverse effect of shrink porosity in metal casting (hence the use of risers).

 

[russ_watters]

Wow, I'd never heard of those things either. Learn something new...

 

[JabberWalkie]

Nice...

Thanks guys!...i knew it couldn't just be water dripping from the roof...had a hunch that there was some cool physics going on here. Thanks guys!