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

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Discussion Overview

The discussion revolves around the phenomenon of icicles forming on top of ice cubes during the freezing process. Participants explore the mechanisms behind this occurrence, including potential physical explanations and comparisons to other natural formations.

Discussion Character

  • Exploratory
  • Debate/contested
  • Conceptual clarification

Main Points Raised

  • One participant notes the formation of icicles on ice cubes but expresses uncertainty about the mechanism, requesting no speculation.
  • Another participant suggests that the icicles form through deposition from above, comparing it to stalagmites.
  • A different participant challenges this view, arguing that in a freezer, everything is frozen and nothing should drip from above, and points out the angle of the icicles.
  • One participant insists that the method of formation involves deposition of liquid water from above, stating it is not negotiable, while acknowledging that there could be various causes for the dripping.
  • Another participant mentions that freezers have defrost cycles, which could lead to liquid water forming on the walls and ceiling.
  • A participant introduces the term "Ice Spikes," explaining that they form as the top layer of water freezes, causing expansion of the water below to push through a smaller hole, where it then freezes.
  • One participant draws a parallel between the formation of ice spikes and the concept of shrink porosity in metal casting.
  • Several participants express surprise and interest in learning about this phenomenon, indicating a shared curiosity about the underlying physics.

Areas of Agreement / Disagreement

Participants express differing views on the mechanisms behind the formation of icicles on ice cubes, with no consensus reached on a single explanation. Some support the idea of deposition from above, while others propose alternative mechanisms like the formation of ice spikes.

Contextual Notes

The discussion includes various assumptions about the conditions within a freezer and the nature of ice formation, which remain unresolved. The terminology used to describe the formations (e.g., stalagmites vs. ice spikes) also reflects differing interpretations.

Who May Find This Useful

Individuals interested in the physics of freezing processes, ice formation, and related phenomena may find this discussion informative.

JabberWalkie
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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.
 

Attachments

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That is formed by deposition from above. Drip, drip, drip. Think stalagmite.
 
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.
 
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.
 
All freezers have defrost cycles, JabberWalkie. There most certainly is liquid water on the walls and ceiling from time to time.
 
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)
 
Last edited:
Dave is exactly right. This is just the inverse effect of shrink porosity in metal casting (hence the use of risers).
 
Wow, I'd never heard of those things either. Learn something new...
 
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!
 

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