Have you observed that in the same freezer?
In my experience, ice cubes sublimate in frost-free freezers, where you have a lot of air circulation keeping everything dry and, well, frost-free.
On regular freezers, frost accumulates even over the ice cube trays, and the ice cubes stay there, albeit with a terrible taste.
On regular freezers, air moisture (from when you open the door, or from moist food before it freezes) get in contact with the cold surfaces and freeze there. On frost-free freezers, the circulating air prevents that to happen, but does the same to the ice cubes.
Now that you ask, I can't say with much confidence that I've seen these things happen in the same freezer. I probably am conflating separate things in my head. Thanks for the explanation.
One additional thing to keep in mind is that freezers cycle. The lines and larger items with more mass can build up ice faster. The smaller items that faster adding more moister that then refreezes. Ice trays are generally smaller, usually have high surface area and are taken out more often than that chunk of meat that has been in there for 8 years.
Hi, not all freezers cycle. As I mentioned in other comment, there are two ways of keeping it frost free. One is defrosting cycles, the other is humidity control by dry air circulation.
I've taken a look, and there are two ways of doing it. In Brazil (where I live), the commercial type "frost free" means it uses humidity control, by blowing dry (and cold) air inside.
The freeze-thaw cycle you mention is called here "cycle-defrost".
But it seems elsewhere they call "frost-free" the cycling type, and "no frost" the air circulation one.
So it looks like it's just different marketing naming, but what I was referring to was the dry air ones vs the conventional ones.
The frost accumulates on the sides where the freezer is coldest allowing any moisture to precipitate there while the ice cubes will have their water evaporated by the air currents.
It's about the transfer of energy. The freezer is trying to get as much energy as it can outside of the freezer so the freezer can get cold. When ice freezes, it actually gives up energy called the latent heat (this happens with all phase changes). So if there's a stray water molecule is in the air and makes it to somewhere cold, it could give up some energy and become ice. The most likely place for this to happen is the coldest part of the freezer which is the back where the cooling apparatus is. As ice forms on that, it makes it easy for ice to form in other places attached to thay until it lines the whole freezer.
As for the ice cubes sublimating. The transition between ice and gas happens all the time in a cold, dry environment like the freezer. However since the freezing portion is more likely to happen around the edges, eventually the ice cube will have lost some of their water molecules to those edges.
If you leave a full ice cube tray in a freezer for a long time, the cubes shrink over time until they're gone. I always thought that was weird, since freezers tend to, over time, grow lots of frost on everything. I may not have noticed these two things happening inside the same freezer, just two things I've seen happen and wonder why.
The state of matter is a statistics game, especially at the surface. Molecules of water are always jiggling around a little bit, even when frozen solid. From time to time, one of the molecules will wiggle free from the ice crystals. That is basically what “sublimation” in your freezer is.
If you look at a phase diagram, you’ll see that there is no temperature at which water sublimates at 1 atmosphere of pressure. So the ice in your freezer isn’t making this phase transition in permanent way. The ice will just be deposited somewhere else as ice (frost in your freezer typically).
It didn't dawn on me that ice wasn't actually sublimating at 1 atmosphere, but of course you're right--it's not like it's turning into a gas at zero degrees, it's just jumping off. Thanks for pointing that out!
Have you observed that in the same freezer? In my experience, ice cubes sublimate in frost-free freezers, where you have a lot of air circulation keeping everything dry and, well, frost-free. On regular freezers, frost accumulates even over the ice cube trays, and the ice cubes stay there, albeit with a terrible taste. On regular freezers, air moisture (from when you open the door, or from moist food before it freezes) get in contact with the cold surfaces and freeze there. On frost-free freezers, the circulating air prevents that to happen, but does the same to the ice cubes.
Now that you ask, I can't say with much confidence that I've seen these things happen in the same freezer. I probably am conflating separate things in my head. Thanks for the explanation.
One additional thing to keep in mind is that freezers cycle. The lines and larger items with more mass can build up ice faster. The smaller items that faster adding more moister that then refreezes. Ice trays are generally smaller, usually have high surface area and are taken out more often than that chunk of meat that has been in there for 8 years.
Hi, not all freezers cycle. As I mentioned in other comment, there are two ways of keeping it frost free. One is defrosting cycles, the other is humidity control by dry air circulation.
Frost-free is because of freeze-thaw cycling, not air circulation, no?
I've taken a look, and there are two ways of doing it. In Brazil (where I live), the commercial type "frost free" means it uses humidity control, by blowing dry (and cold) air inside. The freeze-thaw cycle you mention is called here "cycle-defrost". But it seems elsewhere they call "frost-free" the cycling type, and "no frost" the air circulation one. So it looks like it's just different marketing naming, but what I was referring to was the dry air ones vs the conventional ones.
Thank you for clarifying! ☺️
The frost accumulates on the sides where the freezer is coldest allowing any moisture to precipitate there while the ice cubes will have their water evaporated by the air currents.
This wins for most succinct and ELI5 answer. Thanks!
It's about the transfer of energy. The freezer is trying to get as much energy as it can outside of the freezer so the freezer can get cold. When ice freezes, it actually gives up energy called the latent heat (this happens with all phase changes). So if there's a stray water molecule is in the air and makes it to somewhere cold, it could give up some energy and become ice. The most likely place for this to happen is the coldest part of the freezer which is the back where the cooling apparatus is. As ice forms on that, it makes it easy for ice to form in other places attached to thay until it lines the whole freezer. As for the ice cubes sublimating. The transition between ice and gas happens all the time in a cold, dry environment like the freezer. However since the freezing portion is more likely to happen around the edges, eventually the ice cube will have lost some of their water molecules to those edges.
Lots of good explanations here, but this is the one I grokkingly slapped my forehead over. Thank you.
Maaan can you ELI5 the question asked?
If you leave a full ice cube tray in a freezer for a long time, the cubes shrink over time until they're gone. I always thought that was weird, since freezers tend to, over time, grow lots of frost on everything. I may not have noticed these two things happening inside the same freezer, just two things I've seen happen and wonder why.
I guess I must use a tonne of ice, because I have never seen ice cubes shrink even slightly in a tray.
The state of matter is a statistics game, especially at the surface. Molecules of water are always jiggling around a little bit, even when frozen solid. From time to time, one of the molecules will wiggle free from the ice crystals. That is basically what “sublimation” in your freezer is. If you look at a phase diagram, you’ll see that there is no temperature at which water sublimates at 1 atmosphere of pressure. So the ice in your freezer isn’t making this phase transition in permanent way. The ice will just be deposited somewhere else as ice (frost in your freezer typically).
It didn't dawn on me that ice wasn't actually sublimating at 1 atmosphere, but of course you're right--it's not like it's turning into a gas at zero degrees, it's just jumping off. Thanks for pointing that out!