Tag Archives: water vapour

Desublimation: When water vapour freezes to ice without becoming liquid in between

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One of my favourite phenomena right now is desublimition, or deposition: The phase transition of water vapour to ice that doesn’t go through the liquid phase. It happens when moist air is cooled below the dew point and condensation doesn’t occur spontaneously: When the supercooled water vapour then gets in touch with a cold surface, it turns to ice immediately. And the results are incredibly beautiful!

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These pictures are all from a trip I took with my godson and his family to Möhne Reservoir, the largest artificial lake in western Germany. You can see we were actually on a shore: What a surreal mixture of shells, leaves and frost flowers.

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And we initially just wanted to go over and have a look at the fog that we saw across the Reservoir from where we were throwing stones in the water…

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Getting closer, we were almost afraid that we’d encounter dementors there. We could feel it getting a lot colder, and there was frost on the shore and ice on the water… Spooky :-)

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Frost flowers on ice cream: When you start thinking about phenomena and something really annoying, all of a sudden, becomes really cool.

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Frost flowers on ice cream. You must have seen them before: They sometimes occur when you’ve had some ice cream, put the left-overs back in the freezer, and take them out again. And there you have it: Water-ice crystals all over your lovely ice cream! Completely annoying because, obviously, they only taste like water and mess up your whole ice cream experience (or is that only me)?

You know I’m kinda fascinated with ice crystals on frozen blended strawberries, but last time I had some, there weren’t only crystalline structures, but there was frost on it:

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Frost occurs when water vapour freezes without going through the liquid phase. Look at the awesome crystals!

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Once I started thinking about the process that formed the ice and realised that those were actually frost and not just ordinary ice crystals, they all of a sudden stopped being annoying and instead became something that I kinda look forward to finding when I open a tub of my frozen blended strawberries. Because the structures are different every time, and really really pretty! And also how awesome is it to know that those ice crystals formed from water that wasn’t even liquid? Yes, this is the kind of stuff that makes me happy! :-)

Strawberry ice cream crystals

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My new favorite thing is to put strawberries through a blender and then freeze small portions of that to eat as ice cream later. It is super yummy plus you never know what you’ll see when you open the lid!

Sometimes, you get long crystals like these:

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Ice crystals on strawberry ice cream

And then other times, you get something completely different. Look at those circular shapes! Perhaps that’s where the UFO landed? You can’t really see it in the picture, but those disks come quite a bit higher than the rest of the ice.

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Ice crystals on strawberry ice cream

In the bottom left corner, you see a smudge – that is where I pried off one of the disks to see what might have caused it. Turns out there is a cavity underneath. So somehow bubbles in the strawberry mash freeze out into those disks?

I am guessing that the ice cream in the second picture came from a batch that I beat harder than the one in the first picture, hence more bubbles. Or maybe the one in the first picture sat outside the freezer longer, so the bubbles had all reached the surface and popped before it went into the freezer? What do you guys think? Seems like I should really be carefully writing protocols next time I’m making ice cream! :-)

Help! Weird ice crystals

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Geli, Torge, and all you other ice people – do you know what this is?

Browsing pictures on my phone, I came across the pictures below that I took a while back in Bergen. What you see in the picture below is a photo taken down at the flat surface of a picnic bench. Each individual ice needle is about 1 cm high measured from the wooden surface of the bench. I only saw the crystals on that one bench that one day, but not on any other surface.

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Ice crystals growing on a picnic bench

I’ve googled a little to figure out how these crystals formed, since they don’t look like either ice flowers or ice needles or any other ice crystal that I am used to seeing. However, I haven’t found anything yet.

The picture below is a close-up of some of the crystals and even though it looks like the picture has a very bad resolution and like you can see individual pixels, that is not the case. That impression is caused by the weird shapes of the ice crystals.

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Close-up of some of the ice crystals

Geli, Torge, anyone – do you know what these crystals are and how they form? Or do you have any idea where I could find out more?

P.S.: People who don’t understand why it’s awesome to have a camera on your phone either never had one or don’t have a blog.