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Watch snowflakes grow
February 25, 2014 1:58 PM   Subscribe

Ivanov Vyacheslav has captured video of snowflakes growing. Here's why they grow that way (via snowflakes, previously). But how can one arm know what the other is doing? Here's how. More snowflake formation video from Caltech physicist Kenneth Libbrecht.
posted by beagle (11 comments total) 17 users marked this as a favorite

 
Finally, the special snowflake details I was promised.
posted by Wolfdog at 1:59 PM on February 25 [17 favorites]


radical psoriasis cell formation theory there !
posted by Colonel Panic at 2:54 PM on February 25


Holy shit.
posted by odinsdream at 2:59 PM on February 25


How do we know it's not a flake melting shown in reverse?
posted by yoga at 3:20 PM on February 25 [1 favorite]


Beautiful. Nice use of Avril 14th.
posted by iotic at 3:52 PM on February 25


Very nice, but it doesn't show how big these things sometimes get.
posted by homunculus at 6:12 PM on February 25


I get that the structure of the water molecule causes snowflakes to form six-sided shapes, but can anyone tell me why those six-sided shapes are (approximately) SYMMETRICAL? This really bugs me.
posted by ZenMasterThis at 7:16 PM on February 25


The Here's how link from the FPP claims to explain the symmetry, but I still don't get it and I'm not sure these scientists do either. (There's a lot of "nobody really knows" in several of the quotes in these articles.)
posted by mbrubeck at 8:01 PM on February 25


I get that the structure of the water molecule causes snowflakes to form six-sided shapes, but can anyone tell me why those six-sided shapes are (approximately) SYMMETRICAL? This really bugs me.

The article says in part that, for a given environment, crystals that form in it will look like this rather than like that. Each arm grows the same shaped crystal segment because it's a bunch of atoms and molecules experiencing the same sort of interactions.

And stuff.

If the arms were large enough to experience different environments, or the local environments sufficiently different at small length scales, they'd grow into different shapes. Say, different temperature, humidity, pressure, etc. Meaning, how dense and how energetic the water molecules and air molecules are when a given water molecules drifts and gloms onto a crystal as it's growing.

Looking at the converse, if the arms are different sizes and have different shapes, that'd mean they formed in different environments.

(I don't think I'm saying anything here the original articles didn't say.)
posted by sebastienbailard at 12:00 AM on February 26


The "here's how" link asks But why are snowflake shapes so elaborate?

Here's some stuff that follows simply from what we know:

When an ice crystal is forming, you've got diffusion-limited aggregation going on, but the atoms can't stick just anywhere- they've got to join to the crystal in the right place and orientation. So that right there means that the shapes generated will be pokey/spiney, but still all regular and geometric-like.

But why should snow in low humidity look more like a solid prism, but snow in high humidity look like a spindly fractal?

Here's my post-hocsplanation. Humidity means there's a ton of water ready to glom onto the crystal wherever it can. Heat lets molecules on the growing surface of the crystal hop over to a more energetically favorable position. Fast crystal growth in humid conditions makes the fractalishness of diffusion-limited aggregation win; slower crystal growth gives heat more time to push the molecules around until they find nice stable prism shapes.

This seems ripe for simulation.
posted by Jpfed at 7:01 AM on February 26 [1 favorite]


Ice Crystal Timelapse
posted by homunculus at 11:57 AM on March 1


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