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What's Wrong With This Snowflake?

npr.org

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Re: What's Wrong With This Snowflake?

#11

Post by icefox »

hga wrote: post #2

Source code here: http://psoup.math.wisc.edu/Snowfakes.htm (roughly in the middle of the page).

Just one of the many lovely gem's in the source:

   for (i=1;i
When you see the following line you know you are in for a treat (best part i1 and j1 are not even used in one of the functions where it is declared).

int i,j,i1,j1,iup,no;

Re: What's Wrong With This Snowflake?

#12

Post by pcm »

I'm ashamed to say that I'm guilty of misrepresenting snowflakes.

I wrote an iPhone app last year that allowed you to create virtual paper snowflakes, and I didn't realize until later that all the flakes it created were "abominations" that had 8, 10, or 12 sides.

I was a little surprised by the amount of feedback I received explaining to me exactly what was wrong with the snowflakes in my app. Unfortunately, I haven't gotten around to fixing this egregious error just yet ;) .

Re: What's Wrong With This Snowflake?

#13

Post by arketyp »

sgk284 wrote: post #10
slapshot wrote: post #5

Writing letters about the fact that artistic snowflakes aren't the same as "real" snowflakes is like writing to complain that the symbol of a heart for "I love you While scientifically correct, he's also a little pedantic.

Agreed. Aesthetics > Reality. I wrote a fun little web app to draw snowflakes a few weeks ago: http://www.create-a-snowflake.com/ . I settled on 8 sides, although the first version had an option to have anywhere from 4 to 20 sides.

But the scientific reality is aesthetics too. Seeing how the snowflake is a textbook example of beauty found in nature, I would personally find myself obliged to represent the snowflake according to it, even for the purpose of your application.

Re: What's Wrong With This Snowflake?

#14

Post by DougBTX »

dangoldin wrote: post #9
slapshot wrote: post #5

Writing letters about the fact that artistic snowflakes aren't the same as "real" snowflakes is like writing to complain that the symbol of a heart for "I love you While scientifically correct, he's also a little pedantic.

I think the fact that the error was in a scientific magazine warrants the letter.

Also, it trumps pedantic by being funny.

Re: What's Wrong With This Snowflake?

#15

Post by stcredzero »

Okay, so the crystals tend to follow a 6-sided geometry. Why are snowflakes symmetrical? Why does one arm have to fall into the exact same configuration as the opposite one? Why not have 6 different arms, all following the same 6-sided geometry? What mechanism communicates between the arms to achieve 6-sided symmetry?

Re: What's Wrong With This Snowflake?

#16

Post by JoeAltmaier »

stcredzero wrote: post #15

Okay, so the crystals tend to follow a 6-sided geometry. Why are snowflakes symmetrical ? Why does one arm have to fall into the exact same configuration as the opposite one? Why not have 6 different arms, all following the same 6-sided geometry? What mechanism communicates between the arms to achieve 6-sided symmetry?

I've often wondered about this too. Pseudo-scientific "explanations" of natural phenomenon often ignore the obvious questions. Another interesting question: why do people swallow facile explanations for things with little/no critical dialog?

Re: What's Wrong With This Snowflake?

#17

Post by JoeAltmaier »

stcredzero wrote: post #15

Okay, so the crystals tend to follow a 6-sided geometry. Why are snowflakes symmetrical ? Why does one arm have to fall into the exact same configuration as the opposite one? Why not have 6 different arms, all following the same 6-sided geometry? What mechanism communicates between the arms to achieve 6-sided symmetry?

You're right, frost on a window grows asymmetrically, why not snowflakes?

Re: What's Wrong With This Snowflake?

#18

Post by jey »

icefox wrote: post #11
hga wrote: post #2

Source code here: http://psoup.math.wisc.edu/Snowfakes.htm (roughly in the middle of the page).

Just one of the many lovely gem's in the source: for (i=1;i When you see the following line you know you are in for a treat (best part i1 and j1 are not even used in one of the functions where it is declared). int i,j,i1,j1,iup,no;

It looks as if someone who grew up coding in FORTRAN on punched cards just ran their brain through f2c then wrote that code. It's very old-school FORTRAN-like.

Re: What's Wrong With This Snowflake?

#19

Post by jerf »

stcredzero wrote: post #15

Okay, so the crystals tend to follow a 6-sided geometry. Why are snowflakes symmetrical ? Why does one arm have to fall into the exact same configuration as the opposite one? Why not have 6 different arms, all following the same 6-sided geometry? What mechanism communicates between the arms to achieve 6-sided symmetry?

Well, they don't have to: http://www.its.caltech.edu/~atomic/snowcrystals/class/class....

Given that different conditions produce different crystals (see for instance the description for the "capped columns"), my best guess is simply that each of the 6 sides experienced all-but-identical growth conditions, and thus the correct question is rather why would they be different?

Someone else mentioned 12- and 3-siders, and trying to Google up those images is how I got to that site in the first place. See: http://www.its.caltech.edu/~atomic/snowcrystals/unusual/unus... (Note you have to "-paper" in the Google search, or you'll just be hammered with instructions for paper snowflakes of varying degrees of scientific inauthenticity.)

Edit: Ah, the site addresses that: http://www.its.caltech.edu/~atomic/snowcrystals/faqs/faqs.ht...

"While [a snowflake] grows, the crystal is blown to and fro inside the clouds, so the temperature it sees changes randomly with time. But the crystal growth depends strongly on temperature (as is seen in the morphology diagram). Thus the six arms of the snow crystal each change their growth with time. And because all six arms see the same conditions at the same times, they all grow about the same way. The end result is a complex, branched structure that is also six-fold symmetric. And note also that since snow crystals all follow slightly different paths through the clouds, individual crystals all tend to look different."

And see also the next question, "What synchronizes the growth of the six arms?". I'm hitting the limit of what I feel comfortable just copying and pasting into HN.

Re: What's Wrong With This Snowflake?

#20

Post by Confusion »

stcredzero wrote: post #15

Okay, so the crystals tend to follow a 6-sided geometry. Why are snowflakes symmetrical ? Why does one arm have to fall into the exact same configuration as the opposite one? Why not have 6 different arms, all following the same 6-sided geometry? What mechanism communicates between the arms to achieve 6-sided symmetry?

Without knowing the answer, here is my guess: the way a flake grows depends on a number of environmental factors. Although these factors, like temperature, humidity and wind, all vary as the drop/flake falls down, the factors are nearly constant over the size of the flake. Each part of the flake experiences the same environment and as a result all parts grow in the same fashion.

My alternate guess is that snowflakes actually aren't symmetrical, although they display many local 6-way symmetries.

Edit: ah, the answer by jerf verifies that these guesses were reasonable.

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