Title: Patterns in ice Post by: simon.snake on February 23, 2012, 09:45:14 AM During a recent cold spell (January), a pattern emerged on top of our conservatory roof after some heavy frost.
(http://www.needanother.co.uk/uploads/150120121417.jpg) This looks very fractal like and I wonder how to recreate it in any fractal program available? Title: Re: Patterns in ice Post by: Tglad on February 23, 2012, 01:03:51 PM Beautiful.
My guess is that ice crystals grow more easily from the edge of an already existing ice crystal than just starting on a random part of the roof. So, it looks like the new crystals grow roughly in front of the previous ice crystal, but with a slight angle, and occasionally the conditions are right that two separate routes develop and the resulting tree branches. Possibly the variation in straightness comes from differences in the temperature... the temperature might have dropped quickly and then levelled out as the last parts of the pattern were forming. I doubt a fractal program would reproduce this pattern, but maybe someone has made an ice formation simulation somewhere on the web. Title: Re: Patterns in ice Post by: fractower on February 23, 2012, 09:47:14 PM It looks a lot like diffusion limited aggregate. One possibility is that water is initially slightly salty (are you near an ocean). As ice forms it drives the salt into the surrounding water which lowers its freezing point. This will cause linear features (points grow faster) that tend to repel each other. I will try to code this up and see what happens. In the mean time could you go out and lick the ice to see if it is salty... I double dog dare you!
Title: Re: Patterns in ice Post by: simon.snake on February 23, 2012, 10:59:54 PM Afraid to say I am as far from the coast (Birmingham, UK) as you can get, and this was in January and the cold spell only lasted about a week.
I was browsing my pictures and found it, then thought of this forum and uploaded the picture and posted the message. Will be waiting with anticipation to see what you can come up with. Simon Title: Re: Patterns in ice Post by: cKleinhuis on February 24, 2012, 02:50:37 AM this is exceptional beautiful!
Title: Re: Patterns in ice Post by: KRAFTWERK on February 24, 2012, 10:26:17 AM This is really cool, in many ways! O0
Lovely image! Title: Re: Patterns in ice Post by: DarkBeam on February 24, 2012, 11:38:41 AM See this site.
http://psoup.math.wisc.edu/Snowfakes.htm :o Wonderful pictures, but not easy to understand methods Title: Re: Patterns in ice Post by: simon.snake on February 24, 2012, 12:24:49 PM Strange thing is that unlike the snowflake's quite geometric shape, this appears to be flowing and more irregular.
Was glad I took the photo when I did as a few days later it had all disappeared. Simon Title: Re: Patterns in ice Post by: DarkBeam on February 24, 2012, 12:45:05 PM Because here there is an "additional parameter" (gravity, temperature , whoever knows) that is = 0 in the snowflake equation. :surf: :whistle: :educated:
Title: Re: Patterns in ice Post by: DarkBeam on February 24, 2012, 12:47:03 PM It maybe a mix between normal crystals and the good old fern
http://en.wikipedia.org/wiki/Barnsley_fern :D Title: Re: Patterns in ice Post by: taurus on February 24, 2012, 12:51:08 PM It looks a lot like diffusion limited aggregate. i often saw icy glass panes with the look of diffusion limited aggregate fractals, but this is different. it looks like the freezing water was still creeping for some time before congeal entirely. a really nice structure. great find simon.snake! ;D Title: Re: Patterns in ice Post by: simon.snake on February 24, 2012, 01:25:14 PM The roof of the conservatory is glass, and slopes away from the house at maybe 20 degrees downwards, and is only single glazed.
The picture was taken from the window above the roof so the top of the picture is lower than the bottom of the picture. Seems like some of the fern like structures are going uphill??? Simon Title: Re: Patterns in ice Post by: simon.snake on February 24, 2012, 01:27:45 PM The original picture is much larger than what is shown on the post, so open in another window and zoom in if you like.
Simon Title: Re: Patterns in ice Post by: tit_toinou on February 24, 2012, 03:23:39 PM I have taken the same kind of photos last winter.
This one is awesome ^-^ . Title: Re: Patterns in ice Post by: Mrz00m on February 24, 2012, 03:29:29 PM water is one of the few materials that expands when colder... it shrinks until it approaches zero and then when it freezes, the random mobile molecular structure becomes patterned into straight lines, with a honeycomb crystal form, that's why it tends to brach off at 30 degrees angles, esp. in snowflakes.
Title: Re: Patterns in ice Post by: fractower on February 24, 2012, 04:23:24 PM I attempted to code up a diffusion limited aggregation simulation that modeled a salt which is driven out of ice as it is formed. The ice will locally reduce the freezing point and diffuse away over time. It did not capture the linear growth as I had hoped. Also the simulation grid introduced a artifacts.
Title: Re: Patterns in ice Post by: simon.snake on February 24, 2012, 05:43:16 PM Whichever way you look at it, that's a lovely picture.
Nice job! Simon Title: Re: Patterns in ice Post by: David Makin on February 24, 2012, 11:21:37 PM ....... This looks very fractal like and I wonder how to recreate it in any fractal program available? A modified form of DLA could probably produce something similar (diffusion limited aggregation). Edit: Whoops, sorry I should have read the replies first ;) There's a fast but fake/pseudo DLA algorithm for Ultra Fractal, here's the "default" set up "correctly".... Code: Fractal1 {Title: Re: Patterns in ice Post by: David Makin on February 25, 2012, 12:43:02 AM Decided to have a little play, I only wrote this formula just to see what the possibilities were, it really needs extending to arbitrary "dot" sizes - and of course 3D ;)
Here's my 4th attempt: Code: Fractal1 {Title: Re: Patterns in ice Post by: kram1032 on February 25, 2012, 01:09:06 AM this looks like a fairly complex multi-fractal that needs multiple effects to be taken into account.
I think, diffusion limited aggregation already is the right track. It also looks like there is some wind playing in there. Expansion of the ice during freezing definitely also plays a role. The aggregation a little further up looks like it used a quadratic grid. (If it used a discrete grid at all) Snow and ice DEFINITELY needs hexagonal, especially since the crystal structure is that. Salt probably isn't quite it. This thing has aggregation from random spheres that then freeze up and extend into hexagons, slightly pushing away the surrounding spheres or hexagons. Water by itself has a fairly low probability of freezing. (In fact you can supercool water a couple of degrees below 0°C before it starts freezing). However, if ice already is in it, this process can happen very quickly. Probably, this freezing biasedness on a non-uniformly wet windows has to be modelled too. Title: Re: Patterns in ice Post by: David Makin on February 25, 2012, 01:37:03 AM Had another try:
(http://nocache-nocookies.digitalgott.com/gallery/10/141_25_02_12_1_28_41.jpeg) http://www.fractalforums.com/index.php?action=gallery;sa=view;id=10440 (http://www.fractalforums.com/index.php?action=gallery;sa=view;id=10440) Parameters are with the image. With respect to ice freezing on glass the following need to be considered: temperature and temperature gradient/s, pressure and pressure gradient/s, ice already present, dust/debris/grease on the window and probably some others I've missed such as water purity and ionization. The formula I used for the above just has several ideas I added that relate only in a general way to such physical actions but it can work quite well with a little time/effort tweaking the parameters. The main issue is that it needs extending to arbitrary shapes rather than existing as a fixed grid (of whatever shape/s). One day I'll get back to it and do a 3D version - some of the DLA 3D plant sims are amazing ;) Title: Re: Patterns in ice Post by: kram1032 on February 25, 2012, 03:16:20 AM this looks really nice :)
The pattern on the window has a lot more swirls and tends to look much closer to trees and/or wind-lines, but this is already a very good approximation, I'd say... If you adjust it slightly, this could also be a very nice model of a mountain with glaciers... Title: Re: Patterns in ice Post by: weavers on February 25, 2012, 05:44:07 PM Greetings and Salutations to you Master David Makin. Forsaken, in the beacon and lettuce nutriments bold caught ,yes tis true, we wish 2 speak 2 U. Perturber fractal observer, what in the cold, freezing cold we save for you, you may take a trip, return n a skip, and come another day, and when the ice melts you will fine your beacon and lettuce fresh again for you again that day! Once fresh and delicious, but now, into me man called ice I be. Preserver of history, Picture of me, I see you admire, sire, greatful, 2, U, 2 C, and one like you appreciate the service provided by the ice of me, before you, were you, were I , the Ice man be I. Could ya, please take another picture, we hold under the ice worlds secrets, where gold lay, waiting for your hands to hold! Please do more pictures of the snow, to you we told, the fractals of snow, our brothers want to know, look in the ice and see us microscopically obsessing and waiting fore you to take a swim while in a form when saw water we be warm, be warm, but beware when we turn cold, ice, is cold, notice if you be so kind, tree structuralities frosty trees bifurcating, relating stretching, the only permissible notion specializing in freezing strategies of time, is ice, we have to figure out, how to get out the secrets in side of me. Open your freezer, conversate with me again, with your iphone snap shot picture facility. I promise to stay still, respecting your fractal eye compositional skills. I won't move so you can get a steady shot, I got ice here there, friends in south and north injured radicals cells who try to live in me D eoxycholate-L actose-A gar at -78 C, don't love me, cause I hurt them, but complicated grief, and healing hinges on not hurt feeling, feeling do not occur when you are frozen, does not occur, your mind blurs, you may be eligible to participate, to see if you can survey in me, we preservers of people who roamed the earth a long, long, long, times ago. One day, we will thaw them, out so you can be introduces to your ancestors! We enjoyed the pictoriality, as a study in fratalfrozenalities, omission not in your compositions, greatful we be, to see the Cardioid shapes, See it here.http://en.wikipedia.org/wiki/File:Cardioid_animation.gif Resembling outer space star dust materials, shapes! Please add in to us, a drop or two a red blood colored ink, surprises will surprise your eyes, as what you see changes before thee, try a colored led on it too, from me to 2 U! Till we meet again. Thanks friend . |