----- Original Message -----
Sent: Saturday, August 14, 2010 9:47
PM
Subject: Re: PF gallery Aug 14, 2010 Ice
Disks
This may become too off-topic fro the forum, so please respond to me
personally at
ygelmanphoto@xxxxxxxxx and I'll try
including interested discussants in my replies.
But I'll just put this out generally.
It was a good idea to look for reference articles -- I didn't even begin
to think about it that way. But the wikipedia article refers to ice
formed in moving water -- in which the circular shape is made by ice in eddies
rubbing against rock or other ice. Also, the size of the discs in these
articles are very large -- with photos of 10-25 foot disks and mention
of one over 60 meters.
One very
interesting
article from MIT in 1993 described theories of ice di Charles River
that year, but also very large.
Here are some specifics of the disks in my photo:
1. The water was contained in a depression, or well, of plastic
canvas;
2. Dimensions of the well were about 2 feet x 1.5 feet across and
about 3 inches deep at the center;
3. The well was located under a tree;
4. The disks formed overnight;
5. The largest disks were about 4 inches in diameter, opaque, with
slight roughness on the upper surface;
6. When first observed, the
disks were surrounded by a layer of thin ice that was nearly
clear;
7. The clear ice contained many small opaque imperfections that may
also have been disks;
I can't believe that rotating water had anything to do with this.
There may have been something dropping into the well from the tree
branches, say small p drops.
Or, there may have been insects(?) in the water that somehow caused
initial crystallization that grew out from the center.
The trouble with crystallization growing out is that I've never heard of
circular crystallization.
That's all I can say for now.
-yoram
On Aug 14, 2010, at 10:05 AM, Palma Allen wrote:
