Let me see if I can get the link in here to a mpg I took or a jpg. I was at the beach the other day and noticed these circular slush rings riding on the surface of the water. They appeared to be someplace between one and two feet in diameter. I guessed that they formed from the motion of the water, but I’ve never seen them before. Has anyone? Do they have a name? (Besides rings of slush riding on the surface). Nah, I can’t figure out how to get the link in, so just try to imagine a beach with about 20 - 30 feet of ice and snow left at the edge. Waves slowly coming in, and maybe about another 20-30 feet of slush floating on the waves. The rings are just that - rings. There’s water in the center but they are almost perfectly circular. Any suggestions? xo C
Is this in a lake or an ocean? I’ve seen lots of strange formations of ice or algae in both, but there are lots of things that make circles. A pic would help. If you don’t have one online, Yahoo Photos is free and pretty easy to use. Once the pic is up, just view it in your browser, copy the URL from the address bar, and drop it into a post.
Ok, I’m going to try this Yahoo site to see if I can post to it and then link to it. But, to answer your question, this is at the cold water’s edge of Lake Michigan, at a spot where there is seldom any algae growing and certainly not at this time of year. Lemme see what this 21st century holds as far as computers, pictures, links, etc. Stay tuned. If I have to, I’ll bump this. These are really weird. I mean, I’ve observed the lakefront just about every year of my life and never have I seen these. And I’m an old timer, I’ll tell ya. Why, back in the day…well, don’t get me started but I’ll say this - when I was a kid, computers were made out of wood! xo C.
Ok. I tried two methods of finding websites to host the jpg’s that I wanted to link to. No dice. So, let me just ask for speculation from the teeming millions - what do you think causes these circles to form? They float on the surface of fairly shallow water. If it were warm out, I’d say I cold easily wade at that depth. They are separate from one another, and do not overlap. Some are about 3 feet across, maybe even more. There appears to be more slush between the rings than within them. In fact, it looks pretty much like clear water inside the rings. This layer of slush reaches about 30 feet out from the edge of the beach but the rings don’t appear to extend that far. What do you think these are? What might cause them? Are there any limnologists around who might want to take a shot at this? Truly, in 60 years, I’ve never seen this.
So it’s a continuous layer of slush with circular holes? Is slush piled up at the edges? If so, all I can think of would be whirlpools (eddies from a current), or upwelling water at each centre (maybe from hot spots on the bottom). If they’re evenly spaced, I’d suspect the stumps of old pilings, or maybe holes where pilings have been pulled out.
There’s no hassle hosting images at ImageShack. (For this purpose, anyway.)
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I’ll try here. these things
Is there flat ice in the clear center of the rings?
If wave action broke up an ice shelf you’d end up with tabular (flat topped) bergs. Collisions between bergs would wear off any sharp edges.
A cold snap or onshore wind could drive slush up between the bergs, and if the berg height were just right, those collisions could squirt some of the slushy mix up onto the outside edges of the bergs, where it’d harden into rings, as you see.
nope - the center of the rings appears to be lake water. These rings are as “flexible” as the surface of the water, so they’re not flat, rounded off ice sheets with slush washed up on their edges. I keep thinking that they have formed somehow from the wave action, but I can’t really see how. There’s no real horizontally circular motion evident anywhere - only vertical, as one might expect in the cross section of a wave. Is there some way that that motion could be translated into a horizontal form? I’ve never seen this during any other time of year, either. I mean if there were some way for the cone of motion within a wave to be manifested horizontally, then we’d see rings of all sorts of flotsam all year, and we don’t. Any other speculation? xo C.
I will point out that the rings are not “almost perfectly circular”, but oviods with apparent ratios of between 2:1 or 3:1 (even allowing for the foreshortening in the photo). The long axes are mostly pretty much aligned with the shoreline, which to me implies wave action of some sort.
I don’t suppose you have any photos taken from straight above? What were the waves doing at the time? Any power craft in the water nearby?
'They may look oval, but they are almost perfectly circular. No, I don’t have any pictures taken from directly above. I must have left my hot air balloon home that day. There were no power craft in the area that day. The waves were moving in to the shore at pretty much their usual speed, meaning a little slower than usual due to the slush on the surface. The waves amplitude was less than 2 feet, wave length about 12 - 15 feet, I’d guess. I did take a couple short mpeg’s but I don’t know how to let anyone view them. I had enough trouble finding a way to get the jpg’s up. (thank you, Larry Mudd). These are rings. xo C.
What was the weather like recently? I have no idea whether or not this would give the effect mentions, but here’s my wild, irresponsible speculation: there was something like a temperature inversion in the water. The water started out somewhat warmer than freezing, then cooled suddenly from the top, leaving a layer of warmer water below it. The warmer water wanted to be on top, but couldn’t get there without moving the colder water out of the way. So at some point, large bubbles of warmer water started detaching themselves from the lower layer and rising through the upper layer. The circulation due to the bubble as it rose pushed the slush out of the way in the circular pattern you see there.
I can think of a million things wrong with this scenario, though, most notably that I doubt that the water could have gotten warm enough this time of year, and that wave action probably would have destroyed any inversion like I’m proposing. If anyone else wants to propose another theory, it’s probably preferable to this one.
Weather is typical at this time of year. The south end of Lake Michigan along the shore has been covered with ice, but that is melting on the warmer days. Now there’s just 10-30 feet of it extending out into the water. Upwelling of warm water would have to come from a warm source, wouldn’t it? I don’t know what that would be, but it’s a theory that may have some merit.
MikeS might have it! If you got a good snowfall, the temperature of the surface water might drop enough to create the inversion. With low waves and not too much wind, the turnover could make circles. (Since I posted the description above, it’s been nagging at me, and I remembered when I saw the pic. Long ago I made a semi-failed pot of soup that tasted OK but had a layer of greasy sludge on top after I put it in the fridge overnight. When I started to reheat it the next day, it looked much the same as these, except for colour.)
Here’s an odd idea – is it possible that these are an example of Benard Cells? Benard cells are typically hexagonal, but if they don’t quite tough they might be circular. Or perhaps the slush at the edges piles up in sucvh a way that theyend up looking circular (the slush rings trotate, maybe, and the accumulating slush doesn’ty diappear, so in time you get circular rings rather than hexagonal ones. Maybe.)
Benard cells are the result of columnar convection currents in a heated liquid. You can see them in coffee cups, I’m told (drawing in Walker’s The Flying Circus of Physics), where bubbles and/or creamer build up at the cell edges and make them visible. The cells are hexagonal because you get close packing of roughly cylindrical objects. I’m told that hexagonal stone pillars, like The Giant’s Causeway in Ireland, are the result of cooled Benard cells in what was originally lava.
In any event, here are overhead views of Benard cells made visible in a dish of liquid:
http://www.physiology.rwth-aachen.de/user/jaeger/diplom/kontra_e.html