We moved from California to Connecticut last year, and one of the joys (?) of New England living is the cold winters.
On our back balcony is a big empty plant pot, waiting for spring planting, along with the small dish-shaped holder it goes in. The pot is upside down, but the dish is right-side up, and fills with water when it rains. When it’s cold, the water freezes; sometimes just a few millimeters on top, and sometimes solidly all the way to the bottom.
This morning I went out, and there was a relatively thin layer of ice, but it also had a rather puzzling and regular-sided hole in it. The edges of the opening seem almost perfectly straight - about as straight as I’ve ever seen in nature - and there’s also a sort of beveling. Here are a couple of photos:
Anyone know what happened here? I assume that there’s some relatively straightforward explanation to be found among the physics crowd.
Edit: I should add that there was nothing unusual, as far as I could tell, in the water or over it.
Does the morning light shine on the dish through any rectangular gaps? Under the right circumstances (just the right level of warmth that a little extra light could push the temperature over the tipping point) I could imagine that ice in shade might be still freezing while ice in sun was melting
Interesting. My piece of ice certainly does resemble the patterns in the fourth picture, although the hole in mine seems much broader (as a percentage of total surface area) than any of the others pictured on Wikipedia. Thanks for the link.
No sun at that time of morning. It was still below freezing when I took the pictures. Also, I highly doubt that any sort of melting activity would produce such regular lines and shapes.
Was the ice sheet directly on top of the liquid water, or was there an air gap between?
You would usually see such ice formations on puddles in the early winter, in the morning after a frost, an inch or so above the water-level (or, indeed, above the frozen mud)! I believe they are formed by the sublimation of water vapor, without transition through the liquid state.
It’s fun to think of, we who live up here in the cold take such small miracles more or less for granted, without asking the question: How?
