This morning it just barely dipped below freezing, the first time in several days. Off I went to the usual black cars. And once again the frost to me looked like things I’d seen before. I decided to take a few pictures anyway, and once again I was surprised at what I saw in the zoomed images. To my eye, the site in the image below looked like small droplets that froze and then grew hoar.

But the camera revealed a little more variety. The site looks like a miniature seashore with a bunch of white shells of various shapes. The clumping of crystals is a little puzzling, as the close-ups below show no obvious resemblance to a frozen droplet. In some clumps, the hexagonal sides of the crystals are clear, in others, the crystals appear to be tilted up on end, such that their hexagonal sides are not shown in profile. In one case on the left, the crystals are rounded in outline, and some are not clumps at all, just a single crystal. (As with all images in this blog, a click will enlarge them.)

With my camera battery running low, I moved on to the tubs and rice fields.

The latter had some ground-freezing with a strange lattice/mesh-like design. I see this often, but this morning’s ground had particularly striking designs. One of them looks like crabs.

Some of the lines in the ice (i.e., the arms of the ‘crabs’ above) appear to consist of ice surrounding a small twig. But by breaking some, I found that some of them do not. Their needle-like shape and horizontal orientation probably arose in a thin pool of water surrounding a wet dirt clump. When liquid water freezes in a small puddle, it does so from an edge, where it sends out a thin, straight blade of ice with a depth equal to the water depth that lies below the freezing level. Subsequently, the frozen dirt clump was pushed up by the same process that makes the brown ground ice columns I discussed in my previous post. This lifting-up brings the horizontal, ice needles as well. Later, hoar starts forming on them, making them white. At least, that is what I think happens. Some of the horizontal mesh of white needles can look rather pretty.

- JN