I often see curious ice patterns on the surface of frozen water. On Christmas morning, I saw this strange pattern on one of the farmer's outdoor bathtubs. The foreground region looks a little like terraced rice fields on both sides of a mountain pass, but each terrace seems to have a structure like veins on a leaf. Indeed, the pattern within the 'mountain' on the right looks very much like a leaf. I have no idea how these patterns formed. The image is about 3 cm across.
On my morning icespotting trip the other day (12/23), I caught a glimpse of an unusual sight - a sun pillar. I thought I saw one once last winter, but this one was unmistakable. It seemed more striking even than the one in Robert Greenler's book "Rainbows, Haloes, and Glories", a classic book on atmospheric displays. A line of light above the sun forms when sunlight reflects off the bottoms of falling crystals that fall a certain way - nearly horizontal. A pillar can form from either columnar crystals, oriented like a log floating on water, or tabular crystals, oriented like a frisbee in flight. For the reflection to reach our eyes, only the crystals that appear above the sun can reflect sunlight to our eye. So we see the reflections coming from the region directly above the sun, as in the picture. The same effect can occur below the sun, when the sunlight reflects of the tops of the crystals. I took this picture on the sunset setting of my camera, which boosts the reds, but the view to my eye was, if anything, more stunning.
Our first snowfall this season came overnight with a howling westerly, but left just a light dusting. Only certain surfaces with a wide view of the sky were cool enough to preserve the snow. The only place in our yard was the roof of our car, which I've found in the past to cool about 8 degrees Celcius below that of the air at head-height. But looking out our window this morning (the 19th), I saw something else that came down - a spider. It might have come from the telephone wire about 30 feet above the car, or, with all the wind, might have blown in from a more distant place. We see these colorful spiders on their webs all over our yard and have come to view a few of them as familiar friends. The one near our front door last year seemed to freeze up and die when the first cold weather came, but later, after being warmed by the sun, popped back into action. I set this fallen spider out in a warm and dry spot, but alas, it did not recover.
Around midnight, a gentle snow began to fall. It continues to come down, but the air temperature is still hovering right at the freezing point. Throughout the night I’d wake up and peek out the window to see snow falling onto wet streets – it was just a bit too warm for the snow crystals to not melt when they hit the pavement.
Come morning, the roads were slushy and slick, but the temperature remained stubbornly warm.
You never know till you try, so I caught a few falling flakes to see if I could get their photos. They began to melt the moment they landed on the glass plate, and by the time they were positioned beneath the camera lens, they were well-nigh gone.
One shot of one departing crystal, just before it became a drop of water (click on the picture for a larger image):
Here are two faces of water - crystal and liquid forms - together in the same place, briefly. These are not the only two forms of water, of course, but it's interesting to see them juxtaposed like this.
Last week’s storm brought several inches of hard driving, wet snow to Kalamazoo. But after the blizzard passed temperatures grew more mild, and soon patches of grass began to emerge from the melting snow cover.
A slight dusting of lake effect snow a couple of days ago is all we’ve seen of the white stuff since then. I spent a few disappointing hours out in the light snow, catching only highly irregular crystals and the broken arms of dendrites.
Here’s the one and only whole crystal I managed to photograph – it’s a start!
The farmer's bathtub finally froze over. The surface had an interesting freezing pattern, but I've photographed similar ones many times before. So I picked up a rock, broke the surface, put a chunk between two crossed polaroid sheets and shot a picture.
The colors arise from the birefringent nature of ice, which means that light can pass through crossed polarizers if ice lies in between. But only some colors can make it through both polarizers.
Here in this neighborhood of Japan, we finally had our first good frost day. By frost, I mean any ice that forms from vapor that condenses (wet or dry) onto a surface. We rarely get snow, typically just one or two short-lived, wet snowfalls over winter, but we often get frost. Frost might be common here because the temperature just dips a little below freezing (0 degrees Celcius), winter skies are often clear, and the humidity is high. For example, in my yard, about seven feet above ground (where I have a safe place for my temperature/humidity meter), the relative humidity last night stayed between 80 and 87% and the air temperature got down to 1.6 Celcius. But the temperature on surfaces exposed to the sky got colder. For example, on some metal plates I put in our carport, the temperature reached -6.0 Celcius. Roofs of cars parked in a more exposed area probably got even colder. The pictures below show frost from two black car roofs.
These pictures show a mixture of two types of frost: windowpane, or film, frost, which is often clear and curvy, and hoar frost, which is white and straight. Film frost grows along the surface; hoar grows out of the surface. For the snow crystal fan who lives in a place with little snow, hoar frost is the next best thing. I say this because hoar grows just like snow - sometimes like a branch of a thin star and sometimes like a column. Film frost is ice that grows in a thin film of liquid water that condensed like dew on the surface. For reasons that remain mysterious, film frost usually curves. After the liquid in the film crystallizes, hoar crystals sprout off the ice, growing upward, away from the surface. In the top image, hoar has just started, but enough has grown to make the curved ice white, in good contrast with the black surface below. In the bottom image, if you look closely, you can see the stubble of hoar whiskers growing as tiny ice columns off the surface (at this magnification, it is hard to determine if the hoar consists of columns or thin-star branches).
The thing that is totally bizzare about film frost is that the ice not only curves, but each curve consists of a crystal structure that twists. Hoar and snow do not twist. To picture what I mean by twist, imagine holding a huge snow star and twisting each branch in such a way that the crystal resembles a six-blade propeller. Real snow doesn't twist, but film frost does. Because the hoar grows off the twisting ice, the hoar columns tilt differently in different regions. You can see this if you look closely at the bottom image.
The Kalamazoo Gazette ran a front page article about The Story of Snow on Wednesday, December 9.
The weather was quite accomodating as a blizzard moved into west Michigan around the same time.
A little while ago the New York Public Library came out with their recommended list of children's books called 100 Titles for Reading and Sharing. The Story of Snow is included!
Here's a nice stellar dentrite from last December - almost a year ago. This winter is turning out to be pretty mild so far, here in Michigan at least...