Anticipating Snowfall...

January 25th, 2010
The January thaw lasted extra long this year, with temperatures yesterday topping 50F here in Kalamazoo. But in the winter the warm days are usually precede a cold snap - and it's cooling off a bit now. A little snow is actually blowing in the air. Let's hope for snowfall and a chance for photos. Above is one taken three weeks ago, on January 4, 2010, the last opportunity for snow crystal photos hereabouts. - Mark

Eyes and Dry Moats

January 22nd, 2010

Though I appreciate seeing the old and familiar, when I venture outside on frosty mornings, I usually see at least three unexpected things. Three unexpected things before breakfast. A few days ago, the frost at first appeared more hoary than curvy, but when I peered over the top of a black SUV, I saw ice curves in the shape of an eye. Just for fun, I put an image of it next to a mirror-reversed copy, to give the following composite.

Call it the eyes of frost. Like me, you've probably seen curvy growth before, even if it didn't take the form of an eye. But let's venture into the eye of frost and notice something new: straight-segmented web-like growth.

I've never seen that before, and I never expected it.

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USA Today's Book Roundup

January 21st, 2010

The Story of Snow is featured in today's USA Today's  Book Roundup - in an article entitled Weather the Winter with a Picture Book. The book is described as "an artistic science lesson about the rise and fall of snow crystals."  The article also features Carl's Snowy Afternoon by Alexandra Day, Life in the Boreal Forest by Brenda Z. Guiberson, illustrated by Gennady Spirin and Testing the Ice: A True Story About Jackie Robinson by Sharon Robinson, illustrated by Kadir Nelson.

You can read the on-line version here: 

http://www.usatoday.com/life/books/reviews/2010-01-21-roundup21_ST_N.htm

...

Last night I spoke at the Grand Rapids Camera Club and provided a demo of how to take snow crystal photo. The turnout was great with well over 100 people in the room, and it was a lot of fun.

The presentation is a bit of a stroll down memory lane and the evolution of the process I use to take snow crystal photos. Of course, it starts at the beginning, with the very first snow crystal shots I managed to make. Here they are - from the winter of 1998/99. It was my second or third try at it, only very small crystals were falling, and on a wing and prayer I snapped a few shots with a high magnification setup, manual flash, and ancient Spotmatic film camera. I was really happy with the results, but it was the end of the season and there were no more opportunities that winter.

It took me a few more years till I was able to duplicate these results, but these photos gave me the inspiration to keep on trying...

 

Snow Crystal
Snow Crystal
As always - click on the image for a larger file.
- Mark

The Maltese Cross in Pond Ice

January 21st, 2010

A few days after my encounter with the pawprints and grey muck, one of the ponds did freeze over. After me and my camera spent about 30 minutes admiring this rare event, I went and ruined the complete glaze job by punching a hole in it. Although the top surface had lots of interesting curves and shallow grooves, the underside, only about 8-mm below, was flat and featureless. I suppose this is because the surface marking the melt-line (i.e., 0 degrees C) is flat. But when I put a piece of pond glaze between two polaroid sheets, with one polaroid 'crossed' to the other, I saw an odd sight.

The large black "X" that appears here is sometimes called the "Maltese cross". Elizabeth Wood, in her classic little book "Crystals and Light", calls it the "black cross". And when I looked up some cross shapes online, I thought the above figure looked more like the German "iron cross". Anyway, whatever you call it, it doesn't seem to fit the scene.

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Reviews in McClatchy Newspapers

January 19th, 2010

On Monday several of the newspapers for the McClatchy company ran a review of The Story of Snow in their "Read It:" column.  An excerpt: "Part science, part art, this beautiful book explains a bit of the chemistry behind winter's cold, white precipitation and also features startlingly detailed and amazing photos of ice crystals."

Here's a link to the review in The Sacramento Bee:

http://www.sacbee.com/848/story/2452637.html

Monday evening also brought a bit of snow to SW Michigan. The crystals were not terribly clean or symmetric, but here are a couple of snaps:

Snow Crystal Photo
Snow Crystal Photo
- Mark

Strange Pawprints in the Ice

January 15th, 2010

On account of the recent cold spell, I went up the hill behind us in search of a glazed-over pond. Ponds can have interesting freezing patterns and, if the ice is thick enough, a little excitement. I've never seen these ponds freeze, but then again, I've never thought it likely enough to warrant a visit in winter. The first two ponds I visited (technically, man-made reservoirs for flooding the rice fields) had ice only over a small section at one end. I had better luck with with a drained pond. This 'pond' looked more like a dirty mud pit, but I saw evidence of ice on one side. So, ignoring the warning signs (more on that later), I walked down and around to the icy end. From eye-level, and even from a crouch, this ice looked like snow.

But except for the holes that exposed the dirt underneath and the twiggy matter on top, the surface was smooth and level, like that of a glazed pond or puddle.  Indeed, a partially glazed-over pond is probably what it had been. The whiteness was due to some fuzzy growth underneath that I could see in the large gaps (see the image below).

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NSTA Recommends: The Story of Snow

January 14th, 2010

A little while ago I mentioned that The Story of Snow was named an Outstanding Science Trade Book for 2010 by the national Science Teachers Association and Children's Book Council. Here's a link to a review that appeared a couple of days ago on the NSTA's website:

http://www.nsta.org/recommends/ViewProduct.aspx?ProductID=19598

To quote reviewer Diana Wiig: "I loved this book! What a wonderful combination of art and science. The explanations are thorough, yet simply stated. The photos/illustrations are exceptional."

We're in the midst of the January thaw here in Michigan, with balmy temperatures up to 40F and yesterday a rare sunny day.No new snow crystal photos for now.  

Here's an old  photo -  taken on film in 2003.

Snow Crystal Photo
- Mark

Snakeskin Frost and Other Curiosities

January 12th, 2010

You can see a lot on just one black car. The nearly uniform appearance of white frost shows, upon closer inspection, a variety of forms. The first black car of yesterday morning didn’t seem so striking, and I considered passing it by. But, thinking of something that happened a few weeks ago, I hung around and took some pictures. You see, a few weeks ago, I discovered in my morning photos one picture that looked like snakeskin. It was the only one like it in my entire collection, but unfortunately a bit fuzzy. So, I swore thereafter to always look at the photos as I take them, then if something really new comes along, I can take many shots and hope that at least one is in good focus. Luckily, I stumbled upon the snakeskin frost on this car, but once again, only took one shot (alas - it also looks fuzzy). I guess I'll never learn.

If you click on the picture and zoom in, you'll see that the crystals are shaped  like thin disks, laid down nearly flush against the car roof, like the scales on a snake’s skin. The bright crystals are the ones oriented to reflect the sky, whereas the dark crystals have a different orientation. These disks are tabular forms like the hexagonal plate, except without the flat, prismatic sides. But the same roof also had columnar forms:

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Frost World

January 9th, 2010

Whenever I am taking a picture on macro near the maximum close-up to an object, the aperture on my little Canon automatically sets to the maximum size, which means that the resulting  images  are in focus only at the center. Ever since I got the camera in late 2008, I've wondered how to get past this problem. In flash mode, the aperture decreases, extending the area of focus, but the image gets overexposed. Yesterday morning, I finally hit upon the (obvious) solution: set the camera to flash mode, but block the flash with aluminum foil. I had thought before that the result would be too dark, but with some white hoar in the picture, the image is bright enough. (Later I found that the image is fine, though a bit dark, even without hoar.) For a reason I don't understand, the exposure time is still relatively long with the flash on and the ISO value set low, so I probably need to better stabilize my little makeshift wooden 'tripod' and set a longer delay to allow vibrations enough time to damp out. Even so, the improvement gives me more room to explore in the miniature world of frost, which I call 'frost world'. For example, the image below, taken on the roof of a black car yesterday, shows some pyramid structures sticking up, a few valleys, straight ruts, straight streets, and parallel curving streets. The basic structure was laid down when the film of condensed water froze, which I call "film frost" (though it has no standard name) and then later hoar crystals grew up off the surface, adding a little white to the landscape. In this image, nearly all of the hoar is hexagonal.

When I took a picture of a frosty leave, the image in my viewfinder had an odd out-of-focus look (below), so I took a bunch more shots.

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They Came From Out of the Tub

January 8th, 2010

Last night it rained, but the skies cleared before morning, letting the air temperature drop to about 2 degrees C. The weather, it seemed, would be perfect for lacy white frost patterns on cars. But it didn't quite turn out that way. A little bit before sunrise, I went out on my rounds. I took a few pictures of ice on parked cars and then headed for the rice fields. Neither tub had ice, so I walked to the abandoned car on the other side of the roadway. Nothing of note there either, but in those few minutes a blade of ice had started across one tub. Soon there were several. With a stick, I went under one blade, lifted it up, and noticed the thin serrated fingers that had been growing into the water, hidden under the surface. The disturbance of the water surface caused the growing mesh of ice lines to drift, unattached to the tub walls. I don't see this in puddles. In the puddles, the ice is always anchored to the shore, presumably because the ice starts from the shore, where there are more things to nucleate from.

In the tub I saw a curvy piece and fished it out. Laid out on the rusted lid of a nearby barrel, the ice looked strange, like a fossil of some prehistoric creature.

The critter is about 3-4 inches head to tail and paper thin. As the crystal grew from liquid water, called 'melt' by material scientists, it is said to be "melt-grown". I call such crystals "puddle crystals". Anyway, soon ice was starting on the other tub. Out in the middle of an open patch of water, I saw a small hexagon. With a stick I tried lifting it out.  I  found that the central hexagon had six large branches that had been hiding just under the surface. But the crystal slipped off my stick and cut under the water's surface - never to be seen again. Needing something better than a stick, I found a piece of a plastic lid that had been left in a nearby ditch and tore off a piece. Then next time I saw a small, isolated hexagon, I lifted it out and put it on the barrel lid.  See the photo below.

Though the central hexagon that I could see on the water was less than a half inch across, the full crystal was about one and a half inches across. Curious how the water would cover up all six branches symmetrically...  Anyway, despite the large width of our 'puddle star', it too is paper thin.  And being so flat and featureless on both sides, it evenly reflects the bluish skylight. The serrated pattern on the branches make this crystal a dendrite, like the dendritic snow crystal. But a puddle crystal grows much faster than a snow crystal because the melt (i.e., liquid water) is more densely packed with water molecules than the air from which snow grows. Also, when a snow crystal branch grows, it removes water vapor from the nearby air. This depletion of vapor is most severe near the base of the branches, and thus snow-crystal branches hardly widen - they mainly grow at the tip and at the tips of the side-shoots (called side-branches). But the melt is never depleted of water molecules, so the branches of puddle crystals keep widening until they merge. Another difference between puddle crystals and snow crystals is that puddle crystals viewed broadwise have a curving outline. The snow crystal usually has a polygonal outline, that is, made from straight lines.

- JN