story of snow
Cover illustration
See permission.
The Bulletin
of the Center for Children's Books

The Big Picture, a regular Bulletin feature both on-line and off, is an in-depth look at selected new titles and trends. See the archive for selections from previous months.
The Story of Snow: The Science of Winter’s Wonder

by Mark Cassino with Jon Nelson; illus. by Nora Aoyagi and with photographs by Mark Cassino

Pity the generations of science students (more than a few Bulletin readers, I suspect, included in their numbers) who muddled through books devoid of the breathtaking photography which children now routinely enjoy: the droplet caught mid-splash by Walter Wick in A Drop of Water (BCCB 2/97), or the frog flicking his dinner off a leaf in Nic Bishop Frogs (BCCB 3/08). Nature photographer Cassino’s gallery of snow crystals is the sort of riveting exhibition that will have eyes locked to the pages, mesmerized by the intricate forms themselves and the “How did he do that?!” wonder at Cassino’s technique of capturing images of these ephemeral delicacies. Crystals shimmer in icy blues and steely grays, variously sturdy as Depression glass, airy as fine lace, or radiant as faceted beads.

It takes a team, though, to develop a discrete set of pictures, however glorious, into a cogent science lesson, and Nelson’s spare but effective text leads readers smoothly through the development of crystals and flakes. First comes the “speck,” the tiny particle to which water vapor will adhere. Next comes the accretion of vapor that freezes into a hexagonal crystal. Finally, depending on temperature and humidity in the cloud in which the crystals form, they grow into their most common, or even uncommon shapes: the feathery “star” or dendrite; the smaller and simpler, armless plate; or the extremely tiny solid, hollow, or capped column. Nelson also accounts for imperfections and oddities—the twelve-armed crystals that are actually attached twins, the partially truncated shapes that were halted in development or damaged in their fall, the glassy surfaces pimpled with beads of rime. On the ever-thorny question of identical snowflakes, Nelson remains diplomatic: “Some simple plate crystals may appear exactly alike. . . . When it comes to more complicated snow crystals though, odds are that no two are exactly alike.” Data is meted out in short paragraphs and italicized annotations that accompany photos and diagrams, and the easy interplay between text and image encourages viewers to pause from the text and “read” the magnified crystals before rushing on to the next topic. Vocabulary is uncomplicated but correct, and the picture-book format commends itself to classroom as well as independent reading.

Since understanding the development of crystals and flakes within clouds is key to understanding snowfall, Cassino’s still photographs can only assist the audience so far. Nora Aoyagi supplies the visuals that convey change over time and relative size: a twelve-step diagram on the formation of snow crystals; encircled dots that approximate the actual size of the photographed beauties; drawings that explicate how hexagons attach in joined rings; and imaginary fold lines that help readers identify symmetry. In a closing spread, she and Nelson provide instructions on “How to Catch Your Own Snow Crystals” by employing a dark, rigid collecting board, a magnifying glass, and patience: “Make sure it’s cold enough”; and “Look for tiny snow crystals, not big snowflakes. (Remember—snowflakes are lots of snow crystals lumped together.)”

Photography enthusiasts may wish Cassino had offered remarks on the execution of his art. Did he use a digital or film camera? How was magnification accomplished? Did the crystals pose for him in a climate-controlled studio, or did he spy them frolicking in the wild? This, however, must be left as another lesson for another day; meanwhile, readers can simply revel in the results. Northern children can happily anticipate a nice heavy snowfall in which to mount a crystal discovery expedition, while friends far to the South are left to rue their monotonously sunny days and balmy nights.

Elizabeth Bush, Reviewer


story of snow

Cover image by Mark Cassino and Nora Aoyagi from The Story of Snow: The Science of Winter's Wonder ©2009. Used by permission of Chronicle Books.

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This page was last updated on December 1, 2009.