Let it snow!

Youngsters who like snow really should get acquainted with Kenneth Libbrecht.

The physics professor at the California Institute of Technology has written the books on snowflakes -- including The Snowflake, The Art of the Snowflake and Ken Libbrecht's Field Guide to Snowflakes. He took the photographs for the 2006 snowflake postage stamps, and he maintains a nifty website on the subject: www.SnowCrystals.com.

His latest book is for kids: The Secret Life of a Snowflake, An Up-Close Look at the Art & Science of Snowflakes (Voyageur, 48 pages, $17, ages 6 to 12), a fascinating look at the science of frozen crystals that will appeal to adults, too.

Libbrecht photographs snowflakes under a microscope, frequently shining colored lights from behind and enlarging the results to create spectacular images that look like neon wonders. The picture book is filled with photographs of snowflakes -- and of course, no two are alike.

On one page, 14 snowflakes are positioned around an enlarged Lincoln penny, showing the range of sizes and structures of the crystals.

Libbrecht walks readers through mysteries such as why snowflakes are always hexagons (because of the way water molecules line up within the crystal), how lopsided snowflakes grow, why some snowflakes aren't flakes at all but ice needles or columns and how it takes 100,000 cloud droplets to make one snowflake.

His book, a beautiful blend of art and science, includes instructions for the proper way to fold and cut a snowflake from paper. About the only thing he doesn't tell is how he manages to put a snowflake on a slide under a microscope and photograph it before it melts.