Following the lure of snowflakes

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The first trace of snow fell in my backyard this year on Oct. 5. Snow accumulated to a depth of 4.1 inches on Oct. 26 and contained 0.30 inches of water. I know this because I am now an official weather monitor in Wellington. Before becoming obsessed with measuring snow, I had already become an expert at throwing it, sculpting it into snowmen, shoveling it, sliding on it and sometimes cursing it. I have also admired the nearly infinite variety of snowflakes and replicated their crystalline forms (See below.).

I recently discovered a “Manual for Snowflake Observation, Identification, and Replication” online written by three Colorado State University researchers some 25 years ago. With a bit of Googling I discovered that the authors had turned their fascination with frozen water into successful academic careers. However dangerous curiosity might be for cats, it often leads people to new ideas, fascinating places and fulfilling occupations.

One of the most celebrated snowflake collectors was Wilson “Snowflake” Bentley who spent Vermont winters in the late 19th century collecting and photographing snowflakes. In 1931, he published a book called Snow Crystals that became a hit for the meteorologically inclined. In 1962, Dover Books did a reprint containing all 2,453 illustrations. Bentley’s work also inspires designers of all sorts who relish the idea of using nature’s unique crystalline forms in their work.

William R. Cotton, one of the authors of the CSU snowflake manual, is now a professor emeritus at Colorado State in the Department of Atmospheric Science. He found himself immersed in snowflakes because he loved to fly — and has been flying since age 16. Icarus may have suffered from overheated waxy wings, but most modern pilots fear potentially fatal complications caused by ice-laden wings.

Another author, Thomas C. Peterson, is now President of the WMO Commission for Climatology and Principal Scientist with the National Oceanic and Atmospheric Administration’s (NOAA) National Climatic Data Center. He helped compile the data set of precipitation and temperature that extends back to 1697 and 1701, respectively. When someone compares a current precipitation or temperature with old records, they are referring to his compilation. Peterson says, “Snowflakes are not only beautiful, but they tell a story about what conditions were like in the cloud where they grew.” The manual was distributed to observers along the Front Range “as a way to better understand the cloud conditions above them that planes were going through.”

I didn’t make a positive identification for the third author, Jia-dong Yeh, but did find someone with that name and about the right age who is an Associate Research Fellow with the National Academy for Educational Research in Taiwan.

Those perusing the manual (See…/Snowflake_identification_manual.pdf ) will discover the dozen general categories of snowflake crystals and how to distinguish them, under what conditions each type forms, and techniques for capturing, photographing, and creating molds of snowflakes. Replicating snowflakes for more leisurely observation is fairly quick and fun. All you need is a glass slide (or a small piece of picture glass) and a spray can of clear artist’s fixative, like Krylon (usually used for protecting a charcoal or pastel drawing).

1. Pre-cool the slide and can of fixative outside until they are at snowflake temperature.
2. Spray one side of the slide with the fixative
3. Expose the slide to snowflakes for 1-10 seconds, depending on the rate of snowfall. You can even wave the slide back and forth to induce collisions with snowflakes.
4. Place the slide in a cold but sheltered place like a garage or shed for several hours.
The fixative will evaporate and re-condense around the snowflake crystals. When the water evaporates, a plastic mold remains behind. Examine the crystal forms at leisure inside with a magnifying glass. Of course, you can also capture actual snowflakes on any flat, collecting surface covered with something like black velvet and look at them in all their glory before they melt.

Anyone into measuring snowfall and other precipitation will be interested in CoCoRaHS: The Community Collaborative Rain, Hail and Snow Network. CoCoRaHS began in Fort Collins after the devastating flash flood of July 28, 1997. The network received support from the National Science Foundation and NOAA and has now expanded to all 50 states. Learn more at and become a weather monitor yourself.

Kids will enjoy capturing, observing, and measuring snow, too. And who knows might happen when enjoyment morphs into curiosity and even obsession? The winter skies come filled with glittering, crystalline opportunities.

The CSU manual begins with a short poem by John Whitaker Watson, worth repeating here:
“Oh! The snow, the beautiful snow,
Filling the sky and the Earth below…
Beautiful snow from the heavens above
Pure as an angel and fickle as love!