STEMvisions Blog

There’s nothing lovelier than the first snowfall of winter. Fluffy white flakes slowly drift down to cover your hair and clothes in their crystalline patterns. Just like all of nature’s most beautiful things, we can describe the beauty of snow with science! With the help of a turn-of-the-century scientist and knowledge of crystal formation, we can crack the code on these snow crystals. Including the big questions: Is it true that no two snowflakes are alike?  

What’s the science behind these beautiful snowflakes?

In many ways, snow was just a beautiful enigma until Wilson Bentley set out to uncover its mystery. Wilson “Snowflake” Bentley was born in Jericho, Vermont, in 1865. Bentley, like many others living in rural Vermont, worked the family farm. However, his true passions lay elsewhere. Vermont, and Jericho especially, is a very wintry place with no shortage of snowfall. The delicate intricacies of this snow caught Bentley’s attention, and he developed a photographic method, photomicrography, to obtain a closer look. Bentley’s method used a microscope and camera system to capture high-quality images of the snowflakes at extremely high magnification. The work was delicate (and cold), but Bentley managed to photograph over 5,000 snowflakes this way before he died in 1931. Before Bentley’s death, he donated a portion of his collection to the Smithsonian Institution, thanking the institution for protecting it against “all possibility of loss and destruction, through fire or accident.” 

In Bentley’s photographs, white snow crystals are displayed starkly against a black background. This type of display makes it easy to observe the unique crystalline forms of each snowflake. You’ve probably heard it said that every snowflake is unique. Is that true? 

To uncover this mystery, we should first talk a little about how snowflakes form. Snowflakes form when water vapor in clouds condenses immediately to ice (a process called deposition, meaning a liquid phase change is skipped) around a small particle, like dust. Because of water's molecular structure, these new snowflakes begin to form a crystal pattern. The “classic” snowflake is a six-sided crystal, but variations in humidity and temperature can alter its shape.  Sometimes the flakes can form in columns, thin needles, or a flat shape called plates. While scientists have learned a lot about snowflakes, even they don’t know exactly why some of these shapes occur when they do.

While these flakes might all be in some kind of crystal form, this doesn’t mean that they are all the same. The uniqueness of snowflakes comes in part from environmental factors of their formations (e.g., collisions, etc.) and also the high number of possible formations crystals can make. That is to say, there are a lot of unique combinations you can make with crystal structures because of their many components. These factors combined mean that, for all intents and purposes, it’s true that no two snowflakes are alike! 

References:  

• Griffin, Julia. "The Science of Snowflakes, and Why No Two Are Alike." PBS. PBS, n.d. Web. 13 July 2016.

• "Wilson A. “Snowflake” Bentley Snowflake Shape Activity." (n.d.): n. pag. Smithsonian Institution Archives. Web. 13 July 2016.