A Snowflake's Journey: Symmetry in Nature

Written by Kristine Manganelli (Somerset County 4-H Coordinator)

As we move into the winter season, the world outside has become quiet and barren. But if we look closely, there is still plenty of life happening all around and there are many opportunities for scientific exploration waiting to be discovered. In this post, we will be looking really closely…with microscopic detail, at a tiny phenomenon of winter weather.

Here in New Jersey we had our first snow a few weeks ago, and after two full winters without a substantial snowfall, it felt like a gift from nature. There is something about the way snow coats everything with a layer of glittering white that seems to change the surroundings from a familiar setting, to a wonderland. The snow covered ground acts like sound-proofing, muffling out all sounds except the snow crunching beneath your feet. Spending time in this frozen landscape inspired me to dig a little deeper into the science of snowy weather.

Perhaps you’ve heard the idea that “no two snowflakes are the same.” All the way back on January 15, 1885 a man named Wilson Bentley from Jericho, Vermont became the first person to photograph a single snowflake. He was able to capture these tiny bits of frozen water using a method of photographing through a microscope. He went on to capture over 5,000 photos of snowflakes, each entirely different than the last.

If a single snowflake is examined in this way, the microscope offers a view showing elaborate detail unable to be seen by the naked eye. Snowflakes are actually crystalized water vapors, or ice crystals, that take shape on their journey from a cloud to the ground. As the water vapor drops and begins to freeze, it crystallizes, creating intricate patterns. Bentley hypothesized that each snowflake is unique because they each experience a distinct set of environmental conditions as they fall.

Centuries later, it turns out that he was right! Varying conditions such as temperature and humidity in the air affect how the snowflake will shape and grow. Therefore, in order to have identical snowflakes, these conditions would have to be mimicked exactly. In nature where conditions are complex and variable, repeating identical conditions is close to impossible. Just one gust of wind, or one degree drop in temperature can form a completely different crystal structure. For example, in low humidity, snowflakes grow slowly and form simpler, smoother facets. Those that grow in high humidity, do so more rapidly and have complex branches.

Crystallization occurs as the liquid transforms into a solid state, the atoms and molecules arrange in an orderly pattern. For this to happen, each water vapor requires a nucleus to form around. During this process called nucleation, the water molecules come together around a particle of dust in the atmosphere, and condense on its surface to form an ice crystal. It grows bigger as it falls towards the ground and more water molecules latch on.

The water solidifies in a crystal-lattice structure arranged in hexagonal rings. This gives each snowflake a hexagon shaped base with 6 sides. Each of these sides are identical, so if you fold a snowflake in half, it would be exactly the same on each side. This is called symmetry, and snowflakes have 6-sided symmetry.

Snowflakes are symmetrical because they follow the order of water molecules arranged in a solid state. While solid, water molecules form bonds to one another, called hydrogen bonds that are drawn to arrange themselves in specific, predetermined spaces. Think of it like tiling a floor; once a pattern is chosen, each tile must be laid in a certain space in order to maintain and continue the pattern.

This complex perfection is incredibly common in nature on large and microscopic scales. Picture the pattern of a pine cone or the center of a sunflower. Snowflakes are just another example of nature’s majesty. The next time you watch beautiful snowflakes drift down from the sky, remember the magic of perfect patterns emerging from random conditions.

Get Outside

If we are lucky enough to get another snowfall, be sure to spend time outside! Remember, if properly dressed, cold weather can be enjoyable! Try animal tracking to see what critters visit your yard. The snow makes it easy to find and identify animal prints. Use the guide from The Old Farmer’s Almanac to help
If there is no snow anytime soon, use the instructions from Martha Stewart to create the perfect, 6-sided symmetrical snowflake

Sources:

Hsu, Charlotte. “The chemistry of snowflakes, explained.” University at Buffalo, The State University of New York, January 2018, http://www.buffalo.edu/news/tipsheets/2018/001.html. Accessed 4 Jan. 2021.
Libbrecht, Ken. “The Formation of Snow Crystals.” American Scientist, https://www.americanscientist.org/article/the-formation-of-snow-crystals. Accessed 4 Jan. 2021.
“Snowflake Bentley.” Jericho Historical Society, https://snowflakebentley.com/. Accessed 4 Jan. 2021.
“Why are snowflakes symmetrical? How can ice crystallizing on one arm 'know' the shape of the other arms on the flake?” Scientific American, December 2006, https://www.scientificamerican.com/article/why-are-snowflakes-symmet/. Accessed 4 Jan. 2021.
“Why do snowflakes crystallize into such intricate structures?” Scientific American, January 2004, https://www.scientificamerican.com/article/why-do-snowflakes-crystal/. Accessed 4 Jan. 2021.