I am a snow lover. I always have been. Most people love it as a child, but shoveling, dangerous drives or a painful slip has turned many a young snow lover into a less than enthusiastic admirer. Whether you love snow or are a misguided soul, it is undeniably sparkling, cold, crystalline and beautiful. But what exactly is it? While cutting six-sided crystal shapes from paper into snowflake art is part of our culture, how well do you really know these flakes and crystals?
At the heart of every snowflake is a tiny speck of something far too tiny to see. Salt, dirt and pollen can start snowflakes. It could be ash. Next time you sit around a bonfire and watch smoke and minute particles going skyward, you may be seeing future snow crystals heading off.
What goes up must come down. Watching snow crystals do their ballet as they drift to earth, I wonder if I am in one of those snowflakes. Hair is lost every time we brush, and skin is constantly sloughed off. It will break down, and bits may be sent aloft. You, too, could be at the center of a snow crystal. Some folk might be saying “eeew,” but I love that the core of every snowflake came from someplace. Knowing that reminds me how connected everything is.
To grow into a snow crystal, and then perhaps join other crystals to form a clump and a snowflake, that speck, wherever it came from, has to be cold. Snow crystals start high in the atmosphere. When a speck is chilled, it will attract water vapor. When water vapor droplets stick to the speck, they become fluid and then freeze, forming a six-sided crystal.
A simple plate snow crystal is a hexagon. This is pretty straightforward, but temperature and moisture complicate things, forming a variety of shapes. As the speck grows, it gets heavy and starts to fall to earth.
Tips for snow crystal identification
- When snow crystals land on the ground, they lose their fine and delicate shapes. If you want to go crystal spotting, do it as the snow drifts down.
- Wait for a gentle snowfall. If it is wild and windy, it will be fun to be outside but hard to catch crystals.
- Wear dark fleece clothing, or bring a piece of dark felt. Let the fabric get as cold as the ambient temperature. Then, when crystals land on it, you will have a few moments to observe them against the dark background before they melt.
- Bring a magnifying glass or hand lens. Seeing the intricate patterns of these tiny ice gems magnified 10 or 20 times is breathtaking.
Look for these snow crystal shapes
Snow crystals can be classified into five groups, seven groups, 10 groups or 35 groups, depending on which snowflake guide you favor. The table below lists seven basic shapes to look for, and what conditions cause them to form. It is a good place to start, and you can always dig deeper if the topic interests you.
- Dendrites: Our iconic, branched, star-like crystal. The branches can break and regrow, adding to their unique patterns. The word comes from “dendron,” which is Greek for tree. They form in moist air between 3 and 10 degrees Fahrenheit.
- Plates: Hexagonal, symmetrical or not, with no branches. These form at both 28 and 5 degrees.
- Columns: Short and wide, or long and thin, these often have conical indentations at the ends and are also called hollow columns. They form at between 14 to 21 degrees.
- Needles: Spiky and jagged, like shards of broken glass. They form at around 23 degrees.
- Capped columns: A crystal which starts out as a column, but moves to a moister cloud and starts to form plates on the ends.
- Sector plates: Flat plates that grow arms, sectors. Like dendrites, these are classic, familiar shapes.
- Graupel: Opaque, lumpy, asymmetrical with no branches. These form when snow crystals are rounded by water vapor sticking to them and freezing, adding to the lumpy appearance.
These are just a few categories, and not all crystals will fit into one of them. To learn more about snow crystals and classification, I suggest you check out Edward R. LaChapelle’s “Field Guide to Snow Crystals.” Also, check out anything by Wilson Bentley, who devoted his life to photographing snow crystals. Kenneth G. Libbrecht, a California Institute of Technology professor of physics, wrote many books about snowflakes. And for a clear and appealing explanation of snow for children young and old, check out “The Story of Snow” by Mark Cassino and Jon Nelson.
There are people on this planet who never experience snow. Their lives are probably complete, and even if they are not, hopefully they think they are. Thankfully we live in Maine with snow. There is more coming, and when it does, get out there and take a look. Plate, dendrite, column, whatever shape your crystals have, remember they started as a speck. You never know who or what is at the heart of that snow crystal.
Karen O. Zimmermann lives and explores on Mount Desert Island, finding delight in the changing seasons and the world of nature both underfoot and overhead. A Maine Master Naturalist, she is the author of the BDN blog Maine Morsels.