Most of us grew up learning that every little snowflake was unique–probably as a way to make us as individuals feel special. Unfortunately, like many lessons you learned in childhood, this is one that undoes itself once you learn more about the world around you. Like how one cubic foot of snow can contain like a billion flakes. How are they all supposed to be unique when there are an incomprehensibly large amount of them? So let’s talk about it, how unique are snowflakes, really?
Further Reading: Why Does It Snow and How Does Snow Form?
So broadly, snowflakes come in a handful of different shapes with differing classifications. When water freezes in the atmosphere to make crystals, it does so in hexagons. Perhaps, because hexagons are rather special. No really, bees agree.
Ice crystals that make up snowflakes form a hexagonal crystal lattice. Which really just means the repeating structures in the crystal are hexagonal. The specific morphology of a snowflake can be manipulated too, based on the temperature and moisture hanging around when the snowflake first formed.
There are around 80 distinct shapes for snowflakes, which are then lumped into a handful of categories as follows. Obviously, these 80 shapes can have slight variations between them, it’s an archetype thing.
Snowflake Shape Archetypes
- Just a bunch of needles lumped together.
- Just a bunch of columns of ice crystals.
- Flat snow crystals, often with extensions called dendrites. They’re the little branches or “arms” you see when you think of a “generic snowflake.”
- Column + Plate
- Columns with planes at the ends.
- Side Planes
- Crystals with extended slide planes, scale-like side planes, or some combination of those planes and columns.
- As the name suggests, these crystals are rimed.
- Miscellaneous assembly of ice and rimed particles or other broken crystals.
- Assembly of column, hexagonal plates, irregular bits and bobs.
At -2.8 to 0 degrees Celsius, snowflakes form like flat plates. But if you go further down in temperature, you get more needle-like snowflakes with arms and stuff. Even colder, you get hollow columns. Humidity affects snowflakes similarly. If it’s low, snowflakes will be flatter and more plate-like, while higher humidity will give you flakes with more crystals on their edges. You know, because humidity means there’s more water in the air.
So Are They Unique?
So right out the gate, we have a pretty heavy limitation on snowflake shapes. They have to be hexagons–six sided. Six arms, six sides, some variation of that. Why is that? Well it’s because water molecules freeze together in that pattern. So snowflakes, made of frozen water, can only be different variations of that pattern.
But we don’t exist in a perfect world where snowflakes are made of just water and all freeze at the same temperatures. Snowflakes hit different things on the way down by virtue of floating through different clouds, they form at different humidities and temperatures, and so on.
So while snowflakes may form identically, they may be different after falling for miles upon miles when they finally hit the ground. Or your hand. Or your tongue.
The short answer, considering this then, is actually yes. Snowflakes are unique! Quite literally, there are more possible combinations of snowflake than there are atoms in the universe. Obviously, we can’t prove that two identical snowflakes have fallen, but the possibilities are functionally infinite for our tiny human brains. So while snowflakes can be so similar they’re basically the same, there exist minute differences that do make them different.
Childhood successfully not-ruined, we suppose.
Let’s fantasize about snow this Winter by looking at snow covered cities here.