Is Every Snowflake Really Unique?

Snowflakes fall by the trillions during every snowstorm, so how could each one be unique? Learn about the incredible crystal physics behind snowflake development in this episode of BrainStuff, based on this article: https://science.howstuffworks.com/nature/climate-weather/atmospheric/is-every-snowflake-actually-unique.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff, a production of iHeart Radio, Hey
brain Stuff, Lauren vogel Bomb. Here consider the long and
arduous plight of the snowflake. Those delicate, intricate crystals have
traveled many miles before they plummet to the ground alongside
their trillions of cousins, And although they fly in multitudes,

(00:24):
the word on the snow slipped street is that no
two are exactly alike. But can every snowflake really be different?
The short answer is yes, every snowflake really is unique,
but you might find some that are exceedingly similar, particularly
at the beginning of a flake's development. But fully formed
snowflakes are indeed structurally different, if only by the tiniest

(00:46):
of degrees. Understanding why snowflakes take unique forms means understanding
how they're formed in the first place. It all starts
at Earth's surface, as water evaporates from oceans, rivers, and
lakes and rise into the atmosphere in the form of
gaseous water vapor, which we sometimes see as clouds. In
the summertime, those clouds drift around the skies, providing shade

(01:09):
and breaking up the blue horizon. But in winter things change.
The cold air forces molecules of water vapor into little
liquid droplets that condensed onto any nearby particulate matter such
as pollen or dust. These tiny ice crystals are the
baby virgins of what soon may become full grown snowflakes.

(01:31):
The crystals float through the sky and collide with molecules
of water vapor. As vapor contacts the crystals, the water
vapor skips from its state as a gas straight to
a solid crystal, adding to the original nucleus of the snowflake.
This process happens over and over again, building the snowflake
from a nearly imperceptible crystal into a larger flake that,

(01:53):
given the right conditions, falls to the ground. And knowing
all of this, it may still be difficult to believe
that in a sky full of snowflakes, no two are alike,
but the flake making process practically ensures that these tiny
crystals are all unique, even when they fall by the billions.
As the very first ice crystals come together in a

(02:14):
group of fledgling snowflakes, the new flakes often look strikingly similar.
That's largely due to the fact that ice crystals typically
take a hexagonal or six sided lattice shape because of
the way that hydrogen atoms bond with oxygen to make water,
but certain edges of the ice crystals will be jagged.
These uneven areas attract more water molecules than the smoother

(02:36):
parts of the hexagon. Each little arm will sprout more
of the same, growing into an intricate and uniform snowflake.
If snowflake development stopped within the first few moments of birth,
we'd wind up with a lot more flakes that look alike.
But snowflakes keep gathering more and more crystals, which clustered
together on top of one another indistinct patterns. As those

(03:00):
clusters of crystals continue their snowflake fiesta, other guests visit
the flake making party. Notably, humidity and temperature both play
major roles and whether the snowflake gets bigger and bigger
or fizzles out. As you can probably imagine, temperature is
critical to ice crystal formation and structure. Between temperatures of

(03:22):
twenty seven and thirty two degrees fahrenheit that's negative two
point eight and zero celsius a, crystals take on a
plate like or prism like appearance. These are your prototypical
six armed snowflakes that don't have a lot of extra pizzas.
Drop the temperature a few degrees though, and you'll see
needle like structures starting to form a little lower and

(03:44):
hollow columns develop, and even colder, you'll see stars sprouting
fern like arms. Meanwhile, lower humidity tends to result in
flatter flakes. Higher humidity means more crystal development in edges
on corners. So add some extra moisture at those really

(04:04):
frigid temperatures, and suddenly snowflakes may become mesmerizingly beautiful. They
can contain a multitude of intersecting plates and needles and
spaces a minute masterpieces falling from the heavens. Okay, So,
physics and weather conditions determine snowflakes shape and size, but
math determines that those flakes are unique. Consider that each

(04:28):
snowflake is made up of a huge number of water molecules.
By one estimate, as many as a quintillion molecules per flake.
Because each little branch of a snowflake can spawn many others,
there are dozens and dozens of ways for various crystalline
features to join. There are so many possible arrangements that

(04:48):
some scientists say there are twice as many possible crystal
combinations as there are atoms in the whole universe. Those
kinds of numbers are so large that we can't really
even comprehend them. But if the math holds, those numbers
mean that it is awfully unlikely that any two snowflakes
have ever been, or ever will be exactly alike. Furthermore,

(05:12):
there are all kinds of other factors at play in
snowflake formation. At any given instance. Even the tiniest fluctuation
and temperature and humidity alters crystal construction a miniature. Impurities
like flux of dust change the crystals too. The angles
with which water molecules collide with existing crystals matter as well,
and snowflakes smash into each other as they zoom and

(05:34):
swoop through the air, where their branches shatter new one's form,
adding to the uniqueness of every translucent little flake in
the swirling atmosphere miles above Earth's surface. All of these
variables ceaselessly change. Conditions that hold in one small space
are just a tiny bit different than those inches away

(05:55):
in any direction, and all of it transforms crystals and
their subsequent snowflakes in infinite ways, so snowflakes really are
nearly unlimited in their specialness. They're tiny and ephemeral testaments
of the strange and constant change in the world and
universe all around us. Today's episode is based on the

(06:20):
article is every snowflake Actually Unique? On how stuff works
dot com? Written by Nathan Chandler. Brainstuff is production by
Heart Radio in partnership with how stuff works dot Com,
and it's produced by Tyler Clang. For more podcasts for
my heart Radio, visit the heart Radio app, Apple Podcasts,
or wherever you listen to your favorite shows.