Science of Snowflakes: How Snow Crystals Get their Amazing Shapes [Video]

A new video shows how the delicate little crystals form as they fall to earth.

In a new YouTube video, Bytesize Science  explained the science of snowflakes and how they get their unusual form when falling from the sky.

How do snowflakes grow into their individual shapes? It starts with a speck of dust, scientists say.

“Formation of snowflakes from their origins in bits of dust in clouds that become droplets of water falling to Earth. When the droplets cool, six crystal faces form because water molecules bond in hexagonal networks when they freeze,” Bytesize Science explains.

“Ice crystals grow fastest at the corners between the faces, fostering development of the six branches that exist in most snowflakes. As snowflakes continue to develop, the branches can spread, grow long and pointy, or branch off into new arms.”

“As each snowflake rises and falls through warmer and cooler air, it develops its own distinctive shape.”

Scientists prefer the term “snow crystal” to that of snowflake. According to snowcrystals.com: “A snow crystal, as the name implies, is a single crystal of ice.”

“A snowflake is a more general term; it can mean an individual snow crystal, or a few snow crystals stuck together, or large agglomerations of snow crystals that form ‘puff-balls’ that float down from the clouds.”

As Kenneth Libbrecht, a physics professor at the California Institute of Technology and avid snowflake photographer, says that water molecules are ultimately responsible for the familiar six-sided shape we associate with snowflakes.

“Atoms and molecules can hook up in different ways and, in the case of water, they like to hook up into a hexagonal lattice. That underlying structure is how the crystal gets its sixfold symmetry.”

The two main factors that influence the form of the crystalline are temperature and humidity. If their levels changes, so does the growth pattern of the crystal.

While under low humidity plates and simple hexagonal blocks are made, at high levels of the factor, more branched structures are formed.

“[A snowflake’s] final shape is a history lesson of how the thing grew,” said John Hallett, director of the Ice Physics Laboratory at the Desert Research Institute in Reno, Nev.

He went on, adding: “The outside edge of the crystal is where it grew last, and as you go inward you can tell [the conditions of] where it was before.”

“It’s a mystery as to why [snowflake shapes] go from plates to columns to plates to columns as the temperature lowers. That’s one of the things I’ve been trying to understand. It has been a mystery for about 75 years, and it’s still unsolved.”

And though it may appear otherwise, the arms of a snowflake are not perfectly symmetrical.

“If you look at the dendritic arms of a snowflake carefully, they usually are a bit different,” Hallett explained. “The atmosphere is a turbulent place, and crystals tend to oscillate as they are blown around, so even different corners see slightly different environments.”

So is it really true that no two snowflakes are alike?

“It’s like shuffling a deck and getting the exact same shuffle for 52 cards,” Libbrecht said. “You could shuffle every second for the entire life of the universe, and you wouldn’t come close to getting two of the same.”

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