The expression ‘no two snowflakes are the same’ is a great metaphor for the uniqueness of people, but is it actually possible for every snowflake to be completely original?
Professor Ken Libbrecht, at the California Institute of Technology, explained the science behind snowflakes to KQED.
“It goes back to how they’re made in the clouds,” he said.
Snowflakes are made by humid air which has been cooled to the point where water vapour joins and form bonds. The molecules in the water vapour (one part oxygen to two parts hydrogen – hence H2O) connect together in the hexagonal shape we associate with snowflakes. As more crystals form, they attach at the points of the hexagon to make your traditional snowflake.
With all the variables that nature throws around, you’re highly unlikely to find two naturally made snowflakes which are the same.
But in a controlled environment, it’s a totally different matter.
Professor Libbrecht constructed a device in a refrigeration chamber which replicates the environment in which snowflakes are traditionally made.
The refrigeration unit contains a tub of hot water which evaporates, creating vapour. When the unit is humid enough, Professor Libbrecht releases condensed air, which triggers an immediate cooling effect in the chamber. This causes water crystals to appear from the vapour, which start off like the little hexagons mentioned before, at which point things get more science-y.
Professor Libbrecht catches the crystals, which he calls “seed crystals”, on a refrigerated plate. He sticks the seeds under a microscope and then adjusts the temperature and humidity so they have something to grow with, allowing him to successfully manipulate the seeds to grow how he wants – with a little practice, of course.
What’s perhaps more interesting is what happens when he puts multiple seeds on a single tray. Because each seed is being manipulated in the same environment without the variables, Professor Libbrecht is able to produce “identical” snowflakes.
However, this science isn’t all fun and games and songs from Frozen – there’s actually a method to the madness. As crystals are used in a lot of everyday objects, being able to study how they grow is an important way to refine and improve their uses.
And yes, now you have ‘Let it go’ stuck in your head.