Originally shared by Don Komarechka


Originally shared by Don Komarechka

Snowflake-a-Day #16
Today’s snowflake has a very “alien” feeling center, with many strange tentacles reaching towards the center. The fun thing is, that’s the where they start – not where they end! View large!

A snowflake grows from the center outward, so picture this tiny crystal just at the point where those tentacles begin, that’s the start of cavities forming in the ice. The conditions change slightly to allow them to contract but then expand again, a process that repeats as the crystal grows until ultimately the cavities in the ice expand so much that they reach the corners, cutting the crystal into two planes. Immediately after that happens, the rules of engagement change.

The lower plate accelerates its growth because it’s thinner (the knife-edge instability), leaving the top plate to grow out much more slowly. By the looks of the snowflake, nothing is growing fast – hard 60 degree edges are a sign of this – but the bottom layer expanded until the branching instability took hold and forced the corners of the crystal to expand outward and a further rapid pace.

I wish I knew of some way to easily animate the growth of this snowflake to help everyone visualize how it was formed, but regardless of how you imagine it I’m certain you’ll enjoy the center of this tiny snowflake. The colours caused by thin film interference are present, but much more muted than I have seen in other crystals. This can be due to the angle of the light or the thickness of the cavities between the layers of ice, and if you’re really curious about the science, here’s a great primer: http://web.pdx.edu/~bseipel/203-CH23.pdf

There are a few “spots” on the snowflake that you’ll notice as you look around. These are caused by super-cooled water droplets that collide with the snowflake. Water can stay liquid beyond the freezing point of water if it’s pure, but as soon as it comes in contact with something it will freeze instantly. These little hydrometeors impact onto the snowflake and embed themselves onto the ice structure. They don’t add to the crystal formations, but instead scar it. If this happens in greater numbers we call it “rime”, and if the rime is extreme enough to turn the snowflake into a cluster of just these impacts it can be called “graupel”. There’s a lot of words to describe snow!

The faint circle in the very center is also interesting, but why don’t we save that for another day? Snowflakes offer endless complexity and details! If you want to discover all of the photographic techniques, give my book Sky Crystals a read: https://www.skycrystals.ca/book/ - which also contains over 100 pages of understandable science that describes everything you see in a snowflake. They are beautiful and mysterious, but somehow become even more interesting when you can understand them. :)

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