From the extremely complex to the tiniest gems, many snowflakes have perplexing features, and this one is no different. See the bright lines inside? In all the years observing and photographing snowflakes, I have never seen anything like this before.
It’s a little shocking to still be able to uncover new mysteries in the world of snowflakes. I even reached out to Ken Libbrecht, physicist and professor at CalTech who studies snowflakes in his laboratory, for help on this one. His response: “I don't have any explanation for the mechanism, but I suspect it will be complicated, resulting from some kind of inward-growing features on the faces of the plates.”
While there are definite signs of inward crystal growth (this can be seen as subtle curves and ripples on either side of the snowflake), I’m not sure it properly explains what we’re seeing. If you see the little V-shaped notches on the outer footprint of the snowflake, this is directly in the middle of the prism facets – and it’s also where all of these diagonal lines converge. To better understand this, it might be helpful to imagine the snowflake at a smaller size, moments earlier in its life when these bubbles were forming.
As the inner portion of the lines begin on a diagonal line, this means they didn’t all start growing at the same time. The lines closer to the center started first, and gradually the others began in a roughly consistent way. The lines are all running parallel to certain sides of the snowflake as well, something I haven’t seen before. The closest similarity I can find would be to this snowflake from a number of years ago, but it’s bubble paths run perpendicular to the outer edges: https://www.flickr.com/photos/donkom/15820188480/
Furthermore, I don’t even think these lines are bubbles in the ice. There ARE bubbles and cavities inside this snowflake – these are the areas that are slightly brighter like the inner hexagon shape. If these lines were bubbles, they’d roughly match the same brightness. Being so bright might mean that they are grooves in the surface of the snowflake with hard-edged crystal facets able to send more light back to the camera as a direct reflection. I had a few shots from a different less-reflective angle that seem to support this – here’s an example: http://donkom.ca/bts/DKP_3378.jpg
While that might explain the “how”, the “why” is still unanswered. The slight prism effect and shadows surrounding them support the faceted groove theory since they are on the opposite side of the crystal, but why on the surface? Typically bubbles form inside a snowflake where there is less access to available building blocks (water vapour); this tends to be in the center of a prism facet – the furthest point from the corners that receive the fastest growth. This is why snowflakes don’t stay hexagons but grow branches from the corners.
For a tiny little gem roughly 1mm across, it shows us that we do not have full and complete understanding of one of the basic building blocks of life: water. To have this revealed two feet from my back door in a snowflake? I am humbled.
If you like unraveling these mysteries, then you need to pick up one of the few remaining copies of my book Sky Crystals: https://www.skycrystals.ca/book/ (or the eBook: https://www.skycrystals.ca/ebook/ )
If you’d like to see how these tiny gems compare in size to the larger ones, my poster print “The Snowflake” features over 400 crystals of varying sizes, all meticulously measured and placed in relative size to each-other: https://www.skycrystals.ca/poster/