First Snowfall

We’ve just received our first snowfall of the season, and I’d like to do something special, something I’ve never done before. This snowflake image is being released into the “Public Domain”. This snowflake goes out to the world, for any purpose anyone wishes. It’ll be a fun experiment to see where it ends up!

“Public Domain” means I give up all rights to the image. You are not required to credit me (though I’d like it if you would!), you can use the image for any commercial or non-commercial purpose what-so-ever. You can make and sell prints, put it on a coffee mug, or anything you can imagine. This is the only time I have ever placed an image in the public domain. Have fun with it!

This particular snowflake has plenty of detail and symmetry, making it an iconic symbol of winter. Very few snowflakes would rival this one in visual balance: radiating textures and complexity sealed within a much more simple outer shape. Many of these internal details are bubbles trapped in the ice, which happens when the top and bottom “edge” of a snowflake grow faster than the inner portion of the crystal. Whatever sticks out the farthest grows the fastest, which applies on many size scales for a snowflake – it’s also the reason why branches grow from each corner of a smaller hexagon shape.

You can see this hexagon shape in the center. This little “gem” is what remains of a pair of tiny hexagons that were connected by a center column, looking initially like a barbell. At warmer temperatures, snowflakes will grow into columns instead of plates, but if the temperature then drops, plates grow from either side of the column to get this shape… then the race is on! If one small hexagon grows faster than the other, its footprint would stick out farther than its rival. Once this happens, the larger hexagon will grow rapidly and leave the competition at the same size without access to more building blocks (water vapour) to grow. As the winning side grows outward, branches form and we get the classic snowflake shape with the right stable conditions.

A snowflake can “split” into new rival plates as well, which happens when a cavity in the ice grows large enough to encompass the entire end of a growing branch. This is all the same physics at play, and what allows for bubbles to form in the ice. Once the tip of a branch is split, they may continue to grow outward together for a time, but one side will always win over the other. This creates tiny “shelves” that can be seen where the largest side-branches in the snowflake appear. If you look closely, you can even see the top shelf casting a shadow on the underlying ice.

Amazingly complex structures form from simple water molecules attaching themselves together with the right conditions. Even two snowflakes growing in the same part of the same cloud will inherently be different, as even the tiniest change in humidity and temperature can make a big difference; these small changes echo out through the entire crystal as growth continues, amplifying the earlier history of the snowflake. If conditions are unstable, you often get very unbalanced / asymmetrical crystals – and this is by far the most common type of snowflake. To find well balanced and symmetrical snowflakes like this is not easy, but well worth the effort. And even by the time it lands in my home-made black mitten to be photographed, it has already started to evaporate back into thin air.