This broad-armed beauty was a great selection to illustrate some of the size differences in snowflakes. Attached are a number of smaller crystals to give scale!
Snowflakes come in a large variety of forms, and this one illustrates what happens when a stellar dendrite crystal grows slowly. Generally speaking, the broader the branches the slower the growth. This is true of frost as well – crystals that spent the entire night growing will often have a clamshell-like appearance.
Small hexagonal snowflakes can only get so large before the “branching instability” kicks in. This is essentially the point where a snowflake is forced to start branching because the corners of the hexagon receive more and more water vapour than the inner area of the prism facets. The simple logic is that whatever sticks out the farthest, grows the fastest. I’ve seen some of the larger plates get as big as 1.5mm, but normally they are found around 1mm or less. As you can see, the larger snowflake started growing branches much earlier than its smaller counterparts!
You’ll also notice some uneven growth on the larger branch tips – all pointing up and to the right, but none on the bottom half of the snowflake. During the final stage of this snowflake’s journey, as it began to fall it likely passed through a layer of cloud that had slightly higher humidity, and it did so in a stable fall – one direction was collecting all of this available water vapour. These final “icing on the cake” features are common, as even subtle changes in temperature or humidity can greatly affect the growth of a snowflake!
As soon as a snowflake leaves the cloud, it starts to fade away. Thinner branches tend to round out quickly as they sublimate, but thankfully the added mass of broad branches makes they maintain pristine 60-degree edges for a longer period of time. When photographing snowflakes, I need to work as quickly as possible to get the results I’m after. Usually within the first two minutes of a snowflake falling to Earth, I’m already engaged in photographing it.
Notice how the bottom two smaller crystals are a little darker? That’s because their angle to the light is slightly different and I’m not getting as strong of a “glare” off of their surfaces. To find the right angle that provides maximum reflection off the surface of the snowflake, I need to quickly rotate the camera around the snowflake as the center of rotation, taking test shots until I lock into it. Because the snowflake is the center of rotation, it’s impossible to use a tripod. Every single one of my snowflake photographs have been shot entirely handheld!
Like this snowflake and the accompanying text? There’s a whole book out there waiting for you to read at https://www.skycrystals.ca/ - 304 page hardcover or eBook, but if you want the hardcover there are only 49 copies left!
Don’t forget to listen to my weekly podcast as well, Photo Geek Weekly: http://www.photogeekweekly.com/ tons of geek photography news topics in each episode!