Anatomy of a Snowflake
Have you ever wondered how snowflakes are formed, and are they really all different? Well, this post is for you!
“Q: How are snowflakes formed?
A: A snowflake begins to form when an extremely cold water droplet freezes onto a pollen or dust particle in the sky. This creates an ice crystal. As the ice crystal falls to the ground, water vapor freezes onto the primary crystal, building new crystals – the six arms of the snowflake.
That’s the short answer.
The more detailed explanation is this:
The ice crystals that make up snowflakes are symmetrical (or patterned) because they reflect the internal order of the crystal’s water molecules as they arrange themselves in predetermined spaces (known as “crystallization”) to form a six-sided snowflake.
Ultimately, it is the temperature at which a crystal forms — and to a lesser extent the humidity of the air — that determines the basic shape of the ice crystal. Thus, we see long needle-like crystals at 23 degrees F and very flat plate-like crystals at 5 degrees F.
The intricate shape of a single arm of the snowflake is determined by the atmospheric conditions experienced by entire ice crystal as it falls. A crystal might begin to grow arms in one manner, and then minutes or even seconds later, slight changes in the surrounding temperature or humidity causes the crystal to grow in another way. Although the six-sided shape is always maintained, the ice crystal (and its six arms) may branch off in new directions. Because each arm experiences the same atmospheric conditions, the arms look identical.
Q: So, why are no two snowflakes exactly alike?
A: Well, that’s because individual snowflakes all follow slightly different paths from the sky to the ground —and thus encounter slightly different atmospheric conditions along the way. Therefore, they all tend to look unique, resembling everything from prisms and needles to the familiar lacy pattern.”
The above was excerpted from NOAA’s earth science stories webpage. Their explanations are far better than mine could ever be, so I figured I’d just copy and paste the explanation, and then attempt to break it down into my experience photographing snowflakes during our last few Western Washington snow events. While our snow events have been minor, it’s been incredibly fun to hunt down snowflakes at the beginning of the snowfall to photograph.
Below are a handful of images I have taken over the past few weeks. I’m slightly limited on macro imaging due to not having a true macro lens, but my husband recently bought me a set of Diopter filters, which are essentially a big magnifying glass for my camera lens. It has made a big difference and I can’t wait for another round of good snowfall to try again.
These snowflakes fell at the warmer end of the freezing spectrum, as you can see by the long needle-like crystals on most of these.
On the more technical side of things, both cameras were used to take these images, a Nikon D3200 and a D5100. The lens used is a 50mm Prime F/1.8 Nikkor lens. Before I got the Diopter filters, I reversed the 50mm lens and carefully depressed the aperture control as needed to control my focal point. This allowed me to get much closer than the 1 foot minimum focusing distance the 50mm usually requires when mounted normally on the camera. There is a reversing ring that you can buy to do this, however I have just done it manually by hand and have had no issues. However, now that I have the Diopter filter set, I can leave the lens on normally and adjust settings as normal, but I can get much closer (usually a few inches away depending upon my focal point). With the filter, and depending on lighting, I was typically shooting each image between f/2.8-f/6, and my ISO ranged from 100-1600 depending upon whether it was dark outside or not. Shutter speed was also light dependent, but ranged anywhere from 1/60-1/250 of a second. The key with this is to be sure that you don’t drop your shutter speed below your effective focal length, or your images will be blurry. A few of the ones shot at 1/60 of a second are slightly blurry as, technically, on a crop sensor camera, my 50mm is actually a 75mm. Sometimes I forget that, and don’t adjust accordingly. On the other hand, you could use a tripod but it is incredibly hard to get up close to a snowflake when using one, unless you have something like extension tubes or a longer focal length macro lens.
Snowflakes are a very fun and fascinating subject. It’s really neat to see how different they really are. While one might look similar to another, when you look closer, you can see subtle differences that the atmosphere has caused. One snowflake may have shorter arms, or a more needle-like appearance while another has a fatter, stubbier appearance. Regardless, it’s very neat to take a close up look.