If you’re based in the UK this week you will have had to have been tremendously fortunate not to have been paid a visit by a blanket of snow, however thin, despite it being nearer Easter than Christmas. Such weather always evokes in me a great sense of homeliness. I am compelled to barricade myself indoors with good books and copious amounts of my favourite nibbles. While doing just that and watching the tiny crystals of snow gracefully descend from the azure sky I began to ponder the humble snowflake. These tiny “blobs,” as they appear to our uncultivated eye, are in fact wondrously intricate hexagonal structures. In this post I will dig a little deeper and help explain how snowflakes form and what makes them such fine examples of nature’s inherent beauty.
Snowflakes are made up of water which has frozen and formed “snow crystals” in the clouds. Within every crystal the water molecules are all arranged in a precise hexagonal array, resulting in the “snowflake” often being depicted with its characteristic 6-fold symmetry. As these microscopic crystals fall to Earth they combine to form complex, multi-crystal structures, this is what we observe in the form of the macroscopic snowflake.
Watch a video here!: https://www.youtube.com/watch?v=-6zr2eLpduI
A snowflake begins to form when in sub-zero conditions when a water droplet freezes onto a pollen or dust particle in the sky, creating an ice crystal. As the ice crystal falls to Earth, water vapor freezes onto this primary crystal, which becomes the nucleus of the flake, building larger crystals and the six arms of the snowflake are formed.
The flakes then grow via was water vapour from the air is deposited onto the ice crystal surface. Because water droplets are so much more numerous than the ice crystals due to their sheer abundance, the crystals are able to grow quickly and to much larger sizes than the initiating crystal. This process is known as the Wegener–Bergeron–Findeisen process.
These massive crystal structures which can easily reach millimeters in diameter fall through the atmosphere easily due to their mass. As they do so the acquire further mass through colliding and adhering together in clusters, or aggregates. These aggregates are usually the type of ice particle that falls to the ground i.e. our humble snowflake.
The most hauntingly beautiful aspect of the snowflake is that it is a unique structure, no two are ever identical. Each is an inimitable assembly of crystals born purely by a chance combination of temperature, air humidity and the exact path taken by the snowflake as it tumbles through the clouds.
Spinning model of H2O (i.e. water) crystels. The hexagonal shape is obvious. 
A stellar snow crystal originates with the formation of a small hexagonal plate. As the crystal grows, branches begin to protrude from the six corners of the plate. Throughout its descent through the clouds, the crystal experiences ever changing temperatures and humidities, and each encounter results in the protrusions evolving slightly differently.
As they fall the snowflakes tend to maintain their six-fold radial which originated from the initiating water crystal. Despite each arm growing independently the environmental variations in across the flake are not sufficient to cause variations between arms of the same flake.
Snowflake Generation: hexagonal structure of water crystals means 6-fold symmetry is maintained within the marco-structure of the snow-flake 
Snow-flakes are of course 3D structures and the primordial crystal will therefore have both 2 hexagonal facets and 6 prisim side facets. These hexagonal prisms can be long, slender, hexagonal columns, or thin, flat, hexagonal plates, or anything in between.
There are an almost infinite number of possible snowflake shapes:
Some flakes develop flat faces or “facets” – giving them gemstone-like appearence. It is the reflective indices of these type of flakes which makes snow glem in the midday sun. These “little faces” develop as the air strikes the crystal. The water molecules stick especially well to rough spots on the flake’s surface, where there are lots of available chemical bonds. They adhere less well to smooth surfaces, with fewer bonds. Consequently, the smooth surfaces accumulate material more slowly than rough surfaces. The rough parts soon fill in, leaving just the smooth, faceted surfaces.
A Facetted – “wide flat faced”- snowflake.
Some snowflakes develop extensive networks of branches. These smaller daughter branches are formed in the same way as the main branches. These crystals tend to be larger and faster than there flatter facetted cousins. Most flakes will initially form the facet structures. The process by which these flakes then acquire more complicated branches is known as physical morphogenesis – the spontaneous creation of pattern and form by inanimate materials, the process by which order arises from chaos.
Extremely intricate branches can form.
There is so much complexity to these little “blobs” of ice. They are the quintessential example of how the natural world can produce the perfect paradox, possessing both chaos and beauty simultaneously. I hope this article has done these little works of accidental art justice and if you are even more intrigued by snowflakes I recommend flicking through  or if you want to delve even further into natures chaotic beauty I recommend starting with .