Let it snow, let it snow, let it snow!
There are few things more beautiful than the intricacy of a snowflake, but how exactly are they formed? Why are they symmetrical? Why are no two the same?
Let’s find out!
The birth of a snowflake:
Snowflakes form in cold weather when water droplets in the atmosphere freeze onto a particulate; perhaps pollen or some dust. As the particle has now gained a bit of weight (don’t we all over the holidays?), it begins to fall towards the ground. As the ice crystal is falling, water vapour freezes onto it, building new crystals and laying the foundation for a snow flake to form. The temperature at which a crystal forms and the humidity of the air determines the basic shape of the ice crystal. For example, we tend to see long needle-like crystals at -2 degrees C and very flat plate-like crystals at -15 degrees C.
Symmetry!
Many snowflakes are symmetrical; this is due to the crystallisation of water molecules. When water molecules are in a solid state, such as in ice and snow, they form weak bonds (called hydrogen bonds) with one another. This process means that they arrange themselves in predetermined spaces which results in the symmetrical, hexagonal shape of the snowflake.
No two the same?
If you take into account the number of water molecules and isotopes of oxygen and hydrogen, then it is safe to say that no two snowflakes are identical. However, it is possible to find two that look pretty similar, but even this is a huge improbability- I definitely wouldn't recommend spending your life trying to find snowflake twins!
When you think about it, each snowflake will follow a slightly different path through the atmosphere and will encounter different conditions along its journey; so they all tend to look unique- more diversity to awe at!
-Jean
Images courtesy of Alexey Kljatov