Snowflakes are frozen bits of water that form around a “nucleus.” That nucleus is something that must already exist in the air – like a dust or pollen particle.
How are snowflakes made?
All political jokes aside, snowflakes are actually an interesting natural phenomenon.
According to the National Oceanic and Atmospheric Administration (cited below): “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.”
This doesn’t mean the air is dirty or polluted – after all, pollen is completely natural!
Who are snowflakes so unique?
You may be wondering why all snowflakes are unique if they each require the same circumstances in order to form.
NOAA has an answer for that!
Snowflakes are made up of ice crystals. These build up around the nucleus symetrically “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.”
A combination of air temperature, humidity, and the speed at which they fall determine precisely how the ice crystals form into different shapes. When it warmer, the crystals have a longer, sharper shape and when it’s cold, they tend to be shorter and flatter.
Snowflakes always have six sides, but those “arms” can branch off in different directions depending on those factors as well.
That’s why no two snowflakes are exactly alike.
Of course, when you get 5 or 6 feet of snow, it’s pretty hard to think about those snowflakes as individuals! They all go in the same shovel! — WTF fun facts
Source: “How do snowflakes form? Get the science behind snow” — NOAA