The shape of snowflakes is related to the crystallization of water in the atmosphere. When the water molecules in the atmosphere are cooled below the freezing point, they begin to condense and form ice crystals. Ice crystals have their own regular geometry. Ice crystal belongs to hexagonal crystal system, and the most typical shape of hexagonal crystal system is hexagonal prism. However, when the growth of crystals in the main axis direction is very slow, and the growth of crystals in the auxiliary axis direction is fast, the crystals show hexagonal flakes.
Snowflakes will vibrate when floating, and this vibration is carried out around the symmetrical point, which is the initial ice crystal, which is the reason why the shape of snowflakes does not change in the process of falling.
In the polar region, sometimes due to the lack of atmospheric water vapor and extremely low humidity, ice crystals can eventually form the standard form of hexagonal prism. Therefore, in polar regions, sometimes even hexagonal snow crystals can be seen.