How Do Snowflakes Form?

What do humans and snowflakes have in common? Just like every person has a unique fingerprint, every snowflake has a different geometry and shape. When an extremely cold droplet of water freezes over a speck of dust or pollen in the sky, it forms an ice crystal, which serves as a base for the rest of the snowflake to grow upon. As the crystal falls towards the ground, water vapor in the atmosphere freezes onto it.

The ice crystal grows six ‘arms’ as it grows to form a snowflake. The uniqueness of snowflake geometry can be attributed to slight changes in temperature, humidity, and pressure. The height or altitude at which the ice crystals start to form snowflakes has a major effect on a snowflake’s shape, size, and geometry. The effect of temperature is quite pronounced. At 23°F, needle-like crystals form, and at 5°F flat crystals form. Watch this video showing the formation of snowflakes.

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