How Snow Forms — From Water Vapour to Snowflake

Snow vs Frozen Rain

A common misconception is that snow is frozen rain. In reality, snowflakes form through a completely different process. Rain freezes; snow crystallises.

The Formation Process

1. Water vapour rises into a cloud where temperatures are below freezing
2. The vapour encounters a tiny ice nucleus — often a speck of dust, pollen, or bacteria
3. Water vapour deposits directly onto the nucleus as ice (skipping the liquid phase)
4. The ice crystal grows into a hexagonal structure as more vapour attaches
5. The snowflake falls when it becomes heavy enough, continuing to grow on its descent

Why Snowflakes Are Hexagonal

Water molecules bond at 120° angles due to their molecular structure. This produces six-sided symmetry in every ice crystal, from simple plates to elaborate branching stars.

Types of Snowflakes

Are All Snowflakes Unique?

Simple snowflakes (small plates and needles) can look identical. But complex stellar dendrites have so many variables (temperature, humidity, wind during their 30-60 minute descent) that two identical ones are statistically near impossible.

Snow-to-Liquid Ratio

Fresh fluffy snow at -10°C has a ratio of about 15:1 (15cm of snow melts to 1cm of water). Wet snow near 0°C can be as low as 5:1.

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