No two alike: The science behind the uniqueness of snowflakes

Trillions upon trillions of snowflakes fall each winter with no two being exactly the same. And the weather is the reason. It all begins high up in the clouds. This is where the snow crystals form, each one starting as a hexagonal prism. As they fall through the sky, the flakes are buffeted with the constantly changing temperature and humidity, influencing their growth in real time. Shapes can range from the dendrites you see in Christmas décor to more rare forms like needles and columns. Their final appearance is like a love letter from the sky, revealing the intricate details of the weather on the way down.