The formation of a snowflake begins when a microscopic cloud droplet freezes as a tiny ice particle. Water vapour that condenses on its surface causes the ice to develop flat, polished surfaces, known as facets, which continue to grow into a hexagonal prism shape. At each corner of the hexagon shape, new branches extend outwards each at the same rate. All snowflakes have six sides and can be either prism-shaped, plate-shaped or star-shaped.
As the snowflake moves around within the cloud, it encounters a variety of temperatures that change the growth behaviour of each flake, causing the six branches of the crystal to grow in exactly the same way, creating six-way symmetry and a unique flake every time.
The first person to photograph a snowflake was American Wilson Bentley. Bentley took his first snowflake snap in 1885, using a bellows camera and a compound microscope, and went on to assemble a large collection of beautiful snow crystal images.
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