Wilson Bentley, a “bona-fide snowflake obsessive,” snapped close-ups of snowflakes in the late 1800s and early 1900s.

“But always, from the very beginning it was the snowflakes that fascinated me most.” Under his microscope, Bentley discovered that each snowflake had its own careful and fleeting geometry.

Watch: This absolutely breathtaking photography of frost crystals will remind you of nature's microscopic beauty.

...but these are freshly fallen snowflakes, or snow crystals, resting on wool. They are around 1 millimeter in size and were captured using a simple, cheap photography technique. When the snow ...

If humidity is low, there isn’t as much water vapour in the atmosphere so the snowflakes form something called 'plates', the flat hexagonal shapes you see if you look at them under a microscope.