I didn’t know snowflakes come in all sorts of geometric shapes.
From the link:
The beautiful six-fold symmetry of snowflakes is the result of the hydrogen bonds that water molecules form when they freeze.
But snowflakes can form other shapes too when the growth of the crystal is perturbed on one side. In theory, diamonds, trapezoids and other irregular shapes can all occur. And yet the one most commonly observed (after hexagons) is the triangle. The puzzle for is why? What process causes deformed snowflakes to become triangles rather than say squares or rectangles?