Generally, six-sided hexagonal crystals are shaped in high clouds; needles or flat six-sided crystals are shaped in middle height clouds, and a wide variety of six-sided shapes are formed in low clouds. Colder temperatures produce snowflakes with sharper tips on the sides of the crystals and may lead to branching of the snowflake arms (dendrites).

Snowflakes, famously, are six-sided but they also have six-fold symmetry. Ian Stewart, Emeritus Professor of Mathematics, explains how the formation of ice crystals in clouds results in infinitely symmetrical snowflakes.