SNOWFLAKES

Snow is formed somewhat similarly to rain, except the water crystallizes and becomes ice. It starts out as forming as a hexagon that grows larger and larger. Eventually, the ice begins to branch off of the point of the hexagon, simply because that is the farthest point away from the mass. It branches off again and again until it finally either becomes structurally unstable or falls from the cloud in a snowstorm.  I am actually not sure if the water crystallizing lets snowflakes form without particles, but I am guessing that they still would because the ice has got to start somewhere.