A hexagonal grid holds water. Frozen cells and their neighbours are receptive and keep their water, gaining γ; other cells share vapour by diffusion α. A cell freezes once it holds 1 or more.
Tap left to dry the air, right to wet it; the flake regrows. The same ?seed= always gives the same run.
LITReiter’s snowflake model (2005). Every 30 steps the frozen ledger must match a recount and vapour must not go negative, or the page throws.
AMBERReal habit depends on temperature and supersaturation (the Nakaya diagram).