Dendritic growth of a snowflake
= Dendritic growth of a snowflake
An exposed tip receives vapour more efficiently than a sheltered surface and can amplify its lead, producing <crystal dendrites> and side branches. The planar thermal <solidification> mechanism is an analogy, not a complete vapour-growth model. The <hexagonal ice crystal anisotropy> selects six preferred directions; an isotropic linear instability alone does not select six arms.