Snowflake
...with narrowed hollow features in their ends. Needles contain thin hollow regions, and sometimes the ends split into additional needle branches. Spatial dendrites are made from numerous individual ice crystals muddled together. Capped columns started out developing as columns, but then suddenly switched to plate-like growth. Rimed crystals are frozen water droplets that freeze onto a falling snow crystal. Irregular Crystals are ill-formed snowflakes that appear during warm snowfalls. The growth of snow crystals depends on a sense of balance between faceting and branching. Faceting has a tendency to make simple flat surfaces, while branching tends to make more complex structures. The interaction between faceting and branching is a fragile one, depending strongly on things for example temperature and humidity. This means snow crystals can grow in countless different ways, resulting in the great assortment we see in snow crystal forms. Water freezes into ice causing water molecules to stack together and form a regular crystalline lattice. The ice lattice has a six-fold symmetry. How do molecular forces, that operate at the molecule scale to produce the crystal lattice, control the shape of a sow crystal some ten million times larger? The answer is how crystals form facets. Crystal faceting is how snow crystals form sharp edges and flat faces. Facets [term] appear on countless growing crystals [class] because some surfaces grow at a greatly slower rate [differences]. Crystal faceting begins with a small round ice crystal with a surface quite rough on a molecular scale, with a large number of hanging chemical bonds. Water molecules from the air readily attach to these rough surfaces, which grow relatively quickly. The facet planes tend to be smoother on a molecular scale, with fewer hanging bonds [cause]. Water molecules cannot easily attach to these smooth surfaces, hence the facet surfaces advance more slowly [effect]. Snow crystals form elaborate and complex shapes. Snowflake branching explains how the simple act of water vapor freezing into ice can produce intricate designs. Water molecules have to diffuse through the air to reach the crystal, and this diffusion slows their growth. The farther water molecules have to diffuse through the air, the longer it takes them to make contact with the growing crystal. Picture a flat ice surface growing in the air. If a minor elevation appears on the surface, then the growth will stick out a smidgen father than the rest of the crystal. What this all means is that the water molecules can reach the growth faster than they could r...