  This monograph reviews our current understanding of the physical dynamics of
ice crystal growth, focusing on the spontaneous formation of complex structures
from water vapor (called snow crystals) as a function of temperature,
supersaturation, background gas pressure, and other extrinsic parameters. Snow
crystal growth is a remarkably rich and rather poorly understood phenomenon,
requiring a synthesis of concepts from materials science, crystal-growth
theory, statistical mechanics, diffusion-limited solidification, finite-element
modeling, and molecular surface processes. Building upon recent advances in
precision measurement techniques, computation modeling methods, and molecular
dynamics simulations of crystalline surfaces, I believe we are moving rapidly
toward the long-sought goal of developing a full physical model of snow crystal
formation, using ab initio molecular dynamics simulations to create a
semi-empirical characterization of the nanoscale surface attachment kinetics,
and then incorporating that into a full computational model that reproduces the
growth of macroscopic crystalline structures. Section 1 of this monograph deals
mainly with the material properties of ice Ih in equilibrium, including
thermodynamics quantities, facet surface structures, terrace step energies, and
crystal twinning behaviors.
