Abstract

The snowflake has a substantial influence on the entire fabric of life in northern latitudes. Moreover, the scientific method itself was driven by the strikingly detailed observations of snowflakes made by René Descartes. Since his time amateurs and professionals alike have catalogued the great varieties of shapes observed in the natural environment but the modern studies of Ukichiro Nakaya launched the systematic study of these objects. Nakaya was originally motivated to infer much of the temperature and humidity history of the snow crystal by observing its morphology on the ground and hence he referred to them as “letters from the sky.” However, his systematic laboratory studies revealed the basic physics of crystal growth and thereby snowflakes and all other materials were forever entwined. Indeed, crystal growth experiments on the international space station use ice, the growth of so called “negative crystals” in clathrates within the great ice sheets hold clues about the Earth’s past climate and influence the study of solar neutrino’s, and the mechanisms by which many organisms thwart the threat posed by low temperatures revolve around many of the same processes. Hence, understanding the behavior of snowflakes extends well beyond meteorological musings. These connections and the basic processes that drive them are the topic of this talk.