History of snowflake studies
Rough sketches of snowflakes were published by Olaus Magnus of Uppsala around 1550. Johannes Kepler made more detailed pictures and identified hexagonal symmetry around 1611. Over the course of the next few centuries, following work by René Descartes, Robert Hooke and others, progressively more accurate pictures were made and correlations between weather conditions and snowflake forms were found. Thousands of photographs of snowflakes were taken by Wilson Bentley over the period 1884–1931. Beginning in 1932 an extensive study of snowflakes was made by Ukichiro Nakaya, who in 1936 also produced the first artificial snowflakes. Most of the fairly small amount of more recent work on snowflakes has been done as part of more general studies on dendritic crystal growth. Note that tree-like snowflakes are what make snow fluffy, while simple hexagons make it denser and more slippery. The proportion of different types of snowflakes is important in understanding phenomena such as avalanches.