American Scientist

January-February 2007

Volume: 95 Number: 1

The simple act of freezing water vapor produces snowflakes with fernlike branches, multilayered faceted plates and a myriad of other shapes. The temperature and humidity ranges required to produce these various ice gems have been mapped out for 75 years, but it remains largely unknown just why certain conditions lead to specific structures and why minor changes in temperature can radically alter the resulting snowflake forms. As Kenneth G. Libbrecht explains in "The Formation of Snow Crystals," a new theory on snowflake growth, along with computer modeling and laboratory-grown crystals, may finally start filling in the gaps. A better understanding of how snow crystals build up from base materials could aid in the semiconductor and nanofabrication industries. (Images courtesy of Kenneth G. Libbrecht.)