Ukichiro Nakaya

Ukichiro Nakaya (1900-1962) was a Japanese physicist who in 1936 became the first person to create artificial snowflakes under controlled laboratory conditions, using a rabbit hair fiber suspended in a cold chamber as a nucleation site. Through extensive experimentation varying temperature and humidity, he produced a detailed classification linking specific snow crystal shapes to the atmospheric conditions under which they formed, a body of work summarized in his own well known phrase describing snow crystals as letters sent from the sky, allowing their form to be read as a record of the conditions high in the clouds where they grew. His research established snow crystal morphology as a quantitative tool for atmospheric science and remains foundational to the study of ice crystal formation. He also carried out research on frost, sea ice and other ice phenomena during a career spent largely at Hokkaido University.