A global classification of snow crystals, ice crystals, and solid precipitation based on observations from middle latitudes to polar regions

This paper presents an extensive revision of Magono and Lee's (1966) classification of natural snow crystals, which has been widely used in snow and ice studies to describe snow crystal shapes. The new classification catalogs snow crystals and other solid precipitation particles into 121 categories, in contrast to Magono and Lee's 80 categories. Of these, 28 categories were created to classify new types of snow crystals that have been discovered in polar regions since 1968, seven were created after reconsidering the original categories, and six categories were created to classify solid precipitation particles such as frozen cloud particles and small raindrops. Because our observational area extended from middle latitudes (Japan) to polar regions, we refer to our new classification scheme as ‘global-scale classification’ or ‘global classification’. The global classification consists of three levels – general, intermediate, and elementary – which are composed of 8, 39, and 121 categories, respectively. This paper describes the characteristics of each type of snow crystal, ice crystal, and solid precipitation particle. •We offer a new classification of snow crystals, ice crystals and solid precipitation.•A total of 121 types of these particles are shown in photos and schematic drawings.•Photos of these particles were taken in Japan and in polar regions from −50 to 10°C.•We refer to our new classification scheme as “global classification”.•“Global classification” is a revision of a classic work by Magono and Lee (1966).