Snow Crystal Classifications
There are a few different schemes for classifying natural snow crystals and other types of frozen precipitation. The classifications all distinguish between the basic plate-like and columnar crystal morphologies, but differ in the number of categories and other details. The categories are all arbitrary to some degree, but are useful for defining a common language with which to describe snow crystal observations. The classification schemes also provide a convenient "field guide" when observing natural snowfalls.
on Snow and Ice
A fairly simple and widely used classification for solid precipitation is that proposed in 1951 by the International Commission on Snow and Ice. This scheme defines the seven principal snow crystal types as plates, stellar crystals, columns, needles, spatial dendrites, capped columns, and irregular forms. To these are added three additional types of frozen precipitation: graupel, ice pellets, and hail.
Nakaya identified seven major groupings of snow crystals, which subdivide further into 41 individual morphological types.
Magono and Lee
The most complex classification scheme is an extension of Nakaya's table, published by Magono and Lee in 1966. A few of the 80 separate morphological types are shown at the left, and the full version can be seen by clicking on the image. An inspection of all the entries in this table gives one a good feel for the full range of snow crystal precipitation.