Main grain shape classes are classified according to the International classification for seasonal snow on the ground
(IACS, 2009) by using
either a symbol or a unique twoletter upper case abbreviation code. Subclasses are classified either by using the proper symbol
or a four-letter abbreviation code, where two lower case letters are appended to the main class code. To this classification, three further subclasses were added
to describe the iced surfaces measured in this work.
For a more comprehensive description of the snow classification used and of the snow grains characteristics, see the
snowcrystal.it pages on this topic.
Another search procedure
is based on aggregating in surface classes different snow forms, considering the texture modification
from recently deposited or precipitated crystals to advanced melting and refreezing of forms.
In C1 class are included the recent forms term - precipitated particles (PP), decomposed and fragmented grains (DF), and surface hoars (SH);
In C3 class are included the modified forms, produced by both equilibrium and kinetic growth metamorphism -
rounded grains (RG) and faceted crystals (FC);
In C5 class are included the melt forms (MF), representing the final stage before the transformation in perpetual snow and ice formation;
Two intermediate transitional classes where recognized between C1 and C3 and between C3 and C5.
Ice surfaces have been distinguished based on their geographical location.
SISpec