THE FORMATION OF ICE CRYSTALS 
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TasiE I. GENERAL CLASSIFICATION OF SNOW CRYSTALS 
II 
Ill 
IV 
VI 
VII 
The development of photomicrography gave rise to a 
tendency to attach particular importance to the regular 
hexagonal crystals of planar type, although in reality 
spatial and irregular types occur in greater quantity. 
M Needle erystal 1. Simple needle a. Elementary needle 
b. Bundle of elementary needles 
2. Combination 
C Columnar erystal 1. Simple column a. Pyramid 
b. Bullet type 
c. Hexagonal column 
2. Combination a. Combination of bullets 
b. Combination of columns 
1D Planar erystal 1. Regular crystal developed in | a. Simple plate 
one plane 6. Branches in sector form 
c. Plate with simple extensions 
d. Broad branches 
e. Simple stellar form 
f. Ordinary dendritic form 
g. Fern-like crystal 
h. Stellar with plates at ends 
1. Plate with dendritic extensions 
2. Crystal with irregular num- | a. Three-branched crystal 
ber of branches b. Four-branched crystal 
c. Others 
8. Crystal with twelve branches] a. Fern-like 
b. Broad branches 
4. Malformed crystal Many varieties 
5. Spatial assemblage of plane | a. Spatial hexagonal type 
branches b. Radiating type 
CP | Combination of colum- | 7. Capped column a. Column with plates 
nar and planar crys- 6. Column with dendritic crystals 
tals c. Complicated capped column 
2. Bullets with plane crystals | a. Bullets with plates 
6. Bullets with dendritic crystals 
8. Irregular assemblage of col- 
umns and plates 
S Columnar erystal with extended side planes 
R Rimed crystal 1. Rimed crystal 
2. Thick plate 
8. Graupel-like snow a. Hexagonal type 
6b. Lump type 
4. Graupel a. Hexagonal graupel 
6. Lump graupel 
c. Cone-like graupel 
If Irregular snow particle | 7. Ice particle 
2. Rimed particle 
8. Miscellaneous 
Before the method of photomicrography was fully de- 
veloped, crystals with spatial structure were often re- 
ported in the literature, but they have been more or 
less neglected by workers using photomicrography. In 
