|T Needle crystals||1. Simple needle||a. Elementary needle
b. Bundle of elementary needles
|U Columnar crystal||1. Simple column@@||a. Pyramid, Bullet type
b. Hexagonal column
|2. Combination||a. Combination of bullets
b. Combination of columns
|V Plane crystal||1. Regular crystal developed in
|a. Symple plate
b. Blanches in sector form
c. Plate with simple extensions
d. Broad branches
e. Simple stellar form
f. Ordinary dendritic form
g. Fernlike crystal
h. Stellar crystal with plates at ends
i. Plate with dendritic extensions.
|2. Crystal with irregular number
|a. Three-branched crystal
b. Four-branched crystal
|3. Crystal with twelve branches||a. Fernlike crystal
b. Broad branches
|4. Malformed crystal||Many varieties|
|5. Spacial assemblage of plane
|a. Special hexagonal type
b. Radiating type
|W Combination of
@@column and plane
|1. Column with plane crystals at
|a. Column with plates
b. Column with dendritic crystal
c. Complicated capped column
|2. Bullets with plane crystals||a. Bullets with plates
b. Bullets with dendritic crystals
|3. Irregular assemblage of columns and plates|
|X Columnar crystals with extended side planes|
|Y Rimed crystals
|1. Rimed crystal|
|2. Thick plate|
|3. Graupellike snow||a. Hexagonal type
b. Lump type
|4. Graupel||a. Hexagonal graupel
b. Lump graupel
c. Conelike graupel
|Z Irregular snow
|1. Ice particle|
|2. Rimed particle|
General classificasion of snow crystals made by Dr. Nakayai4j
Crystal with twelve fernlike branches
Crystal with twelve broad branches
Branches in sector form
Simple stellar form
iSj@Nakaya, U., 1954. Snow Crystals, Natural and Artifical. Harvard University Press, Cambridge.
iTj@Kikuchi, K., 1987. The Discovery of Eighteen-Branched Snow Crystals. J. Meteor. Soc. Japan, 65, 309-311.
@In Hokkaido, Japan, it begins to snow with periodic wind of winter becoming strong. The temperature gradually lowers every day and becomes less than 0 all day. So, the snow becomes leave on ground without melting. I consider this is the same process anywhere in the world if it is Temperate Zone district in a high latitude area.
@We usually distinguish a snowy state from powdery snow, large - snowflakes,
or sleet. But there can recognize a figure of a snow crystal when I enlarge
it with a microscope even at the time of any kind of snow.
@It is said that a snow crystal does not "have a thing of form same for two"
because the form is delicately different when observe it with a microscope.
Therefore, there is fresh surprise whenever I watch another one.
@But, I think there may be completely a crystal of the same form when I
see innumerable snow falling in sequence from the sky bacause a snow
crystal such as a minute glasswork continues to fall unlimitedly in area one
@In this site, I show snow crystals which photographed in Hokkaido and
photographed it since I make a replica once. I want to introduce one part of
its mysterious figure.
Classification of snow crystals
@It is known that form of a snow crystal changes by climatic condition when it falls. In other words, it is changed mainly by temperature and the humidity. Dr. Ukichiro Nakaya who clarified it stated that "the snow crystal is a letter sent from the sky" and showed that a state of the atmosphere from the upper air at that time to the surface of the ground was ticked away in form and a design of a snow crystal.
@In his study, Dr. Nakaya repeated observation in Sapporo City and Mt. Tokachi and took a picture of more than 3,000 pieces of natural snow. And he made general classification list of snow crystals which classified snow crystals as seven kinds greatly.
|Snow Crystals in Hokkaido|
@In his classification, snow crystals are classified into "Needle
crystal", "Columnar crystal", "Plane crystal",
"Combination of column and plane crystals", "Columnar crystal
with extended side planes", "Rimed crystal", and "Irregular
snow particle". In the later study, snow crystals seem to be classified
more finely. But, I think to call snow crystals along his classification
in this site because a study of Dr. Nakaya was carried out mainly in Hokkaido.
@In above table, I showed only the name of snow crystals which came out to his general classification . So, it may be difficult for you to imagine the form of each snow crystal. I hope to look at figures indicated in his report, if you want to know them preciously. But, it is able to understand by this table that a regular form of snow crystal which we have an image generally is only one part of snow crystals which falls on ground innumerably.
About form of snow crystals
@The regular crystal developed in one plane is very beautiful because the symmetry form is not able to consider as a natural product.
@It is known that the form of a snow crystal is basically a hexagonal column which consist of two pieces, that is two basal surfaces and six pieces of cylinder surfaces. And it grows up in the plane crystals such as the simple plate or the fernlike crystal if growth of the cylinder surface is fast.
@Otherwise, it grows up to a slim crystal when growth of a base is fast, such as the needle crystal or the columnar crystal. And it seems to change by the temperature when it grows up whether growth of which surface is fast.
@Why the growth direction of a crystal turns into by the temperature is not mentioned here, but this is the crystal habit change of snow. It is appeared the tempereture of changing is 0 > plane >-4 > columnar >-10 > plane >-22 > columnar.(3) There is three changing point as temperature falls.
@Thus, snow crystals grow up in the form of both the column and the planes are combinationed when it step over the temperature of a crystal habit change during it falls on ground.
@The difference of form by such a crystal habit change is also seen in frost crystals as well as snow crystals. I introduce about frost crystals in page 4.
The beautiful clystal developed in one plane
Column with plates
Branches in sector form with two
piecies of planes
Note of the Snow Crystal Observation