140 
JOHANNES GRUNOW 
on 
=) a 
| 
| 
a 
| 
5 10 15 20 Bb 30 
= 
50 55 
3 20 45 60 
Fia. 11—Percentage frequency distribution of diameters of cloud droplets attached to snow crystals, 
Hohenpeissenberg 
(dendrites, needles) that grow within the lower 
layers of the troposphere, their growth being fa- 
vored by the maritime climate of Hokkaido 
which has excessive humidity. Also the maximum 
size of dendritic forms found on Mt. Tokachi is 
3.0 mm, still considerably higher than the value 
1.8 mm of Mt. Hohenpeissenberg with nearly 
equal elevation but with a more continental cli- 
mate. 
Differences of the same kind were also found 
by simultaneous snow-erystal observations of Mt. 
Hohenpeissenberg and Mt. Zugspitze with the 
visual method according to the International 
Classification of Snow (Fig. 10). Three years of 
additional observations by the meteorological ob- 
servers of these stations have demonstrated the 
suitability of this scale discussed at the Confer- 
ence of Woods Hole in 1955. On Mt. Hohenpeis- 
senberg those types prevail by number and size 
that need only moderately low temperatures and 
nearly water saturation for their growth, for in- 
stance, stellar crystals, needles, and graupel. On 
Mt. Zugspitze those forms dominate that origi- 
nate in upper precipitation clouds, and at much 
lower temperatures, and are erystals of Class 7 
(irregular crystals) which mostly prove to be 
spatial plates if viewed under the microscope. 
Thus even with application of simplest observa- 
tion methods the snow erystal as indirect aerolog- 
ical sonde is capable of furnishing valuable refer- 
ences. 
Dimension of cloud droplets—Finally a num- 
ber of microphotos of rimed crystals were used to 
measure the diameters of water droplets attached 
to snow crystals in order to obtain their size spec- 
trum. It was found that these derivations show 
parallels to former investigations, with which the 
abundance of fog precipitation was put in rela- 
tion to the spectrum of droplets of different air 
masses (Fig. 11). The individual frequency curves 
are composed of different part collectives, but the 
total number is not sufficient for their exact anal- 
ysis, for instance, by the procedure of Hssen- 
wanger [1954]. Arctic cold air is characterized by 
a narrow spectrum with small diameters, warm 
air and degenerated air masses by a broad spec- 
trum with larger diameters. 
Conclusions—The suitability of the snow crys- 
tal as aerological sonde is found confirmed by 
many single manipulations and it is expected that 
the further evaluation of this observation ma- 
