SNOW-CRYSTAL ANALYSIS AS INDIRECT AEROLOGY 
at temperatures < —20° C coincides with the ap- 
pearance of high precipitation clouds that are 
verified by aerological soundings. The prevalent 
occurrence of supersaturation forms points to the 
predominating production of precipitation in 
lower, nearly water-saturated layers. From the 
alternating occurrence of certain forms the sink- 
ing or rising or a cell-like structure of the pre- 
cipitation clouds can be deduced. Thus this dia- 
gram is in conformity with the general survey 
according to the method of Weickmann. 
The variations of the size of certain crystal 
types with time is given in isolines of relative fre- 
137 
quency of the diameter. An example is given 
for the Operation 27 in the group of plates, 
sectors, and broad branches (Fig. 7). Frequency 
of the particular forms, the most frequent diam- 
eters, width of spectrum, and size of the maxi- 
mum of the spectral curve, respectively, do not 
run parallel to each other. A relation seems to be 
indicated, however, in such a manner that a small 
variety of forms of one type corresponds to a rela- 
tively narrow spectrum, that few appearing forms 
thus show nearly similar dimensions. On the other 
hand with a large percentage of one form the di- 
mensions vary a great deal. The size spectra can 
607% = 
nna 
56 mul HELA 
52 ry TT 
48 | 
| it 
eet ttt 
tity ete 
40 id bul 
By +4 ies 
eee hed BY ea HH _|.] 
2 Se a JI 
28 ub 
2% oo 1 | I 
20 nad il a 1 tala leas n Cree 
| i manne 
a re TTT I TT oh 02 0a «605 07) 10 20 «30 50 7,0 H 
Ht TTT oH 204% 14 Ls ri aa 
2 oan rt HH HY 
| CLL S RERIIMOIIIE son Pe 
an AE cea 
a + ett 12 | | te E + LL 
eH HA ITI ae 
ERIE LL }- 8 Li LH 
aa 
yi 02 03 05 07 10 20 3050 7.0 iT ae t 
| | 
10 
LN 
all CUT 
atl a TTT 
10 ' 
oy Q2 03 
05 07 10 2p «40 50 70 0 
Fig. 8—Dimensions of single crystal forms; frequency of their occurrence 
expressed as percentage; Hohenpeissenberg, March 1958 
