FREQUENCY DISTRIBUTION OF PRECIPITATION 
Asheville, N.C 
1893-1956 
20 24 29 35 42 5O INCHES 18 
Madras, India 
1813 —1900 
2 27 34 4 SI 63 78 95 INCHES 
Fic. 4—Frequency distribution of annual precipitation amount for Ashe- 
ville, N. C., and Madras, India 
a priori and then a frequency distribution for 
those defined groups is established. This is an 
expeditious way to present climatological sum- 
marizations. The author feels that in cases 
where the various basic processes are not com- 
pletely known, we should try the reverse way 
and analyze the total material to find out how 
many and which subgroups may appear. This 
approach is elucidated in the following discus- 
sion. 
In the previous sections the author has sug- 
gested the use of the logarithmic scale. We start 
now the analysis with annual amount of pre- 
cipitation. Figure 4 demonstrates for two dif- 
ferent stations and climates (Asheville, N.C., 
and Madras, India), that for the annual amount, 
in general, the various rainfall processes become 
effaced. We obtain one collective, following one 
normal distribution in a logarithmic scale, ex- 
cept for locations in a pronounced desert climate. 
In the consideration of monthly amounts, the 
mixture of the rainfall processes becomes obvi- 
ous [Hssenwanger, 1959]. This means that these 
frequency distributions cannot be considered any 
more as one collective and the problem is one of 
how to separate those frequencies into the indi- 
vidual parts and to investigate the physical basis 
for the partial groups. As a demonstration sam- 
ple the daily precipitation amounts for Ashe- 
ville may serve. First a frequency distribution 
(in logarithmic scale) has been arranged for 
each single month and then the frequencies have 
been split into partial collectives, each one a 
gaussian distribution. The author [Hssenwanger, 
1954, 1957] has developed an objective method 
for this resolution. The survey (Table 2) shows 
TaBLE 2—Asheville daily precipitation, 1907-1956 (50 yr); analysis of frequency 
distribution in logarithmic scale 
Excessive I, Heavy II, Moderate III, Slight 3 
Month = 
Xm || NV o tm, || NN o tne Ne o ten N o Lom INT <e. tm N o $ 
= 
Jan. 0.8) 11} 1.1] 0.4) 22) 0.9) 0.1 | 35) 1.2) 0.03 1.1) 0.01) 12} 0.8) 534 
Feb. 0.8} 9} 1.0) 0.3} 43) 1.5} 0.1 | 18) 1.0) 0.03) 20} 1.3) 0.01) 10) 0.9) 534 
Mar. 0.8} 17) 0.8) 0.3} 41] 1.2) 0.06) 29) 1.5) 0.01} 13) 1.1) 602 
Apr. 0.6) 25) 1.2) 0.2) 38} 1.3} 0.05} 32) 1.5 0.01} 15) 1.2) 526 
May 0.5) 35) 1.4] 0.2) 20) 0.8) 0.06; 27) 1.2 0.01} 18) 1.1} 600 
June 0.5) 35) 1.6] 0.2) 26] 1.5) 0.05) 27) 1.5 0.01; 12) 1.2) 650 
July Plea =e OSSRG2 eS eis ase ORO i225 | le2| 0.01} 13) 1.1) 742 
Aug. 1.3) 9) 1.2] 0.4) 32) 1.1) 0.1) 21) 0.9) 0.05) 22) 1.2 0.01) 16) 1.1) 628 
Sept. 1.3) 9) 1.0) 0.3) 54) 1.7 ee) eeu ORO3|- 26) 1 0.01) 11) 0.8) 463 
Oct. 1.3] 15) 1.2) 0.5) 17) 0.9] 0.2) 26) 0.9) 0.05; 19} 0.9 0.01) 23) 1.1) 368 
Nov. 0.6) 15) 1.3) 0.3) 30} 1.4) 0.06} 33) 1.4 0.01) 22) 1.1) 382 
Dec. 0.8] 11) 1.1] 0.3} 42} 1.3} 0.06} 30} 1.3 0.01) 17) 1.1) 506 
N in percent. 
Im in inches. 
o in units. 
