WMOD00517

• Title: On the Use of Homoclimes for Estimating Environmental Effects of Precipitation Management
• Date: 8/2/1976
• Weather Modification - Doc Type: Report

Given that the homoclime for a postulated
altered precipitation regime can be found, we
next ask, what should one observe and analyse?
This is governed by how the issues are stated.
What are we concerned about? The "natural"
environment (if such can be found)? Possible
demographic or sociological changes? Changed
patterns of land use? Figure 7 illustrates a
very crude collection on non-numeric data asso-
ciated with the precipitation gradient along
the 100' C isotherm. Experiments with appli-
cation of classification methods to a more
comprehensive data collection are planned. The
figure does suggest, however, that a precipi-
tation increase of 15 percent brings only very
not easily noticed, even though the cumulative effect of many such

..

C A

M E

C

Fig. 5 - Annual mean isohyets and isotherms
in the midwestern United States

slight and subtle changes,
steps' is boldly apparent.

- 581 -

presumably to local terrain effects. With
such short distances, it is very likely that a
homoclime corresponding to a 10- or even a 20-
percent precipitation increase can be found
within the same physiographic and biotic prov-
ince as the idioclime. The opportunity is not
restricted to the plains. Figure 6 shows that
the Sierra province of California affords an
enormous range of precipitation amounts along
a single isotherm.

u .. ,
0 15
l.LJ . . I
a:: W / .
~ . .
.... . .
. I .
c:{ Q . . .
a:: I . - .
l.LJ 10 . . . -
~ . - ,- . I -<. .
.-
~ Q -
.
l.LJ . . /. . - 0
.... - . .
. t . .
W .
Z /.. - ,
c:{ I · -
w 5
~ 0 .
f... I . . -
-' I ~
c:{
~ (f) I -1
z -
z 0
c:{
0 0.5 1.0 1.5 2.0 2.5
MEAN ANNUAL PRECIPITATION, m
Fig. 6 - Climogram of California stations above 1150 m elevation