WMOD00453

• Project Name: Park Range Atmospheric Water Resources Program
• Title: Park Range Atmospheric Water Resources Program - Phase I
• Date: 1/1/1967
• Weather Modification - Doc Type: Report

36

~

PIBAL POINTS
It MARCH 1965

/

-----0,
..----;. .
,

10-7500'
8- .000'

~ PREDICTED

Figure 43e.-Plume Dimensions and Pibal Soundings for 11
March 1965.

even a 1 percent concentration of Ag nuclei in a
replica can be detected with at least a 10:1 SIN
ratio by present activation analysis techniques,
table 6.

Table 6.-Silver Content in Snowcrystal Replicas Produced
by Silver Iodide Seeding.

SamPle No.

Silver content (in pgrams)

1_____________________________________________________________________________ 67 X 10"

2_____________________________________________________________________________ 27 X 10"

3_______________________________,_____________________________________________ 53 X 10"

4_____________________________________________________________________________ 55 X 10"

Analysis sensitivity ::::::: 10 pgrams
Hence, 1 percent occurrence of AgI nuclei would
give S IN of

30 X 10' X 10-'
10 = 30

pgrams = picograms = 10-12 grams.

Conclusion.- The presence and quantity of super-
cooled water drops-and their variation with time
-can be used as indicators of a deficiency in natural
freezing nuclei.

PARK RANGE ATMOSPHERIC WATER RESOURCES PROGRAM

Operational Consequence.-Natural freezing
nuclei count must be monitored routinely through-
out Phase II, say at 12-hour intervals during non-
storm periods and at I-hour intervals during a
storm. Replicas must be taken in the target area and
environs-Rabbit Ears Pass, the laboratory, Steam-
boat Springs, Emerald Mountain-during storm
periods for evidence of supercooled water drops.

How Many Artificial Nuclei
Were Being Dispersed?
Method.-Calibrate artificial nuclei generators
during dispersing periods using the cold box
technique.
Data.-Calibration data from Skyfire reports4;
Colorado State University calibration data.
Analysis.- The calibration curve for a typical AgI-
Acetone-Propane Sky fire generator4 is shown in
figure 49. CSU calibration data, for the Skyfire

<Fuquay, D., 1957: "The Project Skyfire Cloud-Seeding
Generator". Research Paper No. 48, Intermountain Forest
and Range Experiment Station, Forest Service, USDA, Ogden,
Utah, p. 8.

115 mi R.
- ________ PIBAL POINTS

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, """'~/"
'~"""""'''. -"
l 1:1,1 I II~ If

I 11111111111111.
IIIIIII
~!
I

10-."00'
11-."00'
e-losoo'
0-110110'

~ PREDICTED

--. MEASURED --. Ale TRACKS

Figure 43f.-Plume Dimensions and Pibal Soundings for 25
March 1965.