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

42

PARK RANGE ATMOSPHERIC WATER RESOURCES PROGRAM

NATURAL FREEllNG NUCLEI COUNT
AS A FUNCTION OF
TIME

APRIL 1965

8D

VALLEY VIEW LODGE- BIGG WARNER EXPANSION CHAMBER
COLORADO STATE UN IV, EOU IPMENT a OBSERVER
OBSERVED 0900 a 1800 EACH DAY

7.0

\18\ 1'81 12011211 1221

6.0

1231

24

II

ANAL YS IS PERIOD
NUMBER

12511261

".

5.0
.
NUCLEI 4D
LITER
3.0
2,0 -~ "\; 'v -tV
/ .
1D
0
2 4 6 8 10 12 14 16 18 20 22 24 26 28 30 32
DAY OF MONTH

Figure 47c.-Freezing Nuclei Count as Measured at Valley View Lodge.

of at least 10. Elf~ctron microscope examination of
representative replicas may show (1) whether the
AgI is acting as a nucleus for snowflake or is a
scavenging particle, and (2) what the mean AgI
nucleus diameter is.
Conclusion.- The amount of AgI in snowcrystal
replicas can be determined by existing analysis
techniques. The results should have a SIN ratio of
at least 10 under actual storm conditions if AgI
nuclei are participating to the extent of 1 percent.
It would be desirable to explore the feasibility of
determining actual AgI nuclei locations in snow-
crystals-by the electron microscope technique-and
the proportion of AgI nuclei vs. natural nuclei by
computational techniques, viz for a given total
of snowcrystals, a known Ag concentration and an
assumed AgI nucleus diameter to find the likely
ratio of naturally to artificially formed snowcrystals.
Operational Consequence.-Snowflake replicas
from the target and environs are required at several
times-say each hour-in each storm period. In-
itially, the replicas must be taken regardless of
whether the storm is nucleated or not-to establish

background count and analysis sensitivity. The repli-
cas will be taken manually by personnel at Rabbit
Ears Pass, the laboratory, Steamboat Springs, Mt.
Harris and Emerald Mountain. All of these loca-
tions have facilities for human shelter and electrical
power for heating, cooking and so forth.

Did Artificial Nucleation Alter
Storm Characteristics?
Method.-Determine precipitation-rate and inter-
station storm precipitation ratios for storms in the
target area-parametric in physical quantities such
as wind, temperature, freezing level, nuclei count-
under natural and artificial nucleation conditions.
Compare characteristics to determine whether nat-
ural signatures have been altered appreciably by
artificial nucleation.
Data.--Natural precipitation-rate histories from
the measurement network between 1 February and
1 May 1965. Climatological data from 1 November
1964 to 1 June 1965. Surface and upper-air wind,
temperature data, nuclei count from Valley View