WMOD00505

• Contract/Permit #: 14-06-D-5640
• Project Name: Park Range Atmospheric Resources Program
• Title: Park Range Atmospheric Resources Program - Final Report
• Date: 9/30/1969
• Weather Modification - Doc Type: Report

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PREFACE

The Steamboat Springs area, on the windward
side of the Park Range of the Rocky Mountains in
Colorado, is almost ideal for physical experimenta-
tion on orographically induced, convectiv1e clouds.
The valleys and slopes of the Range are reasonably
accessible for instrumentation and observation; the
isolated mountains west of St.eamboat Springs pro-
vide excellent vantage points for radar surveillance
and for high-altitude nucleation. A large part of
the target area is over Government-owned land,
and drainage from the area is into the Bureau of
Reclamation's Colorado River Storage system.
The experimental site was recommend(~d to the
Bureau of ReclaII1ation by independent meteoro-
10giqll consultants, including Bollay Associates,
Inc., of Boulder, Colo., an organization haying con-
siderable previous experience in research on
weather modification. This firm performeq the
investigations described in this report under con-
tract with the Bureau of Reclamation. The investi-
gations, designated as Phase I of the Park Range
program, were starteq ~Il Novembflf 1964 :;\nd com-
pleted in June 1965. Phase 1I of the program is in
progress and will be t4e subject of It subsequent
report.
The Park Range Program is intended to deter-
mi.ne to wh,!I,t exient the precipitation in a moun-
tainous region can be increased by artificial nuclea-
tion of moisture,bearing cloud formations. Phase I
W;lS devoteq to the collection and processing of
nuclei and to the lltudy of diffusion and lprecipita-
tion processes under natural conditions. The "set-
up" of facilities and equipment, the methods of
tracking lltorms over the target area, the measur{l.
ments and observations, and the results and con-
clusions of Phase I are embodied in this report.
Phase II involves controlled artificial nucleation of
moisture-bearing clolJd!l Qver the !lame target area

with an evaluation of effect by companson of pre-
cipitation and runoff under artificially induced and
under natural conditions.
This report on the Phase I part of the program
describes the experimental plan, the facilities, and
equipment used in the studies; the methods of
detel"1D.ining nuclei concentration; and the diffusion
and precipitation processes in the Park Range area.
Phase I data are analyzed for their application to
the Phase II program. Also include~ are support-
ing maps, photographs, climatological and meteoro-
logical data, graphs, and charts.
Briefly, the Phase I study shows that conventional
artificial nuclei generators can be effectively used
from a selected site for a majority of spring and
winter storms in the area. The concentration and
extent of targeting with artificial nucleation can be
detel"1D.ined for a particular storm by testing snow
samples for silver concentration throughout the
target areas. This concentration and extent can be
checked with zinc sulphide, which was used in the
Phase I operation as the tracer material for the
diffusion tests. The ratio of natural to artificially
formed snow crystals can be reasonably expected to
indicate the extent of participation by the artificial
freezing nuclei.
The continued pursuit of the Park Range studies,
together with those of other cooperating firms and
agencies, can contribute considerably to the learn-
ing which is necessary if man is to tap the vast re-
source of atmospheric water.
The extensive systems of storage reservoirs and
irrigation facilities constructed by the Bureau of
Reclamation over the past 64 years have been most
effective in their purpose of reclaiming the semiarid
land in the 17 western States to useful production.
These reservoirs serve to regulate the flow of rivers,
which would otherwise be lost, by storing excess

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