WMOD00372

• Project Name: High Plains Cooperative Program
• Title: The Design of HIPLEX-1
• Date: 4/1/1979
• Weather Modification - Doc Type: Report

1. Physical investigations of cumulus congestus clouds. - ~he
physical investigations that form the basis of the evaluation
include the following: '

a. Obtain measurements of the specific response variabl~s
to be used in statistical tests of the hypotheses.

b. Synthesize the measurements from all observing systems into
a model of the microphysical and dynamTCal processes in the
clouds and compare the predictions of the hypotheses to those
of the model. Elements of this effort, in addition to the
response variables, include: '

"t

. Description of the ice crystals and ice-crystal plume
following seeding and the origin and development of
graupel,

. Description of differences in buoyancy and other dynamic
effects between seeded and unseeded clouds, including
investigations of the assumption that dynamic effects are
not important in the small cumulus congestus clouds,

"

. Verification of the assumptions about the suitability of
these clouds for modification (liquid water content,
droplet spectra, natural ice deficit, etc.),

. Verification of the proper seeding rate for these clouds,
and

. Descriptions of entrainment processes, air motion in
the clouds, the origins of natural ice, and secondary
ice-crystal production processes.

2. Physical investigations outside the structure of the randomized
experiment. - The clouds that are the targets for the randomized
experiment produce little or no precipitation naturally. Seeding
is expected to provide only modest, but perhaps agriculturally
significant, amounts of rain. Larger cloud systems were excluded
from the present experiment because weaknesses in our understanding
of those systems prevented our formulating a convincing physical
hypothesis for them. Continuing physical studies of the larger
cloud systems is needed so that HIPLEX can evolve to experiments
with the greater rain-producing systems, as specified in objective
5 of section III.

The equipment and instrumentation used in HIPLEX-l make possible
some comprehensive observations in the larger cloud systems.
Particularly important questions that need consideration, and that
will impede future experiments if unanswered, include:

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