WMOD00436

• Project Name: Project Skywater
• Title: HIPLEX - 1978 Operations Plan - Miles City, Montana
• Date: 1/1/1978
• Weather Modification - Doc Type: Report

C. Objectives for 1978

In order to improve understanding of natural cloud processes and

certain aspects of weather modificati.on technology, several specific

objectives have been established for the 1978 field season in Montana. These

objectives, along with some specific approaches to meeting the objE!ctives,

are listed below:

1. It is intended to develop an improved understanding of the prec:ipi-

tat ion mechanisms in both natural and seeded developing cumulus congestus

(towering cumulus) clouds and convective complexes (small- to moderate-sized

cumulonimbus), especially in the feeder cells (new growth appendages) of

these complexes.

Cloud physics aircraft measurements during 1976 and 1977 were usually

limited to cloud temperatures of -IOoe and warmer because aircraft perform-

ance did not permit repeated penetrations at higher, colder levels, These

measurements indicated that both developing cumulus congestus towers and

feeder cells usually had low ice crystal concentrations as they passed

o
through the -10 C level. The measurements also indicated that the ice

phase mechanism was generally responsible for precipitation formati.on, and

further suggested that initial ice crystal formation occurred at about the

o
-15 C level.

During the 1978 field season, a new King-Air Super 200 turboprop air-

craft will be the primary cloud physics plane. In addition, the Learjet

seeding aircraft will have an improved cloud physics measurement system,

including ice crystal monitoring capability. These high performance air-

craft will permit sampling at all levels in developing cloud turrets, and,

in fact, the aircraft will often be able to climb with turrets as they

ascend. This improved performance should make it possible to study the

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