WSP08013

• File Number: 8027
• Description: Section D General Correspondence - Federal Agencies - US DOI-BOR - Region 7
• State: CO
• Basin: Statewide
• Date: 11/2/1966
• Author: DOI-BOR
• Title: Plan to Develop Technology for Increasing Water Yield from Atmospheric Sources - An Atmospheric Water Resources Program
• Water Supply Pro - Doc Type: Report/Study

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So far, man has concentrated his efforts on attempts to affect insta-

bilities in the first three categories, These efforts have consisted

primarily, but not exclusively, of injecting into the atmosphere mate-

rials which are intended to form or serve as condensation, sublima-

tion or freezing nuclei. These artificially injected nuclei are com-

monly called "seeds."

An array of available seeding materials, by triggering one or more of

the instabilities described above" can augment the three physical steps

that are required to convert water vapor to raindrops. These three

steps are:

1. Cooling the air, usually by lifting, until saturation occurs

2. Transfer of water vapor onto particulate nuclei to form a

cloud of droplets or ice crystals

3. Growth of water particles in clouds to sizes large enough

to cause them to fall out of the clouds and reach the ground

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Man's understanding of the physical processes involved in precipitation
is far from complete. There is, however, great practical benefit to
be derived from thoughtful application of what is already known and
from added knowledge being gained from research and experimental
work under existing programs, An immediate effort aimed at creat-
ing and improving tools and techniques for the practical application
of precipitation modification is now clearly justified,

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