WMOD00301 ‎(2)‎

• Title: Conceptual Plan to Develop Water Augmentation by Weather Modification in the Colorado River
• Date: 5/14/1979
• Weather Modification - Doc Type: Report

D R AFT

SECTION V - WINTER OROGRAPHIC PRECIPITATION
MANAGEMENT - PRESENT LEVEL OF UNDERSTANDING

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The potential to increase the amount of water available in the
western United States and specifically within the Colorado River
Basin lies primarily in the ability to increase winter snowfall.
Additional water pr'oduced by seeding winter orographic clouds is
released for irrigation, domestic, and energy use when the snow melts
and runs off in thE~ late spring and summer.

A. Basic Principles

Clouds are produced when three basic conditions are present in the
atmosphere: (1) there is a sufficient quantity of moisture in the
form of water vapor', (2) there is a mechanism by which air is cooled
to the water saturation point and beyond, and (3) there is a sufficient
quantity of small aerosol particles to act as condensation nuclei.
Clouds form when air rises, expands, and cools causing water vapor to
condense producing liquid water in the form of cloud droplets.

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Precipitation in the form of snow is produced when ice crystals form
around ice nuclei. These ice crystals then grow at the expense of
the supercooled (bE!low freezing) cloud droplets until they are large
enough to fall as snow. To increase the precipitation from a cloud,
its ability to convert cloud liquid water to precipitation must be

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