WMOD00413

• Title: Validation of Precipitation Management by Seeding Winter Orographic Clouds in the Colorado River Basin
• Date: 9/1/1993
• Weather Modification - Doc Type: Report

Scavenged: in this report, the process whereby small particles, such as silver iodide or indium,
are swept out of the atmosphere by cloud droplets and ice crystals.

Service: U.S. Fish and Wildlife Service.

Sublimation (ice): the transition of solid ice directly into water vapor that takes place when the
atmospheric vapor pressure is below saturation with respect to ice.

Supercooled liquid water: water in the liquid state at temperatures below the freezing point of
bulk water (0' OC); supercooled cloud droplets are common in many winter clouds over the
intermountain West between temperatures of 0 and -15 oC, and sometimes exist at significantly
lower temperatures.

TDY: temporary duty assignment.

T&D: transport and dispersion.

2D-C: two-dimensional cloud.

2D-P: two-dimensional precipation.

Upper Colorado River Basin: area drained by the Colorado River and its tributaries above Lee
Ferry, Arizona; hereafter Basin.

Vapor pressure: in this report, the pressure exerted by the molecules of water vapor;
saturation vapor pressure exists when water vapor is in equilibrium with a plane sUIface of
liquid water or ice; saturation vapor pressure with respect to water is higher than with respect
to ice at any temperature below 0 oC, which is why ice crystals can grow rapidly when
surrounded by supercooled liquid water droplets.

WMO: World Meteorological Organization.

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