Weather Mod Critical Issues Report

• Project Type: General OWC
• Project Name: Weather Modification
• Title: Critical Issues in Weather Modification Research
• Date: 1/1/2004
• Water Conservation - Doc Type: Final Report

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from the release of latent heat (primarily from freezing). and from redistribution of
condensed water \\'ithin the targeted cloud tUITets.

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FiKlIrf! I. lIail.\'Ul'pre.uion CO!1('epls.from WJfO Technical Document No. 76-1. [1)1)6.

3.1.2 E\'idclu:e of cloud s('('dill~ errCl'Cs

Progress in the numerical simulation ofhailstonns and hailstone evolution has
occurred. and is disclIssed below in Section 3.4. Contrary to statements in the NRC
rcpon.lhcre arc reasonable models that simulate the dcn:lopmcnt of hail in realistic
hailstorm environments. Cloud seeding simulations show the crfects of carly rainout and
bcnclicial competition in reducing hail from relatively ellicient hailstorms. but the
possible increase of hail and rain from some relatively inellicienl storms. The models
also show the lot'ation of hail embryos close to the forward region of the major updraft.
The major grO\\lh of the icc particlcs occurs in high liquid \vatc.:r regions between _SoC
and -3SoC. usually between _lOoe and -250C. Trajectory analyses indicate that particlcs
that grow to relati\'c1y large size begin their major gro\\ th cycle in a \'ery narrow ribbon-
like region in an area ofwcak upJral1 near the updralVdowndraft interface on the forward

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