WMOD00437

• Title: HIPLEX - 1978-79 Operations Plan - Big Spring-Snyder, Texas
• Date: 4/1/1978
• Weather Modification - Doc Type: Report

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4. SEEDING HYPOTHESES FOR TEXAS HIPLEX
4.1 CUmulus-Type Clouds
Two seeding hypotheses have been developed for the Texas HIPLEX
area and are similar to those developed for the Miles City area at the
Dillon-Frisco, Colorado, meeting in December. Both of these hyp01~eses
will be applied to cumulus mediocris, cumulus congestus, or towering
cumulus before echo development while the cloud is growing through the
-40C to -lOoC region. The first hypothesis refers to light seeding
while the second refers to heavy seeding. These hypotheses are as
follows:
Hypothesis 1: An increase in the ice crystal concentration
through silver iodide seeding in the region where cloud water is present
and the temperature is -40C to -lOoC will lead to additional precipita-
tion through the base of the cloud. The sequence of processes leading
to this increase is hypothesized to be:
a. Production of 1-10 per liter ice crystal concentrati.on
in the super-cooled water cloud between -40C and -lOoC.
b. Freezing of water drops or diffusional growth of the
ice crystals to a size where riming can occur.
c. Change in cloud liquid water content.
d. Accretional growth to precipitation sizes.
e. Earlier precipitation development and earlier first
echo.
f. Fall of precipitation through cloud base.
Hypothesis 2: Same statement. as for Hypothesis 1. The sequence
of processes leading to this increase is hypothesized to be:
a. Production of greater than or equal to 100 per liter
ice crystal concentrat.ion in the super-cooled water cloud
from -40C to -lOoC.
b. Substantial glaciation of the cloud with an associated
release of latent heat and buoyancy increase.
c. Increases in cloud top heights and subcloud convergence.
d. Increased mesoscale moisture flux into the cloud and
condensation within the cloud.

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e.

Conversion of extra condensate to precipitation.
Fall of precipitation through cloud base.

f.

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