(note: Research studies using liquid carbon dioxide (dry ice) instead of silver iodide for weather modification purposes were conducted in northern Kyushu, Japan, on October 27, 1999 and again in western China on April 20, 2001. However, due to copyright laws, the materials have been paraphrased here. The original copyrighted materials can be seen here and here.)
A LOW-LEVEL PENETRATION SEEDING EXPERIMENT OF LIQUID CARBON DIOXIDEIN A CONVECTIVE CLOUD
Japan Society of Hydrology and Water Resources
In order to create large amounts of precipitation, a new cloud injection method using liquid carbon dioxide (LC) was suggested.
The new chemical was applied to the extremely cold cloud mass in northern Kyushu, Japan, on October 27 1999.
In the experiment, observation by other planes was carried out and the features of a typical modified structure were observed on the ground by radar sources.
As a result, the aircraft observation confirmed the extended growth of the cloud together with a fuzzy aspect of the cloud surface, which is consistent with ice particles.
A NUMERICAL COMPARISON STUDY OF CLOUD SEEDING BY SILVER IODIDE AND LIQUID CARBON DIOXIDE
Institute of Atmospheric Physics,Chinese Academy of Sciences , Chinese of Meteorological Sciences, Beijing, CHINA
A comparison study on dynamic and microphysical effects of cloud seeding by silver iodide (AgI) and liquid carbon dioxide (liquid CO) was made using a three dimensional cloud model with cloud seeding processes.
The model was based on a rawinsonde sounding taken from a station located in western China on 20 April 2001.
The model results show that using liquid carbon dioxide and silver iodide has almost the same dynamic effect on the simulated clouds.
The seeding is able to induce the formation of weak convective cells in both seeded and unseeded regions due to latent heat released by the transformation from liquid saturation to ice saturation.
However, the initial spraying of liquid carbon dioxide in water with temperature of 0 to - 5 °C help to produce much stronger rainfall by forming many convective new cells at low levels in the later stage of the seeded clouds.
The accumulated rainfall at the surface can be increased and moved, and can be concentrated downstream of the seeded clouds.