Paul Chehade - History of Weather Modification Problems with Experiments - Chapter III of VI.

Paul Chehade – History  of  Weather Modification Problems with Experiments – Chapter III of VI.

Weather modification is the effort of man to change naturally occurring weather, for the benefit of someone. The best-known kind of weather modification is cloud seeding, with the goal of producing rain or snow, suppressing hail , or weakening hurricanes.

Problems with Experiments:

Before one can understand legal problems of cloud seeding, including tort liability for cloud seeding, one must first understand something about cloud seeding experiments. The following terse discussion is a summary of some of the problems associated with cloud seeding. Because I have not had the time to make a thorough review of the meteorological literature, but only looked at some review articles, I have not provided citations to the original sources.

The traditional cloud seeding experiment randomly selected clouds to seed  and measured precipitation in the target area as the sole criterion of the effect of seeding. Such experiments reported in the meteorological literature superficially appear to give contradictory results: some experiments show a significant enhancement of precipitation, other experiments show no effect, and some experiments show a decrease in precipitation. Cotton (1986) has clearly explained why such a simple experiment is not adequate.

Most importantly, we lack detailed scientific knowledge on the natural production of rain, hail, or snow. Without such knowledge, we cannot predict the best time and place to seed clouds. Different physical processes may be important at different times in each cloud’s life cycle, which may give a narrow window of opportunity for intervention via injection of AgI nuclei. Further, we cannot accurately predict when and where the effect of seeding will occur.

Some cloud seeding has used smoke containing AgI from generators on the ground to provide nuclei for clouds. The AgI is supposedly transported to approximately the -10 celsius region of a cumulus cloud by naturally occurring updrafts. However, there is concern whether the AgI actually reaches this region of the target cloud and, if it does reach that region, whether the AgI is uniformly dispersed over this region of the target cloud. While ground-based AgI generators are less expensive to operate than AgI generators aboard airplanes, airplanes are a much surer way to deliver the AgI to the appropriate region of the target cloud.

AgI does not magically disappear a few hours after its release. There have been sporadic suggestions in meteorology journals and symposia that enhanced rainfall may [also] occur between 100 and 300 kilometers downwind from the point where the AgI was released. Aside from possibly modifying the weather at great distances from the intended target area, such effects could contaminate scientific experiments so that “natural” clouds in the control (i.e., nonseeded) group may contain some AgI. Such contamination would make it more difficult to prove that AgI is effective in modifying clouds.

However, even with our limited knowledge of atmospheric physics, we know that different types of clouds behave differently. For example: isolated orographic clouds differ from large, multi-celled clouds associated with a front on a surface pressure map, and both differ from tropical cumulus clouds with a top warmer than -5 celsius. Therefore, one must be careful not to apply successes (or failures) with one type of cloud to another type of cloud.

Current knowledge suggests that cloud seeding produces a small perturbation (e.g., perhaps 10% extra rainfall as the result of cloud seeding) of a phenomena that has much larger natural fluctuations [e.g., in the range from 250% to 400%. While a 10% increase in rain can be economically significant, this small increase superimposed on much larger natural fluctuations poses a very difficult problem for statistical analysis of cloud seeding experiments.

There are hundreds of articles in the scientific literature on the subject of cloud seeding, but few are available on the Internet. Dr. William R. Cotton, a professor of atmospheric science at Colorado State University in Fort Collins, has posted a comprehensive review of weather modification experiments during 1989-1997. There is also a good critical review of cloud seeding experiments in Australia, written in May 1995 by Brian F. Ryan and Brian S. Sadler.

History of Weather Modification Basic Technology – Chapter I
History of Weather Modification Earlier History – Chapter II
History of Weather Modification Problems with Experiments – Chapter III
History of Weather Modification American Meteorology Society’s – Chapter IV
History of Weather Modification Ethical Issues – Chapter V
History of Weather Modification Support of Basic Scientific Research Chapter VI

For more information please visit:  www.paulchehade.org

Follow Paul Chehade on Facebook:https://www.facebook.com/paulchehadeII

Follow Paul Chehade on Twitter: https://twitter.com/paulchehade

# # #