Paul Chehade - History of Weather Modification American Meteorology Society's - Chapter IV of VI.

Paul Chehade – History  of  Weather Modification American Meteorology Society’s – Chapter IV 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.

American Meteorology Society’s:

Policy on Weather Modification:

In anonymous policy statements without any bibliographic citations, the American Meteorological Society declared:

Operations that dissipate super cooled fog and low stratus (clouds containing water droplets at subfreezing temperatures) by seeding with ice-forming agents (e.g., dry ice, liquid nitrogen, compressed air, silver iodide, etc.) have become routine at some airports.

There is statistical evidence that precipitation from super cooled orographic clouds (clouds that develop over mountains) has been seasonally increased by about 10%. The physical cause-and-effect relationships, however, have not been fully documented.

Some experiments with warm-based convective clouds [bases about 10 Celsius or warmer] involving heavy silver iodide seeding have suggested a positive effect on individual convective cells, but conclusive evidence that such seeding can increase rainfall from multicell storms has yet to be established.

There are indications that precipitation changes, either increases or decreases, can also occur at some distance beyond intended target areas. Improved quantification of these extended (extra-area) effects is needed to satisfy public concerns and assess hydrologic impacts.

The efficacy of projects intended to mitigate the severity of hailstorms remains indeterminate. Statistical assessments of certain operational projects indicate successful reduction of crop hail damage, but scientific establishment of cause and effect are incomplete. Results of various operational and experimental projects provide a range of outcomes.

Hurricane modification experiments of the 1950s and 1960s were inconclusive. Although strong research interest continued into the 1970s, no organized research effort was undertaken, and few studies have been devoted to this subject for the past 20 years.

The use of untested weather modification techniques during severe droughts, as a means of increasing precipitation, is not recommended. Opportunities to increase precipitation are typically minimal during droughts and only well-tested techniques should be considered, realizing that only limited precipitation augmentation will probably result.

The above-cited Policy Statements from the American Meteorological Society are apparently intended to provide easy-to-read guidance to nonscientists (e.g., government officials, legislators, and potential clients of cloud seeders). These policy statements provide an authoritative, consensus view of the then current scientific knowledge. However, these policy statements are not a limitation on what might be achieved in the future.

The World Meteorological Organization (WMO) has a statement on weather modification.

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

# # #