SCIENCE& TECH. OF CLOUD SEEDING

Prof.T. Shivaji Rao

Director, Centre for Environmental Studies,

Visakhapatnam-530 045 

On 8-8-2008, the Chinese Meteorological experts made a great success of cloud seeding operations for preventing the rain-bearing clouds approaching the Olympic stadium in Beijing to get impregnated with overdosage of silver iodide chemical particles so that thecloud water which normally becomes large raindrops of 2mm to 5mm size get reversed to become small sized 0.02mmcloud droplets that were prevented from  raining and consequently were pushed away from the Olympic stadium into theneighbouring areas where they shed their normal rainfall.  Thus the Chinese scinetists once again proved that cloud seeding is not only a 100%scientific based phenomina but also a highly successful proven technology inthe hands of skilled and dedicated experts whohave devoted their life and workfor not only providing substantial extra rainwater to millions of farmers but also to prevent excwessive rains due to cyclonic storms which cause avoidablefloods.  On this occassion I request you and the Minister for Agriculture to send a congratulating messages to the Chinese Governemnt and also the Head of the Meteorological bureau at Beijing for the success one cloud seeding operations for the benefit of the state and the people of China. 

Many scientists and bureaucrats in India are known to heep unscientific criticism against cloud seedingo perations by stating that the science behind cloud seeding is not yet fully proven. This is a cent percentill-informed you about cloud seeding which is a God sent Gift to Mankind and among whom the intelligent sections have recognised the availability of ample evidence. Even if it is reputation I am herewith enclosing by a separateattachment on How Cloud seeding is hundred percent a scientific phenomena.  Consequently the patriotic meteorologists and scientists of China have researched for 40 years and established its scientific basis and also proved that it is a successful technology in the handsof skilled and dedicated expertswho follow the stipulated standard procedures during the conduct of the cloudseeding operations.  See the following website
http://english.people.com.cn/english/200007/14/eng20000714_45496.html
The Chinese experts have made China today the world leader in cloud seeding technology by employing 37,000 technicians with a budget of Rs.450 crores per year to produce about 2000TMC of extra rainfall that is equivalent to the annual flow in a Major river like Krishna in Andhra Pradesh.  The latest cloud seeding operations to keep clear skies over the olympic stadium in Beijing on 08-08-2008 is another marvellous example of the proven technology of cloud seeding. Hence poor countries like India must send delegations of politicians,officials and scientists from different states to visit China and prepare reports on how cloud seeding technology can be substantially used to increase annual rainfall by about 30% for resolving the emerging problems of water scarcity for drinking, industry, irrigation and hydro-power generation.  Inspite of good rains inseveral parts of the state if some of the reservoirs  in Andhra pradesh like Nagarjunasagar, Srisailam,Somasila, Kandaleru are not full it simply means that human efforts have not been adequately made to get more water into them and it should  be treated as ahuman failure.Shortage of Water in the reservoirs of Karnataka,Tamilnadu,kerala and Maharashta clearly indicate that water scarcity is only a man-made problem due to the apathy of political leaders at the states and Central Government levels.Unless the farmers exert pressure over their elected representatives,the Government machinery does not move to take up cloud seeding in proper time to augment water supplies to save poor people

It is surprising that while Australia and Honduras are conducting cloud seedingexperiments to augment annual rainfall during different periods of water leveldepletions recorded in reservoirs used for hydro-power generation by resortingto cloud seeding operations we in Andhra Pradesh have not yet started to usecloud seeding operations to generate more hydro-electricity for eleminating thepower-cuts by using cloud seeding operations at an inexpensive cost with costbenefit ratio of 1:30.  Infact the Sun God is providing freely substantialamounts of heat to enable the water in the seas to get evaporated into the skywhere the moisture gets transformed into clouds that give rainfall to man andnature.  If man makes genuine attempts to increase this rainfall by about30% by cloud seeding operations she need not experience powercuts anddarknights and industrial breakdowns.  The state Finance Minister andseveral other ministers received from the hands of the Chief MInister copies ofmy book on cloud seeding tofight the droughts and if only the make use of thescientific knowledge they can put it to public useof great importance foreliminating poverty, unemployment, drinking water shortage, food scarcityandscarcity of hydro-power.  I hope you will kindly go through theattachments and discuss with the secretaries of various departments dealingwith urban water supply, rural water supply, electrical power generation,industry, major irrigation, medium and minor irrigation, rural development,state pollution control boards, environment and forests, fisheries agriculture,animal husbandry, tribal welfare so that their demands for genuine developmentcan be met by augmentation of the water resource which is considered as theBlue Gold by the intelligent Americans. In the light of the above facts Irequest to you to kindly take immediate action to use cloud seeding for thebenefit of man and nature because cloud seeding is a God given gift and it isfor man to use it for his benefit or to misuse it for his downfall.

WHAT IS THE SCIENTIFIC BASIS FOR THE SUCCESS OF CLOUD SEEDING OPERATIONS ?

Due to the heat from the Sun the water in the rivers, lakes and Oceans becomes water vapour.  As this hot moist water vapour in the air rises into  the sky the  temperature gets reduced at 7oC per km height in the sky, the water vapour condenses over smoke and dust particles to form cloud droplets of 20 microns in diameter [micron is a millionth of a meter]  A million cloud droplets must join together to form a raindrop of 1mm size to fall over the earth as rainfall or snowfall

Rain Formation:  If a warm cloud does not contain sufficient number of giant size water drops or hygroscopic particles  the cloud cannot give 10% to 20% of its moisture as rainfall. In cold clouds whose tops attain freezing level in the sky, insufficient number of ice-nuclei prevents the clouds from giving  more than 20% of the water content as in the form of rainfall or snowfall.

How Cloud Seeding Helps?: If warm clouds have to give more rain we have to inject into them chemicals like hygroscopic common salt or Calcium powder into such clouds We have to inject  Silver Iodide particles into cold clouds which extend into the freezing zone for about  15km into the sky.  So the  injection of seeding  chemicals into the clouds causes them to produce additional rainfall upto 25 %

Why Cloud Seeding Is Unavoidable?:  In Modern Times Urbanization, industrialization and deforestation are increasing the environmental pollution and global warming which are preventing the clouds from giving the normal rainfall and consequently drinking water supply and agriculture production, hydro power generation and employment opportunities are adversely effected.  Hence cloud seeding must be undertaken to supply more water to correct the above man made problems.

Does cloud seeding promote the stealing of one region’s water by people of another region?

 According to one expert ,the amount of moisture that falls "naturally" as rain at any point in the world is a very, very small fraction of the total amount of water (actually water vapor) that is moving over that point at any time. So if you cause more rain to fall from a thunderstorm through weather modification than what would fall normally, the additional amount of water vapor it removes would be insignificant and hard to detect. The churning in the atmosphere that occurs as the winds push it along would quickly replenish the water vapor that was removed. Thus there would be little or no discernable difference in available water vapor downwind from where the precipitation fell out. Also, you need to realize that the extra rain caused by cloud seeding is not removed from the system but rather moves back into the atmosphere through evaporation or transpiration from plants, and is then available to help produce more clouds down wind. This is part of the hydrological cycle, which is what drives most of the weather on this planet. If you would like to learn more, try out the following web sites at: www.weathermodification.org,

 http://www.popularmechanics.com/science/earth/4254233.html,

 http://www.indiawaterportal.org/blog/index.php/2007/11/16/cloud-seeding,

http://profshivajirao.googlepages.com/warmcloudseeding,

http://profshivajirao.googlepages.com/coldcloudseeding

http://www.weathermodification.org/publications.htm 

What is scientific secret for warm clouds to produce about 10% 25% additional rainfall?:

When hygroscopic chemicals like common salt are sprinkled into the warm clouds the water molecules with their negative oxygen ends interact with the positive sodium ions and the positive ends of hydrogen surround the negative chloride ions.  Consequently the water molecules pull out sodium ions and chloride ions one by one from the salt crystal and in the process Giant Condensation Nuclei (GCN) of over 40 microns are formed.  These Giant nuclei help to transform lakhs of smaller cloud drops into big rain drops of about 1 mm in size.  Due to the chemical reaction heat is liberated within the cloud and consequently more moist air is sucked into the cloud that grows in its size and thereby rainfall is also increased.   Depending upon the geographical, topographical and meteorological conditions the additional rain varies from 10% to 25% in a given area.  Some warm clouds of about 1km height do not give rain and due to insufficient number of giant size nuclei (GCN) some larger clouds give only10% to 20% of their water content as rain while the remaining water content dissipates as moisture into the atmosphere Hence we  have to inject optimum number of chemical nuclei to extract more water than what the clouds give in their natural course. See the following figure.

 

Slide 8

Note-1:    Each ion of the solid crystal becomes surrounded by water molecules, with the negative end [O-] of the water molecules approaching closest to the positive sodium ions [Na+], and the positive end[H+] of the water molecules surrounding the negative chloride ions[Cl-]. The water molecules pull these ions, one by one, away from the rest of the crystal and in the process Giant condensation nuclei[GCN] for Rain Drops form

 

What is scientific secret for Cold clouds to produce about 15% 30% additional rainfall?:

At temperatures below freezing, the saturation vapour pressure of ice is less than that over a droplet of water. Water evaporates from droplet and deposits on ice.The water droplet droplet dissipates while ice crystal grows into a snowflake. .  Due to the chemical reaction heat is liberated within the cloud and consequently more moist air is sucked into the cloud that grows in its size and thereby rainfall is also increased.    Depending upon the geographical, topographical and meteorological conditions the additional rain varies from 15 to 30%.  Due to insufficient number of ice nuclei some cold clouds do not give rain and some larger clouds give only10% to 20% of their water content as rain while the remaining water content dissipates as moisture into the atmosphere. Hence we have to inject optimum number of ice nuclei or their equivalent nuclei in the form of silver iodide to extract more water than what the clouds give in their natural course.  

Note-2:   At temperatures below freezing the saturation vapor pressure of ice is less than that over a droplet of water. This means that a water vapor gradient exists between the droplet and the ice. Water can evaporate off the droplet and deposit on the ice in response to the water vapor gradient. The droplet will dissipate in size while the ice crystal grows into a snow flake. Once the snow flake is large enough, it will fall to the surface. Thus, precipitation that falls in the middle and high latitudes starts out as snow. Whether it hits the surface as snow or rain depends on the temperature conditions through which the snowflake falls.

CLOUD SEEDING METHODS BY USING AEROPLANES AND GROUND GENERATORS:

http://legaleaglesflyordie.blogspot.com/2008/08/invention-spotlight-cloud-seeding.html

http://www.indiawaterportal.org/blog/index.php/2007/11/16/cloud-seeding/  

http://shivajirao32.googlepages.com/coldcloudseeding 

http://www.gitam.edu/cos/env/English-Book.pdf 

http://www.gitam.edu/cos/env/English-Book-FirstPages.pdf


 

 

TECHNOLOGY OF CLOUD SEEDING AS PRACTISED IN AUSTRALIA

1. An overview  [condensed version]  http://www.cmar.csiro.au/e-print/open/cloud.htm

Guidelines for the utilisation of cloud seeding as a tool for water management in Australia are recommended here. They are based on the experience of about50 year of cloud seeding in Australia and have been developed to aid planning and decision-making for water managers in effective partnership with atmospheric scientists and commercial operators.

The guidelines are developed as principles that recommend the disciplines to be followed in the planning and implementation of a cloud seeding experiment that seeks to maximise the opportunities for defining and achieving a successful outcome. The central theme is one of a planned approach, with clear accountabilities and quality assurance, proper understanding and realistic performance objectives and measurements.

Four main parties to an experiment are identified and their roles discussed. These parties are:

1.Water Manager .2.Design Scientist 3.Cloud Seeding Operator, and 4.Review Scientist.

In particular circumstances the roles may vary somewhat, but important separations must remain. Thus, for example, there should be a clear role separation between Commercial Operator and Design or Review Scientist. However, there may be circumstances where it is appropriate for the Design Scientist and Operator may come from the same oganisation.

Rainfall enhancement operations should proceed under guidance of a documented plan, the production of which will be managed by the Water Manager as client.[state Govt.,]

The Design Scientist is contracted by the Water Manager for his meteorological and statistical expertise to give objective advice on the seeding potential of the project, to design it based on international practice so that project will adequately address the objectives and provide a measurable outcome that can be evaluated by the Water Manager[state Govt.,].

The Cloud Seeding Operator is responsible for all operational aspects specified in the project plan and is contracted by the Water Manager[state Govt.,]

An Independent Review Scientist is contracted by the Water Manager,[state Govt.,]

a] in the planning stages of the project to ensure that the proposed project meets best international practice and that during its conduct the integrity of the project is maintained. b]At the end of the project an Independent Review Scientist is again contracted to assess the results of the experiment.

The two contracts need not necessarly be undertaken by the same scientist.

2. Principles

2.1 Regional Evaluation

As a background to any specific program of rainfall enhancement, it is desirable to identify meteorological regions that are likely to be favourable to cloud seeding, and those regions where cloud seeding is likely to be unfavourable. The cloud seeding experiments discussed in Part I of the paper serve as a starting point for a climatology of clouds suitable for seeding with silver iodide.

The majority of Australian cloud seeding experiments have been designed on the so called static cloud seeding hypothesis, namely that excess supercooled liquid water in the clouds can be converted into precipitation by seeding the clouds with a substance that generates ice crystals. In nearly all cases complexes of silver iodide have been used as the primary seeding agent.

2.2 Regional assessment of potential for rainfall enhancement to produce beneficial water management outcomes.

In Australia the areas with the most favourable potential for rainfall enhancement to produce beneficial outcomes are where suitable climatic conditions are juxtaposed with high value water developments that are already at full utilisation.

Water Managers should treat the development of any precipitation enhancement project as a four stage process:

1]The pre-planning of experiments and operations

2]Design of the experiment

3]Conduct of the experiment

4]Evaluation of results

These principles for designing a rainfall enhancement experiment have been employed in all recent projects undertaken or supervised by CSIRO. They include the recommendations of the World Meteorological Organisation to Government Decision Makers (WMO, 1986).

2.2.1 Stage 1: Pre-planning

The elements of the pre-planning are set out below and would be undertaken by the Design Scientist for the Water Manager. These steps may be pursued iteratively with subsequent phases of refinement dependent on justification or otherwise. They are most likely to overlap the design phase of the experiment. In the negotiation prior to the contract between the Water Manager and the Design Scientist it is important to:

Identify Key Participants, their roles and partnerships

Agree to the essential contents required within the project plan

Assess meteorological and cloud conditions and develop an hypothesis for rainfall enhancement

Define rainfall enhancement objectives and goals

Define expected water management outcomes

Establish a benefit/cost assessment for expected range of possibilities

The last three points are closely linked so that the process of defining the objectives and goals of the project, the water management outcomes and the economic assessment would not be developed in isolation.

Identify Key Participants, their roles and partnerships

At this stage the Key Participants are the Water Manager and the Design Scientist, together they should develop the contents of the project plan that identifies the skill, resources and budget required to undertake a cloud seeding experiment.

Agree to the essential contents required within the project plan

In developing the project plan the Design Scientist needs to have the technical expertise to assess the meteorology and cloud conditions and to provide the Water Manager with a hypothesis for rainfall enhancement. The Design Scientist would define rainfall enhancement objectives and goals based on the seeding hypothesis. The Water Manager would convert the potential rainfall enhancement outcomes into water management outcomes and establish a benefit/cost assessment for the possible range of outcomes and then would decide whether or not to proceed with the design stage of the project plan.

Assess meteorological and cloud conditions and develop an hypothesis for rainfall enhancement

The assessment of the meteorological cloud conditions requires, at the very least, a study of the climatology of the region based on archived Bureau of Meteorology surface and upper air analyses, radar studies and satellite imagery. In addition special observing and numerical modelling studies may be required to validate the seeding hypothesis.

Suitable clouds should be defined based on the seeding hypothesis. A preliminary analysis should define the frequency of occurrence of the suitable clouds, and the wind speed and direction at the seeding level for such clouds. These parameters contribute to the definition of the target and control areas for any experiment.

Define rainfall enhancement objectives and goals

Statistical techniques should be applied to determine the probability of detecting a range of seeding outcomes in a given time period. The seeding outcomes should be based on the physical seeding hypothesis. Statistical simulation and the seeding hypothesis should be the basis for defining the necessary length of the cloud seeding experiment to detect the expected rainfall increase.

Define expected water management outcomes

The Water Manager should be responsible for defining the desired water management outcomes from the project and with the aid of the Design Scientist assessing practical benefits to be pursued. The Water Manager should also assess any potential or expected negative environmental or economic effects.

Establish a benefit/cost assessment for expected range of possibilities

The Water Manager should undertake a cost/benefit assessment to determine the economic viability of the project and seek a review of this assessment by the Review Scientist. The Water Manager should assess the worth of the project on the basis of the pre-planning analyses in consultation with interested parties who may be favourably or unfavourably affected. If the project is to proceed the Water Manager should carefully define its experimental and water management objectives in conjunction with other interested parties.

2.2.2 Stage 2: Design of Experiment

Once the decision to proceed with the cloud seeding experiment is made by the Water Manager, the Water Manager and Design Scientist should proceed to Stage 2 (the Design of the experiment) using the following steps:

Document project plan

Design of statistical evaluation methods and consequent project evaluation

Establish specifications for cloud seeding operations and monitoring

Identify environmental and social issues of concern

Arrange independent scientific review of the plan

Prepare and award contract

Document project plan

The project plan or prospectus should restate the defined objectives, expected outcomes (benefits and negative impacts). It should determine the design of the experimental side of the project and define the operational areas and suitable days for the experiment. The experimental design should be based on a statistical analysis that uses past records from an existing raingauge network. These rainfall records should be continuous over a period of the order of 30 years. The experiment should define only a small number of key hypotheses to be tested so as to avoid the problems that arise from a multiplicity of statistical significance tests. The seeding technique and pluviograph/rain gauge networks should be specified together with other specialised measurements, such as extra radiosondes. Seeding and research aircraft flight patterns should be presented and finally the methodology to be used in the statistical analyses and physical assessment documented.

The cloud seeding and cloud observing requirements in the project plan determine the minimum specifications for a cloud seeding aircraft and if ground based seeding is to be used, the positioning of the seeding generators should be specified. As a precursor to locating the generators, it is important to carry out numerical simulations of the dispersion of the plume from the generator to show that the seeding material will enter the clouds at the required location for effectively seeding the target area.

The role and location of remote sensing equipment such as a liquid water radiometer or operational radar would be defined together with the techniques to be used in the analysis phase of the experiment.

The operational application of numerical modelling techniques would be specified and in particular the role of atmospheric numerical models in deciding the suitability of a seeded day, the targeting the rainfall and in the analysis of the experiment should be clearly documented.

Design of statistical evaluation methods and consequent project evaluation

Comparison of precipitation during seeded periods with that during historical periods presents problems because of climatic and other changes from one period to another. Problems also arise because of changes in the instrumental recording of the data. For these reasons historical analyses are not generally accepted as a technique to validate a seeding experiment.

Historically, statistical analyses of cloud seeding experiments require the establishment of target and control areas in the design of the experiment together with a rigorously defined analysis technique that is specified prior to the commencement of the experiment. Currently, randomised experiments are considered the most reliable technique for detecting cloud seeding effects. The randomised experiments require a number of cases that can be calculated on the basis of the natural variability of the precipitation, the magnitude of the expected effect and the certainty required in claiming the positive effects of seeding. The reliability of the randomised experiments is crucially dependent on both the quality and the length of the historical rainfall records.

The methodology for assessment of hydrological outcomes and the translation of these outcomes into an assessment of a cost/benefit evaluation should be determined and specified in the plan. The efficacy of the cost/benefit analysis will in part be determined by the availability of historically reliable economic and hydrologic data sets.

Establish specifications for cloud seeding operations and monitoring

The prospectus should define the preliminary procedures to be undertaken by the Cloud Seeding Operator both before takeoff and on the way to the seeding area. The Cloud Seeding Operator should examine all the relevant information about conditions including forecasts, reports from previous seeding or reconnaissance flight, relevant satellite and radar imagery. On the way to the seeding area the flight plan should allow the Operator to observe both cloud conditions and winds at various heights on climb.

The seeding equipment and seeding material should be specified in the prospectus together with the aiming strategies for the clouds being seeded. For example the technique of seeding stratiform clouds differs from cumulus clouds. The prospectus should also deal with what is done on occasions declared "unseeded".

Identify environmental and social issues of concern

The prospectus should address environmental and social issues that may concern the public. For example, the prospectus should comment on the impact of the seeding operation on the physical and biophysical environment as well as the likely down wind effects on communities outside the seeding area. The prospectus should state the environmental safeguards and monitoring employed. In some cases a Referee may be appointed with the power to stop the experiment if excessive rain is likely to be detrimental to the seeded area.

Arrange independent scientific review of the plan

The prospectus should be reviewed by an independent Review Scientist to help ensure that all the procedures are in accordance with developing world practice and science and to ensure the integrity and credibility of the analyses is preserved by publishing analysis procedures beforehand.

2.2.3 Stage 3-Conduct of rainfall enhancement operations

Following the decision of the Water Manager to proceed with the cloud seeding operation, a contract should be let with the Cloud Seeding Operator. During the conduct of the experiment it is important that the Cloud Seeding Operator follow the procedures of:

Project management and reporting

Seeding procedures

Cloud physics measurements during the operation

as defined in the science plan for the cloud seeding project. These procedures should not be changed without the agreement of the Water Manager, Design Scientist and the Project Review Scientist.

The science of statistics has developed rules for the conduct of experiments. Violation of these rules by the Operator will reduce the credibility of the results of the analysis of the cloud seeding operation. The rules generally are directed to the task of obtaining an unbiased set of data. Consciously or unconsciously, persons working on the project may have a bias regarding its results. This will affect the quality of the data and the subsequent analysis and therefore precautions in the design of the experiment are taken to exclude this bias. Consequently, the Cloud Seeding Operator must maintain high standards of reporting to the Water Manager so as to ensure that the integrity of the experimental procedure is never questioned.

The successful treatment of any suitable cloud requires that sufficient quantities of the appropriate seeding material enter the cloud in a timely, well-targeted fashion. The stringent spatial and temporal targeting specified in the seeding procedures must be followed by the Operator at all times. To undertake these tasks professionally the Operator needs to have a commitment to understand the science of the project.

Cloud physics and meteorological measurement must be made during the seeding operation to ensure that seeding takes place under the optimum physical conditions as defined by the seeding hypothesis. The statistical analyses are enhanced if physical predictors are employed in the statistical analysis of the seeding experiment.

2.2.4 Stage 4-Post operational evaluation

The post operational evaluation should:

Re-assess the meteorology of the cloud systems in the light of observation made during the cloud seeding operation

Evaluate the statistical success or otherwise of the experiment

Carry out explanatory analyses of data from the experiment

Evaluate the water management and economic outcomes

Disseminate the results of the evaluation of the project

The overall post-operational analysis together with recommendations should be prepared in a final report by the Design Scientist for the Water Manager. Before accepting the final report the Water Manager should submit the final report to the Review Scientist for an independent assessment.

Re-assess the meteorology of the cloud system in the light of seeding operation results

The meteorology of the cloud systems should be re-analysed using all of the available data collected during the life time of the project. The data should be analysed in such a way as to document the types and frequency of clouds suitable for seeding.

Where possible, the physical evidence both for and against the seeding hypothesis should be examined. The physical analysis should take account of all of the available observational and modelling information. The analysis may be complex and require measurements made by a seeding aircraft, a dedicated cloud physics research aircraft and remote sensing equipment such as satellite imagery, radars and liquid water radiometers.

The information from the meteorological and cloud physics analysis should be used to initialise cloud models to further test the seeding hypothesis.

Evaluate the statistical success or otherwise of the experiment

The small number of analyses specified in the prospectus as being the determinants of the experimental outcome should be carried out. These will be directed towards confirming the seeding hypothesis by detecting, with an agreed level of statistical significance, increases in the area rainfall measures on specified occasions. The number of such analyses should be small (ideally one or two) to avoid statistical problems arising from multiplicity of statistical significance tests.The analyses performed should possess high statistical power to ensure maximum ability to detect the expected effects and should be robust against unexpected features of the data.

Carry out explanatory analyses of data from the experiment

The Design Scientist should carry out extensive analyses of data from the experiment, extracting maximum value from the large amount of data on rainfall, meteorology and cloud physics that will have been accumulated. These analyses are virtually unlimited in scope, but it should be emphasised that they do not contribute to any statistical assessment of the experiment, which flows only from the pre-specified analyses.

Explanatory analyses may be directed at:

examining and elaborating aspects of the seeding hypothesis

looking at subsets of the data, either in space or time

carrying out analyses suggested by the features of the data actually obtained

improving the selection of suitable conditions and seeding strategies for obtaining the maximum effect of seeding in the designated target area in future operations

Evaluate the water management and economic outcomes

The hydrological outcomes of the project should be assessed in relation to the project objectives and in accordance with procedures stipulated in the project plan.

The economic outcomes of the project should be assessed in relation to the project objectives and in accordance with the procedures stipulated in the project plan and the water management outcome evaluations should be developed in consultation with the parties interested in the potential benefits and impacts of the experiment.

Disseminate the results of the evaluation of the project.

The post operational analysis of the statistical, water management and economic outcomes of the project, together with the basis of the assessment should be presented in the form of a final project report.

This report should set out valid conclusions to be derived from the project with respect to:

whether the project objectives were fulfilled

any new knowledge acquired from the project relating to the operational worth of further rainfall enhancement programs or to the regional science of rain enhancement

any recommended further actions or suspension of actions in respect to rainfall enhancement

After review by the Review Scientist the report should be published in a suitable form and distributed with the objectives of:

satisfying the needs of parties with a direct interest in the project outcome

providing accountability for the operation

adding to regional knowledge on the potential benefits, difficulties or failure of rainfall enhancement as a water management tool

 3. Conclusions

Many years of research in Australia have shown that, given the appropriate conditions cloud seeding can modify clouds and induce rain. The problem for Water Managers in applying the technique as a water management tool is that the conditions for cloud seeding to work occur relatively infrequently and the duration of the cloud seeding experiment necessary to demonstrated increased rainfall over a given area may be excessively long thereby making the experiment too costly. History has also demonstrated that deficiencies in the statistical design of a cloud seeding experiment generate controversy and lead to inconclusive results.The central theme of the principles is one of a planned approach, with clear accountabilities and quality assurance with proper understanding, realistic performance objectives and measurement.