This report presents the proceedings of the international workshop and brainstorming session on “Evaluation of Cloud Seeding Operations in Andhra Pradesh” organized by the Centre for Atmospheric Sciences and Weather Modification Technologies (CASWMT) and Jawahar Lal Technological University (JNTU) in order to take stock of the situation, in particular the successes and failures arising out of five years of cloud seeding operations from 2004 to 2008. There were nearly 50 experts from various parts of the country and 2 international experts in the workshop and brainstorming sessions.

There were three technical sessions on the first day of the workshop in which experience from Andhra Pradesh cloud seeding programme, from IITM and IMD and from abroad were presented. The brainstorming sessions in the subsequent two days dealt with protocols, infrastructure, evaluation methodologies and daily operations required for future cloud seeding programme.  It was felt that the present cloud seeding programme is going on well subjected to some infrastructural limitations. Regarding the monitoring and evaluation being carried out by CASWMT and JNTU, it was felt that the evaluation methods employed in this  programme is on par with the any other evaluation methods employed in developed  countries like USA, South Africa, etc.    

Some of the notable lessons learnt in the AP Cloud Seeding Programme in the last 5 years were discussed in the workshop –

• Most of the seeding programme should be done in warm clouds. Particle size of seeding material should be different for continental clouds and maritime clouds and 0.5 kg hygroscopic flares are more successful in the cloud seeding programme.
• The results of the programme have shown that on an average there was a rainfall enhancement up to 14 per cent in mandals where cloud seeding occurred during 2005-08. Therefore the experts were of the opinion that the present cloud seeding programme of AP could continue for another 5 years.
• Experts were of the opinion that there is a deficiency in the infrastructure while serving the twelve districts covered under the programme. They have recommended at least 3 full Polarimetric Doppler radars with 3 aircrafts stationed at appropriate places for better cloud seeding.
• The actual requirement is of the order of about 5 aircrafts and 4 radars. In order to have an objective evaluation of cloud seeding programme, at least one rain gauge per 50 sqkm is recommended in the RSAD districts.  
• Moreover it is recommended that a cloud physics aircraft is essential to study various microphysical properties of the cloud and for aerosol mapping. 
• Pilot projects are also suggested to have an intensive rain gauge network at the rate of one rain gauge per one sqkm area in limited mandals on an experimental basis and to vary the particle size of the seeding material on similar clouds to know the exact particle size of seeding.

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