Cloud seeding, deliberate introduction into clouds of various substances that act as condensation nuclei or ice nuclei in an attempt to induce precipitation.
What exactly is cloud seeding?
The technology sprays particles of salts like silver iodide and chloride on clouds using a special aircraft, rockets or from dispersion devices located on the ground. These salt particles act as a core (cloud condensation nuclei or ice-nucleating particles) which draw water vapour within the cloud towards them and the moisture latches on, condensing into water droplets leading to the formation of raindrops.
History
The first experiments with cloud seeding were conducted in 1946 by American chemist and meteorologist Vincent J. Schaefer, and since then seeding has been performed from aircraft, rockets, cannons, and ground generators.
In news
In 2021 UAE tests the use of electric charge drones in cloud-seeding operations to make rain. The drones will fly at low altitudes and deliver an electric charge to air molecules. The charge modifies the growth of tiny water droplets into larger drops that fall as rain. As clouds naturally carry positive and negative charges, altering the size of the charges could cause the water droplets to grow and merge, thus producing rain.
cloud seeding in India?
In 1952 late climatologist S. K. Banerji, the first Indian director-general of Indian Meteorological Department experimented with cloud seeding with salt and silver iodide through hydrogen-filled balloons released from the ground.
Tata firms also took stabs at cloud seeding in the Western Ghats region in 1951 using ground-based silver iodide generators. The Rain and Cloud Physics Research (RCPR) unit of Indian Institute of Tropical Meteorology (IITM) in Pune carried out randomized warm cloud modification experiments through salt seeding during 1957-1966 in north India. Over the next three decades, India experimented in this direction in Maharashtra, Karnataka and Uttar Pradesh.
Research on cloud seeding in India received a boost since 2018 with the Union Ministry of Earth Sciences investing in data collection and experiments.
Research by the IITM in Pune, especially over the last two years (2018 and 2019) will result in a white paper with the scientific facts on the ground for cloud seeding, should states wish to take it up as a measure to increase rainwater.
While the Union Ministry of Earth Sciences has no plans to have a national programme on cloud seeding, it has already spent Rs 45 crore on research in 2018. In 2019, the work will continue, costing a total Rs 100 crore.
The IITM has initiated a national level campaign designed to make progress in aerosol and cloud microphysics observations over the Indian region, which can be used to propose guidelines for cloud seeding. The project called the Cloud-Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX), will be focussing on aerosol-cloud-precipitation interactions in the pre-monsoon and monsoon environment.