• A storm hit the United Arab Emirates and Oman earlier this week bringing record rainfall that flooded highways, inundated houses, grid-locked traffic and trapped people in their homes.

• The storm had initially hit Oman on April 14 before it pounded the UAE on April 16, knocking out power and causing huge disruptions to flights as runways were turned into rivers.

• Rainfall is rare in the UAE and elsewhere on the Arabian Peninsula, which  is typically known for its dry desert climate. Summer air temperatures can soar above 50 degrees Celsius.

• The UAE and Oman also lack drainage systems to cope with heavy rains and submerged roads are not uncommon during rainfall.

• Questions were raised whether cloud seeding, a process that the UAE frequently conducts, could have caused these heavy rains.

• The National Center of Meteorology, a government taskforce responsible for cloud seeding missions in the UAE, said it had not carried out the weather modification technique in the run-up to the heavy storms.

What is cloud seeding?

• Cloud seeding is a process in which chemicals are implanted into clouds to increase rainfall in an environment where water scarcity is a concern.

• The UAE, located in one of the hottest and driest regions on earth, has been leading the effort to seed clouds and increase precipitation.

• Cloud seeding is a weather modification technique that aims to enhance the amount of rain falling from rain-bearing clouds.

• It is a technique that aims to add particles to clouds using aircrafts to enhance condensation and droplet and ice crystal formation.

• The most common substances used for cloud seeding include silver iodide, potassium iodide and dry ice (solid carbon dioxide). 

• These agents provide the nuclei around which water vapour can condense, ultimately leading to the formation of rain or snow.

• Cloud seeding is of two types — hygroscopic and glaciogenic.

• The hygroscopic seeding is done at the base of warm clouds using seed particles with an affinity for water vapour. It uses hygroscopic flares of calcium chloride particles released at the convective cloud base.

• The glaciogenic seeding is carried out in cold clouds by seeding near the cloud top using silver iodide particles, which may form ice particles in clouds.

How is it done?

• It is only effective in certain locations in a limited number of weather conditions. Also, cloud seeding requires existing clouds. It will not produce rain out of thin air.

• Not all types of clouds are suitable for seeding. Clouds must be deep enough and of a suitable temperature to be seeded effectively. The wind must also be below a certain speed.

• A seeder aircraft is flown to the seedable target area. The aircraft is equipped with cloud-seeding flares that can produce seed particles. When the aircraft reaches the target area, cloud properties are investigated by the aircraft. If found suitable, the cloud seeding flares are burned near the cloud base where there is upward air motion, which takes seed particles into the cloud.

• Seed particles aid the water molecules present in the cloud to condense around them rapidly. Large cloud drops are formed when small and large drops collide and coalesce, resulting in rainfall. 

• This weather modification technique has been utilised in various parts of the world, primarily in regions experiencing water scarcity or drought conditions. 

• However, the effectiveness and environmental impact of cloud seeding remain subjects of ongoing research and discussion.

Cloud seeding in India

• Last year, cloud seeding experiment in Solapur region of Maharashtra resulted in 18 per cent more than normal conditions, according to a study published in the Bulletin of the American Meteorological Society (BAMS). Scientists from the Indian Institute of Tropical Meteorology in Pune and other institutes conducted the study.

• In June 2023, IIT-Kanpur successfully conducted a test for artificial rain via cloud seeding over a limited area on the campus.

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