IITM Pune demonstrates cloud seeding can produce rainfall
- October 29, 2023
- Posted by: OptimizeIAS Team
- Category: DPN Topics
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IITM Pune demonstrates cloud seeding can produce rainfall
Subject : Geography
Section: Physical geography
Context:
- A cloud seeding experiment was carried out in Solapur city, and in return it was able to achieve 18% relative enhancement in rainfall.
About Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX phase-4):
- It was a scientific investigation conducted in Solapur city during the summer monsoon period of 2018 and 2019 by IITM Pune.
- Solapur city (in Maharashtra) falls on the leeward side of the Western Ghats and hence gets low rainfall — 384 mm and 422 mm of total rainfall during the period June to September 2018 and 2019, respectively.
- Enhancement in rainfall is approximately 8.67mm as a result of the experiment.
- The primary objective was to investigate the efficacy of hygroscopic seeding in deep convective clouds and to develop a cloud seeding protocol.
Study findings:
- Cloud seeding is an effective strategy for enhancing rainfall in a region under suitable conditions.
- Selection of clouds is based on: Liquid water content in the cloud, the vertical motion in the cloud, which is an indicator of the growth of the cloud.
- Calcium chloride flare was used for seeding the clouds.
- The seeding was done at the base of the warm convective clouds and at a time when the clouds were in their growing stage so that the seed particles could enter the clouds with minimum dispersion.
- The convective cloud bases are found at 500-1,500 metres altitude during the summer monsoon period and around 2,000 metres or more altitude during the monsoon break periods, which depends on the moisture content in the lower atmosphere.
- Major finding: Not all cumulus clouds produce rainfall when cloud seeding is done.
- The approximate cost of producing water through cloud seeding was 18 paisa per litre. The cost will drop by more than 50% if we use indigenous seeding aircraft.
- Cloud seeding alone cannot mitigate droughts but can help produce 18% more rainfall and partially address water requirements.
- The study has helped develop a high-resolution numerical model that can help stakeholders to identify target locations, clouds that can be seeded, and a suitable seeding strategy to enhance rainfall in an area.
Cloud seeding:
- It is a type of weather modification that aims to change the amount or type of precipitation that falls from clouds by dispersing substances into the air that serve as cloud condensation or ice nuclei, which alter the microphysical processes within the cloud.
- Its effectiveness is debated; some studies have suggested that it is difficult to show clearly that cloud seeding has a very large effect.
- The usual objective is to increase precipitation (rain or snow), either for its own sake or to prevent precipitation from occurring in days afterward.
Chemicals used for cloud seeding:
- The most common chemicals used for cloud seeding include silver iodide, potassium iodide and dry ice (solid carbon dioxide).
- Liquid propane, which expands into a gas, has also been used.
- This can produce ice crystals at higher temperatures than silver iodide.
- In the CAIPEEX experiment, Calcium chloride flare is used.
Concerns:
- Some chemicals are potentially harmful to the natural environment and the plants which depend on the contaminated rain to produce food.
- It is a very expensive process.
- It could have many dire consequences to the environment if not well regulated.
- Dry areas are not usually well-positioned to handle certain weather conditions, and thus, may become easily flooded and cause more harm to the already struggling environment.
- For cloud seeding to be successful, certain uncontrollable conditions have to be met. for example:
- Clouds have to be present, not just any cloud but clouds capable of producing rain.
- The atmospheric conditions must also suit the process as certain conditions could lead to an unwarranted result like the rain falling in a different location or not falling at all.
Source: TH