Context:
Indian Institute of Tropical Meteorology (IITM), Pune demonstrated that cloud seeding (CS) has the potential to decrease uncertainty in rainfall.
About CAIPEEX:
- Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX)
- A scientific investigation conducted in Solapur city during the summer monsoon period of 2018 and 2019.
- Launched by – Ministry of Earth Sciences
- Objective – To investigate the efficacy of hygroscopic seeding in deep convective clouds and to develop a cloud seeding protocol.
- Results of the experiment –
- Was able to achieve 18% relative enhancement in rainfall over 100 sq.km area.
- Cloud Seeding alone cannot mitigate droughts
- Approximate cost of producing water was 18 paisa per litre
What to Know? – Cloud Seeding
How are clouds formed in the atmosphere?
- Clouds are formed when water vapour condenses around tiny particles such as dust or salt, known as ice nuclei, present in the atmosphere.
What is Cloud Seeding?
- It is a method of weather modification that enhances a cloud’s capacity to generate rainfall or snowfall and can be implemented using ground-based generators or aircraft.
What are the chemicals used?
- It uses silver iodide (AgI) and dry ice (solid carbon dioxide) to improve the creation of ice crystals in clouds.
- Other chemicals – Potassium Iodide, CO2 in the form of dry ice, Propane, Calcium Carbide, Calcium chloride, Ammonium Nitrate, Sodium Chloride, and Urea compounds.
How does it work?
- Some tiny ice nuclei are introduced into certain types of subfreezing clouds.
- These nuclei provide a base for snowflakes to form which grow and fall from the clouds back to the surface of the Earth.
What are types of cloud seeding?
- Hygroscopic cloud seeding: disperses salts through flares or explosives in the lower portions of clouds.
- Dynamic cloud seeding: boosts vertical air currents encouraging more water to pass through the clouds.
- Static cloud seeding: involves spreading a chemical like Agl into moisture-laden clouds.
Applications:
- Increasing rainfall, weather regulation, mitigating hail damage, enhancing natural water supply, tackle air pollution
Challenges:
- Potentially Harmful Chemicals, expensive process, Unknown impact in long-term.
Varshadhare Project, initiated by the Karnataka government, aims to increase rainfall by augmenting the precipitation from clouds through cloud seeding.
Source: The Hindu
Previous Year Question
In the context of which of the following do some scientists suggest the use of cirrus cloud thinning technique and the injection of sulphate aerosol into stratosphere?
[UPSC Civil Services Exam – 2019 Prelims]
(a) Creating the artificial rains in some regions
(b) Reducing the frequency and intensity of tropical cyclones
(c) Reducing the adverse effects of solar wind on the Earth
(d) Reducing the global warming
Answer: (d)
Explanation:
Stratospheric Aerosol Injection (SAI) is a technique that would involve spraying large quantities of inorganic particles (e.g., Sulphur dioxide) into the stratosphere to act as a reflective barrier against incoming sunlight, thus helping to reduce the global warming.
