Date : 15/11/2023

Relevance:GS Paper 3 – Environment and Ecology

Keywords: IIT Kanpur, Cloud Seeding, CAIPEEX-IV, National Clean Air Programme

Context-

The persistent issue of severe pollution in Delhi has prompted the government to explore innovative solutions, including the controversial method of artificial rain or cloud seeding. This experimental endeavor, though not new to the global scientific community, remains a nebulous science, especially when applied in non-monsoon months. The Delhi government recently collaborated with experts from the Indian Institute of Technology (IIT), Kanpur, in an attempt to address the alarming air quality crisis. The proposed plan involves flying aircraft into rain clouds and dispersing a proprietary salt solution with the hope of inducing rainfall. While cloud seeding has a history dating back to the 1940s, its success is contingent upon various factors, making it a complex and unpredictable undertaking.

Understanding Cloud Seeding

Clouds form when water vapor condenses around small particles to create droplets. These droplets then collide and grow until the cloud becomes saturated, leading to rainfall. Cloud seeding involves injecting clouds with substances known as "seeds," typically salts like silver iodide, potassium iodide, or sodium chloride. These seeds act as nuclei around which additional cloud droplets can form. The dispersion of these seeds into the clouds can be carried out by aircraft or ground-based generators.

Sachchida Nand Tripathi, a Professor at IIT Kanpur and Steering Committee member of the National Clean Air Programme, explains that cloud seeding accelerates cloud microphysical processes. The dispersed substance must provide cloud condensation nuclei and ice nuclei, obtained from different salts. Cloud condensation nuclei help form cloud droplets, while ice nuclei aid in the formation of ice crystals. As ice crystals grow faster than droplets, they become larger and fall, resulting in precipitation.

Conditions Required for Cloud Seeding

Successful cloud seeding depends on specific atmospheric conditions. Firstly, there must be sufficient cloud cover, and clouds of a particular type are necessary. M Rajeevan, former secretary of the Ministry of Earth Sciences, emphasizes the need for an adequate number of cloud droplets inside the clouds. Cloud seeding aims to increase the radius of these droplets, making them larger and more likely to result in rainfall. Cloud seeding is not feasible with a clear sky.

In winter, clouds form over Delhi when a western disturbance moves over the region. These disturbances, originating in the Caspian or Mediterranean Sea, bring non-monsoonal rainfall to northwest India. However, the stability of the atmosphere in winter makes it challenging to find clouds suitable for seeding. Even if clouds are present, their height and liquid water content must be considered.

Past Cloud Seeding Experiments in India

Cloud seeding experiments in India have predominantly occurred during the monsoon season in states like Karnataka, Maharashtra, and Tamil Nadu. One notable experiment, the fourth phase of the Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX-IV), took place in drought-prone Solapur, Maharashtra, during the monsoon seasons of 2018 and 2019. The results indicated a relative enhancement of 18% in rainfall.

IIT Kanpur conducted cloud seeding experiments in April and May of 2018, the pre-monsoon months, on their campus. Out of six trials, five resulted in rain. Despite these experiments, cloud seeding has faced challenges in gaining widespread acceptance and implementation.In 2018, there was a proposal to conduct cloud seeding in Delhi, but it faced obstacles such as the need for multiple permissions and the absence of seeding equipment on IIT Kanpur's aircraft. Thara Prabhakaran, a scientist at the Indian Institute of Tropical Meteorology (IITM) and a specialist in cloud microphysics, emphasized the complexity and uncertainties involved in cloud seeding. While some advantages were observed during the monsoon season, the field remains intricate and uncertain.

In 2018, there was a proposal to conduct cloud seeding in Delhi, but it faced obstacles such as the need for multiple permissions and the absence of seeding equipment on IIT Kanpur's aircraft. Thara Prabhakaran, a scientist at the Indian Institute of Tropical Meteorology (IITM) and a specialist in cloud microphysics, emphasized the complexity and uncertainties involved in cloud seeding. While some advantages were observed during the monsoon season, the field remains intricate and uncertain.

Cloud Seeding for Pollution Mitigation: A Novel Approach

Cloud seeding in India has primarily been explored for managing drought-like conditions rather than addressing pollution. The Solapur experiment focused on understanding cloud seeding, but the complexities of cloud microphysics presented challenges. The impact of cloud seeding on pollution levels has not been extensively studied in India.

Gufran Beig, founder project director SAFAR, and chair professor at the National Institute of Advanced Studies, highlighted that the upcoming cloud seeding in Delhi aims to reduce pollution levels by inducing significant rainfall. While the effects may be temporary, successful cloud seeding could disrupt the flow of pollutants.

Conclusion:

The Delhi government's foray into cloud seeding to combat severe pollution reflects the urgency and complexity of environmental challenges. While the science behind cloud seeding has made strides since its inception, the uncertainties and challenges associated with this intervention cannot be understated. The Solapur experiment provides valuable insights, emphasizing the need for a cautious and informed approach when applying cloud seeding to different regions and seasons.

As Delhi awaits the proposed cloud seeding experiment, the outcomes will likely shape the future discourse on artificial rain induction as a pollution mitigation strategy. The delicate balance between scientific curiosity, environmental responsibility, and the potential consequences of manipulating natural processes underscores the need for thorough research, transparency, and ethical considerations in deploying such interventions. As the world grapples with evolving environmental crises, innovative solutions like cloud seeding demand rigorous scrutiny to ensure a sustainable and responsible approach to addressing complex challenges.

Source- The Hindu