Seeding cloud to clean the air

Subject: History

Section: Art and Culture

Context: Delhi govt plans ‘cloud seeding’ to induce rains amid pollution

What is cloud seeding:

Cloud seeding involves injecting clouds with substances like silver iodide, potassium iodide, or sodium chloride to accelerate cloud microphysical processes.
These substances serve as nuclei around which cloud droplets can form.
The process aims to create larger droplets that can reach the Earth’s surface without evaporating.
Different salts are used to provide cloud condensation nuclei and ice nuclei, essential for forming cloud droplets and ice crystals, respectively.
Cloud seeding is intended to enhance precipitation by promoting the growth of droplets and increasing the likelihood of rainfall.

What are the conditions required for cloud seeding to be done:

Cloud seeding is dependent on the presence of a sufficient number of clouds and specific cloud types.
Effective cloud seeding requires clouds with an adequate depth and an ample number of cloud droplets.
The process aims to increase the size of cloud droplets, leading to their growth and eventual precipitation.
In winter, clouds typically form over Delhi when influenced by western disturbances originating in the Caspian or Mediterranean Sea.
While radar systems can help assess the likelihood of cloud formation,the height and liquid water content of the clouds also need to be considered for successful cloud seeding.

Has cloud seeding been done before in India, and has it been successful:

Cloud seeding experiments in India have primarily been conducted during the monsoon season in states like Karnataka, Maharashtra, and Tamil Nadu.
A notable experiment, CAIPEEX-IV, conducted in drought-prone Solapur, Maharashtra, during the 2018 and 2019 monsoon seasons, showed a relative enhancement of 18% in rainfall.
While there have been attempts in pre-monsoon months, such as IIT Kanpur’s trials in April and May 2018, the success of cloud seeding remains uncertain and complex due to various factors influencing precipitation, making further research necessary for potential applications in winter or other seasons.

How it is expected to help with pollution levels

Cloud seeding in India has primarily focused on addressing drought conditions, and there haven’t been attempts specifically aimed at reducing pollution.
While China has explored weather management options, the complex and non-linear nature of cloud processes makes it challenging to predict the outcomes of cloud seeding accurately.
The impact of cloud seeding on pollution reduction would require dedicated studies, considering India’s unique conditions.
The initiative to use cloud seeding for air pollution control is a novel approach, aiming to induce rainfall that can temporarily wash away pollutants, although the long-term effectiveness remains uncertain.