To address this issue, the Indian Institute of Technology (IIT) Kanpur has proposed the idea of “artificial rain” to reduce pollution levels in the national capital. This project has been in development since 2018, and the institute conducted trials in July of this year, as reported by the Economic Times. The researchers have secured the necessary permissions from government authorities, including the Directorate General of Civil Aviation (DGCA), to carry out cloud seeding for this purpose.

Manindra Agrawal, a professor in the computer science and engineering department at IIT Kanpur and the driving force behind this project, explained that artificial rain could provide temporary relief for up to a week to residents in the National Capital Region (NCR) suffering from poor air quality, according to the ET report.

The Graded Response Action Plan (GRAP) classifies its actions into four stages: Stage I – ‘Poor’ (AQI 201-300); Stage II – ‘Very Poor’ (AQI 301-400); Stage III – ‘Severe’ (AQI 401-450); and Stage IV – ‘Severe Plus’ (AQI >450).

What is cloud seeding?

Cloud seeding is an artificial method used to increase rainfall by introducing certain substances into clouds that serves various purposes, including reducing the impact of droughts, preventing forest fires, increasing precipitation, and enhancing air quality.

During cloud seeding, chemicals like silver iodide, potassium iodide, and dry ice are released into the sky using airplanes and helicopters. These chemicals attract water vapour, leading to the formation of rain clouds. It usually takes about half an hour for this method to make it rain.

According to the ScienceDirect, cloud seeding techniques can be divided into two categories. Hygroscopic cloud seeding aims to accelerate the coalescence of droplets in liquid clouds, resulting in the formation of larger droplets that lead to precipitation. In this method, salt particles are typically dispersed at the cloud’s base. The other technique, glaciogenic cloud seeding, focuses on inducing ice production in supercooled clouds, leading to precipitation. Glaciogenic cloud seeding involves dispersing efficient ice nuclei, such as silver iodide particles or dry ice, into the cloud, which triggers heterogeneous ice nucleation.

Implementation

This process also requires obtaining several approvals, including those from the DGCA, the ministry of home affairs (MHA), and the Special Protection Group responsible for the prime minister’s security, to allow aircraft to fly over the national capital, which is in dire need of cleaner air. Moreover, the success of the artificial rain depends on specific meteorological conditions, such as the presence of moisture-laden clouds and suitable wind patterns.

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Updated: 08 Nov 2023, 08:03 PM IST