IIT-Kanpur's plan to wash away Delhi's pollution awaits clearance

On November 6, it was reported that the CPCB and IIT-Kanpur, using an ISRO aircraft, would use a technique called cloud seeding to create artificial rains in a bid to wash away air pollution in Delhi.

The unprecedented move came in the wake of air quality levels in Delhi reaching hazardous levels, and efforts at creating artificial rains were to commence from November 10.

Cloud seeding is a technique wherein substances (mostly salts) are dispersed into the air to change the amount of and/or type of precipitation that falls from clouds.

The technique has been in use for decades, and has been used by several countries, including India to alter precipitation to suit agricultural and other needs.

However, this would be India's first use of cloud seeding to tackle pollution.

Cloud seeding is commonly carried out using aircraft.

Planes fly into cloud formations and disperse salts which, when they come into contact with moisture in clouds, creates ice crystals and rain droplets.

The presence of salts helps droplets expand faster.

However, for a successful cloud seeding operation, identifying the right type of cloud, using the right salt mix is of critical importance.

On Wednesday, ET reported that the ISRO aircraft was awaiting clearance to fly to Delhi for cloud seeding from the Ministry of Environment, Forests and Climate Change.

According to an official who requested anonymity, the aircraft would also need clearances from the Directorate General of Civil Aviation (DGCA), the Ministry of Defence, the Indian Air Force, and the Intelligence Bureau.

It should be noted here that if clearances take too long, there might be difficulties in executing the plan.

While it is relatively easy to seed clouds in pre-monsoon and monsoon seasons, seeding clouds in winter is quite tough as clouds are not particularly moisture laden.

Additionally, owing to complications surrounding cloud formation, the window for executing the plan is rather small.