The IIT Kanpur project ‘Cloud seeding’ is a weather modification technique which involves the process of creating an artificial rainfall system by injecting small particles called ‘seeds’ into the clouds. The seeds are incorporated by plane or just by spraying from the ground It works only in case of enough pre-existing clouds in the atmosphere. The incorporated seeds tend to freeze water around them and become large enough to fall off in form of snow or rain droplets under favorable conditions. These seeds comprise of silver or potassium iodides, dry ice (solid carbon dioxide), or liquid propane.
Motive of cloud seeding project:
Under this project the scientists of IIT Kanpur planned to induce artificial rain via cloud seeding to clear smog in Delhi. ISRO collaborated with this projects by providing national Remote Sensing Agency which could fly into the clouds and incorporate silver iodide which forms ice-crystals, making clouds heavier and denser and thereby leading to condense into rainfall and clear the sky. The 2018 project of cloud seeding was stand still to certain time due to non-availability of aircraft and technical support from Central Govt. but was later approved and got all clearances from Defense and Home ministries for the project. Hindustan Aeronautical Limited(HAL) also collaborated with IIT Kanpur and provided Dornier aircraft along with their pilots for logistical support to the project.
Success rate of cloud seeding technique:
Karnataka Cabinet approved a budget of 91 crores in May 2019 for this project for a period of two years which involved two aircraft spraying chemicals while the experiment has also been in practice in states like Nagpur, Solapur, Hyderabad, Ahmedabad, Jodhpur and recently Varanasi. India Institute of Tropical Meteorology, Pune has been using the cloud seeding technique since several years currently. The success rate is about 60-70 percent which further depends upon local atmospheric conditions Other private companies have also started adopting for this technology specially in places like Maharashtra and Karnataka.
The concern:
Apart from silver toxicity, when cloud seeding is done in large scale, a negative impact about messing with balance of nature occurred because of increase in the evaporation rate outside the seeding location. Since, the amount of moisture in the atmosphere is decided by the balance between evaporation and condensation.
The benefit of cloud technique:
For years’ cloud seeding technique has been used to mitigate hailstorms along with enhancement of rain and snowfall to cover up water storage in reservoirs and underground. These small-scale projects are not to be confused with geoengineering schemes that propose tinkering with the planet’s weather by modifying Earth’s ability to reflect solar energy. Currently, more than 50 countries worldwide participate in cloud-seeding operations.