Here’s how things would unfold if Sachchida Nand Tripathi has his way.
During winter, an ISRO aircraft flying three kilometres above ground uses its flare launchers to shoot hygroscopic (water-inducing) salts at target clouds over Delhi-NCR. Updraughts—which can reach speeds of 50 metres a second in storm conditions, but average 5-8 m/s in summer months—may be absent this time of year. But here’s hoping they’re present, because these upward air currents will help disperse the salts. The salts serve as additional nuclei for precipitation to occur.
The outcome, hopes Tripathi, is that raindrops will form as a result, showering down on the national capital and bringing temporary respite from Delhi’s air pollution woes.
…if Sachchida Nand Tripathi has his way.
The atmospheric science specialist, who heads the department of civil engineering at IIT-Kanpur, is collaborating with the Central Pollution Control Board (CPCB), the India Meteorological Department (IMD), and ISRO to use cloud seeding for artificial rain and air pollution abatement in the capital. But induced rain has a chequered history. More so in India, where the science of weather modification is a knee-jerk reaction to natural calamities. Advocate cloud seeding trials for the man-made disaster of air pollution, and you’re bound to get kaleidoscopic responses from Tripathi’s fellow experts:
“Preposterous.” — BN Goswami, former director, Indian Institute of Tropical Meteorology (IITM)
“Needs further investigation to say anything.” —Thara Prabhakaran, project director of IITM’s Cloud Aerosol Interaction and Precipitation Enhancement Experiment (CAIPEEX)
“Hygroscopic seeding requires warm, tropical cumulus clouds, which don’t form in winter in the northwestern states. How will this be possible?” — RR Kelkar, former director general, IMD
“I’m not saying don’t try. But cloud seeding itself needs further substantiation.” —Saurabh Bhardwaj, earth science and climate change division, TERI (The Energy and Resources Institute)
