During this year’s monsoon, weather scientists will fly airplanes loaded with silver iodide over clouds hovering above Solapur, Maharashtra and begin a three-year investigation into an old question: does cloud seeding produce sufficient rain?
The ₹250-crore programme, coordinated by the Indian Institute of Tropical Meteorology, will be the first controlled experiment to quantify the extent to which clouds form water drops large enough to make rain.
Seeding involves spraying chemicals into clouds. China used the technique during the 2008 Olympics to veer rain away from the inaugural venue and now has a full-fledged department that blasts rockets into clouds to induce rain and control pollution.
“The benefits of cloud seeding aren’t well understood. Lots of organisations make claims,” Madhavan Rajeevan, Secretary, Ministry of Earth Sciences, said. “It’s time we have a proper scientific evaluation that State governments can rely upon.”
Maharashtra has frequently toyed with the idea of cloud seeding because of the frequency of droughts over the Vidarbha region. The State Cabinet had approved a plan to seed clouds for 113 hours with a rainfall level of 1,381mm, at ₹28 crore. However above-normal rains pushed the plan to the back-burner.
For their experiment, scientists will fly two aircraft and spray dry ice and silver iodide on 100 clouds and compare them with 100 unseeded clouds. Ground radar will track the clouds and verify which ones contributed rain. The programme will account for the variability of the monsoon. The move is part of a larger experiment of the Earth Sciences Ministry to understand how clouds and aerosols interact and influence climate.