INITIATIVE/ANTI-HAIL
mittee, which had members from the Union Ministry of Agriculture and Farmers' Welfare, the Indian Council of Agricultural Research, India Meteorological Department, Dr Yashwant Singh Parmar University of Horticulture and Forestry AND the Himachal Pradesh state government, visited Shimla in 2012 and wrote in its report that the state's horticulture department had installed these cannons without any scientific research.
Another question that remains unsettled is when could a cumulonimbus cloud lead to hail formation. Akash Bhimta says that earlier the radar installed at Tumru would alert whenever such a cloud would be formed and the technician, who was an employee of Newton Systems, would immediately start firing the cannon till the cloud dissipated. But the radar stopped functioning after two years and the technicians left. Now the cannon is operated by the state's horticulture department. "Operating the gun without a radar is just like acting on a whim. No one knows if the cloud will lead to hail. They just fire whenever they see a cloud. Sometimes, there is hail while the gun is being fired," says Bhati. Kumar also says that the guns are effective only with radar, which ensures timely firing.
It is also unclear if the cannon can adversely affect rainfall or damage mountains, triggering landslides. Kumar says that the sound is not loud enough to damage the mountains, but the subject needs more research.
Sound blasts from the cannon heat up the cloud, purportedly scuttling formation of hail
Hail is usually formed in cumulonimbus cloud (spanning 2-13 km from the ground) with a strong upward draft.The Hail gets formed when the draft pushes the falling droplets / snow flakes upward. In the process, they keep accumulating moisture till they are too heavy to stay in the cloud
DIVERGENT DUCT sends this extremely strong wave, travelling at 700-1,000 metre/second,
5-6 km into the cloud.The cannon blasts soundwaves every 4-5 seconds for 15-20 minutes to prevent hail formation
Mixture of LPG and air reaches DETONATION TUBE via fuel-air inlet
National Centre for Atmospheric Science, Department of Meteorology, University of Reading, UK, says a rise in global temperature has led to a rise in atmospheric moisture, which could be behind the uptick in hail incidents.
With such uncertainties, farmers' fascination with an unproven technology on the basis of anecdotal evidence does not appear unreasonable, especially when a season's effort and crop are at stake.