The Mexican state of Coahuila will be an experimental area to test a new rain-making technique. Until now, creating rain involved flying over a supercooled cloud at a high altitude and sprinkling it with silver iodide crystals, which have a structure similar to that of ice. However, this method increases rainfall by only 10-15 per cent.

The new method allows for rain to be extracted from warmer clouds by darting flares consisting of potassium chloride particles. A normal sortie would release some 1,400 gm of potassium chloride particles in four minutes. This method of extraction helps the cloud to relieve nearly 70 per cent of its moisture. Scientists from the National Centre for Atmospheric Research, Boulder, Colorado, us, along with other researchers from several Mexican universities, are present in full force to conduct the experiments.For the next four summers, the clouds above the state of Coahuila, which is currently in the throes of a severe drought, will be 'seeded' to form rain. The experiments are being funded by the us-based National Science Foundation.