The concept of altering weather soon may get some added credibility. Residents of Mexico's parched state of Coahuila just hope to get some rain.
In a program that links scientists from the U.S. National Center for Atmospheric Research (NCAR) with others working for the Mexican government and agricultural and industrial labs, researchers will test a new technique to enhance and perhaps induce rainfall. In field trials planned for June through October for the next four years, scientists will use pyrotechnic flares mounted on aircraft to seed clouds: as the plane flies at the base of the cloud, the burning flares produce moisture-retaining particles that rise into the cloud and attract water vapor. When the technique succeeds, the water particles become droplets which can become bonafide precipitation.