From AMS Glossary
Procedures to prevent the occurrence of lightning.
Seeding below cloud base with 10-cm fiber chaff in a Colorado study resulted in corona discharges that caused a discharging current to flow within developing or active thunderstorms. Electric fields below thunderstorms seeded with chaff decayed much faster than electric fields below nonseeded storms, and chaff seeding of existing thunderstorms greatly reduced cloud-to-ground flashes compared to nonseeded storms. Recent evidence suggests that chaff releases may result in a significant decrease in downwind cloud-to-ground lightning. Another experimental approach is to use lasers to discharge lightning in an overhead cloud in order to divert the flash from striking people or highly sensitive equipment on the ground; more research is needed to make this a realistic method of lightning suppression. In the 1960s, seeding with silver iodide was considered in order to produce an excess of ice crystals to cause numerous coronal discharges within the thunderstorm and reduce the need for the flash to reach the ground, but the test results were complex and difficult to identify. Finally, electric space charge was released into the atmosphere from a network of high-voltage wires on the ground to produce corona discharge, but a field test showed minimal effects on suppressing lightning.