Experimental Cloud Seeding Program 1976/1977

Three seasons of single cloud experiments conducted in Rhodesia in 1968/69, 1973/74 and 1974/75 indicated that rainfall could be increased by seeding cumulus clouds with silver iodide, provided that the cloud-top temperatures were colder than about -10°C.... In 1974/75, trials conducted with clouds failing to attain -10°C indicated that silver iodide was nearly always ineffective at these warmer temperatures. It was decided to resume these experiments on warmer clouds in 1976/77, but increasing the quantity of silver iodide used for the seeding, to see whether this succeeded in stimulating rain where the light dose had failed...