The Kenya hail suppression program

Abstract

Beginning in October 1967, an operational hail suppression  program was initiated in an area located some 130 miles  northwest of Nairobi, Kenya, East Africa. The project was supported by private companies which have approximately 45,000 acres of select tea in production. Within the operational  area, average precipitation is about 71 inches and hail on the  ground is experienced on more than 200 days per year. During  the period October 1967 through January 1975, silver iodide was applied by aircraft at cloud base in the inflow area identified to  be relevant to that volume of cloud which gives birth to, and  allows growth of, hailstones. Program design included a rate of  silver iodide application sufficient to produce ice nuclei  concentrations of 100 - 1,000 per liter effective at -15C within  this important hail producing volume of cloud. A total of 1582  operational days and 2,910 seeding flight hours have been  logged. More than 5,700 individual cumulus cells have been  seeded. In comparisons of hail damage from seeded and non- seeded cumulus developments, the average damage to tea has  apparently been reduced by approximately 40%.