Near absence of lightning in torrential rainfall producing Micronesian thunderstorms

The near absence of lightning in the torrential rain producing, tall, convective clouds at Ponape, Micronesia was studied by the use of special radiosondes. A unique rainwater accumulation process involving frozen raindrop‐hail formation was found to take place in a narrow layer of altitude just above the freezing level. However, the concentration of frozen particles, including graupel, was one order of magnitude less than that required to trigger lightning. This may be the reason for the weakness of electrical activity in Micronesian thunderstorms.