Electric charge of cloud droplets and drizzle drops in warm clouds along the Mauna Loa-Mauna Kea saddle road of Hawaii Island

Measurements of electric charge on cloud droplets and drizzle drops were performed in clouds along the Mauna Loa-Mauna Kea saddle road on the Island of Hawaii. Positively charged cloud droplets were found to predominate in the upper part of these warm clouds, whereas negatively charged cloud droplets predominated in the lower part. More than 80% of the drizzle drops were observed to be electrified negatively. It is proposed that in warm clouds, cloud droplets are electrified negatively when they are formed at the cloud base, that drizzle drops accumulate negative electric charge through the diffusion process, and that the positive ions are carried upward and attach to the cloud droplets at the upper part of the clouds.