Doing the math: 1,000,000,000 x 0.5 = 500,000,000 grams of water droplets in our cloud. That is about 500,000 kilograms or 1.1 million pounds (about 551 tons). But, that “heavy” cloud is floating over your head because the air below it is even heavier— the lesser density of the cloud allows it to float on the dryer and more-dense air.
Planes, helicopters- lots heavy stuff not falling faster than lighter ones
https://www.usgs.gov/water-science-school/science/how-much-does-a-cloud-weigh
Planes, helicopters- lots heavy stuff not falling faster than lighter ones