Short answers, pulled from the story.
Rain is a form of atmospheric precipitation made of water droplets that condense from atmospheric water vapor and fall by gravity. It forms when air cools to its dew point and saturates, condensing on nuclei such as dust, ice, and salt, after which droplets coalesce until they grow heavy enough to fall.
Cherrapunji, on the southern slopes of the Eastern Himalaya in Shillong, India, is the confirmed wettest place on Earth, with an average annual rainfall of 11430 mm. Its highest single-year total was 22987 mm in 1861, and Lloró in Chocó, Colombia is probably the rainiest place overall, averaging 523.6 in per year.
It rains more on Saturdays because weekday car exhaust and other pollution build up cloud condensation nuclei over five days, peaking by Saturday. In heavily populated coastal areas such as the United States' Eastern Seaboard, there is a 22 percent higher chance of rain on Saturdays than on Mondays.
Raindrops are not teardrop shaped. Small drops are spherical, while larger drops flatten on the bottom like hamburger buns, and the very largest ones are shaped like parachutes. Raindrops range from 0.1 to 9 mm in mean diameter and tend to break up at larger sizes.
The phrase acid rain was first used by Scottish chemist Robert Augus Smith in 1852. Rain becomes acidic mainly due to sulfuric acid and nitric acid, and on America's East Coast its pH ranges from 5.0-5.6 for Atlantic-derived rain down to as low as 2.0 in local thunderstorms.
Rain holds religious and cultural significance worldwide. The ancient Sumerians believed rain was the semen of the sky god An falling to the earth goddess Ki, and in Botswana the Setswana word for rain, pula, names the national currency. Rituals to bring rain include Native American rain dances and Days of Prayer for Rain in the State of Texas in 2011.