Short answers, pulled from the story.
Hail is a form of solid atmospheric precipitation made of balls or irregular lumps of ice, each called a hailstone, produced inside thunderstorms. It differs from ice pellets, which Americans call sleet, because ice pellets generally fall in cold weather while hail growth is greatly inhibited during low surface temperatures.
Hail forms in strong thunderstorms with intense updrafts, beginning as water droplets that rise and become supercooled before freezing on condensation nuclei. The updraft, with winds as high as 110 mph, carries the hailstone through varying zones of humidity and supercooled water, building alternating translucent and opaque layers until its weight overcomes the updraft and it falls.
The largest hailstone by diameter officially measured was 7.9 in across in Vivian, South Dakota, on the 23rd of July 2010. The heaviest weighed 1.02 kg and fell in Gopalganj District, Bangladesh, on the 14th of April 1986, while the largest circumference of 18.74 in was recorded in Aurora, Nebraska, on the 22nd of June 2003.
Hail occurs most frequently within continental interiors at mid-latitudes and along mountain ranges. Kericho, Kenya averages hailstorms on 50 days a year and once recorded 132 days of hail in one year, and central Argentina from Mendoza to Cordoba sees 10-30 storms per year, while Cheyenne, Wyoming is North America's most hail-prone city with nine to ten hailstorms per season.
In 2023, hailstorms cost the United States $46 billion in damage to cars, roofs, and crops, according to the Insurance Institute for Business & Home Safety. Wheat, corn, soybeans, and tobacco are the crops most sensitive to hail, and aircraft can be seriously damaged within seconds once hailstones exceed 0.5 in in diameter.
Efforts to suppress hail date to the Middle Ages, when Europeans rang church bells and fired cannons, an idea that survives as modern hail cannons. After World War II, cloud seeding with silver iodide was claimed to cut Soviet crop damage by 70-98%, but those results were never reproduced in randomized Western trials, and 15 countries ran hail suppression programs between 1965 and 2005.
Terminal velocity of hail rises with size, with a 1 cm hailstone falling at about 9 m/s and an 8 cm hailstone reaching 48 m/s. The exact speed also depends on the stone's drag coefficient, wind, collisions with raindrops or other hailstones, and melting, and because hailstones are not perfect spheres their drag is difficult to calculate.