B Initially meteorologists thought these huge ice balls might have fallen from passing planes, but closer analysis revealed they had the "onionskin layering of ice typical of 1hailstones. Hailstones are caused by winds known as updrafts that blow upward in thunderstorms. Droplets of 'supercooled water are carried upwards where they come into contact with ice crystals or dust particles and instantly freeze, causing a hailstone to grow around these particles Hailstones cycle between the updraft and the top of the cloud over and again, growing with each revolution as they come into contact with moisture. At some point they become too heavy and fall to the ground.