Hailstones are hard, small block of ice. It is a type of precipitation in the atmosphere, that falls from the sky as a bullet of ice. Hailstones are produced during thunderstorm, when raindrops are lifted up into the atmosphere by the rising air. When the rising air reach to a point in the atmosphere that is below freezing point, the rain drops become supercooled and hailstones are formed. The hailstones are suspended in the air in a large cloud by a strong updraft of wind. When the hailstones becomes too heavy, so that the updraft of wind can not hold it, it begins to fall down.