hail (in the picture is grapefruit size)

Aggregate hailstone. Large hailstone with smaller stones visible. Ruler shows radius of this remarkable hail stone. Diameter is approximately 6 inches - the size of a grapefruit. Credit: NOAA Photo Library, NOAA Central Library How does large hail form or why does hail form?Updrafts within thunderstorms push rain high into the cloud where very cold air freezes it. Once frozen it starts to fall but gets caught in another strong updraft where it gathers more moisture on its way back up making it larger. If the updrafts are strong enough they will continue this process for long periods of time allowing the hail to accumulate more moisture and more moisture. In a severe thunderstorm downdrafts may act like a wedge and increase the intensity of the updraft. Updrafts can get so strong they even intrude into the stable stratosphere. When updrafts are this strong it becomes possible to suspend large hail for long periods of time further adding moisture to the hail, sometimes building it to incredible sizes. Updraft winds can be from 100 to 120 miles per hour when producing baseball and larger size hail.