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Pellets of ice.
When rising moist warm air in a Cumulonimbus (Cb) cloud becomes saturated and water particles form, these particles continue to be carried upwards by the rising updrafts, turning to ice. These small ice particles then descend where they meet and join together with water droplets and are carried upwards again by the updrafts in the cloud, freezing again to become an ice pellet or Hail The cycle continues, with the ice pellets getting larger each time, until, as the Cb becomes mature, the updrafts weaken and they are insufficient to carry the weight of the ice pellets. At that point the pellets fall to earth. Hail pellets can be as large as a golf ball and can cause considerable damage to aircraft whether on the ground or in the air.
Accident & Incident Reports involving Hail Damage
- A321, en-route, Gimpo South Korea, 2006 (On 9 June 2006, an Airbus 321-100, operated by Asiana Airlines, encountered a thunderstorm accompanied by Hail around 20 miles southeast of Anyang VOR at an altitude of 11,500 ft, while descending for an approach to Gimpo Airport. The radome was detached and the cockpit windshield was cracked due to impact with Hail.)
- A321, en-route, Vienna Austria, 2003 (On 26th May 2003, a British Midland A321 suffered severe damage from hail en route near Vienna.)