how is it formed?
In strong thunderstorm clouds,with intense updrafts, high liquid water content, great vertical extent, large water droplets, and where a good portion of the cloud layer is below freezing .
Hail
Hail forms in strong thunderstorm clouds, particularly those with intense updrafts, high liquid water content, great vertical extent, large water droplets, and where a good portion of the cloud layer is below freezing . 
what do you call ice falling from the sky Hail or sleet.
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Hail [SEP] Formation
Hail forms in strong thunderstorm clouds, particularly those with intense updrafts, high liquid water content, great vertical extent, large water droplets, and where a good portion of the cloud layer is below freezing . These types of strong updrafts can also indicate the presence of a tornado. The growth rate of hailstones is impacted by factors such as higher elevation, lower freezing zones, and wind shear.