well, here's from the Wikipedia:
Quote:

Hail is a type of graupel, a form of precipitation, composed of spears or irregular lumps of ice. It occurs when supercooled water droplets (remaining in a liquid state despite being below the freezing point, 0°C/32°F) in a storm cloud aggregate around some solid object, such as a dust particle or an already-forming hailstone. The water then freezes around the object. Depending on the wind patterns within the cloud, the hailstone may continue to circulate for some time, increasing in size. Eventually, the hailstone falls to the ground, when the updraft is no longer strong enough to support its weight.



Hail

never heard of graupel.

formerly known as etaoin...