Dear of troy: here is a good URL about hailstone formation:
http://www.islandnet.com/~see/weather/elements/hailform.htm

Once when our carpool was going home at about 4:45 PM, we saw a thundercloud ahead, and
just a few monents later hailstones the size of golfballs were hitting the windshield, threatening to
shatter it. I have read that rising air currents may delay fall of stones and build up extra
layers on them. I have read about military pilots having to eject at high altitudes and having
rising air currents actually causing them to be lifted up quite a ways.