What factors govern the ultimate size of hailstorms?

Answer 1

Hail forms due to thunderstorms carrying water upwards, and past their freezing point. As the tiny ice balls known as hail float around in the atmosphere, additional water freezing onto them causes them to grow.

Answer 2

Hail forms when updrafts keep water droplets on a course of up and down patterns. First, the water droplet freezes as updrafts push it upward. Then, it falls back into warmer parts of the cloud. As more water collects onto it, another updraft pushes it up freezing the newly attached water covering. This process repeats many times until the updraft is not strong enough to keep it in the air. It falls to the ground as hail. You can see how many layers the hailstone has by cutting it open and revealing the rings. The difference in size depends on how long it stays in the process.

Answer 3

The final size of hailstones depends on how many times the forming hailstone (frozen water droplet) has been tossed back into the higher altitude, so gaining another layer of ice. Eventually, the size and weight becomes too much for the clouds to carry, and hailstones begin to fall to earth. While soft hail, or small hard hailstones are the norm, sometimes hailstones the size of Golf balls may happen (take cover!).