Hail is produced by severe and quite intense thunderstorms. They are caused by strong draughts from freezing clouds. Certain conditions have to be met before hail can grow large and every enough to fall to the grounds. These conditions are:
There must be tall enough clouds that rise much higher above the atmosphere
Violent updrafts such as a tornado
Freezing temperatures that are underneath the storm
Hailstones are the nucleus of the ice and turns into a chain of freezing cold water. Later on this can turn into a snowball. Hail can be very damaging to properties and vehicles. Hail can also hurt and even be deadly to people if shelter is not sought out properly.
Ice is formed when the rain starts to freeze at below freezing temperatures.