Hail is a solid form of precipitation composed of large, layered ice particles called pellets that often have spherical shapes.
This phenomenon occurs during thunderstorms in the could type known as cumulus or cumulonimbus.
The pellets are usually formed around a nucleus composed of ice when it collects cloud droplets or drops of rain. In rare cases, several pellets can clump together and give birth to irregular clumps known as giant hail.
The nuclei themselves are cumulus clouds supercooled water droplets or ice crystals. They are the components of the thunderstorm clouds.
Each cloud has different layers, and the nuclei may travel through them several times. The number of times they are carried determines their size. When they grow too large and heavy for the updraft forces, or get caught in a downdraft, then they will finally fall and reach the ground.
