How hail is formed

Hail is a fascinating natural phenomenon that captures the attention and curiosity of many. These ice pellets, ranging in size from small pebbles to large golf balls, are formed under specific atmospheric conditions. To understand how hail is created, we must delve into the intricate process that occurs within thunderstorms.

Hail begins its journey as a tiny ice pellet, typically formed within a cumulonimbus cloud. These towering thunderclouds are characterized by their strong updrafts, which play a vital role in hail formation. As moist air rises rapidly within the cloud, it encounters low temperatures at higher altitudes, causing the water vapor to condense rapidly into water droplets. These droplets freeze as they collide with supercooled water droplets within the cloud, forming small ice crystals.

As the updraft continues to carry the ice crystals upward and downward through the cloud, they encounter supercooled water droplets once again. This process continues, with the ice crystals growing larger and larger as they accumulate additional layers of frozen water. Each time the ice pellet is lifted up and down within the storm, it accumulates another layer, similar to the process of rolling a snowball to create a snowman.

The size of the hailstone is determined by the strength of the updraft within the thunderstorm. Stronger updrafts can lift the growing hailstones higher into the storm’s freezing upper regions, allowing them to grow larger before falling to the ground. On the other hand, weaker updrafts may only support the growth of smaller hailstones that eventually melt before reaching the surface.

In addition to the updrafts, hail formation also relies on another crucial component: the presence of a hailstone embryo. These embryos are tiny ice pellets or frozen particles that serve as the initial nucleus for larger hailstones to form around. They are commonly created when a small ice pellet is carried upwards by the updraft, colliding with supercooled water droplets and freezing onto it. Once the embryo forms, it begins to grow as more water freezes onto its surface, gradually forming the characteristic layered structure of a hailstone.

As the hailstone continues to grow, the layers within it become more pronounced. The innermost layer is typically composed of clear ice, while subsequent layers may consist of cloudy or opaque ice. This variation in ice density occurs due to differences in freezing rates and the presence of air bubbles trapped between the layers.

Once the hailstone becomes too heavy for the updrafts to support, it falls to the ground. Often, hailstones fall as part of a hailstorm, creating a spectacle with their striking impact and the sound they produce upon hitting surfaces. Depending on the size of the hailstone and the speed of its descent, damage to property, crops, and vehicles can occur. In rare cases, exceptionally large hailstones can even pose a threat to human safety.

In conclusion, hail formation is a complex process that involves the interplay of updrafts, supercooled water droplets, and the growth of ice crystals around a hailstone embryo. The size of the hailstone is primarily determined by the strength of the updraft, with larger hailstones requiring stronger updrafts to remain suspended within the thunderstorm. Understanding the science behind hail formation enables us to appreciate this atmospheric phenomenon and its impact on our environment.