How does hail form

Hail is a fascinating weather phenomenon that often accompanies severe thunderstorms. These icy pellets, ranging in size from small pebbles to large golf balls, can cause significant damage to crops, vehicles, and buildings. But how exactly does hail form? Let’s delve into the science behind this captivating weather event.

Hail starts as tiny ice pellets that grow in size as they move upwards and downwards within a thunderstorm cloud, called a cumulonimbus cloud. The process begins when strong updrafts carry water droplets high into the cloud. As these droplets are carried upward, they encounter subfreezing temperatures. This causes the droplets to freeze into ice pellets.

Once the frozen droplets reach the top of the cloud, known as the anvil, they are carried by the powerful winds within the storm cell. But the journey is far from over. Updrafts within the cloud repeatedly lift the ice pellets back into the upper regions of the thunderstorm, where they encounter supercooled water droplets. Supercooled water is liquid water that exists below its normal freezing point without becoming solid. When the ice pellets collide with these supercooled water droplets, a fascinating process called accretion occurs.

Accretion is the process by which the ice pellets grow in size. As the ice pellets collide with the supercooled water droplets, a thin layer of liquid water instantly freezes upon contact, coating the initial ice pellet. But this doesn’t stop there. As the pellet continues to be lifted and moved through the cloud, the process repeats, layering the ice pellet with additional frozen water and making it increasingly larger.

The size of the hailstone ultimately depends on the strength and duration of the updraft within the thunderstorm cloud. The stronger the updraft, the longer the hailstone will stay aloft and the more supercooled water droplets it will encounter, resulting in a larger hailstone. It is not uncommon for hailstones to grow to the size of golf balls or even larger if the updrafts are exceptionally strong.

Once the hailstone grows too heavy for the updraft to support, it falls towards the ground. This process is known as downdraft. Larger hailstones tend to fall at higher speeds due to their significant weight. When they finally reach the ground, the aftermath can be quite destructive. The force with which hailstones fall can damage crops, vehicles, windows, and roofs.

The destructive potential of hail depends on various factors, including size, density, and wind speed. Hailstones with irregular shapes and jagged edges are more likely to cause damage than smooth ones. However, the precise mechanisms behind hailstone shape formation are still not fully understood and are the subject of ongoing research.

In conclusion, hail formation is a complex process that involves supercooled water droplets freezing upon contact with ice pellets. As the frozen pellets are lifted and carried through the thunderstorm cloud, they continue to grow in size through accretion. Once the hailstones become too heavy, they fall to the ground, potentially causing significant damage. Understanding the science behind hail formation helps us appreciate the fascinating and powerful forces of nature that can occur within a thunderstorm.