Flower-shaped hailstones

Q: My friend says he saw different types of hailstones. I never saw anything like them except the stone- like ones. How can different types of hailstones form?

Krishna: Hailstones grow within thunderstorms as water droplets freeze onto ice embryos, such as graupel, and are carried up and down by strong updrafts, accumulating layers of ice. 

Hailstones can be irregular, lumpy, or have bumps and even small spikes. 

Hailstones are classified primarily by their size, ranging from small pellets to large, destructive stones. Common size comparisons include pea, mothball, penny, nickel, quarter, golf ball, tennis ball, baseball, and grapefruit, with larger sizes considered severe. Additionally, hailstones can be categorized by their shape, which may include lumps, bumps, or small spikes. 

Flower-shaped hailstones, also known as hailstones with a "cusped lobe structure," form when ice crystals in thunderstorms develop unique, intricate shapes. These formations occur during the growth phase of hailstones, where they are suspended in the updraft of a thunderstorm, collecting and freezing supercooled water droplets. The specific shape depends on factors like the temperature and moisture within the storm cell. 

Hailstones form when raindrops are carried upwards by strong thunderstorm updrafts into extremely cold areas of the atmosphere, where they freeze. 

As the hailstone continues to rise and fall within the storm, it collides with supercooled water droplets, which freeze onto the hailstone's surface, causing it to grow larger. 

The "flower" or "cusped lobe" shape develops during the growth phase. The changing conditions within the storm (temperature and moisture) can cause the hailstone to grow in a way that creates these distinct lobes or protrusions, resulting in a flower-like appearance.

As the hailstone falls towards the ground, it may melt slightly, revealing the inner structure and the cusped lobes, which can appear quite intricate. 

Flower-shaped hail is often associated with severe thunderstorms, specifically supercells, where the updrafts are strong and rotating, providing the conditions necessary for this type of hail formation. 

In hailstones we have layers. So we start off with an embryo, and then you've got different growth layers. That white growth is what's called dry growth. So basically it's so cold that it's like super cold liquid water freezing on surface. ... All the gas gets trapped inside. So there's lots of air bubbles. They tend to make a weak stone..

Less cold air from climate change could conceivably mean harder hail in the future, but more research is needed to see if that's the case.

Large stones can hurt you and your property.

 Damage from a hailstone is not just dependent on how fast and the exact amount of energy it has. It's how strong are these hailstones. So a really soft one is not actually going to damage your roof very much, especially an asphalt shingle roof. But a really strong one may crack and tear that asphalt shingle pretty easily.

Hailstones contain not only water but also other things too.  So what's in the hail besides water? Past research has found fungi, bacteria, peat moss and microplastics, all of which helps researchers know a bit more about what's in the air that we don't see.