How does hail form?
Hail only forms in thunderstorms. The reason hail is always formed in T-Storms is because those are the storms that have the strong updrafts that allow hail to grow. Let me explain this further. In a T-Storm there are strong winds going up (called updrafts) and strong winds coming down (downdrafts). Although these winds can be next to each other, if they were to be acting against each other it would weaken and likely dissipate the T-Storm. This is actually one way a storm can fizzle out quickly. These updrafts and downdrafts can reach speeds of 100 Mph or faster! You often feel the downdrafts out ahead of a storm since the wind hits the ground and spreads out as a gust of wind ahead of the storm. Hail can start off as something tiny like an ice crystal and grow to become larger than a grapefruit. How does this happen? Well supercooled water drops are the key (for more on supercooled water drops, click here). These liquid drops suspended in the cloud will freeze on contact with an objec
If you’ve ever dissected a hailstone you’ll notice it’s layered. Hail doesn’t just drop straight down. First the raindrop forms, drops, freezes, and an updraft or strong wild will knock it back up, where more water coagulates around the original particle. This can happen many times, leading to the wide variety in size between hailstones. Some are no bigger than small raindrops, others are colossal – the 1986 tornado in Edmonton, Canada, had hailstones as big as two softballs put together. The violent weather prevented the hail from dropping until it was very heavy, so the stones that dropped were very large, but fortunately relatively few in number.
Tornados aren’t the only hazards associated with thunderstorms. Hail, flash floods and lightning can all be deadly. Hail forms as small objects like ice pellets, water droplets or even insects are circulated by powerful winds inside the storm cloud. Since these storms can reach tens of thousands of feet high, their tops are well below feeezing. With each trip from top to bottom, the object picks up another coating of ice and gets bigger. Eventually, this pellet is too heavy to be kept aloft by the winds and it falls to earth as a hailstone.
Ruby from Cabell County wants to know how hail forms. We’ve had a lot of hail storms in the past couple weeks. When you have a thunderstorm this time of year, you can get hail. In a thunderstorm, it can be very cold in the upper part of the cloud. It can be freezing and even well below zero. You also have what’s known as an updraft. That upward moving air. This can take a rain drop to the upper part of the cloud and freeze it. When it becomes heavy enough, it falls to the ground as ice and that’s what we call hail. The stronger the updraft, the larger the hail stones.
Hail stones start as water drops. A strong wind updraft blows the drops up above the freezing level in the clouds and the drops freeze. When they get heavy enough, they fall. When they fall, one of three things can happen; the hail stone will melt and fall as rain, the hail stone won’t melt and will fall as a hail stone or the updraft will be strong enough to blow the hailstone back above the freezing level and the stone will get bigger.
