(WKBN) – Hail — Ice pellets or chunks that fall from the sky in the middle of Summer. How does this happen? Well, we call it a storm for a reason. There’s a lot going on in that cloud!
First, we’ll start off by showing you why we don’t always have hail during thunderstorms.
This is a generic, run-of-the-mill thunderstorm. Also known as an air-mass thunderstorm.
It has a short life cycle. The cumulus stage is when we get warm air rising and condensing to higher and higher altitudes. Mature stage is when we have rising updrafts, but now the falling rain causes downdrafts. Dissipating stage quickly follows. The downdraft chokes off the updraft and the storm ends. In order for ice pellets to grow, we need a longer period of sustained updrafts.
A supercell thunderstorm is different. It has some unique qualities. Instead of just an updraft, it has a rotating updraft. We also have horizontal wind shear. Basically, the winds aloft are moving faster than the winds at the cloud base. This helps the updraft and downdraft to co-exist for a longer timeframe. Now hail can start to grow!
Water drops suspended in the air have a unique quality. Even though they can be well below freezing, they won’t freeze until they touch something. We call them “supercooled.” In the
higher ends of the cloud, we have ice crystals. As crystals fall they encounter these supercooled drops and a hailstone is born. As it continues to fall and rise in the turbulent air, it continues to collect more moisture until it falls, due to its weight or it gets blown into the downdraft. Smaller stones can get blown around pretty easily. Larger stones stay put where they’re spawned.
Hail is measured by things we know, pea, penny, nickels, and quarters. Anything quarter or larger is considered severe. The smaller the stones, the more plentiful they are. The larger stones grow at the expense of the smaller ones, so there aren’t as many.
There are many storms that produce hail, but it melts before it reaches the ground. Hail isn’t a guarantee of a tornado, but it definitely gets our attention. The same ingredients for hail formation indicate a turbulent, rotating storm that could produce a tornado.
Hail is serious for aircraft. A commercial plane flying through a hail storm will oftentimes need to land prematurely. Dented nose cones and cockpit windows have been reported. Hail also can take out car windshields and do significant damage to a home’s siding and roof.
Hail Alley is located where Wyoming, Nebraska, and Colorado come together. They average 7-9 hail days per year. Cheyenne, Wyoming is the hail capital of the United States.
