Goodness, Gracious Great Balls of Ice!

Large hailstone damage

Some things on our planet are so ridiculous that when you really think about them, it’s enough to make you go biblical. Frogs falling from the sky, crop circles, giant swirling hurricanes, belching volcanoes, sulphur-based life forms and Paris Hilton’s immense wealth (and equally as immense lack of IQ). And then there’s hail. The fact that the updrafts within a thunderstorm can be strong enough to hold grapefruit-sized hail in suspension is nothing but ridiculous and wholly impressive.

Great balls of ice!

How Hail is Made 

Falling hail thunderstorms

Hail consists of balls of ice shockingly called “hailstones”. You may even say that hail is frozen rain, but it deserves a slightly more complex explanation than that…

Hail is made within powerful thunderstorms or cold fronts. Cold fronts tend to produce smaller hail that might inconvenience your dog’s plans to go do his business outside (thereby inconveniencing your plans to keep your house hygienic). The large hail responsible for denting cars, destroying crops and severely upsetting your heard of cows is typically associated with large thunderstorm systems that are well-endowed in the vertical and are sustained by powerful updrafts. These traits are especially exhibited by the “Big Daddy” of all small-scale tempests: supercell thunderstorms. These you will find all over the world, but most notoriously skipping across “Tornado Alley” during the northern hemisphere’s summer months.

Supercell thunderstorm
Supercell thunderstorm with rotating mesocyclone (*swoon!*). The presence of such large frozen water particles within the cloud selectively reflects light towards the lower energy (green) end of the color spectrum, which is why thunderstorms that produce large hail tend to make the sky appear a ghostly green.

What cold fronts and thunderstorms have in common is that they are both low pressure systems that suck in air and expell it out their rear. Thunderstorms pull in great volumes of warm and moist air, which rise, cool and condense to form towering cloudy behemoths. Yes, cumulonimbus clouds. The air, once cooled, loses its momentum and proceeds to sink towards the ground. Together, these two channels of air comprise the updraft and downdraft zones that sustain a thunderstorm: its lungs if you’ll indulge a bit of poetic licence.

Now, as you know, temperature decreases with height in the atmosphere. That’s why the tops of high mountains are frozen and it’s why you should always, ALWAYS go for a pee before sky diving. At a certain altitude within a thunderstorm, which can soar to as high as the interface between the troposphere and stratosphere at approximately 10 km above sea level, the temperature reaches zero degrees Celsuis – the temperature at which water freezes. Above this 0°C isotherm (an obnoxious way of saying “line of equal temperature”) all the water droplets in suspension are frozen.

The strong updrafts within a thunderstorm sweep water droplets above the 0°C isotherm where they freeze (consult the pretty diagram below). These pellets of ice then fall back down towards Earth in the downdraft zone, plummeting below the 0°C isotherm and defrosting into big globs of water. This is why thunderstorm rain gets you soaking wet in 10 seconds flat. Just like Channing Tatum in “Magic Mike”.

hail-formation-diagram

However, some of these falling frozen pellets of rain get caught up in the updraft zone again and are swept back up above the 0°C isotherm. Only, they’ve gained a layer of water, which they collected as condensation while chilling out below the 0°C isotherm. This additional layer of moisture freezes, forming a new layer of ice over the original ice pellet.

Concentric layers of ice_hailstone
Concentric layers of ice in a hailstone. Just kidding! It’s a microscopic image of a bacterium’s nipple.

This process can repeat itself several times and each time, the hailstone will grow larger and larger and larger as it collects more and more layers of ice. The next time you’re in the middle of a raging supercell storm, run outside, collect a couple of decent-sized hailstones, run back to the tornado shelter, bolt the trapdoor, watch your dad arm wrestle said trapdoor with an F5 tornado, watch your dad lose, resolve to become a hardcore white vest-wearing, tornado chasing sexpot with a serious deathwish. Oh! And remember those hailstones you collected? Cut them open to see those concentric circles of icy awesomeness.

When a hailstone finally gets too heavy for the thunderstorm’s updrafts to hold in suspension depends entirely on the strength of those updrafts. The stronger they are, the heavier the hailstones. This is why larger hailstones are associated with powerful thunderstorms, such as the Midwest supercells that are sustained by incredibly strong updraft zones.

And when hailstones get heavy, it’s time to run for cover.

large hailstone damage

 Sorry Boys… Size Really Does Matter

Farmers are more obsessed with size than that clutch of vacuous floozies and jockstraps in Jersey Shore. Considering their livelihood depends on it (and not their egos), this is easy to understand and empathize with. But, in no other aspect are they more obsessed with size than with hail. The happiness and health of their livestock and crops depend on it.

Some thunderstorms can create hailstones that are big enough to cave your head in. Even if you do have brains. The next time you’re at a party, scoop an ice cube out your rum and coke and toss it at your mate (preferably the one who’s hitting on your girlfriend). Listen to the dulcet sounds of squealing as it clobbers him in the noggin. Now imagine something easily ten times the size of that ice cube falling thousands of metres (or feet) from the heavens. Yup! Ouch.

Largest hailstone on record
Ermagherd! Ferkerng HUGE herlsterne!

On 23rd June 2010, the largest hailstone in recorded American meteorological history fell in Vivian, South Dakota (image above). This great ball of ice weighed in at 0.88 kg (1.93 lbs) and was a staggering (if it had hit you in the head) 20 cm (8 inches) in diameter.

That’s two inches longer than your average you-know-what, tee hee!

 Class Dismissed: Your Take-Home Message

hail_storms-on-road

Hailstones are physical evidence of the incredible air circulations going on inside a thunderstorm. Can you imagine how strong air must be to prevent something that weighs almost a kilogram from succumbing to gravity? I don’t know about you, but that blows my mind in the most delicious way. And so we see that thunderstorms are about so much more than just thunder and lightning and the occasional airborne cow. These bad tempered weather systems can also be that jerk at a party who throws ice at you.

But, then again, you were chatting up his cherry.

Author: Thea Beckman

Domain Eukarya, kingdom Animalia (Metazoa), phylum Chordata, class Mammalia, order Primates, family Hominidae, genus Homo, species Homo sapiens, subspecies Homo sapiens sapiens... essentially. I have a Master's Degree in Atmospheric science, which doesn't entitle me to be generous with my opinion, but my sense of self importance does! I love writing, I love science, I love reading, but I'm not nuts about long walks on the beach. Short to medium walks are preferable. This is my blog and I have something important to say: https://whybecausescience.wordpress.com/

25 thoughts on “Goodness, Gracious Great Balls of Ice!”

  1. That is fairly awesome right there. I did miss your take on things Ms Beckman. I hope you don’t start throwing ice cubes all willy-nilly now!

    1. Thank you so much! I missed my blog terribly and a few-month hiatus has provided me with the insight that these humble virtual pages are what I am most proud of in this world. The fact that people from all over the world (such as yourself) have found it worthy of their time and devotion is beyond all expectation. Thanks again for your comment, Joetwo.

  2. By the way, “cherry” is South African slang for “girlfriend”. It was brought to my attention that this colloquialism would leave my international audience scratching their heads.

  3. Well at least now they learning about the science-y things as well as some local lekka slang. Kudos on the drop about Ms Hunt. The Supercell thunderstorm with rotating mesocyclone. Where would this normally occur?

    1. Absolutely! I never try to hide my SA heritage in my language. I even shun American spelling! I knew I could trust you to spot that Twister reference. I still have fantasies of Helen stormchasing my hunt. To answer your question… these kinds of monster storms are most typically found in very unstable environments where there is abundant moisture and heat in the lower atmosphere and a cold dry upper atmosphere. Tornadp Alley is the example I keep using, but there are places all over the world that experience severe thunderstorm activity – west of the Drakensberg is a good example. You get warm moist air flowing in from the Agulhas current region, which is overlain by the cold dry air masses from the western deserts. This causes instability, convection, condensation and an enormous release of energy. The Freestate frequently experiences tornadoes and large hail, but not at the same scale as the states. We rarely get F4, F5 twisters.

      Now, to make matters slightly more complicated, there’s another important ingredient you need to make a supercell thunderstorm complete with rotating mesocyclone – wind shear, which is basically a term that describes two air masses moving at different directions and speed to each other. This kind of motion generates little eddies or whirlpools of air, which are then pushed upright by the strong convection currents in the thunderstorm. This is how tornadoes are born. Like I said, there are many places in the world that can experience severe thunderstorm activity. Most are confined to the tropics and sub-tropics where there is lots of water vapour and heat.

      1. nice to see someone else not ashamed of a south african heritage – think i’ve mentioned i was born near where you work? anyway – living in jo’burg now, and we do get fist sized hailstones up here now and then. and i am so glad, ms beckman, that you remembered to mention the highveld in this missive. we do not compare to tornado alley, it’s true, but you try insuring a vehicle against hail damage at a reasonable price up here . . . impossibilities do indeed exist . . .

      2. Struth, those highveld storms are something! I remember spending a few nights in the Drakensberg and while I LOVE thunderstorms, I actually found myself scared during the night. A massive storm was raging overhead and the noise was unbearable! I would say you’re lucky to be able to witness such cool weather at work, but of course there are the inconveniences to consider. The high price of insurance – as you mentioned – is just one. Your dog being de-brained by a falling hailstone is another.

  4. i hope no bacteria from the bacteria board of censors show up to give you grief for showing a rude bacterium pic . . .

      1. interesting blog/website. hope your broken arm mended! The random sydneysider who passed thru cape town late one night, cheers.

  5. yep. ‘well met’ haven’t heard anyone use that expression for a long time – we use far too much slang in Oz! cheers.

  6. I’ve only just found you!! Two posts in and I’m hooked!! This is reminding me that I definitely chose the wrong path in ‘Psychology’ on leaving school!!! Should have stuck at the old Physical Geography!!!

    1. I’m flattered that my blog could make you question your entire career focus, but I don’t think it should. Scientists are obsessive and tend to display certain anti-social, if not downright sociopathic tendencies. I.e. WE NEED YOU!!

  7. Today we had a hail storm here (Northern New Mexico) and the stones were very impressive. They were only pea-sized, but some were round and others triangular. It was Mother Nature,ie., a Scientific Wonder, at her very best… (May 8, 2014)

    1. We hardly ever get impressive hail here in Cape Town (South Africa). We have a Mediterranean climate, so our rain is brought to us by cold fronts. It doesn’t do much to satisfy my obsession with extreme weather. The largest hailstones I’ve ever seen were the size of marbles and that was up the east coast where the climate gets more tropical and the weather more awesome! Needless to say I was dancing around like an idiot having braingasm after braingasm at the size of the hailstones while sheltered under the overhang of the house.

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