There have recently been quite a few severe thunderstorms in the Free State. To those of you who don’t live in South Africa, it’s a province that lies quite far inland to the northeast of Cape Town and to the west of the Drakensberg; the magnificent mountain chain that borders the eastern coastline of South Africa. These severe thunderstorms caused quite a bit of grief for the inhabitants of the Free State, levelling 55 houses and hospitalising 5 people, according to All Africa online publication. But in addition to the heavy rains, lightning and wind damage, these thunderstorms had the ill-grace to drop a couple of tornadoes too!
Now, South Africa is not a country known for tornadoes. Nope, if you’re thinking of tornadoes, your imaginative context is probably located in the aptly named ‘Tornado Alley’ in the mid-western states of America. Now, as someone who has a degree in atmospheric sciences, you can imagine how many questions I was fielding from people who had heard about the severe weather events inland. Not questions as such; statements rather. People rarely ask me questions about the weather. I think they’re afraid of the answers. I can handle that… but what I couldn’t handle was the fact that people were confusing hurricanes with tornadoes!
“Did you hear about the hurricanes in the Free State?”
To anyone in atmospheric, Earth, ocean or any related sciences – regardless of your specialization – confusing tornadoes with hurricanes is like confusing your grandmother with Megan Fox. It’s like confusing an elephant with a pineapple. The concept of a hurricane tearing across the Free State is about as alien to the weather educated as a giraffe cavorting around the North Pole. Wearing snow shoes.
But before you cringe at the memory of you making this rather Herculean error, one must take into account that the majority of you out there aren’t weather educated. And that’s perfectly all right! We’re going to change that right now. Hurricanes and tornadoes: what’s the difference? Moreover, what’s the big deal if you get them confused? Well, when it comes to these two somewhat (ok, VERY) tempestuous weather phenomena, size really, really, REALLY…
… really, REALLY, really, REALLY, REEEEEEEEALLY does count.
HURRICANES: KICKING ASS AND TAKING NAMES
Hurricanes are large tropical storms born over the equator. Fed by prodigious updrafts of hot, moist, sexy air, these giant swirling monsters generate, via condensation alone, 200 times the electrical generating capacity of the entire freaking planet, according to the Atlantic Oceanographic and Meteorological Laboratory. For those of you who like numbers or are easily impressed by them, this equates to 600,000,000,000,000 Watts. This is not even to mention the amount of energy generated by hurricane winds, which is an additional 1,500,000,000,000 Watts of unbridled weather rage! I don’t even know what that number is… a billion million? A trillion zillion billon million?
Ooh! Aah! Hurricane Statistics
- Damage: Should they make landfall, hurricanes can cause tens of billions of dollars’ worth of damage. Katrina was only a category 3 storm when it had its fender-bender with the Mississippi Gulf Coast. And yet its damage was estimated at $81,000,000,000!
- Storm Diameter: Hurricanes are huge systems with an average diameter of 800 km (500 mi), although Hurricane Carla, which raged into the Texas coast in 1961, was an especially big girl at 1280 km (800 mi) across.
- Wind speeds: Hurricanes are wrathful systems with category 5 storms (you do not get larger) generating winds of over 250 km/hr or 156 mi/hr.
- Associated Severe Weather: Hurricanes are social creatures. They have loads of friends they like to bring to the party. These include torrential rainfall, thunderstorms, lightning, hail and storm surges, which is an increase in average sea level that can be in excess of 5 meters or 19 feet! Please note: a storm surge is NOT a tsunami. To add insult to grave injury, hurricanes can even generate tornadoes.
- Weakness: For all their size, energy and capacity for total annihilation, these tropical super storms cannot survive over land. They require a tireless volume of hot, moist air – as is found over the equatorial oceanic regions – in order to preserve storm motion and momentum. That dry continental air just won’t do. Plus, all the friction and turbulence caused by onshore topography (mountains and such) tend to break up the party pretty quickly.
“Cow… ‘Nother Cow!”
“Actually I think that was the same one”
- ‘Twister’, 1996
I regard tornadoes the same way a sadomasochist regards nipple clamps: they’re deliciously terrifying. Having said this, my opinion is fantastically unfounded because I have never, ever witnessed or had my house relocated by a tornado. If I had, I would probably drop the adjective.
A tornado is a raging column of rotating air that extends from the ground to the base of its parent cumulonimbus cloud. Cumulonimbus… that’s the longest and fanciest word everyone remembers from High school geography. I know this because every time I tell someone what I studied, they say, “Oh! That’s like, cumulonimbus clouds and shit!”
Yeah, something like that buddy.
Tornadoes are generated by severe thunderstorms in atmospheric environments full of wind shear and abundant lower level moisture (amongst other ingredients.) Next time you’re in the bath or swimming pool, make your hand flat, put it in the water and paddle. You’ll notice tiny little vortices or whirlpools that spin off in either direction. “Wind shear” really just refers to two masses of air moving at different speeds and/or different directions to each other. And, just like your hand in the pool, shear in the atmosphere generates the same kind of ‘whirlpools’ in the air, although you can’t see them because air is invisible. What happens next in tornado genesis is a powerful updraft of air, which pushes these horizontal columns of rotating air vertical. And this is when shit starts getting real.
Ooh! Aah! Tornado Statistics
- Damage: It just takes one tornado to stray into a heavily built up area to rack up damage totals that would bankrupt an entire country. In May of last year, a single tornado tore through Joplin in Missouri – a city of 50,000 inhabitants. The reports that emerged at the time estimated the damage of insured property alone to be in the region of $3,000,000,000 (billion). From a single tornado. And this doesn’t even take into account the uninsured losses suffered. On the brighter side – Tornado, 1: Insurance companies, 0.
- Wind Speeds: Tornadoes are violent creatures. The wind speeds that tear around the funnel – more specifically, of F5 tornadoes – have been clocked in at over 500 km/hr or 315 mi/hr. This is more than half the cruising speed of a commercial aircraft carrier.
- Associated Severe Weather: Like hurricanes, tornadoes are social. You will generally find them hanging out with lightning, torrential rain, giant hailstones, wind (duh) and the occasional cow or 18-wheeler semi-trailer.
- Lifespan: For all their fury, tornadoes are relatively short-lived and generally last a few minutes before dissipating. The longest ‘twister’ on record raged on for 3.5 hours. This suspected F5 tornado, dubbed the Tri-State Tornado, tore through 350 km (220 mi) of Illinois, Missouri and Indiana on the 18th March in 1925, leaving almost 700 people dead in its wake.
While hurricanes may boast more impressive size statistics than a single tornado, one should note that the kinds of thunderstorms that generate tornadoes are rarely isolated and often travel in waves with one thunderstorm cell feeding the formation of several others. Last year, in fact, the National Severe Storm Laboratory recorded the most prolific outbreak of tornadoes in American history! Between April 25th and April 28th 2011, a staggering 358 tornadoes were recorded, with the majority of them having touched down within a single 24-hour period. Thanks to a much more sophisticated weather forecasting and tornado warning system, this outbreak caused half the death toll as the single Tri-state Tornado of 1925.
Class Dismissed: Your Take-Home Message
There are many big and important differences between hurricanes and tornadoes, most of which are related to scale: scale in size, in wind speeds, in damage done and in lifespan. Hurricanes are huge weather systems that last days and can cause widespread destruction. Tornadoes are much, much smaller weather phenomena generated by severe thunderstorms. In spite of their exponentially smaller size and shorter life spans, they can do incredible localized damage and frequently boast wind speeds greater than even a Category 5 hurricane.
So, to sum it all up and pack it in a nutshell:
Tornadoes can rearrange your back garden and perhaps relocate your house.
Hurricanes can rearrange your province and perhaps the entire eastern coastline of your country.