On Hurricanes, And Why They Suck So Hard
Excerpted from Man Vs. Weather: How To Be Your Own Weatherman
You may remember all the way back to the Introduction (we were so young then, weren’t we? You’ve really let yourself go…) when we discussed that wonderful piece of American history that will forever make little girls named Katrina feel a vague sense of guilt. Well, that was a hurricane, probably the most destructive, cruel and unnecessary weapon that Weather has in it big weapons chest. Tornadoes are one thing—they’re crazy powerful and extremely dangerous, but they’re small. They don’t last all that long.
But a hurricane… You can see them motherscratchers from outer space! They’re hundreds of miles from end to end. They look like the gigantic blurred blades of the world’s largest desk fan, but without the protective grating, so anything they land on just gets pulverized. Winds and thunderclouds just spinning and spinning at phenomenal speeds, sending raindrops pelting against your face as you try in vain to shield yourself. Water levels rising and waves beating against your car and your front lawn, while flood waters pound against your front door. Will you let them in? You might not have a choice.
If tornadoes are the elite ninja assassins of Weather’s evil army, then hurricanes must be the marauding battalions of bloodthirsty barbarians. They’re not content with killing hundreds of people. They kill thousands of people. Sometimes tens of thousands of people. Sometimes even tens of tens of thousands of people.
In November of 1970, a hurricane that formed in the warm waters of the Bay of Bengal off the coast of southern Asia tore through West Bengal in India and East Pakistan. Hurricanes are measured on a scale of Category 1 to Category 5, with 1 being the most refreshing and 5 being the most deadly and unrefreshing. This was a Category 3. (And you might think that’s not so bad, but you may recall that Katrina was a Category 3 when it made land in Louisiana. And you know how that turned out.) Winds picked up to 130 mph, but since in that part of the world, they use kilometers instead of miles, it meant the winds reached 205 km/h, which just made matters that much worse. Waves rose fifty miles into the air. (Actually, that’s not true. I embellished a bit. It was actually fifty feet, but when I wrote that it didn’t seem so impressive. But if you ever saw a fifty-foot wave coming at you, you’d pass your lungs through your lower intestines.)
At the time, India and Pakistan weren’t getting along so well, so even though there was a lot of information coming into the Indian government about the brewing hell-storm, it’s not clear why the East Pakistani people didn’t seem to have any idea they were about to get demolished. People just weren’t prepared, and colossal towers of water swept over them by the thousands, carrying them back out into the bay where they either died or learned to breathe underwater real quick. Either way, most of them were never heard from again.
All told, when Weather had had its fun and decided to recall its barbarians, somewhere between 300,000 and 500,000 people were dead. The difference between those two numbers is about the total population of Jersey City, New Jersey. When you can’t narrow a death count down any closer than that, you’re talking about a lot of dead people. To put it into even better perspective — in case you’re having a difficult time wrapping your head around nearly a half-million people dying all at once — more than half of the local population had died. That’s what “tens of tens of thousands of people”means. Sure, I could have said hundreds of thousands of people to begin with, but it was more dramatic to do it this way.
Hurricanes don’t just form out of nowhere; they’re not just really big storms that occur randomly. They’re complex and precise Weather machines. Luckily for us, there’re all kinds of things that can go wrong in the formation of a hurricane. For every hurricane that Weather could conceivably create, only a fraction of them turn out. Thank God.
First of all, a hurricane needs to feed off heat energy. And the only place they can get a strong enough supply of heat is in the tropics — often off the coast of Mexico or in the North Pacific between July and November — where they can find water temperatures of 80°F or higher over a large distance; that’s why you don’t see the coast of Nova Scotia getting barraged. It also needs light winds, high humidity and a strong Coriolis force to get its winds a’spinnin’. Hurricanes don’t occur close to the equator, because the Coriolis effect is practically nothing down there. Most of them form between the latitudes of 10° and 20°.
A hurricane will begin forming when a couple different thunderstorms converge on one another over a somewhat large area of warm water. Many of these storms may themselves be dissipating hurricanes or hurricanes that never quite made it. In the Atlantic, they often originate as dust storms in Africa. If the surface winds are spinning properly, such that they direct, in the Northern Hemisphere, the storms are sent turning in a counterclockwise (or cyclonic) direction (in the Southern Hemisphere, the opposite would need to be true, with winds blowing clockwise or anticyclonic), the storms form, Voltron-like, into a tropical disturbance (or a tropical wave). It’s not a hurricane yet, but it’s on its way to becoming one.
While the tropical disturbance is spinning, it’s sucking up the warm water beneath it, gaining energy to spin faster and strong. And it’s also generating its own energy by condensing water vapor into rain particles and keeping the residue heat from that process for itself. The disturbance keeps getting more powerful and volatile, while cumulonimbus clouds and thunderstorms develop it its curving movements and the air pressure towards its top rises. Consequently, the higher pressure air begins to get flung outward, toward the area of lower pressure on the outside of the developing storm, which in turn causes a low pressure area below. Surface winds rush inward spinning counterclockwise with the storm winds, pulling all the winds in tighter.
Remember that Sit ‘n Spin toy you had as a kid, and how you would just turn yourself around that little steering wheel in the middle until you couldn’t differentiate the color blue from the smell of chocolate? (What a terrible gift to give to a child.) Remember how when pulled your body in really tight to the steering wheel you could make yourself spin even faster and get even sicker? Well, that’s pretty much the exact same thing that’s happening here. As the winds cluster tighter, they spin faster. They still have the same energy, but they don’t have as far to go around the center, so they just move around it more quickly. This increases the power of the disturbance, and as the disturbance gets more powerful, it sucks up more energy. It’s kind of a cyclonic cycle. Before long, the winds are going 25 to 40 mph, and the tropical disturbance is upgraded to a tropical depression, named for both the decreased air pressure beneath it and the general mood of any islanders who happen to see it forming.
This just keeps on going. It gets stronger and the surface air pressure drops and it converges which makes it faster which makes it stronger which makes the air pressure drop which makes it converge which makes it faster which makes it stronger which… Well, it goes like that for a while, until the winds pick up to 74 mph. At that point, it’s a full on Category 1 hurricane. And what you may notice is that it now has a distinct doughnut hole in its center. That is called the eye. Right there in that eye, everything is calm. There’s very little wind and the sky is clear. It’s ironic, because completely encircling the eye is the area of the strongest winds and most intense storms, the eye wall. The winds of the eye wall are spinning so fast, trying so hard to get into that eye, but because they’re spinning so fast and trying so hard, they can never quite make it. (It’s called centrifugal force, and if you don’t like it, you can talk to Isaac Newton about it.)
While all this is happening, the storm is now like an immense, briny dreidel spinning across the surface of the ocean. If, in its travels, it keeps encountering warm water and conditions that keep it spinning, it will continue to gain energy and momentum. It’s already increased many times in size, but it can get really big. Possibly to several hundred miles in diameter (or half of several hundred feet in radius). And, who knows where the dreidel will spin next, but you can bet that wherever it is, it won’t be bringing any Chanukah cheer.
There are some things that will bust up a hurricane. Strong winds, particularly if higher winds are moving in different directions at different altitudes. This tends to mess up the hurricane’s groove, and then its winds lose focus and go off in different directions. A loss of heat will starve it. So, if the hurricane spins too far north into the cooler high latitude waters, it’ll spin itself right out of a good thing. Same if it goes too far south. The Coriolis effect peters out closer to the equator, and it needs that Coriolis effect to send its air spinning off clockwise from its top, so it can maintain its reactive cyclonic movement at its base. Otherwise, again, the winds lose focus and dissipate.
Another thing that will definitely bust up a good hurricane is hitting land. When it loses its supply of warm water, its clock starts winding down. But, you know, killing a hurricane with landfall is not the way to go. For the people whose homes are on the land that’s stopping the hurricane’s spin, it’s a little like jumping on a grenade.
The first thing you can expect is increased wave height at the shore—they might come as a harbinger a few days in advance, creating swells 30 to 40 feet high. Enjoy the surfing now, because that surfboard is going to get rammed through a wall soon enough. As the hurricane approaches, the air pressure will drop, which will actually cause the sea-level to rise. You might arrive at the beach to find it not there, with waves lapping your feet in the parking lot. Then comes the rain. It’s a lot of rain. Like, maybe 15 to 20 inches in a day’s time. If you’re lucky. Oh, and wind. Lots and lots of wind. As the hurricane descends upon you, that’s when you get the storm surge, a ridiculous rise in water-level by at least five or six feet in a Category 1 or 2, and 20 feet in a Category 5. (Best case scenario, you never get close enough to a Category 5 hurricane to confirm that.)
The rise in water-level from the surge, combined with the heavy winds and the waves they bring, is probably the most destructive part of the hurricane, causing severe flooding and ridiculous property damage. The water comes pouring over your feckless, meager levees like nothing, like it wasn’t even there, like you wasted several days hauling sandbags around like an idiot for no good reason. Because now the water’s coming over and you can’t outrun it, and it takes you and it treats you like it caught you stealing a dirty magazine from its news rack. It just takes you and it hurls you around, smashing you into trees and cars and a shopping cart which was left in the street for some reason. If you can get up from that, you need to get to high ground fast. Any high ground you can find. That tree over there? Climb it! But be careful, hurricane winds have been known to send two-by-fours right through trees. Even if you manage to dodge the two-by-four, that wind isn’t likely to be any more gentle with you.
If you do keep your head and you’re wearing your lucky t-shirt, you just might make it out alive. But, do keep in mind, if the clouds suddenly vanish and the winds abate, the storm might not be over just yet. One morning in 1926, a bunch of people new to Miami Beach, Florida experienced something very similar. The winds that were rocking their nouveau riche hurricane gala all night had stopped. Just stopped. Everything was calm and beautiful. Unfamiliar with hurricanes’ tricks, many of them — ignoring the fevered warnings of a local meteorologist — wandered drunkenly down to the beach to admire the picturesque ring of dark clouds surrounding them. Some of them even waded into the warm ocean water for a morning swim. Within minutes, the calmness of the hurricanes’ eye — in which they had momentarily found themselves — passed them by and they were instead confronted with the violence of the eye wall. Over one hundred people never made it back to their party, or anywhere else for that matter. But you don’t have to make the same mistake. Take this opportunity to jump down from the tree and get yourself into a sturdy house with several floors. But don’t pull the surfboard from the wall it was rammed through and try to get all Dogtown on the waves right now. It’s not worth it.
Hurricanes have caused a lot of damage to human society over the years. They’ve also caused us decent amount of confusion. Like the live pig that one wedged into a tree fifteen feet up in a tree. Why and how? Or the swarm of thousands of butterflies another carried out into the middle of the South Pacific where they flew over and past a boatload of confused sailors. Was that necessary? Or was it just Weather’s idea of fun?
Maybe the weirdest thing that a hurricane has ever done was back in 1876 in North Carolina, when the winds lifted an entire church up from its foundations and carried it floating down the road, around a corner, to another location in town which was — get this! — the place where the parishioners had wanted the church built in the first place. It’s popularly known as the Church Moved by the Hand of God. It’s a very sweet story. Much nicer than when, 24 years later, that same hand of God killed 6,000 citizens and razed the town of Galveston, Texas, in what has long been considered one of the worst disasters, natural or otherwise, to befall the United States. That’s a less sweet story.
From Man vs. Weather: Be Your Own Weatherman,
by Dennis DiClaudio.
Penguin, 2008
