By The Metric Maven
It was an October afternoon, and as I recall, a rather warm, beautiful sunny day, somewhere in the upper 70s F (25 C). I was nine years old and sitting at a desk in my local grade school. As I remember it, we were to get out of school at 3:00 PM for homecoming. Shortly before three o’clock I noticed a small tree outside of our set of windows was beginning to bend in the wind. The wind became stronger and stronger. I could see the tree bend further and further. Our teacher, who was standing at the front of the class with a book in her hand, went to close the window. The wind was blowing so hard, she struggled to close it with her single single hand, as she held a book in the other. There was what seemed like relative silence for a moment after the window closed. The wind continued to increase. At 2:55 PM the lights went out. I watched as a strange set of horizontal grey lines moved from left to right and progressively obscured the view from each window until they all were covered with moving horizontal grey lines. There was a loud roar; it sounded like a train. The custodian ran from room to room, and when he reached ours he yelled out “It’s a tornado, get to the north-west corner.” My fellow class mates scattered almost randomly to each of the four corners of the room. I was crouched behind my desk by that time, and mesmerized by the sight. Every once in a while, in front of the stratified grey lines I instantaneously saw objects just long enough to make them out: a shoe, a can. I did not know it, but I was inside of an F5 tornado. The wind speed would later be estimated at 580 Kilometers per hour (360 MPH).
Something smashed into the front door of the school; the sound of shattering glass punctuated the sound of the tornado. Tree leaves began flowing down the hallway on a cushion of air past our classroom door. A few of the leaves entered into our classroom. It was a surreal experience. Two young girls ran into the classroom with tears flowing freely. They had been in the principal’s office, where the pair had been changing for homecoming. Something had smashed the window in the principal’s office, causing them to flee. The grey lines began to disappear in the same manner they had arrived, and one could slowly and progressively see out of each window. It was raining harder than I had ever seen before. I could suddenly see outside again.
A voice appeared on the public address system of the school. The administrators were afraid there might be a natural gas leak. Everyone was to evacuate immediately. There was a stampede to the school door. When I arrived, I saw that the right hand door had been hit in a manner that folded it in the center, into the school building. I made it out of the remaining open door somehow, but in front of me was the giant root bundle of an uprooted tree. Other children were clawing their way over it through the down-pour, roots, and mud. I was standing next to Doug as rain soaked us both, and told him I wasn’t sure I could make it over the top. Doug was big and very athletic; years later in high school he threw the shot-put. He told me to grab hold of the back side of his belt. I did, and with his aid I made it over the root bundle, and onto the sidewalk.
I thought I was home free. My house was only about 100 meters away. I made it to the corner across the street from my house. I could see it was still there. I waited for a front loader to pass by. I was amazed how quickly people were responding. The school principal saw me and began yelling to come back and go into the next door Junior High building. I argued that I was going to my house. He would have none of it and made me go to the basement of the school.
Downstairs I watched, in the crowded, standing room only, candle-lit room, as some people wept. Some requested divine intervention. Others were terrified the tornado would come back again. I had a scientific bent of mind, and found the idea that the “tornado would come back” rather absurd. It did not. I can say that my view of “grown-ups” took a hit that evening.
The October tornado changed the way people thought in my little town. When the weather became threatening and a tornado watch was issued, I often found myself at the house of friends who had a basement—our house did not. The next year, I was in the basement of a local hair dresser who was terrified of tornadoes. A tornado watch had been issued. At the request of her son, she went upstairs to obtain a glass of water for him. I heard an understated, ill-formed sound of terror, then the sound of a glass shattering upstairs. I ran up as fast as possible to see what was wrong. She was paralyzed with fear and staring. I asked what was the matter, she made only barely recognizable noises as she gestured toward the kitchen window, out of which she was looking. I rushed over and looked out. There it was, a tornado. Again it was grey looking, like the grey across the windows a year before. This one did not fit the classic tornado image. It was not wide at the top and narrow at the bottom, but was of a uniform diameter from the clouds to the ground. The uniform funnel was churning up a nearby farmer’s field tossing debris into the air. It quickly receded back up into the clouds. This was a very ephemeral sight. Someone in town managed to get a photo of it, which I believe was in the local paper.
My experiences with tornadoes (yes there are many more, but I will not further test your patience relating them) have caused for myself a casual fascination with tornadoes. Tornadoes are mysterious and otherworldly, like something out of the Greek myths. The scene of the tornado in The Wizard of Oz with Dorthy’s house rotating as it levitated were very real, and believable. One house in my town had been picked up and moved into a street by the October tornado. The elderly woman inside refused to leave for days when she realized it would be demolished. Some musicians (in my view) have captured the strange surrealism of tornadoes. Jim White’s song A Perfect Day to Chase Tornadoes taps into the emotions precipitated by this strange Midwestern phenomenon. The Drive By Trucker’s song Tornadoes is haunting, with the refrain “it sounded like a train.” That’s how I remembered it. It sounded like a train. I lived one block from railroad tracks, I knew what a train sounded like.
The memories of my experiences with tornadoes were rekindled when I recently read the book Storm Kings — The Untold History of America’s First Tornado Chasers by Lee Sandlin. In the book he relates a terrifying fire tornado, and its strange aftermath. He describes a tornado that was like a moving black mountain which caused some of the worst devastation ever in the US. His strange tales of the effects of tornadoes reminded me of local bricks that had straw driven into them by the October tornado. My father, who is a photographer and printer, documented the devastation, and created what was proverbially known as The Tornado Book. There are many interesting images in it, but for me one stands out as haunting. It is the photograph of a sparrow which was driven into the side of a house by the October tornado like it was a nail. There was a concentric circle of blood around its head. The bird’s mate reportedly lingered around it for a number of days.
How could this happen? I’ve held a sparrow in my hand before. It was so light. It seemed to have a mass of only 20 grams or so. How can these strange otherworldly effects happen from just the movement of air? As I was reading Storm Kings, it struck me that in one of the late Pat Naughtin’s metric newsletters, a reader pointed out that in Boulder Colorado, one cubic meter of air weighs almost exactly one kilogram. It struck me how easy it is to compute the energy of this moving mass of air with the metric system. The amount of energy possessed by a moving object increases as the square of the speed. In this case, using 1 Kg, the formula will reduce to just the velocity (speed) of the air squared then divided by two. This will give us the kinetic energy in joules. The speed in meters/second allows for direct computation, kilometers/hour is offered to render the speeds into contemporary pigfish. When a one meter cube of air is stationary, it has zero kinetic energy. So lets see how the amount of energy possessed by a one meter cube of air changes with speed:
100 Km/h (27.8 meters/second) = 386 joules
200 Km/h (55.6 meters/second) = 1 545 joules
300 Km/h (83.3 meters/second) = 3 469 joules
400 Km/h (111.1 meters/second) = 6 172 joules
500 Km/h (138.9 meters/second) = 9 646 joules
580 Km/h (161.1 meters/second) = 12 977 joules
My reader may be asking: “ok, I see the numbers but what do they mean?” There are many ways to look at this, but let’s take look at how many air cubes are passing by per second. It would be like a string of giant ice cubes passing by, butted up against each other, one right after the other, each having a given amount of energy in it. Well, because we are using metric, and the length of the cubes are one meter, we know that for 100 Km/h (27.8 meters/second) 27.8 cubes of air pass by us each second, and for 200 Km/h, 55.6 cubes pass by each second. We also know how many joules each cube has at its given speed, so we can multiply and find out how many joules of “air energy” pass by each second, but a joule per second is a watt, so we have:
100 Km/h = 10.73 Kilowatts
200 Km/h = 85.90 Kilowatts
300 Km/h = 289.0 Kilowatts
400 Km/h = 685.7 Kilowatts
500 Km/h = 1340.0 Kilowatts
580 Km/h = 2091.0 Kilowatts
A watt is a familiar metric unit used to measure electricity. You can see that the October tornado I was in had approximately 2.09 Megawatts of energy passing through each square meter. A common size of light bulb in the U.S. is one that dissipates 100 watts of power. Let’s look at it in terms of 100 watt light bulbs crammed into a one square meter of area. Note that because it was done with metric we can just drop the Kilowatt designation and move the decimal point on place to the right.
100 Km/h = 107 light bulbs
200 Km/h = 859 light bulbs
300 Km/h = 2 890 light bulbs
400 Km/h = 6 857 light bulbs
500 Km/h = 13 400 light bulbs
580 Km/h = 20 910 light bulbs
Can you imagine how badly burned you would be? You would probably be incinerated in microseconds, if the heat from 20 000 light bulbs was in front of you, and radiating through only a one meter area? Computations like this are sobering. When I look at the October tornado this way, I wonder how anything could have possibly survived. The devastation I witnessed was astonishing. The original Easy-Bake Oven used two 100 watt light bulbs for baking cakes.
What I have done may look complicated to some of my readers, but if I had not used metric values, it would have taken many, many more computational steps. If I had started with a square yard cube instead, and computed the values using Olde English units, well it would have been—well—horribly complicated. Would you use the poundal-foot, or pound-force-foot? Would we express the energy in British Thermal Units? (BTUs). Do BTUs actually mean anything to US citizens? The only time I saw BTUs was in ratings for air conditioners. After a purchase I forgot them immediately. Perhaps we should use Therms instead? As many of my instructors said: “I will leave it for the student to complete as an exercise.” The point is, I was able to do all these computations without consulting a single text book—using metric. This would not be possible if I had been forced to use Olde English units. The waste of energy (human and otherwise) caused by Olde English units in the US remains essentially unexamined, but I’m sure it’s significant. Because we don’t have metric in this nation, it will continue to produce a tornado of wasted effort and leave a devastated, yet unseen landscape across the US.
(Note: These are just back-of-the-envelope estimates for illustration which may or may not be consistent with those of professional meteorologists. Clearly air is compressible and the masses would be inaccurate from this property.)
Postscript: A smaller tornado hit the very north end of Belmond Iowa on June 12, 2013 (2013-06-12). In this era, many films exist of the destruction, one is here. The tornadoes themselves were also filmed. There is film of the damage done by the October 14, 1966 tornado here.
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