If the dark area is very large, the lateral wind velocity induced by the thermal can overwhelm the prevailing winds and produce continuous flow. The parking lot effectively becomes a huge solar air pump. Thermals from East Coast parking lots can rise as fast as 1,000 feet per minute, and can often lift sailplanes to altitudes of 6,000 feet or more. Seagulls, of course, can stay aloft in much weaker lift.
In my opinion, seagulls are attracted to shopping center parking lots in part because of abundant thermal lift, which allows the gulls to soar while looking for food, just as they do in nature.
When we answered “How Do Fish Return to a Lake or Pond That Has Dried Up? in When Do Fish Sleep?, we focused on the ways that fish or eggs could “hide” in the supposedly “dead” lake and how fish can swim back once water has returned. But one enterprising reader, Paul H. Roek of Madison, Tennessee, wants us not to duck and cover, but to cover the ducks:
Waterfowl, especially the plentiful mallard duck, will dine in an active lake on wild rice and other foods that contain fish and frog eggs. Then, flying to nearby lakes and ponds (whether they are recently rejuvenated by water or not) to rest, nest, or sleep, they “recycle” those ingested eggs of fish and frogs, which hatch and are now located in a new home.
Apparently this mystery was studied in “landlocked” lakes or ponds, those not having a stream, creek, or river flowing in or out. This made sense to me, and I have watched the eating habits of ducks, and found small lakes and ponds in my old home state soon had species of fish that were once not there. I had always guessed that some fisherman had caught the fish in one lake and released them in another.
Speaking of ducking and covering, martial arts exponents are still furious about what many of the boxing coaches said in Why Do Clocks Run Clockwise? about why pugilists make a loud sniffing noise when punching. Rodney Sims wrote to us via the Internet:
In martial arts, you are taught not only to exhale when delivering a blow, but to vocalize along with this exhalation when you wish to deliver a particularly powerful blow. In Tae styles, this explosive exhalation is ke-ai (pronounced “kee-eye”). It serves to focus the chi, which is one’s inner power or spirit located at one’s center (just behind your belly button) and push it through the extremity delivering the blow.
Mystical aspect aside, it does work. I speculate that the philosophy of mind, body, and spirit that must be present in order to excel at any coordinated physical activity manifests in different ways through the necessary translation from teacher to student. Finding a way to connect or relate to a youngling in teaching is sometimes difficult, not to mention reaching more than one.
The martial arts teach you that to control yourself, mind, body, and spirit, is to reach for perfection, and value is placed upon such control: involuntary functions can be controlled, more force can be delivered, and things outside of normal understanding can be understood. Martial philosophy aside, it seems logical to assume that so many people are taught to do it, and consequently practice this exhale, that it does work to focus one’s mind. From my experience, boards are easier to break when you ke-ai.
Does Michael Tyson ke-ai when he bites an opponent? While we muse about that, Ryan Pentoney shot us an e-mail that focused on the physical effectiveness of the sniff:
I have been trained in the martial art goshin ru, and through my four years, I have been taught to exhale on all offensive and defensive maneuvers (punches, kicks, blocks, and some stances and movements). I am not familiar enough to speak for boxing specifically, but I can offer an explanation for fighting in general.
Ira Becker’s stab at the question [the owner of world-renowned Gleason’s Gym pooh-poohed the effectiveness of exhaling while delivering a punch] seemed rather senseless…. In general, the body receives the necessary oxygen through the normal breathing patterns and bodily responses observed under such increased activity (wider nostrils, increased adrenaline flow, and an increased heart rate, more relaxed blood vessels, and the constriction of many of the capillary sphincters leading to the digestive and other “non-essential” organs and systems to maximize the amount of blood oxygen to the muscles and other useful organs and systems). The amount of carbon dioxide and oxygen expelled or inhaled, or an inhibition thereof due to the sharp exhale, is negligible. The time spent sharply exhaling converted into an inhale period would not be constructive, seeing as how these exhale periods occur at the time the fighter is throwing a punch (in the case of boxing) — it would not be advisable.
The next time you’re feeling energetic, try throwing a punch or two in succession while inhaling, and then while exhaling. You will probably find that it is harder to inhale while punching (holding your breath isn’t very good either, as you inhibit gas flow altogether).
I believe that there is a greater purpose to the exhaling than simple gas exchange or a psychological reason. I have been taught that exhaling upon striking, blocking, exploding into a stance, or dodging out of the way of an attack severely minimizes the risk of having the wind knocked out of you. When you exhale quickly, your abdominal muscles tighten up and also protect your diaphragm. The opposite is true when you inhale. The end result is disastrous when you are struck in the upper abdominal area when you inhale, and in a fight can spell the end.
While writing about why power lines hum in How Do Astronauts Scratch an Itch? we made one humdinger of a mistake. Readers Bill Schmidt and Harrison Leon Church echoed the sentiments of Bob Potemski of Mission, Kansas, who wrote:
On page 166 you define 1 Hz as one cycle per second (correct, of course), with AC at 60 Hz. In the next sentence you say, “The generator coil spins at sixty revolutions per minute.” Shouldn’t that be per second? Or have I failed physics?
Nope, we failed physics. This is one case where we blinded ourselves with science.
If our eyes are damaged, let’s see if we can get in trouble with our ears. One reader agreed with our answer to an Imponderable about the effect on batteries when cassette players and radios are turned up to full volume (yes, they do indeed drain the batteries faster). But he was worried that some folks might have been misled by the discussion in Why Do Clocks Run Clockwise? Frankly, we have not lost any sleep over the prospect, but we yield the floor to A. Wayne Hinson of Greensboro, North Carolina:
You said that the power is increased only 30 percent when cassette players are turned up to full volume, implying that the cassette player somehow would use less power and make batteries last longer than a radio. This is not the case. With a cassette player, the bulk of the power is used not to drive the speakers, but rather to drive the electrical motor and tape mechanism. The power actually used to drive the speakers would still increase by about 200 percent at full volume, but because the motor and mechanism use so much more power than even the maximum amount used by the speakers, the increase of the total power used would be a fairly low percentage, as you mentioned.
For example, if the amplifier and speakers draw one-third watt of power at low volume and one watt at full volume, but the motor draws one and two-thirds watts by itself, then total power consumption would increase from two watts at low volume to two and two-thirds watts at full volume, a 33 percent increase. A radio giving an equivalent amount of sound energy would use the same amount of power for the amp and speakers, but would not use any to drive a motor. So even though the increase in power for the radio is a far greater percentage, the total power consumed is far less, yielding drastically longer battery life at any volume, even full volume, than the cassette would have even at minimum volume.
Now that we’ve got that straight, the cassette recorder has become a relic, an endangered species.
Actually, we would be an endangered species if Ann P. Mahoney of Charlotte, North Carolina, had her way. She was annoyed with our discussion of why silos are round in When Do Fish Sleep? We quarreled with the notion that the shape had anything to do with forestalling spontaneous combustion, but Mahoney asserts otherwise:
In When Do Fish Sleep? you pooh-poo
h the idea of spontaneous combustion taking place in a silo. I can tell that you aren’t a scientist. (Of course, you’ve never claimed to be one.) You are also obviously not a farmer who has lost a silo to spontaneous combustion….
Riding stables often store grain and hay for the horses in a separate building away from the stable. That way, if spontaneous combustion does occur, they will only lose the grains and the building but not the horses. Most people don’t know that grains can generate enough heat for spontaneous combustion to occur.
Ann, you correctly pegged us as never having lost a silo to spontaneous combustion. Actually, we didn’t mean to suggest that grains never fell victim to spontaneous combustion, only that the shape of the silo didn’t have anything to do with this problem. But, much as we hate to admit it, Mahoney does have a point. Grains most susceptible to spontaneous combustion are unevenly packed, with air pockets creating mold. Round silos are easier to pack tight. Reader Jason Backs of Houston, Texas, provides another reason why you don’t see rectangular silos:
A silo may reach more than one hundred feet high. The outward force exerted on the walls by the silage is tremendous. A silo built with flat walls would never be able to retain its shape. The walls would bulge out and most likely fail. Exceptionally strong, round silos are built by stacking interlocking blocks in a circular pattern. Steel cables are then tightened around the blocks. The force exerted by the silage is distributed evenly around the entire structure. Silos are actually less sound structurally when empty than when full.
O.K. We’re not farmers, we’re writers! But sometimes even that skill fails us. In How Do Astronauts Scratch an Itch? we discussed why glasses sweat when filled with cold beverages. We included the role of heat and humidity in the process, and ended the chapter with the words, “This explains why glasses, as well as humans, tend to sweat more in the summer.” In no way did we mean to imply that humans and glasses sweat for the same reason. In other words, the average farmer could have stated it more clearly than we did. As I. Getman of Woodmere, New York, wrote:
Cooler glasses sweat because they condense moisture from the humidity of the ambient air; people are perceived as sweating when they cannot evaporate the sweat into the ambient air fast enough, for whatever reason. These are opposite, not similar, phenomena.
We knew that. Really. Really!
Speaking of sweating, we mentioned whether swimmers sweat in What Are Hyenas Laughing At, Anyway? We heard from Carole Hole of the Alachua County Library headquarters in Gainesville, Florida, who attended a sports seminar where this very Imponderable arose:
At one meeting, Dr. Robert Cade, a renal medicine specialist from the University of Florida College of Medicine, who was heavily into sports medicine, described experiments he did to decide that very question. He had his swimmers wear a device to retrieve moisture lost through respiration. He weighed them before and after swimming, subtracted the moisture lost via breathing and provided that they did lose unaccounted-for weight, which could be lost only via sweat.
Cade knows a little bit about sweat — he invented Gatorade (which, of course, was named after “his” football team, the Florida Gators).
They’re not selling Gatorade in jugs yet, but in How Does Aspirin Find a Headache? we asserted that the only reason for those little dimples in plastic milk cartons was to add structural integrity to the container. One former maintenance engineer in the plastics industry wants to add another reason. We yield the floor to Barry Peffer of Plain Grove, Pennsylvania:
The reason we had the discs in the sides of the bottles was for volume control. Those discs bolted into the aluminum mold that forms the bottle and could be changed or have a little bit machined off to adjust the volume of milk in the bottle.
The USDA inspectors and milk sellers want the gallon of milk to come right up to the bottom of the threads in the cap. They have to fill it that full so consumers don’t think they are getting cheated and not getting a full gallon. The [dairies] also naturally don’t want to have to put a couple extra ounces in to make it full, then they are giving away product.
The variables in blow-molding the bottles — temperature of the plastic, temperature of the chilled water that runs through the molds that form the bottle, higher or lower humidity or temperature on any given day, a different truckload of raw material from a different lot number — all affect the shrinkage of the bottle over the first twenty-four hours of its “life.”
So the dimples were there as an easy way to adjust volume. Our inspectors had to check the volume with graduated beakers every shift.
Reader Dennis Parrish agreed with our discussion of why ceiling fans get dusty in How Do Astronauts Scratch an Itch? but wanted to add to the mix:
Dust also collects on regular box fans, even though they spin much faster and are vertical. Here’s the reason: As the fan blade turns, there is a thin layer of air that moves with the blades — essentially tagging along for the ride. More simply put, the air next to the fan blade is static. Dust diffuses into that static air and settles on the fan blade as if it were not even moving.
We weren’t so sure about this theory, so we asked a physics type we know and asked him if he agreed with Parrish’s comments. He replied:
Sort of. It’s true that the very thin layer of air right next to the fan blades is fairly motionless. But I think this explains more why dust particles that are already clinging to the blades aren’t thrown off more often, rather than explaining how the dust particles become attached to the blades in the first place.
To me, his depiction sounds like dust particles enter this “thin layer” and then just float around in there, occasionally clinging to the fan blade. But that layer is very thin. A dust particle would be within that layer only momentarily (less than a second), before it would either become attached to a fan blade or rejoin the turbulent boundary of air in front of the fan and be quickly blown away.
The situation can be compared to a bug hitting the windshield of a moving car. Most of the time, the bug will be blown by the airflow in front of the windshield away from the windshield. Occasionally, a bug will penetrate into the thin (relatively slow-moving) region of air just above the windshield and actually hit the glass. But the bug won’t enter that thin region of air and then just hang around suspended there for a while. Similarly, a dust particle moving toward a fan blade will most of the time be blown away from the fan by the general airflow around the fan. Occasionally, a dust particle will penetrate into the thin layer near the blade and become attached to the blade (it clings to the blade mostly because of static electricity forces, I presume). But the dust particle won’t just float around in front of the fan for a while. If it doesn’t cling, the slightest movement away from the blade will blow the dust particle back into the turbulent airflow around the fan.
The relatively slow-moving air right near a fan blade, or a moving windshield, or a wing of a plane, for that matter, is due to “viscous drag,” or as it is sometimes called, “skin friction.”
When you’re in our line of work, the last name you want to see in your e-mail inbox is “snopes.” Snopes.com, also known as the Urban Legends Reference Pages, is our favorite place on the Web for debunking misinformation. So it pains us to admit that we think David P. Mikkelson, who with his wife, Barbara, are the team behind snopes.com, didn’t buy the explanation for the origins of Baby Ruth that was supplied by the candy’s maker (i.e., that the candy was named after President Grover Cleveland’s daughter, Ruth), nor, as a reader suggested, that the candy was named after the granddaughter of the Williamsons, who created the formula for the candy. David Mikkelson writes:
The Williamsons did not “sell the recipe” for the Baby Ruth bar to the Curtiss Candy Company. The Baby Ruth bar came about when Otto Schnering, founder of the Curtiss Candy Company, made some alterations to his company’s first candy offering, a confection known as “Kandy Kake.”
Mr. George Williamson was the head of Curtiss’s rival, the Williamson Candy Company, and thus
the producer of the Baby Ruth bar’s biggest sales competitor, the Oh Henry! bar. The notion that Williamson would be offering product names to his stiffest competition — or that Schnering would name his bar after a relative of his company’s largest rival — is a bit farfetched, don’t you think?
If we thought clearly, we probably wouldn’t have taken the candy maker’s story as gospel. To read the Mikkelsons’ full discussion of the Baby Ruth story, direct your browser to http://www.snopes.com/business/names/babyruth.asp.
But some of our readers with word origins on their minds have their heads buried in books, bless ’em. Danny J. Elek of Geneva-on-the-Lake, Ohio, read our description of the genesis of the term “Good Friday” and recollected this exchange in John Steinbeck’s The Winter of Our Discontent, which was set on Good Friday:
Ethan Hawley: “Why do they call it Good Friday?”
Joey: “It’s from Latin,” said Joey. “Goodus, goodilius, goodum, meaning lousy.
We wrote a book about word origins, Who Put the Butter in Butterfly?, but one of the words we discussed was a number, specifically “86,” and why it means, among other things, that a kitchen is out of a food item or used as a code to eject unruly or nonpaying customers. Patrick S. Doyen of De Soto, Missouri, writes:
You said that 86 was used in the lingo to denote that the kitchen was missing a particular item. I found it an amazing coincidence that in the military’s Uniform Code of Military Justice, Article 86 is unauthorized absence (AWOL). This could be a coincidence, but it wouldn’t surprise me if the first cook to use this slang was an ex-Army mess cook.
Do Elephants Jump? Page 24
