Perhaps we were dozing during some of the year 2000 hoopla, but much to our surprise, the IHO was involved with a rather important event in that year—the debut of a new ocean. The southernmost parts of the Pacific, Atlantic, and Indian oceans (including all the water surrounding Antarctica), up to 60 degrees south, were dubbed the “Southern Ocean.” The name was approved by a majority of the IHO and went into effect in 1999, with Australia among the dissenters. Why wasn’t this a bigger deal than Y2K?
Submitted by Bonnie Wootten of Nanaimo, British Columbia. Thanks also to Terry Garland, via the Internet.
* * *
WHY DO WEATHER THERMOMETERS
USE RED CHEMICAL INSTEAD OF THE
SILVER MERCURY FOUND IN
MEDICAL THERMOMETERS?
* * *
The liquid found in weather thermometers is usually alcohol with red coloring. The main reason why alcohol is preferred over mercury for weather thermometers is that it is much, much cheaper. And alcohol is superior to water because alcohol is far hardier—it won’t freeze even at temperatures well below -40° Fahrenheit.
Why the red additive in weather thermometers? So that you can read it more easily. If weather thermometers used a liquid the color of mercury, you’d have to take the thermometer off the wall to be able to read it.
Since the advantages of alcohol are so apparent, why don’t medical thermometers, notoriously difficult to read, contain red-colored alcohol instead of dingy mercury? Despite its greater cost, mercury is prized for its greater expansion coefficient—that is, it expands much more than alcohol or water when subjected to small increases in temperature. A weather thermometer might measure temperatures between -30° and 120° Fahrenheit, a span of 150°, while a medical thermometer might cover only a 10- to 12° range. A doctor might want to know your temperature to the nearest tenth of a degree; if a liquid with a small expansion coefficient were used, you would need a thermometer the length of a baseball bat to attain the proper degree of sensitivity. We don’t know about you, but we’ll stick with the stick thermometer.
Couldn’t the medical thermometer manufacturers color mercury, then? Actually, they could, but don’t, for reasons that Michael A. DiBiasi, of Becton Dickinson Consumer Products, explains:
When you produce medical instruments, the rule of the road states that the fewer additives that you incorporate into any device or component material, the better off you are in gaining approval to market the device, and in avoiding product recalls that may be tied in to those additives. So fever thermometers use mercury in its natural silver-white color, and the glass tube is usually silk-screened with a background color to make it easier to see the mercury level.
Submitted by Herbert Kraut of Forest Hills, New York.
* * *
WHY DOES SHAMPOO LATHER SO MUCH
BETTER ON THE SECOND APPLICATION?
* * *
Even if our hands and hair are already wet, we can’t seem to get a healthy lather on the first try when we shampoo our hair. But after we rinse, the shampoo foams up like crazy. Why is lather more luxuriant the second time around?
Evidently, it’s because we have greasy hair, according to Dr. John E. Corbett, vice president of technology at Clairol:
In the first shampoo application, the lather is suppressed by the oils in the hair. When the oils are rinsed off [by the first application], the shampoo lathers much better on the second application.
Submitted by Joe Schwartz of Troy, New York.
* * *
WHY DON’T CIGARETTE BUTTS BURN? IS THERE
A PARTICULAR BARRIER BETWEEN THE TOBACCO
AND THE FILTER THAT PREVENTS THE BURN?
* * *
Even cigarettes without filters don’t burn quickly. If the shredded tobacco is packed tightly enough, not enough oxygen is available to feed the combustion process. The degree of porosity of the paper surrounding the tobacco rod can also regulate the degree of burn.
On a filter cigarette, however, an extra impediment is placed on the combustion process; luckily, it is not asbestos. Mary Ann Usrey, of R. J. Reynolds, explains:
The filter is attached to the tobacco rod by a special “tipping” paper which is essentially nonporous. This paper acts to extinguish the burning coal by significantly reducing the available oxygen. So, in effect, there is a barrier between the tobacco and the filter, but it is around the cigarette, not actually between the tobacco and the filter in the interior of the cigarette.
Submitted by Frank H. Anderson of Prince George, Virginia.
* * *
WHY ARE THE OCEANS SALTY?
WHAT KEEPS THE OCEANS AT THE SAME
LEVEL OF SALTINESS?
* * *
Most of the salt in the ocean is there because of the processes of dissolving and leaching from the solid earth over hundreds of millions of years, according to Dr. Eugene C. LaFond, president of LaFond Oceanic Consultants. Rivers take the salt out of rocks and carry them into oceans; these eroded rocks supply the largest portion of salt in the ocean.
But other natural phenomena contribute to the mineral load in the oceans. Salty volcanic rock washes into them. Volcanos also release salty “juvenile water,” water that has never existed before in the form of liquid. Fresh basalt flows up from a giant rift that runs through all the oceans’ basins.
With all of these processes dumping salt into the oceans, one might think that the seas would get saturated with sodium chloride, for oceans, like any other body of water, keep evaporating. Ocean spray is continuously released into the air; and the recycled rain fills the rivers, which aids in the leaching of salt from rocks.
Yet, according to the Sea Secrets Information Services of the International Oceanographic Foundation at the University of Miami, the concentration of salts in the ocean has not changed for quite a while—about, oh, 1.5 billion years or so. So how do oceans rid themselves of some of the salt?
First of all, sodium chloride is extremely soluble, so it doesn’t tend to get concentrated in certain sections of the ocean. The surface area of the oceans is so large (particularly since all the major oceans are interconnected) that the salt is relatively evenly distributed. Second, some of the ions in the salt leave with the sea spray. Third, some of the salt disappears as adsorbates, in the form of gas liquids sticking to particulate matter that sinks below the surface of the ocean. The fourth and most dramatic way sodium chloride is removed from the ocean is by the large accumulations left in salt flats on ocean coasts, where the water is shallow enough to evaporate.
It has taken so long for the salt to accumulate in the oceans that the amount of salt added and subtracted at any particular time is relatively small.
While the amount of other minerals in the ocean has changed dramatically, the level of salt in the ocean, approximately 3.5 percent, remains constant.
Submitted by Merilee Roy of Bradford, Massachusetts.
Thanks also to Nicole Chastrette of New York, New York;
Bob and Elaine Juhre of Kettle Falls, Washington;
John H. Herman of Beaverton, Oregon;
Matthew Anderson of Forked River, New Jersey;
and Cindy Raymond of Vincentown, New Jersey.
* * *
DOES IT EVER REALLY GET
TOO COLD TO SNOW?
* * *
Having withstood a few snowy midwestern winters in our time, we’re not sure we would want to test this hypothesis personally. Luckily, meteorologists have.
No, it never gets too cold to snow, but at extremely low temperatures the amount of snow accumulation on the ground is likely to be much lower than at 25° Fahrenheit. According to Raymond E. Falconer, of the Atmospheric Sciences Research Center, SUNY at Albany, there is so little water vapor available at subzero temperatures that snow takes the shape of tiny ice crystals, which have little volume and do not form deep piles. But at warmer temperatures more water vapor is available, “so the crystals grow larger and form snowflakes, which are an agglomerate of ice crystals.�
�� The warmer the temperature is, the larger the snowflakes become.
What determines the size of the initial snow crystals? It depends upon the distribution of temperature and moisture from the ground up to the cloud base. If snow forming at a high level drops into much drier air below, the result may be no accumulation whatsoever. In the condition known as “virga,” streaks of ice particles fall from the base of a cloud but evaporate completely before hitting the ground.
Submitted by Ronald C. Semone of Washington, D.C.
* * *
WHY DOES GRANULATED SUGAR
TEND TO CLUMP TOGETHER?
* * *
It ain’t the heat, it’s the humidity. Sugar is hygroscopic, meaning that it is capable of absorbing moisture from the air and changing its form as a result of the absorption. When sugar is subjected to 80 percent or higher relative humidity, the moisture dissolves a thin film of sugar on the surface of the sugar crystal. Each of these crystals turns into a sugar solution, linked to one another by a “liquid bridge.”
According to Jerry Hageney, of the Amstar Corporation, when the relative humidity decreases, “the sugar solution gives up its moisture, causing the sugar to become a crystal again. The crystals joined by the liquid bridge become as one crystal. Thus, hundreds of thousands of crystals become linked together to form a rather solid lump.”
Although we can’t see the moist film on sugar exposed to high humidity, it won’t pour quite as smoothly as sugar that has never been exposed to moisture. But when it dries up again, the liquid bridge is a strong one. Bruce Foster, of Sugar Industry Technologists, told us that the technology used to make sugar cubes utilizes this natural phenomenon.
To make sugar cubes, water is added to sugar in a cube-shaped mold. After the sugar forms into cubes, it is dried out, and voilà! you have a chemical-free way to keep sugar stuck together.
Submitted by Patty Payne of Seattle, Washington.
* * *
WHY ARE RAIN CLOUDS DARK?
* * *
Rain is water. Water is light in color. Rain clouds are full of water. Therefore, rain clouds should be light. Impeccable logic, but wrong.
Obviously, there are always water particles in clouds. But when the particles of water are small, they reflect light and are perceived as white. When water particles become large enough to form raindrops, however, they absorb light and appear dark to us below.
* * *
WHERE DOES THE WAX GO
IN DRIPLESS CANDLES?
* * *
Into the flame itself. There are 67 different grades of paraffin, ranging from extremely soft (with low-temperature melting points) to extremely hard (with high-temperature melting points). Conventional candles use paraffin with such low melting points that most will melt in the sun.
Dripless candles use hard paraffin and longer wicks, so that no wax is in direct contact with the flame and so the wax around the wick won’t melt or drip.
Submitted by Chuck and Louisa Keighan of Portland, Oregon.
Thanks also to Stephen J. Michalak of Myrtle Beach, South Carolina;
Mike Hutson of Visalia, California; Richard Roberts of Memphis,
Tennessee; and Beth Kennedy of Exeter, New Hampshire.
* * *
IF HEAT RISES, WHY DOES ICE
FORM ON THE TOP OF WATER
IN LAKES AND PONDS?
* * *
Anyone who has ever filled an ice-cube tray with water knows that room temperature water decreases in density when it freezes. We also know that heat rises. And that the sun would hit the top of the water more directly than water at the bottom. All three scientific verities would seem to indicate that ice would form at the bottom, rather than the top, of lakes and ponds. “What gives?” demand Imponderables readers.
You may not know, however, what Neal P. Rowell, retired professor of physics at the University of South Alabama, told us: Water is most dense at 4° Centigrade (or 39.2° Fahrenheit). This turns out to be the key to the mystery of the rising ice. One of our favorite scientific researchers, Harold Blake, wrote a fine summary of what turns out to be a highly technical answer:
As water cools, it gets more dense. It shrinks. It sinks to the bottom of the pond, lake, rain barrel, wheelbarrow, or dog’s water dish. But at 4° Centigrade, a few degrees above freezing, the water has reached its maximum density. It now starts to expand as it gets cooler. The water that is between 4° Centigrade and 0 Centigrade (the freezing point of water) now starts to rise to the surface. It is lighter, less dense.
Now, more heat has to be lost from the water at freezing to form ice at freezing. This is called the “heat of fusion.” During the freezing process, ice crystals form and expand to a larger volume, fusing together as they expand, and using more freezing water to “cement” themselves together. The ice crystals are very much lighter and remain on the surface.
Once the surface is frozen over, heat dissipates from the edges and freezing is progressive from the edges. When the unfrozen core finally freezes, there is tremendous pressure exerted from the expansion, and the ice surface or container sides yield, a common annoyance with water pipes.
Once the top layer of the lake or pond freezes, the water below will rarely reach 0° Centigrade; the ice acts effectively as insulation. By keeping the temperature of the water below the ice between 0 and 4° Centigrade, the ice helps some aquatic life survive in the winter when a lake is frozen over.
The strangest element of this ice Imponderable is that since water at 4° Centigrade is at its maximum density, it always expands when it changes temperature, whether it gets hotter or cooler.
Submitted by Richard T. Mitch of Dunlap, California.
Thanks also to Kenneth D. MacDonald of Melrose, Massachusetts;
R. Prickett of Stockton, California;
Brian Steiner of Charlotte, North Carolina;
and John Weisling of Grafton, Wisconsin.
* * *
WHY DO THE CLEAREST DAYS
SEEM TO FOLLOW STORMS?
* * *
Our correspondent wondered whether this phenomenon was an illusion. Perhaps we are so happy to see the storm flee that the next day, without battering winds, threatening clouds, and endless precipitation, seems beautiful in contrast.
No, it isn’t an illusion. Meteorologists call this phenomenon “scavenging.” The rainwater that soaks your shoes also cleans away haze and pollutants from the atmosphere and sends it to the ground. At the same time, the wind that wrecks your umbrella during the storm diffuses the irritants that are left in the atmosphere, so that neighbors in surrounding areas aren’t subjected to those endless days of boring, pollution-free environments.
Of course, where the pollutants end up depends upon the direction of the prevailing winds. If you are living in a community with generally bad air quality, the wind is your friend anyway. Chances are, the wind is carrying in air from a region with superior air quality.
Submitted by Jack Schwager of Goldens Bridge, New York.
* * *
WHY DO WHIPS MAKE A CRACKING SOUND WHEN SNAPPED?
* * *
Whips can attain a speed of more than seven hundred miles per hour when snapped, breaking the sound barrier. What you are hearing is a mini sonic boom.
* * *
WHY DON’T PLANETS TWINKLE AT NIGHT?
* * *
What causes a heavenly body to twinkle? Alan MacRobert, of astronomy magazine Sky & Telescope, explains:
Twinkling is caused by light rays being diverted slightly—jiggled around—by turbulence where warm and cool air mixes in the upper atmosphere. One moment a ray of light from the star will hit your eye; the next moment, it misses.
Our eyes fool our brains into thinking that the star is jumping around in the sky.
Stars are so far away from us that even when viewed through a sophisticated telescope, they look like single points of light. Even though planets may at first appear the same size as stars to the naked eye, they are actually little d
isks in the sky. Jeff Kanipe, associate editor of Astronomy, told Imponderables that “the disks of planets like Venus, Mars, Jupiter, and Saturn can be easily seen by looking at them with a pair of binoculars or a small telescope.”
How does this difference in size between stars and planets affect their “twinkling quotient”? We’ve already established that stars appear to the eye as single points. Kanipe explains how that one point turns into a twinkle:
When starlight passes through about 200 miles of Earth’s atmosphere, the light-bending properties of the different layers of air act like lenses that bend and jiggle the rays to such an extent that the star’s position appears to jump about very slightly, causing it to twinkle.
Science Page 4
