May 25, 2008
Tricks of Nature? Otherwordly Oddities Make Trips Unforgettable
By Jay Clarke, The Miami Herald
May 25--A blue moon, a green flash, rogue waves and ball lightning.
Take the green flash. Many people believe it's a myth. But it's a very real occurrence, and I've seen it on three different occasions. And while the existence of rogue waves and ball lightning was pooh-poohed for many years, both are now firmly accepted phenomena. As for the blue moon, well, it all depends on what one means by that term.
A few of these scientific rarities are predictable enough that you can plan trips around them. Organized trips to prime viewing sites for solar eclipses book up years in advance. In winter, visitors flock to Alaska for a chance to see the aurora borealis -- though sightings aren't guaranteed.
Other phenomena are so elusive that seeing them is simply a matter of luck -- and knowing what to look for.
Here's a short list of things to watch for.
This is one event you can actually schedule a time to witness, but success depends on climatic conditions and your location. The green flash is a burst of green light emitted from the setting sun just as it sinks below the horizon. (It can also be seen an instant before a rising sun emerges from the horizon, but that's harder to spot.) Two conditions, however, must be met: The observer must have a clear, sharp horizon (no clouds or other obstructions), as in a cloudless horizon at sea. And as the flash lasts less than a second, one must keep eyes fixed on the sun as it disappears below the horizon. The most beautiful one I saw was in Barbados looking west over the Caribbean; it was a pulsing, brilliant emerald green.
Why it happens: Higher frequency green light moves slower in the dense lower atmosphere than lower frequency reds. So the green rays from the setting sun remain visible for an instant after the red rays are blocked by the earth's horizon.
This rare form of lightning appears as a glowing ball for a few seconds, then disperses or explodes. It may roll and oscillate, emitting sparks and various colors of light. It can be as small as a golf ball or as large as several feet in diameter. The one time I saw it was in Grenoble, France, during a thunderstorm. There was a lightning strike nearby, and the ball, about a foot around, suddenly appeared just above a power line, dancing on it for a few seconds before exploding.
Why: More than a dozen theories have been put forward, but none have been proven. Some of them:
1. Ball lightning is a globe of magnetically trapped plasma (charged particles).
2. It is caused by passage of a microscopic black hole.
3. It is actually a ball of burning vaporized silicon.
4. It is anti-matter.
5. It's a ghost.
6. It's an optical illusion.
These pulsating lights in the sky appear as shimmering screens of green, red and other colors. In the northern hemisphere, the aurora borealis is the show stopper, often seen in winter in far northern latitudes such as Norway and Alaska. The latter has a big tourist industry devoted to aurora-watching. In the southern hemisphere, the light show is called the aurora australis. Few of us will catch it though; it's best seen in Antarctica in the southern winter, March to September.
Why: Particles streaming outward from the sun, called the "solar wind," collide with the lines of magnetic force that focus at the earth's poles. This pressure creates an electric voltage that propels electrons at high speeds, causing atoms of gas in the ionosphere to glow.
ST. ELMO'S FIRE
This electrical discharge appears in an ion-charged atmosphere as a bluish glow at the tip of a ship's mast, on a tall steeple, a lightning rod, wingtip of a aircraft in flight or other pointed objects. It got its name because sailors believed its presence indicated their patron saint was protecting them. It's not that unusual, but how many people look out of their plane's window on a night flight?
Why: The phenomenon is known as a point discharge, occuring when the electrical field potential across objects reaches about 1,000 volts per centimeter. This usually occurs only during thundery weather.
Witnessing a total solar eclipse is an unforgettable event, but usually you have to travel to a far (and often remote) place to see it -- and hope the sky will be clear. Remaining eclipses on the 2008 calendar include a total solar eclipse Aug. 1, visible in northern Canada, Greenland, Siberia, Mongolia and China. One lunar eclipse also lies ahead this year, a partial Aug. 16 that will be visible in South America, Europe, Africa, Asia and Australia.
Why: Solar eclipses occur when the moon moves directly between the earth and the sun, blocking out all or some of the sun's disk. Lunar eclipses happen when the moon moves into the earth's shadow, dimming the moon's light.
This is an unexplained, persistent low-pitched sound reported by people in many places around the world. It usually is compared to the sound of a far-off diesel engine, but it is not heard by everyone and is not detectable by microphones.
The name comes from a well-known case in Taos, N.M., which led to Congress ordering a 1997 investigation of the source of the low-frequency noise. No definite conclusion was reached as to its existence and possible source. For the record, I've never heard it and don't know anyone who has.
Why: Nobody knows.
You've heard the phrase, "once in a blue moon" -- meaning not very often. But how often does a blue moon occur?
The most popular definition is that a blue moon is the second full moon to occur in a single month. That happens about once every 2 1/2 years. The next occurrence is in December of 2009, when the moon is full Dec. 2 and 31.
Another definition is when the moon literally appears bluish, an even rarer event. Usually this occurs when smoke or dust particles rise high the atmosphere, as in a major volcanic eruption. If the particles remain low in the atmosphere, the moon will appear reddish (or bluish).
Why: Because the moon revolves around the earth in just 28 days and our calendar months are longer that that (except February), the moon can occasionally reach full phase twice in a single month.
Or, the case of a truly blue appearance, dust particles in the atmosphere can filter out certain colors, making the moon appear bluish or reddish.
This is one phenomenon you don't want to encounter. Sometimes called a freak wave, it is an enormous wave that apparently comes out of nowhere and smashes into a vessel, often causing severe damage. Some well-publicized occurrences have come on passenger ships. In 1966, such a wave hit the Italian liner Michelangelo, killing two passengers and a crewman. The Queen Elizabeth 2 ran into a 95-foot-high monster in the Atlantic in 1995, but the ship came away with little damage. In 2005, the Norwegian Dawn was hit by a 70-foot wave off the coast of North Carolina, flooding 60 cabins and causing damage on several decks, though there were no major injuries.
I was on a military transport ship in the Pacific returning from Korea when a huge wave struck the ship, smashing windows in the lounge below the bridge and severely injuring at least one passenger. Oddly, the weather was not bad and the sea had relatively few whitecaps.
Why: Scientists still are not sure why a rogue wave forms. Among the theories:
1. Normal waves run into an opposing current, causing them to jam together and coalesce into a huge wave.
2. Waves coming from different directions meet to combine into one large wave.
3. The shape of the seabed may force several small waves to form one large one.
4. High winds push waters into a high wave.
5. Freak waves are a natural phenomenon, perhaps abetted by a normal wave sucking energy from nearby waves.
More than a few people claim to have seen unidentified flying objects. Though some believe the UFOs are spacecraft from other worlds, most turn out to have prosaic explanations -- weather balloons, reflections from high-flying aircraft, marsh gas, planets, man-made satellites glowing in sunlight, tests of secret new aircraft.
My family and I did witness an unusual phenomenon in the sky while driving across central Florida -- the sudden appearance of several virtually stationary lights in the late afternoon sky, brighter than any planet. Did we see hovering UFOs? I think not; we were near the Air Force's Avon Park bombing range, so those lights probably were flares dropped at very high altitude.
Why: Believe whatever you want.
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