How's this for a weather forecast? 'Temperatures in the low 70s tonight, with a slight chance of raining frogs. Thunderstorms tomorrow, with ball lightning and perhaps a few elves.' Frogs from the sky? Ball-shaped lightning and elves? Can that be right? It can. And there's more. Read on.
Thunder, lightning, and ... croaking
You've heard the old saying "It's raining cats and dogs," yet no one expects a downpour of small mammals. But frogs, fish, maggots, and even beer cans have fallen with rain, says Mel Goldstein. He's the chief meteorologist at WTNH-TV in New Haven, Conn. He recalls the story of a yacht race in Acapulco, Mexico, in 1968. The "boats were littered with maggots after the rain," Dr. Goldstein says.
Falling frogs and fish can occur "with any tornado or waterspout that goes over a body of water with frogs and fish," says Marcin Szumowski. He's an assistant professor at the Desert Research Institute in Reno, Nev. Swirling winds moving over bodies of water can suck up small creatures or light objects. They may be carried for many miles before falling as odd rain.
On July 12, 1873, Scientific American reported that a storm in Kansas City, Mo., had blanketed the city with frogs. In 1939, a superintendent working near an outdoor pool in England was caught in a downpour. He ran for cover. When he looked out, he saw large, dark lumps falling. Hundreds of small frogs were coming down with the rain!
The ancient Greeks reported seeing strange glowing balls moving across the sky. They are not alone. Many people all over the world have seen such things. The luminous globes are called ball (or globe) lightning. Sometimes ball lightning is the size of a baseball, but it can be up to six feet across.
Dr. Szumowski says ball lightning is generally "red, or red and yellow, changing to white, and disappearing with a loud bang." It may also leave a bad smell behind. (The odor is believed to be caused by ozone.) It usually lasts for only 20 seconds or so, but it can linger for many
Ball lightning generally occurs during high-energy thunderstorms, but not always. Sometimes it appears seconds after a regular lightning strike, or just before. What's more, ball lightning travels in weird ways. Eyewitnesses describe it moving parallel to the ground. It may also descend vertically from clouds - or bounce! It can hiss, too.
While it's very startling, ball lightning does little damage. Sometimes it leaves scorch marks.
Scientists don't exactly know what ball lighting is or why it acts the way it does. It may be glowing plasma (electrically charged gas) trapped in a series of magnetic fields.
Whirling dust, whirling fire
The fire dust devil begins as a regular dust devil or whirlwind. Dust devils are swirling columns of air full of sand and debris. Columns can be 3,000 feet tall and from three to several hundred feet in diameter. They most often occur at midday in arid regions. That's because the ground temperature must be at least 68 degrees F. hotter than the air directly above.
Doug Sisterson, a research meteorologist at the Argonne (Ill.) National Laboratories, says an intense updraft from the heated ground collects the rising air. The force of the earth's rotation gets the air spinning. When dust is picked up by the swirling air, a dust devil is seen.
They are like mini-tornadoes, but with important differences. Tornadoes pack winds of up to 300 miles per hour. A dust devil spins at only 30 to 70 m.p.h. Tornadoes develop underneath thunderstorms. Dust devils form when the weather is clear, hot, and dry.
Sometimes, a dust devil picks up more than sand. According to Szumowski at the Desert Research Institute, dust devils may also suck up flames from a nearby forest fire. It doesn't happen often, but when it does, it creates "a spectacular image of a rotating fire rope." (For a photo, call up: www.scsr.nevada.edu/~marcin/gifs/firedevil. jpg)
Scientists prove that sprites exist
How far up in the atmosphere is weather produced? According to Dr. Sisterson at the Argonne National Laboratory, the answer was thought to be the top of the troposphere. (See chart at the top of the facing page.) That's about 12 miles up.
But after some dramatic discoveries in the last 10 years, that answer has been revised. The "weather boundary" has been extended well above the troposphere. You can thank sprites, elves, and blue jets for that. Each is linked to extremely powerful storms. Sprites are the most common.
Sprites are barely visible to the naked eye. They sometimes look bluish closest to the clouds, but extend red, wispy flashes upward. Some occur as high as 60 miles above the storm. On images from weather satellites and space shuttles, sprites appear as marvelously complex shapes. They look like "picket fences," "octopi-like," or "enormous strange blobs," according to observers.
No one knows how long the three phenomena have been around. They may be as old as the planet, or they may be more recent. Scientists have found reports going back to 1886. They mention strange lightning shooting high above thunderstorms. But scientists didn't really notice them until they examined images from space.
Sprites were scientifically proven to exist in 1989. Researchers at the University of Minnesota saw strange plumes of light shooting almost 18 miles upward from a storm.
A team from the University of Alaska filmed similar red flashes in 1994. They were named sprites, after the elusive creatures in Shakespeare's play "The Tempest."
Researchers have captured images of sprites (and elves and blue jets) using low-light-level television technology. A person on the ground has a slight chance of seeing one, though. They appear most frequently in the Midwest, as far south as Texas and as far west as Colorado. The space shuttle has spotted them over Australia, Africa, Indonesia, and Panama. Not all violent thunderstorms produce sprites.
What causes them? Don Latham, of the Fire Sciences Laboratory in Missoula, Mont., has a theory. During massive forest fires, sprites are more abundant. It is already known that forest fires produce positively charged particles that rise into the air. You don't need big fires to create sprites, but maybe the positive electrical charges from fires are a link.
Not long after the existence of sprites was verified, blue jets were found. A team of scientists from the University of Alaska was studying a massive hailstorm in Arkansas. Flying nearby, they saw rays of blue light discharging far above the tops of clouds. The rays were streaking along at 216,000 m.p.h.!
Blue jets are very rare, though, and can barely be seen with the naked eye. They may be linked to powerful hailstorms.
These are the latest of the strange weather phenomena to be documented. Elves look like huge bluish or white disks or cone-shaped light coming from the top of a thunderstorm. Some grow to be 250 miles or more in diameter. They can extend 60 miles into the air.
Elves may be produced when electromagnetic pulses move through the ionosphere. This is the atmospheric layer containing electrically charged air. The pulses could come from radio waves within the lightning flashes themselves.
Elves last less than 1/1000th of a second. Like those impish creatures in fairy tales, they're gone in the blink of an eye!
(c) Copyright 2000. The Christian Science Publishing Society