THE VIRGINIAN-PILOT
Copyright (c) 1994, Landmark Communications, Inc.
DATE: Sunday, September 18, 1994 TAG: 9409160201
SECTION: CAROLINA COAST PAGE: 07 EDITION: FINAL
TYPE: Cover Story
SOURCE: BY MASON PETERS
STAFF WRITER
LENGTH: Long : 189 lines
ZZZZZT! Flash! Whaaaaam-BOOOOM!
You've just been all but blinded by a close lightning strike and you're still tingling from the thunder blast that came in the same split-second.
While you're pinching yourself to see if you're still alive and babbling promises about going to church on Sunday, consider this: The National Weather Service still has no official system for evaluating thunderstorms.
``We're upgrading our weather capability all over the country, and I hope we come up with a better way to describe thunderstorms,'' said Dan Gudgel, a National Oceanic and Atmospheric Administration weather expert in Washington. ``Right now, if we hear thunder, that makes it a thunderstorm; if we see lightning, so much the better.
``But there's no record of how many flashes per minute or per hour and no standard way of cataloging the severity of a storm. We can assign a danger value to hurricanes and tornadoes, but so far we don't have a useful measurement system for electrical storms.''
And yes, this has been a busy year for thunderstorms in northeastern North Carolina and Tidewater Virginia.
But while word-of-mouth reports about near-miss lightning bolts have abounded in the Albemarle, the Weather Service still resorts to vague messages that often say no more than ``severe thunderstorm watch along a line from 50 miles west of Fayetteville to 30 miles east of Norfolk.''
There has to be a better form of warning, says Wallace H. Demaurice, the veteran meteorologist who runs the National Weather Service hotspot at Cape Hatteras.
``We don't even have a criteria for what we should call a severe thunderstorm,'' says Demaurice. ``We need to electronically count lightning flashes, particularly cloud-to-ground strikes, and then predict a storm's path and severity in a real-time sense.''
Demaurice has had personal experience with the freakish danger area of a thunderstorm.
``Some years ago, we had a squall that had passed over and out to sea,'' Demaurice recalls, ``I went out to check a rain gauge and, oh, my . . . I was standing in water over my ankles and there was a terrific lightning strike into a tree just a little distance away. One of those `out of the blue' events.
``My hair literally stood on end from the electricity and, let me tell you, I had to hurry in to the bathroom. . . . .''
Now Demaurice checks his radars for an all-clear before he stands in puddles checking rain gauges.
Everybody should be afraid of lightning, Demaurice thinks.
``If you can't get indoors, the inside of an automobile is a good place to be - if it isn't a convertible. The steel body forms an electrical shield, so don't touch any part of it,'' he said.
For the record, Demaurice says that this summer has brought relatively few lightning storms to the Outer Banks, while the nearby North Carolina mainland and the Hampton Roads area had repeated barnburners.
William Alexander, another NOAA lightning specialist who works with Gudgel in Washington said that, ``subjectively'' this has seemed to be a bad year for lightning.
``There have been a lot of storms in Virginia, parts of North Carolina and in the Washington area'' said Alexander, ``But when all of the figures are added up it will probably be an average year.''
Gudgel is even more emphatic.
``Weatherwise, there's probably no such thing as a single `normal' year,'' he said. ``Mother Nature has a way of evening things out even though we humans put labels on anything that seems unusual.
``This year has been warm and humid along parts of the mid-Atlantic coast. Next year may be cold. Over a century or even a few decades the temperature and humidity across the area will be what we call `average.' ''
The electrical nature of lightning has been generally understood since Benjamin Franklin took his life and his kite-string in hand and watched cloud-generated sparks jump from a metal key. It takes about 20,000 volts to make a spark jump one inch at sea level, so go figure the next time you see lightning travel several miles across the sky.
This summer, some of the best brains in atmospheric science are trying to understand a puzzling new kind of ``lightning'' that seems to jump into the stratosphere from the tops of thunderstorm clouds.
Back on earth, there's still plenty of mystery in the familiar storms that send lightning blazing down from late-afternoon thunderheads, dumping inches of rain willy-nilly on city shoppers or beach surfers and leaving thirsty cornfields dry a few miles away.
Meteorologists explain that conditions for lightning are created inside a thunderhead's busy heat engine, where churning air currents move warm and cold cloud masses around - a process that generates energy.
The heart of a thunderstorm is a fearful place in which water droplets are sometimes blown up to freezing heights and then fall back down as hail. And everywhere the atoms in the air are ionized - stripped of electrons - creating positive and negative electrical fields.
Look out below; that's where lightning is born.
When a large enough field potential is built up between the positive and negative areas, the stress can only be relieved by a giant flashover - a heavenly spark plug for the heat engine.
High-speed cameras in recent years have revealed some but not all of the secrets of lightning.
The mighty cloud-to-ground flashes that wrap a flaming ribbon around the old oak tree actually involve a complicated series of events that occur within a fraction of a second.
First, an invisible ``step leader,'' a heavily ionized snake-tongue of electrically conductive ionized air moves down from the cloud base. When the step leader gets close enough to a tree, a church steeple, or your TV antenna, a mighty surge of current flashes up from the ground to cancel out the opposite charge probing down out of the cloud.
To the human eye, it looks like lightning strikes down, but the first flash is usually from the ground up. There may be several back-and-forth flashes microseconds apart along the ionized cloud-to-ground path. The lightning strike ends when a balance is restored between the positive and negative electrical fields.
Lightning rods work because the sharp tips bleed off electrical potential between cloud and ground before it becomes large enough for a strike.
Thunder?
The ancients were sure it was the booming of clouds bumping together, a nice concept. Reality isn't as poetic, but it's a lot more awesome:
The air in the path of a lightning bolt is often heated to 50,000 degrees Fahrenheit; much hotter than the sun's surface. The violent expansion and contraction of the air creates a shock wave, which we hear as thunder.
How far away is a lightning flash? Count the seconds between the flash and the time you hear the thunder, then divide by five. That will give you the approximate distance in miles. If the time is less than a second, you should have stayed home.
Volumes have been written about freakish lightning strikes. The damage from conventional bolts is usually caused by the intense heat almost instantly vaporizing tree trunks or chimney bricks.
The explosive effect accounts for grisly stories of lightning victims being found with their clothes and shoes blown off.
Until recent accounts of above-the-cloud lightning striking up toward the stratosphere created a new mystery, one of the most consistent thunderstorm puzzles has involved so-called ``ball'' lightning.
Ball lightning has been reported in all colors and sizes. Generally it is described as a grapefruit or soccer-ball sized sphere that floats into a room or other area during an electrical storm. Eventually, eyewitnesses insist, the strange object drifts out again or explodes.
The reputable English magazine ``Nature'' in a 1980 article written by Sir Brian Pippard, of the prestigious Cavendish Laboratory at Cambridge University, described the travels of a ``ball of light'' that bounced around the buildings and corridors of the British university.
``Three people who saw it . . . as it moved over the ground . . . agreed it looked about the size of the moon, was blue-white in color, very bright, and was visible for some 4-5 seconds before suddenly vanishing,'' wrote Pippard.
Ball lightning literature is full of equally sober and detailed accounts but so far nobody has come up with a convincing explanation of the phenomenon. ``Nature'' Magazine two years ago carried a report by Japanese scientists who claimed to have created a form of ball lightning in their laboratory.
But whatever form the lightning takes, Alexander, Gudgel and Demaurice warn listeners that all thunderstorms, however small, are dangerous.
Lightning alone causes an average of 93 deaths and 300 injuries each year, Alexander said, and flash floods associated with thunderstorms drown another 140 people, usually at night when the victims become trapped in their automobiles. MEMO: [For a related story, see 'UPWARD LIGHTNING' IS LATEST PIECE OF
SCIENTIFIC PUZZLE in The Carolina Coast on this date.]
ILLUSTRATION: Cover [Color] photograph by Drew C. Wilson.
DAGGERS OF DANGER
Photo by GARY TREW
This dramatic photo of lightning bolts was taken from where the
fishing trawlers dock at JAWS Seafood at Wanchese Harbor on Roanoke
Island.
LIGHTNING SAFETY
North Carolina and Virginia have from 30 to 50 ``thunderstorm
days'' a year, according to National Weather Service officials.
Here are their lightning safety rules:
If you can hear thunder, you're close enough to be struck by
lightning. Take shelter.
If no shelter is available, get inside a hard top automobile and
keep the windows closed.
If possible, get out of boats and away from the water.
If outdoors and you feel your skin tingle and your hair stands on
end, squat low on the ground on the balls of your feet. Place your
hands on your knees with your head between then, making the smallest
target possible.
Keep away from trees and power and telephone poles.
If indoors, turn off air conditioners to avoid compressor damage
from lightning-induced power line surges. Don't take a bath or
shower and use the telephone only in an emergency.
Never park your car in low areas where flash floods may occur.
by CNB