A Newly Discovered Meteorological Phenomenon
Entirely new forms of lightning have been discovered, up to 1,000 times bigger than any previous bolt seen. While normal lightning fires down below clouds, these giant bolts shoot up 80km into space. This lightning, six times more powerful than passenger planes are designed to withstand may be the real killer in a spate of baffling air disasters. And for the documentary revealed the photograph that sparked a secret NASA enquiry. Was this the proof that a high-altitude lightning strike caused the crash of the space shuttle Columbia. This image was shown here but had to removed due to copyright restrictions.
Each day the earth is shaken by 8 million bolts of the skies most powerful force - lightning. Energy from one bolt explodes in a split second but could power a household for six months. At any moment 1800 storms pummel our planet, each one is a giant battery. Inside a storm, water turns to hail, falling ice crashes on rising droplets creating static electricity, charges of up to 100 million volts build up. Arcs of electricity fire out. More than 90% of bolts fire within clouds, but a highly charged storm will fire a cascade of electricity down to the earth drawn to the highest point. A blade of grass can trigger lightning, or even a person. Each year a thousand people die each year after direct hits. A lightning bolt is only 3cm wide, but at 33,000°C it is hotter than the surface of the sun. This heat expands surrounding air which explodes outwards as thunder. Few cloud to ground strikes are longer than 3km and text books always used to say "no lightning could exist above clouds".
But then, weatherman Walt Lyons aimed his camera across the Colorado plains on July 6th 1993, what he saw overturned 200 years of scientific certainty in an instant. He filmed images showing lightning 80km high and 50km wide, firing above the clouds. On investigation it transpired that several pilots had observed the phenomena but were reluctant to talk about it fearing they would be disbelieved or accused of hallucinating.
If a good observer is some distance from a storm he can see above the cloud. In 1989 University of Minnesota Physicist Franz Winkler was testing a camera in these very conditions. He was filing the sky above a storm 200km away. Ordinary lightning was flashing below the horizon but when Professor Winkler played back the tape he saw something different. The camera had recorded a flash obeve the cloud showing twin pillars of light, bit this was where lightning was not supposed to exist. At 10 times the size of Mount Everest the mystery flash dwarfed any bolt ever recorded.
On March 26 1987 NASA launched a $100 million military satellite into a storm cloud. What happened next would make NASA face the skies most powerful force. As the rocket rose into the clouds lightning struck passing through the rocket and hitting the launch pad. With the onboard computers knocked out, mission control had lost control of the rocket and were forced to self-destruct it before it could crash land back to earth.
NASA asked Skeet Vaughan, a veteran pilot, to investigate the phenomenon and provide proof of it's existence. By 1992 the detective work had turned up startling images. They showed the edge of the earth with bright columns fired upwards 70km into space, towering over the horizon. Skeet Vaughan said "We found maybe 19 of these flashes over time and on different shuttle flights". A race began to find out if these giant bolts could bring down the space shuttle. NASA turned to Walt Lyons, a world expert in the detection of distant lightning strikes. Walt set up a remote camera on top of his observatory on Yukka Ridge. On 6th July 1993 he took delivery of the camera, and that very night a massive thunderstorm was raging over Kansas some 300km away. Walt monitored the storm all night and by morning had recorded 250 of these "bings" as he called them. In one night Walt Lyons had proved the phenomenon existed, but it still had no name. A friend suggested calling them sprites which Walt liked because they are fleeting, ephemeral instances.
A year after Walt's discovery a team from the University of Alaska set out to photograph the sprites from the air, up close and in colour, In one night the lightning hunters had bagged hundreds of images that revealed the true colour of sprites. They were red and blue neon type glows, a sign that they might be explosions of electricity exciting gases in the high atmosphere.
From the ground observatory in Colorado, Walt Lyons filmed another peculiarity, the sprites appeared to be dancing across the cloud tops. Ordinary lightning gives warning of it's power with thunder, if sprites were to make a similar sound it would prove them to be more than a mirage.
Dr. Alfred Beddard of the National Oceanics and Atmospherics Administration and his audio array near Boulder, Colorado can hear the frequencies undetectable by human ears, called infrasound. Until the advent of satellites his system was the main warning of rogue atom bomb tests. He can detect sound from the other side of the world. His equipment detected that the sprites do, in fact, produce large sounds but at a sub-audible frequency.
Professor Umran Inan a leading physicist of Stanford University would set his students the task of analysing the sound from the sprites. His analysis and telescopic imaging showed that a sprite which was first thought to shoot upwards, actually fires down. They are not a single bolt but a multitude of interlaced lightning channels. Sprites are generated in the electrical field above a storm. The first thing seen is a flat disc called a halo, it appears at a height of 85km. The field must be strong enough for the halo to grow into a sprite. Electricity flows down to form a red balloon of energy, the size of a mountain range. As the charge flows down, denser air squeezes the current into 30m wide filaments. The sprite showers a 100sq km of these blue lightning shards onto cloud tops and then disappears.
But what pulls vast currents from space to make huge towers of electrical energy? Could some monstrous force conjure sprites from below the clouds? And could this, in turn, help explain some of the most mysterious air disasters since the dawn of the jet age?
Ordinary lightning is also known as negative lightning as it is discharging a negative charge. On occasion, however, lightning can be positive and when it is the flash is of much longer duration releasing far more energy, more than enough to damage an aircraft.
Walt Lyons revisited his data and images and discovered that for every sprite above the clouds, there was a burst of positive lightning below. It was one long, huge discharge from space to the ground.
NASA commissioned Walt Lyons to evaluate the danger posed by sprites to future shuttle missions. Walt decided that the energy of a sprite above cloud level was distributed over a large area and so probably didn't pose any real threat, but added insufficent was known to be definite.
Following the loss of Columbia NASA's accident findings were never made public, but photographic experts concluded that the photograph suggesting a lightning strike as a possible cause was most probably a camera error.