At the first sight of storm clouds over Central Europe, the BLIDS Lightning Information Service goes into action. By measuring the electromagnetic radiation propagated by the bolts of lightning, a sophisticated system can precisely calculate the points of impact. The next step is to warn pilots, farmers and golfers of the impending danger.

Five dead cows in the middle of a field. Police in Ettlingen, a small town near the German city of Karlsruhe, had never seen the likes of it. The vet was mystified, too. Maybe neighbors with a grudge had poisoned the cattle. But why?

In the end, the mystery was resolved like a bolt out of the blue—and some hours ahead of the official explanation produced by the veterinary center. Not feuding farmers, but an electric storm was the killer. Confirmation came from BLIDS, the Siemens Lightning Information Service in Karlsruhe. On the night of the cattle incident, BLIDS technicians had monitored a heavy storm in the region which had scorched the earth with more than a few bolts of lightning.

In the end, determining the real cause of bovine death proved relatively easy. A sophisticated positioning system at BLIDS pinpoints and records all the electric storms raging across Central Europe. A quick check in the database was all it took to establish that a bolt of lightning had struck somewhere pretty close to the scene of the supposed crime.

"Our data," says Stephan Thern, the 41-year-old head of BLIDS, "will give you more or less a fingerprint of the lightning bolt." The data he is referring to show the exact coordinates of where a bolt of lightning strikes, the date and time (to the very second), polarity and the strength of current. The records revealed that on July 14, 1999, at precisely 03:24:04, a negatively charged, earth-to-cloud bolt of lightning had discharged a current

of 6,000 amps in the immediate vicinity of the cow pasture. That’s more than enough juice to put a prime bull on its back. For the farmer, it was an expensive night, with five $1,000 steers reduced to dog meat.

Too bad, because the loss was unnecessary. Had the farmer accessed the data in Karlsruhe, he could have sheltered his cattle from the storm. A BLIDS service for private customers gives early warning of the onset of bad weather. This is how it works: Subscribers request coverage for an area of, say, up to a radius of 20 kilometers (12 miles) around the family business or home. As soon as a storm approaches, the alarm is raised. "A few seconds after we register the first bolt in the area covered, a warning goes out via cell phone, pager, fax or e-mail," explains Thern.

Subscribers can therefore take preemptive action or avoid the storm altogether. Typical users of the service include construction sites, companies transporting hazardous freight, cable car operators, wind power plants, swimming pools, leisure parks, golf courses, and water sports and gliding clubs. The awesome danger a powerful storm can pose to extreme sports was tragically demonstrated on July 28, 1999, near Interlaken in Switzerland. A group of 23 people canyoning down a whitewater stream were killed when it was turned into a fatal torrent by a flash flood.

Whenever the heavens open between Geneva and Hamburg or Bordeaux and Budapest, the BLIDS positioning system tracks the storm front, analyzing speed and direction, and pinpointing the formation of new storm pockets. Filling the monitors at the BLIDS headquarters in Karlsruhe are maps of Germany and Europe, illuminated with yellow dots which seem to multiply by the minute. Each point of light represents a bolt of lightning that only moments before had struck its path across the sky, and was then picked up by sensors scattered throughout a large tract of Europe.

There are nearly 60 of these highly sensitive antennas in the system, installed at intervals of anywhere between 150 and 300 kilometers throughout Germany, Austria, Switzerland, the Benelux countries and several countries in Eastern Europe. The network will soon be expanded to provide coverage for Scandinavia and Italy as well.

BLIDS’ ability to determine the exact location of a lightning bolt is based on a blindingly simple principle. Electromagnetic waves propagated by each bolt are picked up by several sensors. Depending on the location, the waves require more or less time to arrive at a particular sensor. Typical time differences are in the range of a few milliseconds. Armed with this data, the central computer can calculate the point of impact to within 300 meters.

Utility companies are among the biggest users of the service. Many are actually connected to the network around the clock. And with good reason: if there’s a power failure, they are inundated with complaints. Pinpointing lightning damage to overhead lines often used to be a wearisome business. Now, it just takes a couple of mouse-clicks to put a map on the monitor revealing the exact location where lightning has struck. As a result, a repair crew can get to work fast.

There were times when people thought thunder and lightning were expressions of the wrath of God. Back then, a severe storm could lay whole sections of a city to waste. In 1749, for example, lightning struck the gunpowder arsenal in Breslau (today Wroclaw in Poland). The explosion killed 700 people and destroyed more than 1,000 houses.

A year later, in 1750, the American statesman, scientist and inventor Benjamin Franklin demonstrated the electrical nature of the supposed celestial fire and went on to invent the lightning rod. Although churches were frequently struck by lightning storms, the clergy held out for a long time against the "heretical" invention. And when Karl Theodor, Elector of Bavaria, wanted to mount the sensational gadget on the top of Nymphenburg Palace, they had to call out the army to ward off religious protesters.

Even today, there is still no firm consensus as to what exactly occurs when a bolt of lightning is produced. The science books offer some 20 competing theories. But in essence, this is what happens: A potential difference of several hundred million volts builds up between positively and negatively charged clouds, or between the clouds and the earth. In what can be compared to a massive short circuit, this voltage then discharges, causing surges of current of between 20,000 and 100,000 amps to race along a lightning channel some five kilometers long but only a few centimeters wide. In the process, the air in this channel is heated to 30,000 Celsius—six times hotter than the surface of the sun. As a result, the air expands faster than the speed of sound, thereby generating a sonic boom. That’s what thunder is.

Some bolts of lightning generate power of up to 10 billion kilowatts, i.e. 7,000 to 8,000 times the output of a nuclear power plant. But such phenomenal power is only attained for a few millionths of a second—the duration of maximum current flow. Consequently, the average bolt would at most suffice to run a couple of 100 watt bulbs for a day or two.

All the same, the energy that goes up in smoke this way is mind-blowing. At any one time, there are some 2,000 storms raging somewhere around the world. That’s almost 25 million bolts of lightning a day. The busiest time for BLIDS is July, when it registers around 50 percent of the one million or so storms that rage above Germany each year. Highland and alpine regions, as shown by the lightning density charts in Karlsruhe, are particularly susceptible to bad weather.

The frequency of such severe storms often leads to temptation. Property owners have been known to put in an insurance claim when someone’s carelessness causes a roof or a barn to go up in flames during the summer months. Such tricks have about as much chance of success as lightning striking twice in the same place. Most property insurers are major subscribers to BLIDS, and a quick look at the database is enough to tell them whether there was any lightning in the claimant’s region at the time of the blaze. In fact, up to 40 percent of such claims turn out to be fraudulent.

While lightning rods have progressively reduced the danger of fire, lighting can sometimes cause damage that is just as devastating. Worse still, this occurs precisely in those areas where the modern information society is most vulnerable: telecommunications, data processing and air traffic control. In fact, experts estimate that such damage costs several billion dollars a year in Germany alone.

The control tower at Frankfurt Airport, for example, has been put out

of action several times by electrical storms. And at Deutz, a manufacturing firm in Cologne, lightning once demolished around 100 computer terminals and paralyzed the computing center. The cause each time was the electromagnetic field generated by a bolt of lightning, which wormed its way into the system and wreaked havoc by inducing excess voltages.

The more closely computers and data links are networked, the more they approximate huge antenna, greedily attracting electromagnetic pulses generated by lightning sometimes miles away. What’s more, today’s solid-state microelectronics is much more sensitive to the effects of excess voltage than the tubes and relays of old. Even the smallest bolt can create sufficient rogue current to burn out microchips and crash computers.

It’s an experience with which even BLIDS is familiar. Once, during a heavy storm over Karlsruhe, Thern wanted to survey the overall situation. As he turned to his computer, lightning struck, and he was left looking at a blank monitor. .