Storm clouds begin to build above the high plains of Kansas near the Colorado border. The sky grows dark, the wind begins to blow, and rain starts pouring down in sheets. Suddenly the sky is alive with zigzagging flashes of lightning. These fingers of fire shoot across the darkened skies, the closest flashes followed by tremendous claps of thunder so loud that they seem to shake the ground.

Most people would be terrified of such an electrical storm, but the more than 30 atmospheric scientists gathered on the high plains of the United States in the summer of 2000 put aside any fears they may have had so they could study lightning up close. The researchers, from government laboratories, universities, and private companies, had come as part of a scientific effort called the Severe Thunderstorm Electrification and Precipitation Studies (STEPS), a program dedicated to unlocking the secrets of lightning and severe weather. Funded by the National Science Foundation (NSF), an independent U.S. government agency responsible for advancing science and engineering, and with support from the National Oceanic and Atmospheric Administration (NOAA), STEPS is the largest study of lightning ever conducted.

The scientists involved in STEPS hope to put together a clearer picture of the causes of lightning and the relationship between lightning and other severe-weather events, such as tornadoes. To probe those secrets the scientists in Kansas had come well-equipped. They brought with them a new lightning-mapping system, a storm-penetrating airplane, advanced radar equipment, and a variety of mobile and balloon-borne sensors to measure atmospheric pressure, temperature, humidity, winds, and electrification in storms. The field-research portion of STEPS ended in the summer of 2000, but the scientists involved will spend several years analyzing the data they obtained and using it to test theories about lightning and to find ways to develop more effective storm warnings.

In addition to trying to learn about lightning, precipitation, and tornadoes, scientists are also investigating mysterious storm-related electrical phenomena called “sprites,” “blue jets,” and “elves.” Until the 1990's, very little was known about these ghostly, colorful lights that sometimes appear briefly high above thunderstorms. Though scientists' understanding of lightning remained incomplete in 2001, many researchers thought that by using advanced equipment and techniques, including satellites in orbit around the Earth, they would one day have a deeper understanding of lightning and other severe-weather phenomena.

Scientists began the first serious studies of lightning in the 1700's. The American scientist and statesman Benjamin Franklin conducted some of the first important experiments with lightning in the mid-1700's. He was among the first to demonstrate that lightning is an electrical phenomenon, which he did by conducting an experiment that involved flying a kite during a thunderstorm. Since Franklin's time, scientists have gathered a great deal of information about lightning.

One thing they have learned is that Franklin could easily have been killed. Lightning is one of the most powerful weather phenomena on Earth. A lightning flash is a giant electric spark in the sky. A lightning discharge that strikes the ground can be several kilometers long and can deliver enough electrical energy to light a 100-watt light bulb for up to three years. Each year, lightning that strikes the ground worldwide carries about as much electrical energy as is produced annually by the entire U.S. power-generating industry.