Scientists and observers who study tornadoes have made great advancements in the last fifty years. They know that certain conditions need to be present for a tornado to form, although sometimes tornadoes will form when no development is expected. Because scientists and amateurs alike continue to be awed and fascinated by severe weather, they have forged a partnership that benefits both the scientific and the general populations. They combine proven techniques with new tech nologies to advance the study of tornadogenesis, or the formation of tornadoes.

The observations of both professionals and amateurs are instrumental in the study of tornadogenesis. Because tornadoes occur across the United States, and often in rural areas, some times the only record of a tornado event comes from firsthand observation by nonscientists. The record may be a conversation, recollection, photograph, or home movie on videotape. The key...