The boom of thunder and crackle of lightning generally mean one thing: a storm is coming. Curiously, though, the biggest storms of all, hurricanes, are notoriously lacking in lightning. Hurricanes blow, they rain, they flood, but seldom do they crackle. During the record-setting hurricane season of 2005, three of the most powerful storms--Rita, Katrina, and Emily--did have lightning, lots of it. And researchers would like to know why. Richard Blakeslee of the Global Hydrology and Climate Center (GHCC) in Huntsville, Alabama, was one of a team of scientists who explored Hurricane Emily. Hurricanes are most likely to produce lightning when they're making landfall," says Blakeslee. But there were no mountains beneath the "electric hurricanes" of 2005 -- only flat water. It's tempting to think that, because Emily, Rita and Katrina were all exceptionally powerful, their sheer violence somehow explains their lightning. But Blakeslee says that this explanation is too simple. "Other storms have been equally intense and did not produce much lightning," he says. "There must be something else at work."