We've heard the description of what a tornado sounds like: The most common sound is a continuous rumble, like a nearby train.
But twisters also produce noises humans can't hear, and it's that sound, known as "infrasound," that experts said could revolutionize how meteorologists forecast tornadoes.
Infrasound waves have frequencies below the range of human hearing that need special acoustic equipment to be detected. Other weather and geological phenomena, such as hurricanes and volcanoes, also produce infrasound.
The theory goes that tornado-producing thunderstorms emit specific infrasound waves up to two hours before the tornado develops.
"By monitoring tornadoes from hundreds of miles away, we'll be able to decrease false alarm rates and possibly even increase warning times," said Brian Elbing, an assistant professor of mechanical and aerospace engineering at Oklahoma State University. "It also means stormchasers won't need to get so close."
Doppler radar and storm spotters lead the way when it comes to real-time tornado tracking, the Weather Channel said. This infrasound detection could be another tool.
"Since infrasound is an independent data source, combining it with existing methods should help reduce false alarms," Elbing said. "Today, 75% of tornado warnings are false alarms and tend to be ignored."
Much of the research was focused on a tornado that developed in Oklahoma on May 11, 2017, about 12 miles from where Elbing and his team had installed acoustic equipment. Infrasound activity increased about 10 minutes before the tornado developed, he told the Weather Channel.
He said the technology could help detect tornadoes in the Southeast, where twisters tend to be much deadlier than they are in the central USA.
"Complex terrain, irregular road patterns and nighttime tornadoes prevent stormchasers from observing these tornadoes, so long-range, passive monitoring for tornadoes will provide invaluable information about their formation processes and life cycle," he said.
The research was presented last week at a meeting of the Acoustical Society of America.