‘Lis­ten­ing’ to tor­na­does could tip off storm track­ers

USA TODAY US Edition - - NEWS - Doyle Rice

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 re­al­time tor­nado track­ing, the Weather Chan­nel said. 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.”

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,” he said. “So long-range, pas­sive mon­i­tor­ing for tor­na­does will pro­vide in­valu­able in­for­ma­tion.”

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