Low Frequency Sounds from Tornadoes

Tornado Alley is shifting eastward resulting in larger tornadoes in what is termed Dixie Alley. This is particularly concerning because most tornado related deaths have occurred in Dixie Alley without the larger tornadoes common to Tornado Alley. This is because Dixie Alley has hilly terrain that limits the use of weather radar, which is responsible for the significant improvements in tornado warnings over the past 40 years. Infrasound (i.e., sound at frequencies below human hearing) is a potential alternative method for improving tornado warnings because tornadoes are known to emit infrasound during formation and through the life of a tornado. The fluid mechanism(s) responsible for the sound needs to be identified to properly interpret the received signals. This presentation will report on recent laboratory and field work aimed at investigating potential fluid mechanisms.