WEBVTT - How Can We Detect Tornadoes Earlier?

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<v Speaker 1>Welcome to brain Stuff, a production of iHeart Radio, Hey

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<v Speaker 1>brain Stuff, Lauren Bobo bomb Here. In the same way

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<v Speaker 1>that ultra violet light and infrared light exist outside what

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<v Speaker 1>the human eye can perceive, sound waves exist beyond the

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<v Speaker 1>frequencies of what humans can hear. When those sound waves

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<v Speaker 1>are higher frequency than what we can hear, we call

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<v Speaker 1>them ultrasonic, and when they're lower frequency, we call them infrasonic.

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<v Speaker 1>Several natural sources, including volcanoes, avalanches, earthquakes, and meteors, produce

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<v Speaker 1>infrasonic waves, also called infrasound. Animals like elephants and whales

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<v Speaker 1>may communicate with infrasound, and man made inventions like wind

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<v Speaker 1>turbines can generate these sounds too. Detecting infrasonic waves is

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<v Speaker 1>one of the key ways that governments can monitor for

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<v Speaker 1>nuclear bomb tests. That's because infrasonic waves decay very slowly,

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<v Speaker 1>and when they're large enough, they can wrap around the

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<v Speaker 1>globe several times before dissipating. And it turns out that

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<v Speaker 1>tornadoes can produce unique infrasonic waves even before tornado genesis,

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<v Speaker 1>which is when the storm forms an hour or more before.

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<v Speaker 1>Scientists have known about the tornado infrasound connection for several decades,

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<v Speaker 1>but to learn more about this process and to better

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<v Speaker 1>understand how humans could harness this information, a group of

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<v Speaker 1>scientists is developing a long distance, passive way of listening

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<v Speaker 1>in on tornadoes. In doing so, we'd be able to

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<v Speaker 1>deal with the fact that three fourths of all current

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<v Speaker 1>tornado warnings are false alarms and thus too often ignored

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<v Speaker 1>or not taken seriously. Infrasound could represent another source of

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<v Speaker 1>data to add to our arsenal one, Brian Elbing, and

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<v Speaker 1>Oklahoma State University Mechanical and Aerospace engineering professor, said in

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<v Speaker 1>a press release discussing this research. By monitoring tornadoes from

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<v Speaker 1>hundreds of miles away, will be able to decrease false

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<v Speaker 1>alarm rates and possibly even increase warning times. Elbing his

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<v Speaker 1>team built special listening devices using microphones sensitive to low

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<v Speaker 1>frequencies that were then placed inside of containers with noise

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<v Speaker 1>holes and arranged in a triangle for precision measurements. The

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<v Speaker 1>goal was to separate regular wind noise from tornado noise.

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<v Speaker 1>Elbing said, a wind noise is incoherent, so if you

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<v Speaker 1>average it over a large space, it will sum up

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<v Speaker 1>to zero. Conversely, tornado infrasound is coherent, meaning waves look

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<v Speaker 1>alike over large distances, so the pressure waves add together

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<v Speaker 1>and contain information. This new capability could mean that storm

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<v Speaker 1>chasers trying to gather data about tornadoes would be able

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<v Speaker 1>to take fewer risks in their research. Imagine drones equipped

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<v Speaker 1>with special infrasonic microphones, for instance, flying in the vicinity

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<v Speaker 1>of storms, transmitting data to forecasters and scientists. It could

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<v Speaker 1>therefore help save lives by giving people earlier warnings about

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<v Speaker 1>potentially deadly storms. In the United States, tornadoes result in

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<v Speaker 1>hundreds of deaths and billions of dollars in property damage

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<v Speaker 1>every year. By finding these storms earlier and helping us

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<v Speaker 1>understand how those storms form in the first place, this

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<v Speaker 1>sort of research could allow people to get to safety

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<v Speaker 1>and batten down the proverbial hatches. Continued work by other

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<v Speaker 1>teams has shown that infrasound sensor arrays can detect and

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<v Speaker 1>tracked tornadoes that are over sixty miles or KOs away.

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<v Speaker 1>Today's episode was written by Christopher Hassiotis and produced by

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<v Speaker 1>Tyler Klie. For more on this and lots of other

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<v Speaker 1>sound topics, visit how stuff works dot com. Brain Stuff

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<v Speaker 1>is production of I Heart Radio or more podcasts in

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