Infrasound Can Detect Tornadoes an Hour Before They Form

Go down

Infrasound Can Detect Tornadoes an Hour Before They Form

Post by Cr6 on Mon Aug 20, 2018 1:47 am

Infrasound Can Detect Tornadoes an Hour Before They Form

by Christopher Hassiotis May 9, 2018

(more at link:   https://science.howstuffworks.com/nature/natural-disasters/infrasound-can-detect-tornadoes-hour-before-form.htm )

A large tornado heads for a farmhouse in Wynnewood, Oklahoma, on May 9, 2016. The tornado was one of several that struck during consecutive days from May 7-10, 2016. Roger Hill/Barcroft Images/Barcroft Media via Getty Images

In the same way that ultraviolet light exists outside what the human eye can perceive, sound waves exist beyond the frequencies of what humans can hear. We call this type of sound wave "infrasonic."

Several natural sources, including volcanoes, avalanches, earthquakes and meteors, produce infrasonic waves, also called infrasound. Animals like elephants and whales may communicate with infrasound, and man-made inventions like wind turbines can generate infrasound, too. Detecting infrasonic waves is one of the key ways that governments can monitor for nuclear bomb tests. That's because infrasonic waves decay very slowly, and when large enough, can wrap around the globe several times before dissipating.

A tornado can produce unique infrasonic waves even before tornadogenesis, or when the storm forms. In fact, scientists have known about the tornado-infrasound connection for several decades. Now, to learn more about this process, and to better understand how humans could harness this information, a group of scientists recently developed a long-distance, passive way of listening in on tornadoes. In doing so, we'd be able to deal with the fact that three-fourths of all current tornado warnings are false alarms, and thus too often ignored or not taken seriously. Infrasound could represent another source of data to add to our arsenal.

"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 Oklahoma State University mechanical and aerospace engineering professor, in a press release discussing the research.

Cr6
Admin

Posts : 1069
Join date : 2014-08-09

View user profile http://milesmathis.forumotion.com

Back to top Go down

Re: Infrasound Can Detect Tornadoes an Hour Before They Form

Post by Jared Magneson on Sat Aug 25, 2018 8:15 pm

Cool stuff! I dug for some images of their imagery, but it might just be data points or point clouds that they're processing?

Jared Magneson

Posts : 437
Join date : 2016-10-11

View user profile

Back to top Go down

Re: Infrasound Can Detect Tornadoes an Hour Before They Form

Post by Cr6 on Mon Sep 03, 2018 10:32 pm

Looks like a lot of research has been done on this recently. Apparently they even have patented detectors for prediction now.

https://phys.org/news/2018-05-decoding-tornadoes-infrasound.html
Sketch of the hypothesized method for infrasound production from a tornado, which involves radial vibrations of the cortex. Credit: Brian Elbing



Elbing and his team then parse out the tornado infrasound from the wind noise. "Wind noise is incoherent, so if you average it over a large space it will sum up to zero," he said. "Conversely, tornado infrasound is coherent—meaning waves look alike—over large distances, so the pressure waves add together and contain information."

Determining the fluid mechanism responsible for tornadoes' infrasound can revolutionize how meteorologists monitor and forecast—which could ultimately save lives. "This is especially true for Dixie Alley, which isn't known for the largest tornadoes but frequently has the most fatalities," Elbing said. "Complex terrain, irregular road patterns, and nighttime tornadoes prevent storm chasers from observing these tornadoes, so long-range, passive monitoring for tornadoes will provide invaluable information about their formation processes and life cycle."

"Since infrasound is an independent data source, combining it with existing methods should help reduce false alarms," said Elbing. "Today, 75% of tornado warnings are false alarms and tend to be ignored."
...
https://pielkeclimatesci.files.wordpress.com/2009/10/r-327.pdf

Infrasound Emitted by Tornado-Like Vortices: Basic Theory and a Numerical
Comparison to the Acoustic Radiation of a Single-Cell Thunderstorm


This paper addresses the physics and numerical simulation of the adiabatic generation of infrasound by
tornadoes. Classical analytical results regarding the production of infrasound by vortex Rossby waves and
by corotating “suction vortices” are reviewed. Conditions are derived for which critical layers damp vortex
Rossby waves that would otherwise grow and continually produce acoustic radiation. These conditions are
similar to those that theoretically suppress gravity wave radiation from larger mesoscale cyclones
, such as hurricanes. To gain perspective, the Regional Atmospheric Modeling System (RAMS) is used to simulate
the infrasound that radiates from a single-cell thunderstorm in a shear-free environment. In this simulation,
the dominant infrasound in the 0.1–10-Hz frequency band appears to radiate from the vicinity of the melting
level, where diabatic processes involving hail are active. It is shown that the 3D Rossby waves of a
tornado-like vortex (simulated with RAMS) can generate stronger infrasound if the maximum wind speed
of the vortex exceeds a modest threshold. Technical issues regarding the numerical simulation of tornado
infrasound are also addressed. Most importantly, it is shown that simulating tornado infrasound likely
requires a spatial resolution that is an order of magnitude finer than the current practical limit (10-m grid
spacing) for modeling thunderstorms.

Ultrasound levitation of objects:
https://newatlas.com/levitation-acoustic-tractor-beam/53120/






The acoustic tractor beam keeps objects trapped in midair with sound waves that quickly  alternate in direction, preventing an object from spinning out of control (Credit: University of Bristol)


https://www.nextbigfuture.com/2018/01/ultrasonic-sound-tornadoes-levitate-objects-in-a-soundless-void.html

Cr6
Admin

Posts : 1069
Join date : 2014-08-09

View user profile http://milesmathis.forumotion.com

Back to top Go down

Re: Infrasound Can Detect Tornadoes an Hour Before They Form

Post by Cr6 on Mon Sep 03, 2018 10:41 pm

Kind of an interesting fact here:

----------
Geophysical Research Letters banner
Research Letter Free Access
Infrasound in the middle stratosphere measured with a free‐flying acoustic array
Daniel C. Bowman
Jonathan M. Lees
First published: 02 November 2015
https://doi.org/10.1002/2015GL066570

Abstract

Infrasound recorded in the middle stratosphere suggests that the acoustic wavefield above the Earth's surface differs dramatically from the wavefield near the ground. In contrast to nearby surface stations, the balloon‐borne infrasound array detected signals from turbulence, nonlinear ocean wave interactions, building ventilation systems, and other sources that have not been identified yet. Infrasound power spectra also bore little resemblance to spectra recorded on the ground at the same time. Thus, sensors on the Earth's surface likely capture a fraction of the true diversity of acoustic waves in the atmosphere. Future studies building upon this experiment may quantify the acoustic energy flux from the surface to the upper atmosphere, extend the capability of the International Monitoring System to detect nuclear explosions, and lay the observational groundwork for a recently proposed mission to detect earthquakes on Venus using free‐flying microphones.
1 Introduction

Ground‐based infrasound (below audible frequency sound) sensors are a powerful tool for monitoring natural and man‐made phenomena that couple with the atmosphere. Infrasound networks can detect volcanic eruptions [Fee and Matoza, 2013] and meteors [de Groot‐Hedlin and Hedlin, 2014], quantify vertical ground motion during earthquakes [Arrowsmith et al., 2012], and track storms in the ocean [Landès et al., 2012]. They are a key component of the International Monitoring System, a global network for detecting nuclear blasts in support of the Comprehensive Test Ban Treaty [Hedlin et al., 2012]. However, acoustic sensors on the Earth's surface suffer from the following shortcomings: (1) they are a quasi two‐dimensional observation platform for a three‐dimensional phenomenon, (2) the structure of the atmosphere reduces their detection range and may prevent entire classes of signals from being recorded, (3) they are exposed to wind noise, (4) near‐sensor topography can distort acoustic signals, and (5) the sensors are subject to ground vibrations.

https://agupubs.onlinelibrary.wiley.com/doi/full/10.1002/2015GL066570

Cr6
Admin

Posts : 1069
Join date : 2014-08-09

View user profile http://milesmathis.forumotion.com

Back to top Go down

Re: Infrasound Can Detect Tornadoes an Hour Before They Form

Post by Sponsored content


Sponsored content


Back to top Go down

Back to top


 
Permissions in this forum:
You cannot reply to topics in this forum