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New research finds that tornado is formed from scratch, as opposed to popular thought

A tornado in Galatia, Kansas, May 25, 2012 as it disappeared. Credit: Jana Houser.New research challenges existing assumptions about how tornados are formed. Historically, researchers assumed that tornado rotation began in storm clouds, creating a funnel traveling downward. This theory matches which storm hunters usually observe visually in the field. Collars often report that cloud clouds are gradually decreasing until they come into contact with the ground. But new research combines a new type of Doppler radar with photos and videos of tornadoes formed by supercell thunderstorms. The opposite is true: Tornado is materialized from the ground Weather forecasts typically issue tornado warnings based on radar observations of strong rotation above the ground, but the new results indicate that the forecast has to reevaluate their warning procedure, according to the researchers. "We need to rethink paradigms as we must explain tornado formation, and we need to specifically communicate this to forecasters trying to make warnings and issue warnings," said Jana Houser, a meteorologist at Ohio University in Athens who will present the new results here today at the fall of the US Geophysical Union. "You will not really find strong evidence that a tornado falls down, so we must stop making it a priority in our forecast strategies." Research conducted in the 1 970s suggested that tornadoes be formed from rotation that begins several kilometers above Earth's surface. The theory was that this funnel was slowly lowered in the air from below to downwards until it touched the ground. Jana…



A tornado in Galatia, Kansas, May 25, 2012 as it disappeared. Credit: Jana Houser.

New research challenges existing assumptions about how tornados are formed.

Historically, researchers assumed that tornado rotation began in storm clouds, creating a funnel traveling downward. This theory matches which storm hunters usually observe visually in the field. Collars often report that cloud clouds are gradually decreasing until they come into contact with the ground.

But new research combines a new type of Doppler radar with photos and videos of tornadoes formed by supercell thunderstorms. The opposite is true: Tornado is materialized from the ground

Weather forecasts typically issue tornado warnings based on radar observations of strong rotation above the ground, but the new results indicate that the forecast has to reevaluate their warning procedure, according to the researchers.

“We need to rethink paradigms as we must explain tornado formation, and we need to specifically communicate this to forecasters trying to make warnings and issue warnings,” said Jana Houser, a meteorologist at Ohio University in Athens who will present the new results here today at the fall of the US Geophysical Union. “You will not really find strong evidence that a tornado falls down, so we must stop making it a priority in our forecast strategies.”

Research conducted in the 1

970s suggested that tornadoes be formed from rotation that begins several kilometers above Earth’s surface. The theory was that this funnel was slowly lowered in the air from below to downwards until it touched the ground.



Jana Houser is next to Rapid X-Pol radar instrument, a new type of fast-scanning mobile radar system, during a storm hunt on May 8, 2012. Credit: Jana Houser.

Most meteorologists have accepted this theory of tornado formation, but a series of new observations from quick scan wires have begun to change it.

One of the most important cases that contributed to the new understanding of the tornado formation occurred on May 31, 2013. On this day, El Reno formed tornado in downtown Oklahoma and crushed earlier tornado records. It was the largest tornado ever recorded, peaked 4.2 kilometers wide and had wind speeds over 480 kilometers per hour (300 miles per hour), the second highest wind speed was recorded on Earth.

Houser and a team of researchers from the University of Oklahoma happened to monitor the storm with a new kind of mobile Doppler radar system that collected tornado wind speeds every 30 seconds. Afterwards, Anton Seimon, a geographer at Appalachian State University in Boone, North Carolina, had hunted the El Reno storm, collected hundreds of stills and videos of the epic twister from citizens and other storm hunters.

When Houser compared her radar data with images collected by Seimon, she noticed something odd. The pictures clearly showed a visible tornado in the ground several minutes before the radar picked it up.

Confused, Houser went back through radardata and analyzed the data taken on the ground. It’s usually hard to get good radar measurements on or near the ground, but Houser and her team had installed their instruments in a small upturn and there was no barrier between them and the tornado, so this time they had enough data to work with.

She found clear evidence of rotation on the ground before rotation at higher heights. Houser then examined other sets of tornado data and found that in many cases, the rotational velocity of the tornado force develops first at or near the ground instead of starting in the cloud itself. In all four data sets, she analyzed none of the tornades that were formed after the classic down-down process.

“It emphasizes the fact that we need a strong, low level, largely close to ground level rotation, located in the right place, at the right time, considering the larger parenting circles to form a tornado, Houser said.


Explore further:
New study explains the creation of mortal California “firenado”

More information:
agu.confex.com/agu/fm18/meetin … app.cgi / Paper / 432399

Provided by:
American Geophysical Union

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