##### Mar 19, 2008

Did you know that there's a new breakfast food that helps meteorologists predict severe storms? Down South they call it "GrITs."

GrITs stands for Gravity wave Interactions with Tornadoes. "It's a computer model I developed to study how atmospheric gravity waves interact with severe storms," says research meteorologist Tim Coleman of the National Space Science and Technology Center in Huntsville, Alabama.

According to Coleman, wave-storm interactions are very important. If a gravity wave hits a rotating thunderstorm, it can sometimes spin that storm up into a tornado.

What is an atmospheric gravity wave? Coleman explains: "They are similar to waves on the surface of the ocean, but they roll through the air instead of the water. Gravity is what keeps them going. If you push water up and then it plops back down, it creates waves. It's the same with air."

Coleman left his job as a TV weather anchor in Birmingham to work on his Ph.D. in Atmospheric Science at the University of Alabama in Huntsville. "I'm having fun," he says, but his smile and enthusiasm already gave that away.

"You can see gravity waves everywhere," he continues. "When I drove in to work this morning, I saw some waves in the clouds. I even think about wave dynamics on the water when I go fishing now."

Gravity waves get started when an impulse disturbs the atmosphere. An impulse could be, for instance, a wind shear, a thunderstorm updraft, or a sudden change in the jet stream. Gravity waves go billowing out from these disturbances like ripples around a rock thrown in a pond.

When a gravity wave bears down on a rotating thunderstorm, it compresses the storm. This, in turn, causes the storm to spin faster. To understand why, Coleman describes an ice skater spinning with her arms held straight out. "Her spin increases when she pulls her arms inward." Ditto for spinning storms: When they are compressed by gravity waves, they spin faster to conserve angular momentum.

"There is also wind shear in a gravity wave, and the storm can take that wind shear and tilt it and make even more spin. All of these factors may increase storm rotation, making it more powerful and more likely to produce a tornado."

"We've also seen at least one case of a tornado already on the ground (in Birmingham, Alabama, on April 8, 1998) which may have become more intense as it interacted with a gravity wave."

Coleman also points out that gravity waves sometimes come in sets, and with each passing wave, sometimes the tornado or rotating storm will grow stronger.

Tim and his boss, Dr. Kevin Knupp, are beginning the process of training National Weather Service and TV meteorologists to look for gravity waves in real-time, and to use the theories behind the GrITs model to modify forecasts accordingly.

Who would have thought grits could predict bad weather? "Just us meteorologists in Alabama," laughs Coleman. Seriously, though, Gravity wave Interactions with Tornadoes could be the next big thing in severe storm forecasting.

Note: The gravity waves of this story should not be confused with the gravitational waves of astrophysics. One is an ordinary wave of water or air; the other is a ripple in the fabric of spacetime itself.

Source: by Dauna Coulter, Science@NASA

## Related Stories

#### New method proposed for detecting gravitational waves from ends of universe

May 16, 2013

A new window into the nature of the universe may be possible with a device proposed by scientists at the University of Nevada, Reno and Stanford University that would detect elusive gravity waves from the ...

#### 4C+29.30: Black hole powered jets plow into galaxy

May 15, 2013

(Phys.org) —This composite image of a galaxy illustrates how the intense gravity of a supermassive black hole can be tapped to generate immense power. The image contains X-ray data from NASA's Chandra X-ray ...

#### South Africa's new radio telescope reveals giant outbursts from binary star system

May 16, 2013

(Phys.org) —An international team of astronomers have reported the first scientific results from the Karoo Array Telescope (KAT-7) in South Africa, the pathfinder radio telescope for the \$3 billion global ...

#### Study finds semiclassical gravity counterintuitive, but on the horizon of testability

May 08, 2013

(Phys.org) —One of the more controversial theories of quantum gravity, which attempts to unify quantum mechanics and general relativity, is semiclassical gravity, which was proposed in the 1960s. As its name suggests, semiclassical ...

#### New kind of cosmic flash may reveal something never seen before: Birth of a black hole

May 03, 2013

(Phys.org) —When a massive star exhausts its fuel, it collapses under its own gravity and produces a black hole, an object so dense that not even light can escape its gravitational grip. According to a ...

#### Climate change will raise the sea level in the Gulf of Finland

Apr 29, 2013

The Finnish Meteorological Institute has updated its estimates concerning the impact of rising sea levels on the Finnish coast.

## Recommended for you

#### Professor argues Earth's mantle affects long-term sea-level rise estimates

5 hours ago

From Virginia to Florida, there is a prehistoric shoreline that, in some parts, rests more than 280 feet above modern sea level. The shoreline was carved by waves more than 3 million years ago—possible ...

#### Russia evacuates drifting Arctic research station

9 hours ago

Russia has ordered the urgent evacuation of the 16-strong crew of a drifting Arctic research station after ice floe that hosts the floating laboratory began to disintegrate, officials said Thursday.

#### New atmospheric modeling paradigm breaks previously accepted notions

10 hours ago

(Phys.org) —Fortified with new evidence of particles' true disposition, scientists at Pacific Northwest National Laboratory developed a multi-dimensional modeling framework that predicts their formation ...

#### Researchers map historic sea-level change on the New Jersey coastline

11 hours ago

(Phys.org) —Hurricane Sandy caught the public and policymakers off guard when it hit the United States' Atlantic Coast last fall. Because much of the storm's devastation was wrought by flooding in the aftermath, ...

#### Bacterium from Canadian High Arctic and life on Mars

11 hours ago

(Phys.org) —The temperature in the permafrost on Ellesmere Island in the Canadian high Arctic is nearly as cold as that of the surface of Mars. So the recent discovery by a McGill University led team of ...

#### Atlantic research expedition uncovers vast methane-based ecosystem

11 hours ago

A marine research expedition sponsored by the U.S. Bureau of Ocean Energy Management (BOEM) and the National Oceanic and Atmospheric Administration (NOAA) has led to the discovery of perhaps the world's largest methane cold ...

##### earls
4 / 5 (1) Mar 19, 2008
"Gravity Driven Waves" I feel would be a more appropriate label for the phenomenon.

This sort of thing seems rather Universal and should fit a single equation. Something along the lines of frequency and amplitude that translates into rate of rotation. All of the variables need to be identified however.

I'm sure a mathematical description already exists, I wish I had an education.
##### THEY
5 / 5 (1) Mar 19, 2008
I agree with you, considering gravity propagates at the speed of light........ "Gravity waves" is misleading as a name for this weather occurance.
##### Sophos
not rated yet Mar 20, 2008
Gravity wave huh?
Well he was a TV weather man so I guess accuracy is not such a priority to him!

## More news stories

#### Slovenian flyer lands in France on return trip from Arctic

Slovenian adventurer Matevz Lenarcic landed on Thursday in Western France after having overflown the North Pole in an ultra-light plane equipped to measure air pollution.

#### Hubble reveals the ring nebula's true shape

(Phys.org) —The Ring Nebula's distinctive shape makes it a popular illustration for astronomy books. But new observations by NASA's Hubble Space Telescope of the glowing gas shroud around an old, dying, ...

#### Accurate distance measurement resolves major astronomical mystery

(Phys.org) —Sometimes astronomy is like real estate—what's important is location, location, and location. Astronomers have resolved a major problem in their understanding of a class of stars that undergo ...

#### NASA head views progress on asteroid lasso mission

Surrounded by engineers, NASA chief Charles Bolden inspected a prototype spacecraft engine that could power an audacious mission to lasso an asteroid and tow it closer to Earth for astronauts to explore.

#### A hidden population of exotic neutron stars

(Phys.org) —Magnetars – the dense remains of dead stars that erupt sporadically with bursts of high-energy radiation - are some of the most extreme objects known in the Universe. A major campaign using ...

#### King Richard III found in 'untidy lozenge-shaped grave'

An academic paper on the archaeology of the Search for Richard III reveals for the first time specific details of the grave dug for King Richard III and discovered under a car park in Leicester.

#### Glucosamine supplements tied to risk of eye condition

(HealthDay)—Glucosamine supplements that millions of Americans take to help treat hip and knee osteoarthritis may have an unexpected side effect: They may increase risk for developing glaucoma, a small ...

#### Controlling mood through the motions of mitochondria

(Medical Xpress)—Regulating the distribution of power in neurons is done by a system that makes the national electric grid look simple by comparison. Each neuron has several thousand mitochondria confined ...

#### Tests find Rossi's E-Cat has an energy density at least 10 times higher than any conventional energy source

(Phys.org) —In the ongoing saga of Andrea Rossi's energy catalyzer (E-Cat) that promises clean, cheap power for the world, the latest events continue to bring as many questions as answers. Several scient ...

#### Google Drive sports new view and scan enhancements

(Phys.org) —Google Drive has a new look and functions. The makeover in Google Drive features scanning and interface enhancements that put the user into "card" mode. The enhancements make it easy for the ...