Gravity Waves in the Atmosphere can Energize Tornados (Video)
Written by Ian O'Neill
Gravity waves are global events. Much like the ripples on a massive pond, these large-scale waves can propagate from an atmospheric disturbance over thousands of miles. These waves are maintained by the gravitational force of Earth pulling down and the buoyancy of the atmosphere pushing up. Until now it has been hard to link atmospheric gravity waves with other atmospheric phenomena, but new research suggests that gravity waves passing over storms can spin up highly dangerous and damaging tornados… Suddenly gravity waves become very important and may help to forecast where and when tornados may strike…
In a nutshell, meteorologist Tim Coleman of the National Space Science and Technology Center in Huntsville (Alabama) sums up what gravity waves are:
"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
A large number of things may cause gravity waves (not to be confused with gravitational waves, the ripples in space-time), including intense disturbances caused by storm systems, a sudden change in jet stream location or wind shear. The strong oscillation will then travel for hundreds or even thousands of miles.
See a gravity wave in action over Iowa…
Far from gravity waves being a mild curiosity, it seems that they have a large part to play with other atmospheric dynamics down here on the ground.
Tim Coleman and colleagues have found that the passage of gravity waves over the top of storms could intensify or even create tornados. It is all down to the angular momentum of the spinning storm. When storms are large, they slowly rotate. If for some reason they shrink in scale, the spin will increase (imagine an ice-skater spinning on the ice with her arms outstretched, as she brings her arms in, she spins faster). This is the fundamental rule of angular momentum conservation, as the size of a storm contracts, the faster it spins. Ultimately, if the conditions are right, intense tornados can be generated, a huge amount of angular momentum in a tiny volume.
Now gravity waves are believed to have a part to play. As they pass over a storm, the pressure of the overlying gravity wave propagation will compress the storm. As this occurs, a vast amount of angular momentum is forced into a smaller volume. The seeding of baby tornados is therefore possible. Gravity waves also come in sets; one wave will follow another, each periodically compressing the storm, intensifying tornado generation.
So keep your eyes peeled for incoming gravity waves during a storm… tornados may spin to life…
Source: NASA
Filed under: Earth, Environment
March 19th, 2008 at 3:56 pm
I think it would have been better to call these "atmospheric waves" or "air waves" because "gravity waves" may cause a lot of confusion.
March 20th, 2008 at 3:53 am
But airwave is a trademark already.
So gravity wave sounds cooler.
It gives a much better feeling, a notion of something huge and powerful and scary.
Just like tornado sounds scary and powerful.
March 20th, 2008 at 4:45 am
Are these the same type Gravitational Waves that are trying to be detected coming from colliding black holes and such? Or are these completely different beast. I was under the impression that science has never actually detected gravity waves yet?
Thanks
March 20th, 2008 at 5:31 am
Nope, entirlry different activity.
March 20th, 2008 at 5:44 am
That name must be an American-ism. In other parts of the world, these waves aren't called the confusing name 'gravitational waves', they're called 'undular bore waves'.
March 20th, 2008 at 6:05 am
Actually "gravity waves" in reference to these is not a new term at all. It is the general term for waves in a fluid for which the restoring force is gravity. I don't think this is an americanism. There is a further distinction between "surface gravity waves" (the waves (ocean) surfers ride), and "internal waves" that are an oscillation in the volume of a fluid. This story is about internal atmospheric waves.
Internal waves have been well studied in both the atmosphere and in the ocean for a long time. (I think the US Navy has been looking for internal waves caused by submarines.)
In contrast I think "bore waves" are singular waves, often caused by tides. But I'm not sure about this term.
March 20th, 2008 at 11:20 am
gravity waves and gravitational waves
March 20th, 2008 at 11:46 am
Maybe we should use something similar to Star Trek's technobabble generator to name stuff like this.
March 20th, 2008 at 3:13 pm
Well - many universe today articles ARE technobabble or maybe sciencebabble
March 20th, 2008 at 3:57 pm
Is there any correlation between these gravitational waves in the air and rogue waves in the ocean?
March 21st, 2008 at 3:42 am
Glider pilots have for many years been using standing waves in the atmosphere as a means to flying great heights and distances. The hight record was broken recently taking it to something over 50,000 ft http://www.perlanproject.com/recent_news.php?date=2006-08-30 and distance is now 3,008 Kms in a single day flying these waves. They are very well known and documented and very well researched. But they are not described as gravity waves. It seems to me that people with no answers to why their gravity research has not produced any identifiable answers are now clutching at any straw in the wind. The correct title for these waves relates to their location and are either Lee Waves when in the lee of a mountain for example or they are called Frontal waves when they appear at the edge of a weather system.
March 25th, 2008 at 5:35 pm
Hmm the nomenclature of these are very confusing… but I think it does differ from other more traditionally understood phenomenon as they are actually maintained by Earth's gravitational field…
Ian ?
March 27th, 2008 at 2:18 pm
I think several readers skipped over this paragraph:
"A large number of things may cause gravity waves (not to be confused with gravitational waves, the ripples in space-time), including intense disturbances caused by storm systems, a sudden change in jet stream location or wind shear. The strong oscillation will then travel for hundreds or even thousands of miles."
March 28th, 2008 at 8:10 pm
Chris, I didn't skip it and I'm still confused with the nomenclature used here !