SAN FRANCISCO — Gravity waves, mysterious waves that ripple unseen throughout the atmosphere, may be a major source of airplane turbulence, a new study suggests. The new findings, presented Tuesday (Dec. 4) here at the annual meeting of the American Geophysical Union, may help explain why planes get shaky in apparently clear skies. Forecasting those waves may allow planes to reroute around them. "Just like waves on the ocean, as they approach a beach, they can amplify and break. Gravity waves in the atmosphere can amplify and break, and we're finding now that's a major contributor to turbulence in the atmosphere that affects aircrafts."
Gravity waves may explain mysterious airplane turbulence despite clear skies. — Gravity waves, mysterious waves that ripple unseen throughout the atmosphere, may be a major source of airplane turbulence, a new study suggests. The new findings, presented Tuesday (Dec. 4) here at the annual meeting of the American Geophysical Union, may help explain why planes get shaky in apparently clear skies.
Forecasting those waves may allow planes to reroute around them. "Just like waves on the ocean, as they approach a beach, they can amplify and break. Gravity waves in the atmosphere can amplify and break, and we're finding now that's a major contributor to turbulence in the atmosphere that affects aircrafts."
Gravity waves form when air traveling up and down in the atmosphere meets resistance. For instance, clouds rising in the troposphere, the lower level of the atmosphere where air mixes freely, will bump up against the boundary of the much more stable stratosphere, forming ripples in the process. These waves can travel up to 180 miles (300 kilometers) before breaking, said Robert Sharman, a meteorologist at the National Center for Atmospheric Research (NCAR), who conducted the study. "They're waves running around in the atmosphere all the time," Sharman told LiveScience.
Sharman and his colleagues wanted to understand when and where these waves occur. They collected data from commercial aircraft flight recorders, which record the location, duration and intensity of turbulence. Then they recreated these turbulent events using a computer simulation that models the atmosphere. They found that gravity waves "break" on the surfaces of planes, just like ocean waves breaking on the beach, causing much of the turbulence that occurs out of the blue in clear air. In the past, pilots thought airplanes moving up and down in the jet stream caused such turbulence. Many of the waves were formed in storm clouds that tracked the jet stream, but traveled miles away and broke in areas where airplanes were flying.
Originally posted by stirling
They have been trying to measure gravity waves for a long time....deep inside mine shafts there are devices to measure the fluctuations of gravity recievers, Large blocks of metal etc....
The instruments supposedly measure the increments of movement due to gravity waves...
As far as i know they havent picked up a thing yet....
perhaps gravity has similar properties to magnetism, and im willing to bet they are partly related in some way.....
According to NASA's Earth Observatory information service, atmospheric gravity waves "form when buoyancy pushes air up, and gravity pulls it back down". But while simple enough to define, the phenomenon is anything but easy to monitor. This photograph of the Arabian Sea, taken by the Moderate Resolution Imaging Spectroradiometer (MODIS) on NASA's Terra satellite in 2005, was a lucky strike aided by sun glint; when a satellite views the surface of the at the same angle as sunlight reflects off it, smooth ocean water appears mirror-like and rougher surface waters appear dark. Sometimes, adds NASA, "the sun glint region of satellite images reveals interesting ocean or atmospheric features that the sensor doesn't usually observe". In this case, waves clearly visible on the surface are not ocean waves but, rather, the "impression" on the water of atmospheric gravity waves touching the surface on their way down, at their troughs. Note the pattern of small clouds; these often form at the crest of atmospheric gravity waves and are visible in this image.
Originally posted by bobs_uruncle
reply to post by theabsolutetruth
No offense to the OP, but this sounds like a non-issue made up piece of bunk to me. We were trying to perform gravity wave interferometry back in the mid 90's when I was working for NRC clients. What we found was that if gravity waves existed, they would be huge, like possibly parsecs from peak to valley. Light speed limitations in an interferometer that size would create problems with "real-time" measurements, like a couple of years delay. The only way at the time we could create the possiblility of measuring gravity waves in "real-time" was by temporal proxy (it's complex and required a few years of R&D). Now there is also a problem with amplitude and frequency of alleged gravity waves as well as their source proximity. You get that space-time curvature problem with resolution as events get closer. I really doubt "turbulance" is caused by gravity waves, if that were the case they could be easily measured using off the shelf equipment, so this just sounds like junk science (like taxes will fix climate change) and trying to fit a wishlist cause as a solution to a non-related scenario.
Cheers - Daveedit on 12/5.2012 by bobs_uruncle because: (no reason given)
Scientists also suspect that breaking gravity waves can indirectly affect many aspects of the weather, but just how that happens will require better understanding of the basic nature of the waves, said Eckermann. “It’s kind of exciting,” Yale University atmospheric scientist Ron Smith said of the new findings. Smith was not involved with the study. Not only does the discovery of the mountain-produced ripples validate the findings of models that predicted their existence, he said, but it will bring details about the waves’ behavior to light. For years, Smith said, he and other atmospheric scientists looked for signs of the waves by flying weather balloons near mountains. But the balloons could not ascend high enough to detect waves that had climbed into the stratosphere. Now that scientists can see those stratospheric waves, they can determine how mountains and weather patterns interact to create them. “Relying on the satellites is by far the best way to do this, and with this paper by Eckermann [and Wu] we can see the waves reach the upper stratosphere in some places but not others,” Smith said.
In fluid dynamics, gravity waves are waves generated in a fluid medium or at the interface between two media (e.g., the atmosphere and the ocean) which has the restoring force of gravity or buoyancy.
Definitions always matter in science. In this case, gravity waves and gravitational waves sound so similar, it's easy to see why someone might confuse the two.
Originally posted by bobs_uruncle
I guess it simply comes down to definition.
Perturbations within our own planet cause adjustments in gravity potential at arbitrary points (or self organizing points).
Gravity waves are the oscillations of air parcels by the lifting force of bouyancy and the restoring force of gravity. These waves propagate vertically as well as horizontally, and actively transport energy and momentum from the troposphere to the middle and upper atmosphere. Gravity waves are caused by a variety of sources, including the passage of wind across terrestrial landforms, interaction at the velocity shear of the polar jet stream and radiation incident from space. They are found to affect atmospheric tides in the middle atmosphere and terrestrial weather in the lower atmosphere.
The scientific satellite TIMED (Thermosphere*Ionosphere*Mesosphere*Energetics*Dynamics) is currently exploring the Earth's Mesosphere and Lower Thermosphere (60 - 180 km). This region is the least explored and understood region of our atmosphere.