domingo, 18 de marzo de 2012

Jupiter’s Jet Streams Get Thrown Off Course

Jupiter's jet streams. Image credit: NASA/JPL/SSI 
Jupiter's jet streams. Image credit: NASA/JPL/SSI 
Both Earth and Jupiter have jet streams; fast-moving winds that circle the globe. On Jupiter, those jet streams are constrained to very specific bands of the planet, while they meander around the Earth. We can see huge variations of weather when Earth’s jet streams move around – like unusually cold weather in Florida. 
These strange weather patterns can occur on Earth when the jet streams interact with another atmospheric phenomenon called Rossby waves. We have them here on Earth, and they were first identified on Jupiter about 20 years ago.
And now scientists have identified the signature of Rossby waves throwing the jet streams off course on Jupiter. During its flyby of Jupiter, NASA’s Cassini spacecraft captured these images of Jupiter’s atmosphere; 100 were stitched together into a time-lapse movie.

If you watch the movie, you’ll be able to see a series of small, dark, V-shaped “chevrons” forming along the side of the jet stream. Eventually the well-defined atmospheric band starts to ripple and distort because of these Rossby waves. This shows that the jet streams on Jupiter, like Earth, can be thrown off course by the Rossby waves. 
Here’s a quote from the press release:
“A planet’s atmosphere is a lot like the string of an instrument,” says co-author Michael D. Allison of the NASA Goddard Institute for Space Studies in New York. “If you pluck the string, it can resonate at different frequencies, which we hear as different notes. In the same way, an atmosphere can resonate with different modes, which is why we find different kinds of waves.”
By studying these waves, scientists hope to be able to get an idea of what lies beneath Jupiter’s thick cloud layers; to understand the deeper atmospheric composition and structure.
Original source: NASA/JPL/SSI News Release
Source:  Universe Today

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