Titan?s atmosphere a turbulent place

Scientists begin to ask: How?s the weather on Titan? Studying a thin cloud layer of methane in the largely nitrogen and argon atmosphere of Titan, scientists at Johns Hopkins Applied Physics laboratory in Laurel are finding ways to understand turbulence and other weather phenomena on Earth.

“Titan is one place in the solar system where things are happening like things that happen on earth, but in some systems it?s taken to extremes,” Ralph Lorenz said. “If we could build computer weather models that are mostly correct for the Earth and for Titan, we?d have much better modeling capabilities.”

The internationally funded Huygens probe detached from the Cassini spacecraft and descended by parachute through Titan?s atmosphere in January 2005. The Surface Science Package on board Huygens included tilt sensors that measured motions of the probe during its descent. The probe, plummeting at high speed on Titan, experienced a lot of buffeting, though there was little wind.

Lorenze gained insights into the erratic bouncing flight after studying measurements of magnetic disturbances in storms, taken by “radiosonde” in Earth-side weather balloons. Giles Harrison, an atmospheric physicist in the Department of Meteorology at the University of Reading in the United Kingdom, wrote the book on interpreting radiosonde data, Lorenz said.

“The Huygens tilt history was just this long squiggly complex mess, but seeing the fingerprint of cloud turbulence in Harrison?s work showed me what to look for,” Lorenz said.

Armed with that information, he determined a 20-minute period during Huygens? 2 1/2 hour descent ? about 12 miles up ? was affected by in-cloud turbulence.

His analysis helped identify a turbulent cloud layer in Titan?s atmosphere, a significant result for the investigation of Titan?s weather.

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