ScienceDaily (Aug. 15, 2011) — Why does Titan, Saturn’s largest moon, have what looks like an enormous white arrow about the size of Texas on its surface?

A research group led by Jonathan L. Mitchell, UCLA assistant professor of earth and space sciences and of atmospheric and oceanic sciences, has answered this question by using a global circulation model of Titan to demonstrate how planetary-scale atmospheric waves affect the moon’s weather patterns, leading to a “stenciling” effect that results in sharp and sometimes surprising cloud shapes.

“These atmospheric waves are somewhat like the natural, resonant vibration of a wine glass,” Mitchell said. “Individual clouds might ‘ring the bell,’ so to speak, and once the ringing starts, the clouds have to respond to that vibration.”

The fascinating clouds, including arrow-shaped ones, that result from the atmospheric waves can cause intense precipitation — sometimes more than 20 times Titan’s average seasonal rainfall — and could be essential in shaping Titan’s surface by erosion

to read more, go to:    http://www.sciencedaily.com/releases/2011/08/110815194403.htm