Mystery behind cloud on Saturn's moon unravelled

• A research group has explained why Titan, Saturn's largest moon, has what looks like an enormous white arrow about the size of Texas on its surface.
• The researchers use a global circulation model of Titan to demonstrate how planetary—scale atmospheric waves affect the moon's weather patterns, leading to a "stencilling" effect that results in sharp and sometimes surprising cloud shapes.
• "These atmospheric waves are somewhat like the natural, resonant vibration of a wine glass," said Jonathan L. Mitchell, UCLA assistant professor of earth and space sciences and of atmospheric and oceanic sciences, who led the study. "Individual clouds might 'ring the bell,' so to speak, and once the ringing starts, the clouds have to respond to that vibration," he explained.
• 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.

Radar image released by NASA shows what scientists believe to be sea-size bodies of liquid, shown in blue, on the surface of Saturn's largest moon Titan.