Mighty winds fuel megastorms on Titan

OXON HILL, Md. — Beneath the orange haze of Saturn’s moon Titan, methane rains from the sky and pools in lakes — and might even burst forth from massive storm squalls like those seen on Earth.

Titan has garden-variety thunderstorms that bring a bit of rain, then disappear. Now, the Cassini orbiter has seen phenomena that can’t be explained by these run-of-the-mill storms: cloud outbursts, liquid-carved channels and dark regions “reminiscent of rain falling on a parking lot,” planetary scientist Scot Rafkin reported November 11 at a meeting of the American Astronomical Society’s Division for Planetary Sciences.

Using computer simulations of cloud systems, Rafkin found that with a bit of wind shear, Titan could produce giant, long-lasting storm systems. On Titan, though, these storms would be beefed up: The squalls would last for longer than 24 hours and travel for more than 1,000 kilometers while dumping a couple of meters’ worth of methane from clouds three times as high as their counterparts on Earth.

Such storms would cause massive flooding on Earth as well as on Titan. “It’s more than enough to carve the river channels and fluvial features we see on the surface,” says Rafkin, of the Southwest Research Institute in Boulder, Colo. Strong gusts might also explain dunes that should have trouble forming with Titan’s typically weak winds. These squalls are “strong enough and moving in the right direction to coincide with dunes in the tropics,” Rafkin says.