for National Geographic News
Bombarded by violent storms of dry ice, the red planet's ice caps may have fewer silent nights than generally thought, according to new weather models.
Climate experts have long agreed that all is calm during the polar nightsthe sunless winter months on Mars's north and south poles.
The poles are too cold, and the carbon dioxide rich atmosphere too thin and clear, to result in exciting weather, or so the thinking goes.
But now there's mounting evidence that temperature differences in the polar night stir up the atmosphere, creating storms.
"There's a lot of energy being released," said Timothy Titus, space scientist with the U.S. Geological Survey (USGS) in Flagstaff, Arizona.
At a meeting of the American Geophysical Union in San Francisco earlier this month, scientists even proposed that "thunderheads" form over Mars's southern polar cap.
Although it's not clear that a resulting storm would be electrical, some scientists believe it would release drafts akin to what Oklahomans might witness during a prairie thunderclap.
It would "tear apart" an airplane trying to fly through the system, said Anthony Colaprete, a space scientist at NASA's Ames Research Center in Moffett Field, California.
Colaprete calls these proposed tempests thunderstorms, for lack of a better term. But he notes that, unlike Earth thunderstorms, these Martian polar storms in his models don't harbor water. Clouds instead are filled with carbon dioxide crystals, commonly known as dry ice.
Working with colleagues from NASA, Oregon State University, and the Southwest Research Institute in Boulder, Colorado, Colaprete developed 3-D models suggesting that such storms exist.
He believes the typical Martian polar storm cloud develops and disperses quickly, in perhaps an hour and a half.
SOURCES AND RELATED WEB SITES