Wild Storms Rage Far Beyond Mother Earth : Weather: The most impressive of all ‘blocking highs,’ Jupiter’s Great Red Spot, is a caldron of clouds stirred by fierce winds that have been in turmoil for at least 300 years.

If any strange weather occurs in the next few months, some people probably will blame Jupiter and the chunks of comet that slammed into it.

Wrong, but not as far-fetched as it sounds. By studying the effects of the comet’s impacts, scientists may learn more about Earth’s atmosphere and weather. Like Earth, Jupiter and some other planets in the solar system come equipped with an atmosphere, clouds, jet streams and storms.

In fact, Jupiter’s Great Red Spot, the longest-running known storm in the universe, has a lot in common with a weather pattern on Earth called a “blocking high.”

“Both are high-pressure systems that prevent other conditions from intruding,” said Timothy E. Dowling, a planetary scientist at the Massachusetts Institute of Technology. “On Earth, blocking highs can last for months and cause droughts by fending off the rain clouds that would normally water a region. They commonly occur in central Russia and the Midwestern United States.”

The granddaddy of all blocking highs, Jupiter’s Great Red Spot, is a caldron of whirling clouds stirred by fierce winds that have been in turmoil for at least 300 years. At times, as many as three Earths would fit inside it.

Like a rock in a stream, the Red Spot blocks other swiftly passing clouds and sends them spinning into short-lived eddies.

“And there are hundreds of little guys too,” said Dowling. Jupiter roils with smaller versions of the Great Red Spot. These vortices interact with heat from the planet’s interior, setting in motion bands of jet streams. Winds on Jupiter have been calculated at more than 260 m.p.h.

“Instead of meandering unpredictably like terrestrial hurricanes, storms on Jupiter simply drift at a constant rate either eastward or westward,” said Dowling. “One reason for the simpler situation is the lack of mountain ranges and air-sea interfaces that act on Earth to thwart the natural tendency for winds to settle into steady east-west patterns.”

But winds on Jupiter are gentle zephyrs compared to those on Neptune. Orbiting in a deep freeze of minus 328 degrees, Neptune unleashes winds estimated at nearly 1,250 m.p.h., the fastest in the solar system.

The largest storm on Neptune, an Earth-size vortex called the Great Dark Spot, wears a scarf of bright clouds, much like those on Earth’s mountain peaks. Winds racing around Neptune are deflected upward by the storm, creating the rapidly changing companion clouds. The clouds and storms form as convection shoots hydrocarbon gases up into colder regions, where they condense into bright ice.

As with Jupiter and Neptune, internal heat drives Saturn’s turbulence. About every 30 years, a huge area of white clouds erupts near the planet’s equator and encircles Saturn for a few months. The last episode occurred in October, 1990.

In these clouds, moisture condenses and liberates its latent heat, said Dowling. “This kind of storm seems to explode like a bomb. It’s the same kind of energy source that raises cumulus towers high into the air on Earth and powers hurricanes.”

Once mistaken for clouds by telescope astronomers, great dust storms periodically rage across Mars for months, creating a yellowish haze. Some grow so large that they blanket the entire planet.

“We see dune fields on Mars as big as the Sahara,” said Ronald Greeley, an Arizona State University geologist. “It takes 100 m.p.h. winds to raise the dust into the atmosphere.

The violence of extraterrestrial volcanoes also intrigues scientists studying the possible correlation to eruptions on Earth.

“Venus has a large amount of volcanic activity, so much so that it appears that the surface is, in geological terms, relatively new, although the planet itself, like Earth, is 4.5 billion years old,” said Edward C. Stone, director of the Jet Propulsion Laboratory in Pasadena. “The surface has been recoated by volcanic flows to the extent that its average age is only about 500 million years.”