The massive dust storm that engulfed Phoenix last week was unusual for the 20th century, but could become more common in the 21st.

The storm resulted from thunderstorm-cooled air plummeting into the ground like mist pouring from an open freezer, only exponentially more powerful. Combine those winds with extremely dry conditions, and the result was a wall of dust 100 miles wide and 5,000 feet high.

Dust storms are common in the U.S. southwest, but not storms this big. No formal records are kept, but meteorologists said it was the largest such storm in at least 30 years. It was on par with...

Federal prosecutors are asking a judge not to return the domain names of one of Spain’s most popular websites, seized as part of a major U.S. crackdown on internet piracy.

The legal filing over Rojadirecta.com represents the government’s first legal response to a lawsuit challenging “Operation in Our Sites.”

Commenced last year, U.S. Immigration and Customs Enforcement has seized as many as 208 domains the authorities claim are linked to intellectual-property fraud. The court-ordered seizures are aimed at web sites that sell counterfeited goods, as well as sites that facilitate illegal music,...