Via Wikipedia: A roll cloud is a low, horizontal, tube-shaped, and relatively rare type of arcus cloud. They differ from shelf clouds by being completely detached from other cloud features.
“Ring of fire” is a rare type of eclipse. This specific one took place on May 10, 2013, in Australia and south Pacific. The Moon blacked out 95% of the sun, leaving a fiery outline. The next time such an eclipse will take place will be in 22 years.