Sarychev from Space

Usually I try to help you understand the big picture, but every now and then a big photo is just the thing. This is Sarychev volcano, in the Kuril Islands volcanic arc, in eruption on June 12, photographed from the International Space Station. See a much bigger version at NASA's Earth Observatory, where it's the Image of the Day today.

The eruption plume consists of brown ash. The white cloud cap formed in the air pushed upward by the rising plume in the cold stratosphere. It is a pileus cloud (named for an ancient Greek hat), now being penetrated by the eruption plume. The big ring of clear air around the island formed as the air around the plume moved downward in response. On the ground, three ashflows are moving down the volcano's slopes. The one on the bottom appears to be white with steam.

About volcanoes
About volcanism
Volcanic arcs
Kudriavy, another Kuril volcano