Mount Etna has begun to erupt again after a relatively quiet summer. Earlier this week it coughed out rare giant rings of steam along with roiling hot clouds and fountains of lava. Volcanic eruptions have occurred at this spot, where the European and African tectonic plates collide, for about half a million years. Today Etna is one of the world's most active volcanoes, erupting from a rocky cone that rises more than 10,000 feet (3,329 meters) above the southeast coast of the Italian island of Sicily. Photographer and volcanologist Tom Pfeiffer was there on the afternoon of November 11 in the middle of a storm that shrouded the volcano with heavy rain and snow. Icy winds occasionally cleared the sky, giving Pfeiffer and his companion glimpses of the volcano's puffing. "We could hear explosions and spot the occasional ash plume," he recalls. "Suddenly I saw a perfect steam ring racing over the sky. And soon after that a second one, and a third one!"

Photograph by Tom Pfeiffer, www.volcanodiscovery.com