Towering twisters of ash spawned by a pyroclastic flow from a volcanic eruption in Indonesia last month.
When Mount Sinabung erupted in North Sumatra, Indonesia early last month, the pyroclastic flows making their way down the mountain left red-hot deposits along its sides.

Incredibly, as the air above the deposits heated and quickly rose, a group of small "tornadoes" formed, twisting their way down the mountainside as well.

The video of the event, captured by Dr. Richard Roscoe of Photovolcanica, is astoundingly surreal. Check it out above for yourself.