After a few minutes, air heated by the deposit establishes a convective regime and due to the speed of the rising air a series of small tornados (also spelled tornadoes) are formed.
During daylight it is difficult to imaging how hot the deposit is.
To see a pyroclastic flow deposit glowing at night from same location.
Animation (Timelapse) shows pyroclastic flow at Mount Sinabung, Sumatra. Further, a close-up of the lava lobe is shown including the collapse of the lobe front leading to a pyroclastic flow.
Movement of the lobe prior to collapse is just about visible.
To see a pyroclastic flow with Lightning from the same location.
Timelapse animations of Pyroclastic flows resulting from collapses of the viscous andesitic lava lobe erupting from a summit crater of Sinabung Volcano in Sumatra, Indonesia.
Lightning (static discharge) is generated by the fine ash particles in the pyroclastic flow rubbing against eachother and generating static electricity.
Animations were made from individual exposures 1.2-2 seconds long.