Simplified schematic of a volcanic plume

Simplified schematic of a volcanic plume ejecting ash, crystals and fragments of rock from a vent. This rising plume will eventually hit a zone of neutral buoyancy in the atmosphere, where it is then carried by the wind. Material is ejected from both the upward moving jet and falls from the umbrellaing plume. Modified from Wilson and Houghton (2000), Encyclopedia of Volcanology first edition.