Volcanic Ash Plume & Flight Corridors (2D)

This 2D companion swaps the 3D version's orbiting particle scene for a side-on cross-section built to make the aviation-hazard physics legible: an eruption column rises to a height set by the Mastin plume-height/mass-eruption-rate power law, ash then drifts downwind at the wind-speed slider's rate while settling out at a Stokes-law terminal velocity that depends on particle size, and three notional flight levels flip to red the moment the modelled concentration beneath them crosses the ICAO ash-advisory chart's no-fly threshold — showing directly why fine ash from a modest eruption can close air corridors hundreds of kilometres away while coarse ash falls out within sight of the vent.