噴煙

1. Origins, structure, and basic meaning

• Structure: 噴煙 (ふんえん) is a compound noun for a plume of smoke, ash, and gas rising from a volcanic crater.
• Basic usage: 山頂から立ち上る噴煙を観察する makes the volcanic plume the observed object, while 噴煙が空を覆う makes windblown emissions the subject graying the sky.

2. Common pitfalls and similar expressions

• Source at the summit and drifting plume
  • 噴煙が立ち上る rises from the crater, whereas 噴煙が流される travels with wind. The noun differs from an ordinary cloud or industrial smoke.