Which dispersion pattern is a circular dome vapor cloud extending up from the ground?

• A. Hemispheric
• B. Pool
• C. Stream
• D. Irregular

Answer: (A)

Dispersion patterns describe how a released vapor cloud spreads in the air. A circular dome rising from the ground is a hemispheric pattern: the cloud forms a dome over the source with a roughly circular footprint on the surface and lifts upward to create a half-sphere shape. This buoyant ascent causes the dome to extend above the ground, which is why it appears as a circular dome starting at the surface.

The other shapes don’t fit as well: pooling would be liquid lying on the ground; a stream is a narrow, elongated path along the ground; irregular is uneven and jagged due to obstacles or wind variability. So the circular dome extending upward is characteristic of a hemispheric dispersion pattern.