Question

Which ONE of the following options CORRECTLY matches the atmospheric stability conditions with plume conditions/ behaviours given in the table?

Atmospheric Stability Conditions	Plume Conditions/Behaviours
(P) Strong instability	(i) Fanning plume
(Q) Neutral stability	(ii) Fumigation
(R) Surface inversion	(iii) Coning plume
(S) Aloft inversion	(iv) Looping plume

• A. (P) - (i); (Q) - (ii); (R) - (iii); (S) - (iv)
• B. (P) - (iv); (Q) - (iii); (R) - (i); (S) - (ii)
• C. (P) - (iii); (Q) - (iv); (R) - (ii); (S) - (i)
• D. (P) - (ii); (Q) - (i); (R) - (iv); (S) - (iii)

Hint:

Link each stability condition to how much vertical mixing it allows: strong instability gives looping, neutral gives coning, a surface inversion gives fanning, and an elevated (aloft) inversion gives fumigation.

Answer 1

The Correct Option is B

An easy way to keep these straight is to picture the lapse-rate profile as either very steep, medium, or flat/inverted, and think about how much vertical mixing that allows. A strongly unstable atmosphere has a lapse rate steeper than the dry adiabatic rate, so parcels of air keep accelerating up and down, and a plume caught in this turbulence loops wildly, giving the looping plume for strong instability (P to iv). A neutral atmosphere follows the dry adiabatic rate closely, giving only moderate, evenly balanced turbulence in both directions, so the plume grows into a smooth, symmetric cone, the coning plume for neutral stability (Q to iii). When the inversion sits right at the surface and extends up past the stack, the whole depth around the stack is extremely stable and vertical motion is almost completely suppressed, so the plume can only stretch out sideways like a thin flat ribbon or fan, giving the fanning plume for a surface inversion (R to i). Finally, when the inversion is elevated above the stack while the air below (including at stack height) is unstable or neutral, the plume disperses freely downward but is capped from above; as the ground heats up and the unstable layer grows, it eventually reaches up and rapidly folds the trapped plume down to ground level all at once, producing the sudden high ground-level concentration known as fumigation for an aloft inversion (S to ii). Matching each stability picture to its mixing behaviour this way reproduces exactly option (B).

\[\boxed{(P)\text{-(iv)};\ (Q)\text{-(iii)};\ (R)\text{-(i)};\ (S)\text{-(ii)}}\]