Question

Which type of plume is emitted under extreme inversion conditions?
A. Coning
B. Fanning
C. Looping
D. Trapping

Answer 1

Hint: The path and extent of gaseous effluents in the atmosphere is referred to as the plume. The source from which it is released is mostly a stack, commonly known as the chimney. A stable atmosphere occurs immediately above these stacks under extreme inversion conditions; hence the plume flows only horizontally under such circumstances.

Complete answer:
The stacks located in the town often emit or inject the effluents above the ground to a height ranging above several 100 meters. Moreover, the vertical temperature gradient also affects the spread of the plume. Hence on the basis of their behavior, plumes can be of following types:
Looping plume: it is characterized by waves. It occurs due to rapid mixing of the effluent in an unstable atmosphere which intensely disperses the plume.
Coning plume: it occurs when the atmosphere is nearly neutral and the velocity of wind is more than 32 km/hr. The plume thus formed takes the shape of a cone.
Trapping Plume: As the name suggests, this type of plume is trapped in between the inversions and therefore it can diffuse vertically only to a certain height.
Fanning plume: It occurs when the atmosphere is stable just above the emission stack and due to which the spread of plume is mostly in the horizontal direction. This plume is emitted in conditions of extreme inversions when the turbulence is low.

Hence, the correct answer is option (B).

Note: In the atmosphere, the behavior of plume is mostly influenced by the stability of air in that particular region and the long term variations occurring in the seasons. Thus, the form of plume depicts the stability of the environment as well as the dispersion capability of the atmosphere.