RRB Group D Model Paper 1 with solutions

(3) Typically in early evening, if a surface inversion is developing, vertical motion may be slowed or stopped in the area below the plume. The area above the plume continues to disperse. Therefore, the plume is diluted but does not reach the ground. This is a favourable plume. Fumigation occurs when a plume that was originally emitted into a stable layer is mixed rapidly to ground-level when unstable air below the plume reaches plume level. This is an often dangerous, undesirable plume