The Cause and Effects of Air Pollution
Cheryl E. Merritt
Your feedback is important to us!
After viewing our curriculum units, please take a few minutes to help us understand how the units, which were created by public school teachers, may be useful to others.
Give FeedbackEXAMPLES
A. LOOPING—large-scale turbulent eddies cause sizable parcels of air, together with portions of the plume, to deviate from a straight downwind direction
(figure available in print form)
B. CONING—the shape of the plume is commonly vertically symmetrical about what is call the plume line.
(figure available in print form)
C. FANNING—suppressed vertical mixing, but not horizonal mixing entirely causes the plume to spread only parallel to the ground and appears to take on the shape of a fan as seen from below.
(figure available in print form)
D. LOFTING—the lapse rate in the upper portion of the plume is unstable and in the lower it is stable. Mixing is vigorous in the upward direction.
(figure available in print form)
E. FUMIGATION—poses a potentially serious air pollution situation. Here the plume is released just under an elevated inversion layer. When the low-level unstable lapse rate reaches the plume, the effluent suddenly mixes downward toward the ground.
(figure available in print form)
In the effluent from a smelter in a valley is trapped in a radiational inversion, diffusing neither upward or downward, but drifting down the valley, the ground level concentration will be highest. The daily uniform warming of the valley floor erodes the inversion from beneath, and when the layer containing pollutants becomes unstable widespread fumigation occurs along a great length of the valley. SEE DIAGRAM BELOW.
(figure available in print form)
PLUME TRAPPED WITHIN AN INVERSION DRIFTS INLAND UNTIL IT EMERGES FROM THE UPWARD-SLOPING BASE OF THE INVERSION. THE VENTING OF AIR UP A MOUNTAIN SLOPE IS KNOWN AS THE CHIMNEY EFFECT.