Geoscience Reference
In-Depth Information
(a)
(b)
Figure 6.26. (a) Looping, C
Liliya Zakharchenko/Dreamstime.com; and (b) lofting plumes of pollution from
smokestacks. C
Artem Sapegin/Dreamstime.com.
both the Northern and Southern Hemispheres. Descend-
ing and rising air in these cells results in the creation of
large-scale semipermanent high- and low-pressure sys-
tems over the oceans. Pressure systems over continents
(thermal pressure systems) are seasonal and controlled
by ground heating and cooling. Large-scale pressure
systems affect pollution through their effects on stabil-
ity and winds. Surface high-pressure systems enhance
the stability of the boundary layer and increase pollu-
tion buildup. Surface low-pressure systems reduce the
stability of the boundary layer and decrease pollution
buildup. Soil moisture affects stability, winds, and pol-
lutant concentrations. Sea and valley breezes are impor-
tant local-scale winds that enhance or clear out pollution
in an area. Elevated pollution layers, often observed, are
aproduct of the interaction of winds, stability, topogra-
phy, and chemistry.
6.5. If the Earth did not rotate, how would you expect
the current three-cell model of the general circulation
of the atmosphere to change?
6.6. In Figure 6.27, to approximately what altitude will
a parcel of pollution rise adiabatically from the surface
in unsaturated air if the parcel's initial temperature is
25 C? What if its initial temperature is 30 C?
6.7. In Figure 6.27, to approximately what altitude will
a parcel of pollution rise adiabatically from the sur-
face in saturated air if the parcel's initial temperature is
25 C? What if its initial temperature is 30 C? Assume
awetadiabatic lapse rate of 6 Ckm 1 .
6.8. Why do ozone mixing ratios peak in the afternoon,
even though mixing depths are usually maximum in the
afternoon?
6.9. Explain why ozone mixing ratios are higher on the
east side of the Los Angeles Basin, even though ozone
6.9. Problems
6.1. Draw a diagram showing the forces and the gradi-
ent wind around an elevated low-pressure center in the
Southern Hemisphere.
3
Layer 6
2.5
Layer 5
2
6.2. Draw a diagram showing the forces and result-
ing winds around a surface low-pressure center in the
Southern Hemisphere.
Layer 4
1.5
Layer 3
1
w
e
Layer 2
6.3. Should horizontal winds turn clockwise or counter-
clockwise with increasing height in the Southern Hemi-
sphere? Demonstrate your conclusion with a force dia-
gram at the surface and aloft.
0.5
d
Layer 1
0
0
5
10
15
20
25
30
Temperature ( o C)
6.4. Characterize the stability of each of the six layers
in Figure 6.27 with one of the stability criteria given in
Equation 6.4.
Figure 6.27. Environmental temperature profile with
wet and dry adiabatic lapse rate profiles
superimposed.
 
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