Lecture 9: The Atmopshere: Heat re-distribution and winds
I. Differential Heating: latitudinal Variation (modified Figure 9-6, reprinted below)
A. Global Average
B. Latitudinal Variation:
1. Effect of Earth’s curvature
2. angle of incidence
3. Radiation spread
c
a>b
a
c>d
b
d
Fig. 9-6
4.. Variation in thickness of atmosphere
C. Consequence of differential heating with latitude
D. Heat Redistribution by evaporation
Northern Hemisphere, Heat Transfer Schematic
90
60
Precipitation latitudes
40
20
Evaporation latitudes
0
E. Heat redistribution by currents
II. Differential Heating: Seasonal variation in northern hemisphere
( See: www.crh.noaa.gov/fsd/astro/season.htm and Fig. 9-7)
A. Consider elliptical orbit and Tilt of Earth’s axis
B. Summer:
C. Winter
D. Direction of Earth’s rotation
III. Global Winds: Tropospheric circulation
A. Atmospheric convection cells
B. The Coriolis Effect: influences global wind patterns
1. Trajectory of freely moving object
2. Consider speed of objects on a rotating disc
C= 2 π r
C= Circumference
r=
A
r
B
1/2
3. Example: Quito, Ecuador vs. Buffalo, NY
a. both at 79 oW
b. both rotate 360 o/day, CCW
c. circumference & speed greater at Quito
Circumference (km) Speed (km/hr)
Quito
39,792
1,658
Buffalo
30,240
1,260
Small
Circumference
Large
Circumference
Buffalo: rotation in
1 day
Quito: Rotation
in 1 day
d. cannon ball fired from Buffalo South to Quito
e. review figure 9-19
f. cannon ball fired from Quito north to Buffalo
also see:
http://www.physics.ohio-state.edu/~dvandom/Edu/newcor.html
and
http://apollo.lsc.vsc.edu/classes/met130/notes/chapter9/graphics/airplane_globe_arrow.gif
Red arrow: motion of object on ground
Yellow arrow: freely moving object
C. Atmospheric circulation: Three cell model
B. Types: Hadley, Ferrel, Polar (fig 9-11 amended below)
Polar
Ferrel
Hadley
Hadley
Ferrel
Fig. 9-11
Polar
III. Global Winds: Tropospheric circulation (cont.)
A. Atmospheric convection cells (see also fig. 9-9)
B. Types
1. Hadley Cell
2. Ferrel Cells
3. Polar Cells
C. Zones of converging and diverging air
IV Global wind patters
A. Dependable winds
B. NE and SE Trade Winds
C. Westerlies
D. Polar easterlies
E. Regions of convergence
F. Areas of Intense rainfall
G. Distribution of Deserts