ATMOSPHERIC PRESSURE, WIND, AND GLOBAL CIRCULATION - Discovering Physical Geography - page 134

C H E C K Y O U R U N D E R S T A N D I N G

1. Define the concept of air pressure and discuss how it is
measured.

8. What are Rossby waves, and why are they more likely to
form during the winter months than the summer months?

2. Why is air pressure greater at low altitudes than high
altitudes?

9. How does Earth-Sun geometry influence the position
of atmospheric pressure systems?

3. Compare and contrast airflow in a high-pressure system
with that of a low-pressure system in the Northern
Hemisphere.

10. What are the challenges we face in our attempt to
systematically develop wind energy?

11. How is a land-sea circulatory system like a tropical
Hadley cell?

4. Discuss the three factors that influence large-scale
atmospheric circulation.

12. How are land-sea breezes and mountain breezes simi-
lar? What conditions are required for these circulatory
systems to develop?

5. Compare and contrast the various circulatory systems
within the global circulation model.

6. Which place is more likely to be a zone of convection,
the ITCZ or STH? Why does this pattern occur?

13. Within the Atlantic gyre, what is the primary purpose of
the Gulf Stream?

7. Why is the polar front an important feature in the
midlatitudes?

14. Discuss the El Niño pattern, how it differs from the
“normal” pattern, and how it impacts weather.

ANSWERS TO VISUAL CONCEPT CHECKS

V i s u a l C o n C e p t C h e C k 6 . 1
Air pressure decreases from the base of Mount McKinley to the top of the mountain. This occurs
because air molecules tend to be held closely to Earth due to the force of gravity. Given that more
air molecules occur at the base of the mountain than the top, the air pressure (or weight of the air) is
greater at the base of the mountain. Conversely, air pressure decreases with altitude because progres-
sively fewer air molecules exist.

V i s u a l C o n C e p t C h e C k 6 . 2
The high-pressure system in this image is centered over central Europe. This can be determined be-
cause that is the approximate center of the zone of clear (or sunny) skies. Given that this anticyclone
is in the Northern Hemisphere, it spins clockwise. Thus, northerly winds exist on the eastern side of
the system, whereas southerly breezes are on the west. Spain is under the influence of a low-pressure
system, as indicated by the dense cloud cover.

V i s u a l C o n C e p t C h e C k 6 . 3
The answer to this question is c . The ITCZ consists of the band of clouds that extends east and west
through the northern part of South America.