Lab 6 GEOL 2
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University Of Dallas *
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Course
001
Subject
Geology
Date
Dec 6, 2023
Type
Pages
4
Uploaded by ProfStraw9065
1
GEOL1350
Name: __Madison Martinez_
Lab Exercise 6
Atmospheric and Surface Ocean Circulation
Background
When watching weather reports on TV, have you ever noticed how weather patterns (storms
tracks, hurricanes, zones of high and low pressure) tend to move from west to east across the
United States?
This phenomenon is due to zonal wind patterns that we call prevailing winds.
These are not due to day-to-day local wind shifting, but are distinct global zones of weather
development and migration. Zonal refers to belts around the globe like the tropical belt, temperate
belt, or polar belt. They are characterized by distinct prevailing winds. In the tropics and near the
poles storm tracks move from east to west and from west to east in the temperate belt.
The Trade
winds, Westerlies, and Polar easterlies are termed prevailing winds. The Westerlies drive the
weather patterns of the U.S. The region where the Polar Front is located is characterized by
highly seasonal and variable weather patterns as the front migrates back and forth. The weather
on the borders of two prevailing wind zones can be characterized by storms and heavy
precipitation.
We think of the air as being “air”, but if you put some thought into it, it is more like a three-
dimensional object, or fluid. Air flows vertically (rises and sinks) and horizontally.
We as
humans, live at the bottom of one ocean and on top of another. Solar radiation is the driving
mechanism for atmospheric circulation, as incoming radiation heats the Earth’s surface and the
overlying air masses. We know that the equatorial regions are warmer than the poles because the
angle of the sun is more perpendicular to the surface there than at higher latitudes. To maintain
the planet’s heat balance, this hot air must move away from the equator and toward the poles, thus
causing circulation.
Many think of the Coriolis deflection as a “force” which it is not, as it is an APPARENT
deflection due to the rotation of the Earth. This only affects objects that are in motion and is
proportional to the speed and latitude of the body! In the northern hemisphere, the Coriolis
deflection turns objects to the right, and it turns objects to the left in the southern hemisphere.
Contrary to popular belief, Coriolis deflection only applies to large-scale motion and does not
explain why your toilet or bathtub swirls in a particular direction.
Coriolis deflection causes the Earth’s convection cells to bend, producing wind belts on the
Earth’s surface. Between the major wind belts, we find areas with little or no horizontal transport
of air, consequently, no winds! These are parts of the
convection cells where air masses are
moving in a dominantly vertical direction (rising/sinking).
Because air is rising or sinking, air
creates high and low pressure regions, which sets up a series of pressure gradients and convection
cells within the three major cells on earth. Low pressure regions are associated with rising air
(less downward pressure on Earth) and high pressure regions are associated with sinking air. Just
as water will flow downhill, there is a need to release this pressure from high areas to low areas.
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Questions to Answer:
1. (20 points) Draw schematically two curves into the figure below, one for the zonally averaged
incoming visible short wave (Q
SW
) radiation from the sun (solid curve) and one for the zonally
averaged outgoing long-wave infrared (Q
LW
) radiation (dashed curve) from the Earth’s surface
depending on latitude. Label the two curves.
Point out areas of radiative surplus (+) and deficit
(-) on the Earth’s surface. (Hint: You may want to consult Fig. 8.1.4 in your textbook).
2. The more carbon dioxide and other greenhouse gases are present in the atmosphere, the more
heat radiation is trapped in the atmosphere.
The graph below shows measurements of carbon
dioxide in the atmosphere from the Mauna Loa observatory on Hawai’i.
Source:
https://scripps.ucsd.edu/programs/keelingcurve/
Surplus (+)
Deficit (-)
Deficit (-)
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a) (10 points) How much does the amount of CO
2
vary over the course of one year? For a close-
up look at one year go to the link listed above.
CO2 rises and falls around 6-8ppm annualy, but mostly rises about 2ppm per year.
b) (10 points) Describe the pattern of this variation in one year.
What might be the reason for this
pattern?
CO2 goes through a variation throughout the year known as a seasonal cycle. It reaches its lowest
point in the late summer, and its highest in the winter when plants start to decay. The reason for
this cycle is plant growth during the summer removing CO2 and plant decay in the winter no
longer able to remove CO2.
c) (10 points) What is the total change in the average CO
2
concentration since the beginning of
this recording (1957) until now?
The average has increased by over 100ppm since the beginning of this recording until now.
(Appox 106 ppm)
3. (20 points) Draw the major wind belts for the northern and southern hemisphere in the figure
below and label the wind belts.
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4. Describe air movements and prevailing pressures at:
a) (5 points) Horse latitudes
The Horse Latitudes, around 30 degrees north and south of the equator, have calm, hot, and dry
weather. They're known for light, inconsistent winds. These regions are like giant atmospheric
deserts with high pressure above, causing air to sink and suppressing rain.
b) (5 points) Doldrums
The Doldrums, near the equator, are areas of low pressure where the air rises. They're known for
light and fickle winds. These regions often bring humid, cloudy, and stormy weather.
3. (5 points) What is the Intertropical Convergence Zone?
Where the Southeast trade winds and the Northeast trade winds converge.
5. (5 points) What is the difference between the Coriolis deflection in the northern hemisphere
and the southern hemisphere?
The Coriolis deflects to the right in the northern hemisphere, and to the left in the southern
hemisphere.
6. (10 points) Electromagnetic radiation (“light”) travels at a speed of ~3 x 10
8
m s
-1
.
The
distance from Sun to Earth is ~150 x 10
6
km.
How long does radiation from the Sun take to reach
Earth?
Show your calculation.
Speed = 3 x 10^8 ms^-1
Distance = 150 x 10^6 km ———> 150x10^9m
Time = Distance / Speed
Time = (150 x 10^9m) / (3 x 10^8 m/s) = 500 seconds
500/60= 8.333 = 8 mins 20 secs
Time = 500 Seconds or 8 minuets and 20 seconds