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MIDTERM III STUDY GUIDE
GEOL 1080 • INTRODUCTION TO OCEANOGRAPHY
FALL 2009
Utah Valley University
READ THIS FIRST: this outline is not meant to be fully comprehensive. This lists all the major topics we discussed in class, but
it does not completely cover everything involved with every topic, so use this as a guide to your notes, and to what to look
at in the text.
WHAT THE EXAM WILL COVER: The exams will focus on air-sea interactions (Ch 6), climate change (Ch 6 & notes. You will
be responsible for the corresponding chapters from your textbook.
WHEN THE EXAM WILL TAKE PLACE: The exam will be available in the CTC from Saturday 11/21 through Tuesday 11/24
Tuesday will be a late day and will cost $3. Students in section 1 (Tuesday/Thursday) may take the exam in the classroom
on Tuesday at 10:00 am. MWF (section 2) students must take the exam at the CTC.
INSURANCE: Insurance is due 10 am Tuesday 11/24 in the College of Science main office or delivered to me in PS 102. I will
not accept insurance between 10 and 11:15 in PS 102 while other students are taking the exam. Make yourself a
photocopy of your insurance work and be sure to follow the directions to ensure you get full credit.
CALCULATIONS HANDOUT: See the class website.
1. Air – Sea Interactions (Chapter 6)
a. Energy from the Sun
i. Basic driving force behind air and ocean circulation
1) At high latitudes there is less heating (regardless of time of year).
a) At high latitudes there is less incident radiation per m2 area
b) At high latitudes there is more reflection on average
2) Amount of solar heating at any given spot varies with the seasons
3) More heat reaches surface at tropical latitudes than escapes back into space and vice versa in the arctic and
Antarctic. Tropics do not continually warm (and high latitudes don’t continually get colder) because the
excess heat from the tropics is transferred to polar regions by atmospheric and oceanic circulation.
b. The Atmosphere
i. Some basics
1) Composition: mostly N2 (78%) along with some O2 (21%).
2) Divided into troposphere, stratosphere and mesosphere. All weather happens in troposphere – that’s what we
are concerned with.
3) In troposphere, temperature decreases with elevation.
4) Warm air is less dense and rises; cool air is more dense and sinks
5) Convection cell concept
6) Air flows horizontally from regions of high pressure to regions of low pressure.
7) Rising air leaves low pressure at surface; sinking air creates high pressure at surface
ii. Air movement on the Earth
1) Hypothetical nonspinning Earth: Two large convection cells that redistribute heat that is input onto Earth by
Sun
2) But Earth spins, which causes The Coriolis Effect
a) Because the Earth is spinning, objects traveling across Earth appear to curve to the right in the Northern
Hemisphere and to the left in the Southern Hemisphere.
b) Effect is greatest at poles and least at Equator (goes to zero actually).
3) Combination of effects described in nonspinning Earth example and Coriolis effect create circulation cells
and wind belts.
a) Air cannot simply move from poles to equator – Coriolis effect causes it to curve across Earth’s surface.
See figure 6-10.
b) Three convection/circulation cells per hemisphere
c) There is a surface wind belt associated with each cell –
i) NE and SE Trade winds
ii) Prevailing Westerlies (N & S)
iii) Polar Easterlies (N & S)
iv) Doldrums, Horse Latitudes and Polar fronts at cells boundaries. Doldrums and polar fronts are
sites of enhanced precipitation. Doldrums referred to as ‘Intertropical Convergence Zone’ or
ITCZ.
d) Be able to draw figure 6-10.
GEOL 1080, Introduction to Oceanography, Midterm 3 Study Guide, Professor Bunds
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iii. Relatively localized air movements: surface high and low pressure centers, land and sea breezes
1) Surface low pressure centers – air is rising, flowing inwards towards center at and near ground surface.
Coriolis effect deflects motion; in N. Hemisphere, counter-clockwise ‘cyclonic’ flow develops. Be able to
draw this.
2) Surface high pressure centers – air is sinking, flowing outwards from center at and near ground surface.
Coriolis effect deflects motion; in N. Hemisphere, clockwise ‘anticyclonic’ flow. Be able to draw this.
iv. Sea (and land) breezes.
1) Heating of land during day causes air to rise, sucks air inland off the water – this is the ‘sea breeze’ that often
kicks in late on warm days.
2) Cooling of land during night causes air to sink, flow out over ocean. This is a night time, early morning ‘land
breeze.’
v. Storms
1) Mid-latitude storms –
a) Broadly speaking, caused by collisions of cold and warm masses of air along the polar front. When air
masses collide, warm air rises, which causes it to cool, water condenses, it rains/snows.
b) Cold front forms if the mass of cold air is moving more rapidly than the warm air mass, and the cold air
mass forces its way underneath warm air.
c) Warm front forms if the mass of warm air is moving most rapidly and forces its way over the cold air.
2) Tropical Cyclones –
a) Hurricanes in Americas, typhoons in W. Pacific, and cyclones in Indian ocean
b) Low pressure centers that initiate in along the equator, migrate north or south
c) Take advantage of warm ocean and warm moist air, which provides the energy; Coriolis effect, which
causes the system to spin
d) Move towards the west on the trade winds, and to the north or south away from equator (depending on
hemisphere).
e) Transport large amounts of water vapor, and thus energy northwards away from equator
f) Air moves to center, spiral upwards. Rising air cools, water condenses, precipitates. Warm water provides
energy to generate lift.
g) Damage:
i) Winds
ii) Storm surge – the big killer
(1) As storm approaches coast, winds push water onto land
(2) Extreme low pressures allow water level to be higher (atmosphere is pushing down with more
pressure elsewhere, so water level rises under the storm)
(3) Surges can be as high as 12 m; a couple to a few meters is common.
(4) Example: Galveston, TX, 9/8/1900. 6m surge, 6000 deaths, most by drowning. Almost no
warning.
(5) Andrew, 8/1992, $20 billion damage; 160 mph winds; ‘only’ 54 deaths.
vi. Greenhouse Effect
1) Sun heats the Earth by radiating visible light energy to Earth. Earth sends energy to space as infrared
radiation, which keeps Earth from progressively heating over time.
2) Gasses in the atmosphere inhibit escape of infrared radiation, just as glass windows of a greenhouse do. Glass
& atmos. let light in easily – interior gets heated. However, glass & atmos inhibit escape of infrared
radiation (and heat). Car and greenhouse get warm as a result. However, the amount infrared radiation
produced increases with temperature, and eventually the car, greenhouse, or earth is hot enough that it
produces enough infrared so that the fraction that escapes through the glass or atmosphere is equal in energy
to the amount of incident solar radiation. In this way the temperature in the greenhouse and on Earth remains
nearly constant.
3) The gasses in the atmosphere that do this are CO2, H2O, CH4; these are called the greenhouse gasses.
4) Without these gasses and this effect, Earth surface would average about –20oC instead of 13oC. Venus’ surface
temperature is about 470oC due to large amounts of CO2 in its atmosphere.
5) Climate Change is the idea that the climate is changing, which it is. Global Warming is the related and more
specific idea that the climate is getting warmer, which it is.
6) An important question is why is the climate is warming? If amount of greenhouse gasses increases,
greenhouse effect increases, earth warms. By burning fossil fuels, humans have produced increased the
amount of CO2 in the atmosphere by over 30%. Nearly all data indicates that these human-produced
greenhouse gasses are the primary cause of current global warming, although natural climate change may
also be playing a role. For the past 1 million years, ice ages have occurred on a 100,000 year cycle and for
1.5 million years before that, ice ages occurred on a 41,000 year cycle. CO2 concentration in the atmosphere
has varied on exactly the same cycle, with larger concentrations of CO2 having occurred when the Earth’s
GEOL 1080, Introduction to Oceanography, Midterm 3 Study Guide, Professor Bunds
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climate was warmer (“interglacials”). Prior to the industrial revolution, CO2 levels were the same as during
past interglacials. However, during the past ~150 years, CO2 levels have increased by ~30% due to burning
of fossil fuels by humans; at the same time global temperatures have risen 1 to 2oC which is much more than
they rose in the previous centuries; this is some of the powerful evidence for the human contribution to
global warming.
7) Ocean role in CO2 concentrations: oceans absorb CO2 by the reaction CO2 + H2O => H+ + HCO3-. This
acidifies the oceans, and calcite is dissolved (CaCO3 + H+ => Ca2+ + HCO3-)
8) Our useage of fossil fuels and production of greenhouse gasses?
a) 7 x 109 tons per year, net, put into atmosphere by humans.
b) Burning rain forests at rate of about 1 acre per second.
c) How much CO2 is produced when you burn gasoline? Gasoline is (idealized) octane, C8H18. Burning of
octane in an internal combustion engine (i.e., in a car), follows the reaction: C8H18 + 12½ O2 => 8(CO2)
+ 9(H2O) [gasoline + oxygen gas combined by burning forms carbon dioxide gas and water , and in the
process a lot of heat is released]. Thus, 8 CO2 molecules are produced for each octane molecule that is
burned. If you compare the weight of CO2 and octane, you find that burning 1 lb of gasoline produces
3.1 lbs of CO2. A gallon of gas weighs about 6 pounds.
d) Tremendous revenues and profits are generated in the fossil fuel extraction industry. ExxonMobil had net
profits of approximately $40 billion the past two years and holds the record among all privately held
companies for the largest net profit in a quarter (3 months) of approximately 11 billion dollars.
9) Fossil fuel resources
a) Coal – cheap, still fairly plentiful. Creates more pollution than oil or natural gas; pollutants include CO2,
NOx, Sulfur (acid rain), mercury. Produces more CO2 than oil or natural gas. Much electricity in the
U.S. is produced in coal-fired power plants; ~97% of electricity in Utah comes from coal.
b) Petroleum (oil). Has pollution and supply issues. Burning 1 lb of gasoline produces about 3.1 lbs of CO2,
and a gallon of gas weighs about 6 lbs. Supply issue revolves around production rates more than total
reserves, and basic economic theory of natural resource production indicates that we are near the
maximum production rates that we will ever have.
i) Formation requires (1) Source rock, (2) thermal maturation and migration, (3), reservoir rock, (4) seal
rock, and (5) a trap. Be sure to read the handout.
ii) Largest reserves are in the Middle East (1 to 2 trillion barrels probable). There are large reserves in
North America and former Soviet Union countries.
iii) U.S. consumes about 7 billion barrels annually; global consumption is about 28 billion barrels.
c) Natural Gas. Very little toxic pollution, but produces large amounts of CO2 (although somewhat less CO2
than petroleum or coal. Many people strongly prefer its use over coal in electrical power plants.
d) Biofuels. Ethanol (alcohol) and biodiesel are the main types. Currently in the U.S., it takes approximately
1 gallon of petroleum to produce 1 gallon of ethanol, so CO2 emissions are not reduced by ethanol use.
However, mixing small amounts of ethanol with gasoline can improve combustion of the gas in cars
which can significantly reduce pollution and this is done in many parts of the U.S. Ethanol is
successfully produced in Brazil (but with some drawbacks). Ethanol-powered motors produce more
horsepower than those fueled by gasoline.
e) Wind. Clean, has potential to provide a significant proportion of electrical power in the U.S. if we invest
in it and are willing to establish numerous large ‘windmill farms.’
f) Solar. Expensive initial investment is a barrier to its widespread use, although it has become cost effective
in a significant number of applications.
g) Nuclear. Potential for devastating accidents and disposal of highly radioactive waste (that has potential to
be used in bombs) has made it prohibitively expensive to build additional plants in the U.S., although it
currently supplies a significant proportion of our electricity nationally. New technology and/or changes
in political will may lead to a comeback.
h) Hydrogen and electric cars. The electricity or hydrogen must be produced at a power plant utilizing coal,
natural gas, nuclear, wind, or solar energy. However, electric cars do offer an efficiency advantage
(meaning good mileage per lb of CO2 produced when electricity is generated using natural gas or even
coal), and hydrogen cars may as well when more fully developed, and solar or wind power could be
used. Also, there can be advantages to producing the power at plants located outside major population
centers.
2. Calculations. There will be more than one question that involves these types of calculations on the exam. You should
be able to do the following:
a. Calculate volume of a box or a cylinder
i. Using V = l x w x h
ii. Using V = A x h and the fact that the area of a circle is given by A = π x r2
GEOL 1080, Introduction to Oceanography, Midterm 3 Study Guide, Professor Bunds
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b. Convert units, for example convert km to m. Do the conversion before you do any other calculations. There are 100 m
in a kilometer (1000 m = 1 km) (but it IS NOT TRUE that 1000 m2 = 1 km2 so don’t try to do that!!!!!).
c. Calculate the volume of the world’s oceans (or the oceans on some other imaginary sphere), given the Earth’s radius
(6271 km), the fraction of the Earth’s surface that’s covered by oceans (0.718), the average depth of the oceans (3729
m) and the fact that the surface area of a sphere is given by A = 4 x π x r2
d. Calculate the mass of water in a volume, given that mass = V x density. The average density of seawater is 1027 kg/m3
Study Questions
If you want to turn these in, please be sure to answer them on separate sheets of paper and staple everything together! Note that if
you score below C- on the exam you can receive points equivalent to a C- by doing these questions AND the suggested problems from the
back of the appropriate chapters AND turning them all in before the end of the testing period. The suggested chapter problems are listed
on the syllabus (which you received in class and is available on the course website).
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What is the basic driver of atmospheric and oceanic circulation?
If neither the oceans nor the atmosphere circulated globally, how would the typical daily high temperature in Ecuador
change? How would the typical daily high temperature in Antarctica change?
The Sun adds heat energy to the Earth each day. Why doesn’t the Earth get much hotter with each passing day, as a result
(ignoring global warming)?
What are the three most abundant gases in the atmosphere, and what percentage of the atmosphere does each constitute?
What is the troposphere? How does temperature vary with height in the troposphere?
How does the Sun cause air to rise, and indirectly, to sink?
What creates regions of high pressure at the Earth’s surface? What creates regions of low pressure at the Earth’s surface?
Differences in what physical property of air between places on the Earth’s surface causes horizontal movements of air
(winds)?
Combine your answers to questions 6 through 8 to explain how the Sun causes horizontal winds on the Earth’s surface.
Draw the model of the major air circulation patterns on Earth. Include the major convection cells, wind belts, regions of
high and low surface pressure, and regions of enhanced and relatively little precipitation. Be able to draw this model from
memory.
Show how cyclonic flow develops around a low pressure area in the northern hemisphere by drawing and labeling an
illustration.
Show how anti -cyclonic flow develops around a high pressure area in the northern hemisphere by drawing and labeling
an illustration.
Explain what a sea breeze is, and how they form. Use a sketch to aid your explanation.
Why is the duration of precipitation at a particular location from a passing cold front usually shorter than from a warm
front? Use labeled sketches of both a warm and cold front to illustrate your explanation. Be sure you understand both
types of fronts.
Sketch a mid-latitude cyclone with a warm front and a cold front.
How do tropical cyclones differ from midlatitude storms?
How do tropical cyclones cause sea level to rise?
List the factors that favor formation of tropical cyclones in the tropics.
What is the most deadly aspect of tropical cyclones?
How are hurricanes ranked in the U.S.?
What is the difference between a typhoon and a hurricane?
Using a sketch and sentences, explain how storm surge along a coast varies in relation to the position of a hurricane eye.
Explain the greenhouse effect, including the major greenhouse gases in the atmosphere.
How would Earth’s climate be different if there weren’t a greenhouse effect?
How are humans affecting the climate? Explain.
Explain some of the evidence that humans are making a significant contribution to global warming.
How many pounds of CO2 are produced by burning one gallon of gasoline?
28. Why are many people concerned that humans are adding large amounts of CO2 to the atmosphere? Answer this using
your knowledge of the Greenhouse Effect and variations in CO2, climate temperature and glacial cycles in the past
100,000 to 2 million years.
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How much petroleum does the U.S. and the world consume each year?
Calculate the volume of a bay with dimensions 1000 m by 500 m by 10 m deep. Show your work.
Calculate the volume of circular bay with radius 200 m and depth 10 m.
Calculate the volume of a bay with dimensions 20 km long by 5 km wide by 10 m deep. Show your work.
GEOL 1080, Introduction to Oceanography, Midterm 3 Study Guide, Professor Bunds
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33. Calculate the volume of the world’s oceans. Show your work.
34. Calculate the mass of the water in a bay with dimensions 10 km by 5 km by 20 m deep. Assume the water in the bay is
somewhat less saline than average seawater and consequently has a density of 1020 kg/m3
GEOL 1080, Introduction to Oceanography, Midterm 3 Study Guide, Professor Bunds
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