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JMU / Geology / GEOL 102 / What is thermohaline circulation?

What is thermohaline circulation?

What is thermohaline circulation?


School: James Madison University
Department: Geology
Course: Environment: Earth
Professor: William roberts
Term: Fall 2015
Tags: Ocean, Coastlines, Atmosphere, Energy, resources, climate, and waste
Cost: 50
Name: Geol 102 Exam 3 Study Guide
Description: Includes everything we went over in lectures for Exam 3
Uploaded: 04/26/2018
15 Pages 185 Views 4 Unlocks

Geol 102  

What is the thermohaline circulation?

Exam 3 Study Guide

Coastlines and oceans

Continental shelf- flat, shallow, extends off coast

Continental slope- steep drop between shelf and rise

Continental rise- gentle slope between slope and plain

Abyssal plain- deeper, flatter, layer of sediment


∙ Active margin shorelines (leading)

o Narrow continental shelf

o Exposed to high energy waves of open ocean

o Sea cliffs

∙ Passive margin shorelines (trailing)

o Wide continental shelf

o Protected from strong waves

o Sand beaches

∙ You can get erosional shorelines in “passive margins”

What are the three sources of energy power?

Average depth is 3-4 km, deepest part is 11 km

Average salinity of oceans in 3.5%

Mixed layer- affected by what happens at the surface

Transition zone- under mixed layer

Deep ocean- much more resistant to day to day changes

As you go deeper, temperature declines, more saline, more dense

Ocean circulation

Winds drive surface currents

o Surface water follows wind direction

o Deep water goes perpendicular to wind direction

Upwelling and downwelling cycle nutrients and oxygen between deep and  shallow ocean

Thermohaline circulation

Deeper current, driven by changed in density and salinity

What are the resources of fossil fuel?

Don't forget about the age old question of What is the function justification?
If you want to learn more check out When situational influences occur?

o Cold, dense, sinks

o Warm, less dense, rises

Video Notes:

o Beaches are composed of whatever loose material is available o Quartz and felspar are the most common minerals found in rock o Stream flows over solid rock, it breaks down over years and is carried by the  water

o Waves lift up sand grains and move them- over time the sand comes and  goes

o Smaller waves carry sand towards the shore, larger waves pull it back o Longshore current- where the breaking waves rapidly pull water down the  coast, just outside surf zone

o Longshore transport- movement in surf zone and longshore current  

Coastal hazards


∙ Sea cliffs

o Eroded by wave action at the toe

o Eroded by mass wasting higher up

o Active sea cliff- erosion dominated by wave action

o Inactive sea cliff- erosion dominated by running water and mass  wasting

Sea level rise

∙ sea level is always rising and falling

∙ sea level rise can move coastlines- respond to seal level changes by  migrating (inland when water rises)

∙ sea level rise in VA- consistent upward trend long term, from 1930-2010  changes ½ meter

Tsunami “harbor wave”

∙ most are triggered by earthquakes We also discuss several other topics like What are three key problems associated with tuna fishing?

o earthquake causes seafloor to drop as well as sea level, water rushes  to low spot and then creates amplified waves in shallow water

∙ biggest risk in US is Hawaii and west coast, but they can occur on east coast ∙ Indonesia 2004

o Dec. 26

o Caused by magnitude 9.0 earthquake

o Waves up to 30 meters high

o Killed more than 230,000 people

o Damage in India and Africa

∙ Japan 2011

o March 11

o Caused by magnitude 9.0 earthquake

o Waves up to 30 meters high

o Killed more than 15,000 people

o Triggered nuclear accidents

Plastic Pollution

∙ Currents are circular, so material tends to be concentrated in certain areas

The Atmosphere

Atmosphere- the envelope of gases surrounding the earth or another planet

∙ 78% nitrogen, 21% oxygen, .9% argon, .04% carbon dioxide, .06% others ∙ The concentration of oxygen in the atmosphere has changed over time,  changes have greatly affected the evolution of life on Earth

∙ Major layers:

o Thermosphere- outermost part We also discuss several other topics like How is angular momentum defined?

o Mesosphere

o Stratosphere- horizontal mixing

o Troposphere- weather zone, vertical mixing

∙ Air pressure decreases with elevation- causes expansion of the air which uses energy and results in the cooling of air

∙ Cooler air cannot hold as much water vapor, as air moves higher into the  atmosphere or to higher latitudes, vapor condenses into clouds

∙ Incoming solar energy warms the atmosphere, this is balanced by the  outgoing radiation of energy

o 25% reflected

o 25% absorbed and reradiated solar energy

o 45% absorbed solar energy

o 5% absorbed and then reflected solar energy

o Roughly half interacts directly with the atmosphere Don't forget about the age old question of What are the three types of forecasting?
We also discuss several other topics like How would you describe the habitat of cliff swallows?

o Mostly balanced system

∙ The amount of solar energy received varied from place to place o Equator receives more direct sunlight than polar regions

∙ The amount of solar energy received also varies from season to season ∙ Differences cause air mix in an attempt to equalize temperature and  pressure- this drives weather

∙ If the earth didn’t spin, our weather would be simple  

o Weather cells have an impact on how much heat areas get

∙ Mountain ranges can have a significant impact on weather patterns

∙ Oceans and lakes can also influence the weather, water heats and cools more slowly than land

∙ Green house effect- keeps earth at habitable temps, greenhouse gases  concentrated in the troposphere absorb energy from sun and heat radiated  from the ground

o Earth’s temp without GHE would be -19C


∙ Tend to happen the most in August, September, October

∙ Damage

o Heavy rains

o Winds are biggest danger and cause of damage

o Strong winds enhanced by forward movement of hurricane

o Storm surge- mound of water pushed ahead of hurricane raises sea  levels, wind surge has to do with moving direction of winds since  hurricanes move circularly  

Air Pollution

∙ Particulates- fine dust in the air (when you burn coal, natural gas, dust from  erosion)

∙ Ozone

o Bad ozone- ground level- sun promotes reaction with pollutants (NOx + VOC)

 strong and unhealthy oxidant, peaks mid-day (photochemical  smog)

o Good ozone- in stratosphere, absorbs ultraviolet wavelengths, always  has and will if we don’t destroy it

 CFCs- released and rise to stratosphere, sunlight breaks them  down, atomic chlorine destroys ozone, increased ultraviolet rays  reach the Earths surface, raising the risk of skin cancer

 1% decrease in ozone concentration leads to 2% increase in UVB at surface, 2% more skin cancer

 Ozone has reduces 10% in mid-latitudes since the 70s (-


∙ Sulfur oxides (Sox)- byproduct of burning fossil fuels

∙ Nitrogen oxides (NOx)- byproduct of burning fossil fuels

∙ Carbon monoxide (CO)- by product of burning fossil fuels

∙ Hydrocarbons-  

∙ Lead- from fuel

∙ Volatile organic compounds- chemicals that are combustible and readily  move into the atmosphere

∙ Sources- 42% gasoline powered trucks and cars, 21% misc. processes, 16%  aircraft/train,  

∙ Acid rain- clouds formed in areas with high air pollution, makes rain acidic how acidic it is depends on where you are (how much development there is,  how populated)

o Eastern US is more affected

o As water gets more acidic- more and more fish species are affected o Cleopatra’s needle stood in Egypt for thousands of years and began to  dissolve from acid rain when moved to new York city

o rainwater has gotten less and less and less acidic from 1886- 2012  because of regulations  

Energy Resources

Energy is the ability to do work

calorie- energy needed to raise the temp of 1 gram of water 1 degree C

∙ 1 joule = 4.184 calories

∙ 1 British Thermal Unit (BTU) = 1055 joules

∙ 1 watt = 1 joule/sec

∙ 1 horsepower = 746 watts

Three sources of energy power all processes on earth

∙ Solar energy- 173000 terrawatts/year

∙ Radioactive decay- 32 terrawatts/year

∙ Gravitational attraction- 3 terrawatts/year

o 1 terrawatt = 10^12 watts

Some energy from the sun is transferred to

∙ Atmosphere and oceans, creating air flow, evaporation and precipitation, and  ocean currents

∙ Plants by photosynthesis

∙ Animals by eating plants (and other animals)

∙ Heat by combustion and decomposition of organic matter

∙ Lithosphere when organic matter is buried (.1% of carbon in biosphere) Energy in human history

∙ Animal and human muscle

∙ Burning wood

∙ Sailboats

∙ Water wheels

∙ Windmills

∙ Coal-fired steam engines, boilers, furnaces

∙ Electricity from hydropower

∙ Gasoline-powered internal combustion engines

∙ Heating oil and natural gas

∙ Natural gas and coal powered electricity plants

∙ Nuclear power

∙ Photovoltaic cells (solar energy)

∙ Geothermal heat pumps

∙ Biofuels

∙ Wind turbines

2011 Global energy

∙ 36% petroleum

∙ 26% natural gas

∙ 20% coal

∙ 9% renewable energy

∙ 8% nuclear electric power

Biomass- organic matter produces by plants and animals, consisting of carbon and  hydrogen compounds

∙ Most readily available biomass is a renewable resource

Fossil Fuel Resources

∙ Petroleum- oil, natural gas

o Crude oil

 Made of hydrocarbons

 Liquid and gas forms

 Used for plastics, fertilizers, insecticides, synthetic fibers, paints, energy

 Middle east consumption

o Natural gas

 Primarily methane, occurs with

∙ Liquid petroleum

∙ Coal beds

 Mostly used for heating in the past

 More used for power generation in recent years

 Russia and middle east

 Marcellus shale

∙ Coal- nonrenewable

o Plant matter altered by heat and pressure

o Most abundant energy reserve oil and oil shales

o Lower energy cost then other fuels

o Produces a lot of carbon dioxide

o Produces many pollutants

o Coal mining can be dangerous and expensive,  

o Coal is shipped by railroad

o Asian consumption

o Recent downward trend in consumption

Petroleum Deposit Formation

∙ Four conditions for petroleum deposit

o Source rock with commercial quantities of oil or gas; usually  sedimentary; phytoplankton and zooplankton become petroleum o Reservoir rock- where petroleum migrates; porous and permeable o Impermeable caprock allows petroleum to be contained and  concentrated

o Geological structure that “traps” the oil

Hydraulic fracturing- drill a well and perforate the casing with explosives, pump  down fluid and other material to create new fractures in the rock so gas can flow  more freely in the well

Natural gas pipelines- a lot comes from gulf coast

Coal deposits- organic material compressed becomes peat, peat is buried and  compressed and becomes coal- the more its compressed, the more energy it has

∙ Most energy from coal is bituminous, it is the most abundant  

Alternate energy resources

∙ Nonrenewable- nuclear

∙ Renewable- biomass

∙ Inexhaustible- hydroelectric, solar, geothermal, wind


∙ Clean to operate

∙ No carbon dioxide emissions

∙ Accidents can be serious- 3 Mile Island 1979; Chernobyl 1986; Fukishima  2011

∙ Uranium pellets are put in rods and then put in a reactor, to boil water ∙ Mined, processed, put in reactors, spent fuel is either stored or reprocessed  then stored

∙ France is the most dependent, US has the most reactors

∙ Japan has plants located near plate boundaries

∙ US doesn’t have a permanent waste site

o Yucca Mountain- possible location to store waste


∙ Burning wood

∙ Peat (turf) in Ireland

∙ Biodiesel

∙ Ethanol from sugar or corn

∙ Cellulosic ethanol

∙ Ethanol is the most abundant

o Sugar converted to alcohol and used as fuel

Hydroelectric Energy

∙ Provides ¼ of world’s electricity

∙ Water falls and turns turbines

∙ Typically an inexpensive source of electricity

∙ Many environmental problems, displaces people

∙ Tidal power and marine turbines

o Tidal power works like dams

o Marine turbines work like windmills

Solar Energy

∙ Solar-thermal methods heat water to generate electricity o Power towers- panels power the tower, the tower heats water to  produce steam

o Parabolic troughs- water tube  

∙ Uses lots of land and requires vegetation removal

∙ Requires lots of water

∙ Needs to be in a sunny place

Geothermal Energy

∙ From earth’s internal heat

o Near plate boundaries

o Shallow magma/hydrothermal systems

∙ Electricity, space heating, heat pumps

∙ Problems

o Groundwater withdrawal

o Toxic elements in some geothermal waters

Wind Power

∙ Most successful renewable energy source

∙ 2030- could provide 20% of US energy

∙ Larger rotors best

∙ Environmental problems

o Land acquisition

o Unsightly to some

o Wildlife affected (kills birds)

o Erosion from roads

∙ Wind power by region- used the most in Asia

∙ Wind energy produced most in the central part of US

∙ Offshore wind farms

Energy consumption and remaining resources

US Energy consumption- reduced use in coal, adoption of renewable

Remaining non-renewable- nuclear fuel is the most abundant, then coal, heavy  oil (tar sands), crude oil, natural gas

Energy Conservation- been in use for thousands of years

∙ Adobe structures

∙ Ways of letting passive solar energy in to heat homes and block it to cool  homes

∙ Solar chimney- warm air moves through ground and cools naturally before it  enters home

∙ Trees provide shade

∙ High ceilings

∙ LED light bulbs

∙ Better insulation

Building design

∙ “green” architecture involves many characteristics

∙ US Green Building Council (USGBC)

∙ Leadership in energy and environmental design (LEED)

∙ Rating system based on  

o Site selection

o Water/ energy efficiency

o Building materials  

o Indoor environment

o Innovative design


Climate- the long-term averaged conditions for a given locality or region

∙ Can change over time

∙ Mars used to have water and a more developed atmosphere, when it lost its  atmosphere it lost its water

o The evidence is still there- deltas, gullies

What causes climate change?

∙ Shorter term variations

o change in solar energy from day to night changes local conditions o seasonal changes (in most places)

o el nino- changes in wind patterns cause changes in ocean conditions  which cause change in weather, every 2-7 years, buildup of warm  water

o la nina- the opposite

∙ Volcanic activity

o Pinatubo 1990s- volcanic ash and haze in the atmosphere cools for a  few years

 Volcanogenic CO2 warms over long term

∙ Sun spot cycles- can change the amount of energy we get from the sun o Sunspots are hot

o Plentiful during Medieval warm period

o Cant explain variation since then

o River Ice on the Thames- London 1630- cooling period related to sun  spot

∙ Ocean currents

o Gulf stream has impact on climate in western Europe

∙ Thermohaline circulation- deeper ocean currents

o More long term effect on climet

Drivers of climate longer-term change

∙ Orbital parameters- earth’s orbit can change dramatically over time o High eccentricity(elliptical)- low eccentricity(circular)

 Ellipticity cycles every 100,000 years

 Less eccentricity = less dramatic seasonal changes

 More eccentricity = more dramatic seasonal changes

∙ The amount of the earths axis tilt can vary from 24.5- 22.2 degrees o Cycles every 41,000 years

∙ Axis also wobbles- precession- changes the months when each season occurs in a certsin place

o Cycles every 23,000 years

∙ Milankovitch cycles

∙ Long term increase in solar luminosity- the sun is continuously giving off more energy

o 5 billion years ago we received 75% of the energy we receive now ∙ Plate tectonics- continents are moving around the globe

o at certain times in earth’s history we’ve had concentrations of  continents in polar regions, other times continents are concentrated  near the equator

o ocean water heats and cools more slowly, so we have warming tends  when there is more water near the equator and cooling periods when  we have more continents concentrated around the equator

∙ Albedo

Variation in climate during Earth’s history

∙ Over time there have been many changes- periods colder than today and  hotter than today

∙ 21,000 years ago glaciers extended into PA, NY, Midwest

∙ Glaciers give clues about more recent climate change

o18O/16O in the H2O of glacial ice varies with temperature; can be used to correlate temperature with date

o Glacial ice also includes air bubbles; measure greenhouse gas  concentration

o Other proxies- shell composition, tree rings, sediment speleothems Human induced climate change

∙ Carbon dioxide concentrations have increased from the burning of fossil fuels o When CO2 is high, so are CH4 and isotope ratios

∙ Clearing of forests and grasslands

o Rapidly speeds up decomposition, releases CO2 over time

∙ Temperature and fossil fuels

o Changes carbon cycle

∙ Glaciers

o Retreating over time  

∙ Arctic Ice

o 2012 all-time low in Arctic ice

o More efficient at absorbing solar energy


∙ 1996- balance of evidence suggests there is discernible human influence ∙ 2001- evidence shows that most of the warming over the last 50 years is due  to human activity

∙ 2007- most increase in global temperatures is very likely due to increase in  greenhouse gas concentrations

∙ 2013- extremely likely that more than half of increase in temperature was  caused by increase in greenhouse gas concentrations and other human  activity

∙ If we don’t change anything temperatures could rise by 6 degrees from 2000- 2100

∙ By 2050’s there could be warming all over the world

∙ By 2100 sea levels could rise by almost a meter

∙ Could be more precipitation in winter by 2080-2099, drier in the summer ∙ Range of trees can change

Waste Management

Solid Waste

∙ Paper 26%, food 14.9%, yard trimmings 13.3%, plastics 12.9%, rubber,  leather, textiles 9.5%, metals 9%, wood 6.2%, glass 4.4%, other 3.2% ∙ Decrease in per capita waste since 2010

Municipal Waste Disposal Options

∙ Attenuation- diluting or spreading trash/pollutant so thin that it has little  impact

o Most common with liquids, particulates, and gasses

o Permitted attenuation sometimes takes advantage of different pollution limits between air and water

∙ Isolation- encapsulating/removing waste from the environment o Sanitary landfill

 Each day’s trash is spread thin and compacted, covered with 15  cm of soil, covered with 50 cm of soil when finished, leachate  

(water that filters through the landfill) must be dealt with  

∙ Incineration- burning to reduce mass; transfers some waste to atmosphere o Can reduce garbage volume by 90%

o Can generate electricity

o More common in areas with high populations, little open land, and high water tables

o Can be expensive with much opposition


∙ Resource recovery saves materials and energy  

o 96% energy savings for aluminum

∙ Remanufacturing- disassemble worn-out product and fixing it ∙ Growing public awareness

o 10% recycling rate in 1980 to 35% now

∙ Recycling mandated in many states

∙ Batteries are recycled the most because of legal and financial benefits

Private Sewage Disposal

∙ Septic tank separates solids from effluent

o Leach lines distribute effluent into surrounding soil/rock

o Sewage is broken down by anaerobic bacteria in the septic tank and in  leach lines

o Effluent percolating through soil; most bacteria removed

∙ Sewage lines use gravity/pump to move waste into main sewer o Goes to treatment plant, returned to a stream

o Biosolids- sludge

Changing Land

How has land use changed over time?

∙ Development expansion in most places

Land use classification

∙ Developed areas

∙ Farmland

∙ Open water

∙ Barren land

∙ Grassland

∙ Forest

∙ Shrub

∙ Lots of agriculture, forest in VA and PA, not in Iowa

How does land change when it is developed?

∙ Remove trees- increase soil temperatures, decrease infiltration, decrease  habitat

∙ Compact soil- decrease infiltration, increase runoff

∙ Increase impervious surface- decrease infiltration, increase runoff ∙ Remove topsoil- decrease long-term fertility of soil

∙ Plant grass- decrease infiltration

What other land changes are needed when an area is developed

∙ Roads- remove trees, decrease infiltration, increase runoff, provide habitat  for invasive plant species

∙ Power lines- remove trees, provide habitat for invasive plant species ∙ Water, gas, telephone, cable lines, sewer or septic fields- limit areas  where trees can be planted

∙ Retention ponds- needed to control storm water runoff

∙ Parking lots- increase runoff

∙ Use of rip-rap along streams to prevent erosion (big chunks of rock)

Development affects the types of animals and plants that will be present

∙ Synanthropes- benefit from developing land

o Squirrels, pigeons, wasps, sparrows

∙ Misanthropes- don’t stay around developed areas

o Snakes, turtles, quail, bobcat

∙ Invasive plants

o Kudzu (grows up over power lines and other trees and can smother  them), garlic mustard, autumn olive, tree of heaven

Impacts to hydrosphere

∙ Decreased infiltration leads to increased surface runoff to streams and ponds ∙ Increased water temperature- can become uninhabitable for some species ∙ Decreased biodiversity

∙ Increased potential for flooding of areas that wouldn’t have otherwise flooded ∙ Increased sedimentation- reduced water quality

Some good land use practices

∙ Farming practices that can reduce erosion and don’t let as much carbon out  of soil  

∙ Buffer- doesn’t allow building with a certain distance of streams ∙ Fences that trap debris used during development  

∙ Rain garden- promotes infiltration

∙ Impervious concrete- can be driven on and lets water through to promote  infiltration

∙ Rain barrels- capture rain water  

∙ Smart growth subdivisions- developing homes on smaller lots and in  clusters so not as much land is developed

Smart growth principles (know some aspects)

The idea of developing areas where people will want to live, but with the  future in mind

∙ Mix land uses

∙ Take advantage of compact building design

∙ Create a range of housing opportunities and choices

∙ Create walkable neighborhoods

∙ Foster distinctive, attractive communities with a strong sense of place ∙ Preserve open space, farmland, natural beauty, and critical environmental  areas

∙ Strengthen and direct development towards existing communities  ∙ Provide a variety of transportation choices

∙ Make development decisions predictable, fair, and cost effective ∙ Encourage community and stakeholder collaboration in development  decisions

Smart growth at JMU

∙ Wayland Hall- one of 10 greenest dorms in the world, harvest rainwater,  geothermal energy

∙ SSC- energy efficient lighting, recycled materials

∙ Ehall- passive solar heating, composting

∙ Newman Lake- use water for irrigation

∙ Chandler Courtyard- remove concrete so more water can infiltrate ∙ Memorial Hall Stream- planting to reduce erosion  

∙ Sibert Creek Rain Garden- promotes infiltration

∙ East Campus Hillside- plant mixed plants in increase infiltration and  decrease need for maintenance

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