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What is Climate?

What is Climate?

Description

School: Clemson University
Department: Environmental Resource Science
Course: Physical Geology
Professor: Alan coulson
Term: Fall 2015
Tags: Physical Geology and Geology
Cost: 50
Name: GEOLOGY TEST 3 STUDY GUIDE
Description: This study guide covers the material that will be covered on Test 3 of Dr. Coulson's Geology 1010 course
Uploaded: 03/19/2016
18 Pages 5 Views 21 Unlocks
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GEOL 1010 ­ Dr. Coulson ­ TEST 3 STUDY GUIDE


What is Climate?



Highlight = Important Principle Highlight = Key Term

**Geology in the News:​Ice Cores being taken from Atlantis Massif

­ Insight on history of earth and life on other planets

­ Former Clemson Geology major is a researcher

Lecture 9: ​Climatology

Why do we care?

­ Climate change: changing conditions on earth can affect where we live, available resources, etc ­ Studying ancient climate helps predict future trends

Climate Basics

­ Climate ­ average surface conditions over some long period of time

­ Usually want at least a decade of data

­ Weather ­ average surface conditions over short period of time

­ Ex: days, seasons, etc

­ Climate is determined by complex interactions between lithosphere, atmosphere, biologic processes, ocean circulation, etc

­ Feedbacks ­ change in one component of system affects other things that change original component


Weather



­ Positive feedback ­ change in 2nd component enhances change in first

Component

­ A increases, so B increases, which again causes A to

Increase, etc

Ex: more soil➡more weathering➡more soil➡etc

* A can decrease and still enhance B*

Ex: temp (A) lowers➡more glaciers (B)

­ Runaway train effect ­ continuous cycle of positive feedback can

be hard to break, and could continue until a component can’t

change anymore or something else affects it

­ Negative feedback ­ change in 2nd component offsets 1st component

­ Steps:

1. A increases➡ B decreases

2. B decreases ➡A decreases

3. A decreases➡ B increases

4. B increases➡ A increases

­ Seesaw effect ­ increase➡decrease➡increase➡etc

­ Stabilizes the two components

What Controls the Climate?

­ sun=main energy source

­ Insolation ­ IN​coming SOL​ar radiATION


Runaway train effect



­ Varying insolation➡varying climate

1. Orbital parameters 

a. Vary earth’s distance from sun=vary amount of insolation

b. Sun is not directly in center of earth’s orbit

c. Aphelion ­ farthest orbital from sun (~152 million km)

d. Perihelion ­ closest orbital from sun (~147 million km) Don't forget about the age old question of What are People respond to incentives?

* perihelion/aphelion do NOT control winter vs summer*

e. Milankovich cycles ­ cycling changes in earth’s motions in space (3 main)

● Eccentricity ­ earth’s path oscillates from more to less circular

­ ~100,000 years for one full cycle (max➡min➡max)

­ Influences warming/cooling trends during ice ages

● Obliquity ­ aka ‘Tilt’ ­ tilt on earth’s axis changes angle If you want to learn more check out Who is John Smith?

­ ~41,000 years for one cycle

­ Affects seasons

­ Why we have opposite seasons in N/S hemispheres

­ Seasonal contrast ­ changing obliq. angle changes temp contrast

between summer and winter

­ High angle/contrast = hot summer and cold winter

­ Low angle/contrast = more moderate

­ Eccentricity can also affect contrast (see powerpoint)

● Precession ­ ‘wobbling’ of earth on the axis

­ Spinning motion (unlike obliquity, which is rocking)

­ 22,000 years for complete cycle

­ Determines which hemisphere is pointed toward the sun

2, Atmosphere 

­ First thing that insolation encounters

­ Troposphere ­ lowermost layer

­ Where most weather phenomena occur Don't forget about the age old question of what are Three types of neurons?

­ ~30% insolation reflected back into space

­ Albedo ­ measurement of reflectivity ­ varies with material

­ 4% ground, 6% atmosphere, 20% clouds

­ Atmosphere composition

­ Nitrogen­78%, Oxygen­21%, Carbon Dioxide, Water, etc<1%

­ Greenhouse gases ­ trap insolation close to earth’s surface, and some energy is re­radiated back into space

­ Greenhouse gases slow this process and as a result, warm earth

­ Called greenhouse effect 

* GGs might be in small %, but they trap a lot of insolation

­ Removing all GGs ➡ 33°C lower temp

­ Insolation changes with latitude

­ At equator ­ given amount of insolation covers relatively small area because it strikes earth perpendicular to surface

­ Same amount insolation covers large area at poles

­ Explains why poles are colder

­ Energy imbalance on earth

­ Processes redistribute excess energy Don't forget about the age old question of What is the story of Prophet Muhammad?

­ Heat transport: several cells help move heat energy away

from equator and toward poles

­ Hadley Cells ­ transport heat from equator ±30° We also discuss several other topics like For the fiscal year, sales were $12,090,000, sales discounts were $240,000, sales returns and allowances were $70,000, and the cost of merchandise sold was?

lat.

­ Works a lot like convection

­ Steps

1. Insolation warms the air close to the

ground

2. As it rises, it begins to cool and gets

pushed aside by warmer air from beneath

it

a. Creates low pressure at the

equator

3. As air mass cools, some water vapor

cools (rain)

a. Why equator has rainforests/lots

of rain

4. Pushed aside air moves N/S

5. Cools as air moves N/S➡loss of water

vapor

6. By the time air mass ~30° lat, it is dense

enough to sink to earth’s surface

a. Creates high pressure at surface

b. Little rain

7. At surface, air absorbs more insolation

and heats up as wind until it rises again Don't forget about the age old question of Who is the greatest ruler of the empire of mali in 1236-1374 AD?

a. Some wind blows N or S

­ Ferrel and Polar cells operate same way at

different latitudes

­ All 3 interlock

­ El Nino ­ periodic changes in wind strength over pacific during some winters

­ Affect global weather patterns

­ Normal pacific conditions:

­ West Pacific Warm Pool (WPWP) ­ area

of warm water in Pacific (near Australia,

on equator)

­ Normal winter conditions

1. Trade winds push water west

2. ‘Void’ left is filled by cool water upwelling

east

3. WPWP heats air above it, causing air to

rise

a. Creates low atmo. Pressure

above it

4. Rising air cools causes lots of rain

a. Like beginning of Hadley cells

­ W Pacific is warm/wet, East is cool/dry

­ El Nino Winter conditions

1. Trade winds weaken/stop

2. WPWP flows back to east

3. Eastern waters become warm, so

upwelling stops

4. Low pressure area MUST follow warm

water (warm water creates it)

a. Southern oscillation ­ resulting

flip­flop in air pressure between

west/east

5. Rain MUST follow low pressure area

­ W Pacific is cool/dry, East is wet/warm

­ El Nino effects

­ Quasi ­ periodicity of once every 4­7yrs

­ Scientists know what happen during El

Nino, but don’t know why trade winds

occasionally weaken and cause one

­ La Nina ­ trade winds strengthen instead of weaken

­ Opposite effects of El Nino

­ Ex: eastern pacific gets

cooler/drier than usual

** Geology in the News​: New study suggests oxygen buildup on earth might have started during Archean Eon instead of Proterozoic

­ 1.8 billion years earlier

The Hydrosphere

­ All of the water on earth

­ Water has high heat capacity

­ Ex: Gulf Stream brings warm water from gulf or Mx. to Europe

­ Use ocean currents to help

­ Thermohaline Circulation ­ on map: red (hot)=surface, blue (cold)=floor of ocean ­ Why does water sink in N Atlantic?

­ Colder water results in denser water and higher salt concentration (makes

it heavier)

­ In recent decades, we’ve noticed that the process is slowing down

­ Due to overall higher temp of earth

­ Glaciers (fresh water) melting and diluting water

­ Negative feedback loop (some balancing occurs)

The Biosphere

­ Plants

­ Draws down carbon dioxide for photosynthesis

­ Affects albedo (measures re­radiation)

­ Animals

­ Release carbon dioxide and methane

­ Biological Pump ­ how biosphere moves carbon to Lithosphere

­ Interaction of biosphere, atmosphere, hydrosphere, and lithosphere

The Cryosphere

­ All snow/ice on earth

­ Ice covers ~9% of land surface (varies on seasonal basis)

­ Most land surfaces albedo ~15­25%

­ snow/ice albedo ~40­90%

The Lithosphere

­ Tectonics affect climate in many ways

1. Continental position 

a. Close to equator, poles, etc

2. Continent size 

a. Pangea (most continents joined together) was dry, arid, desert­like

3. Collision zone uplift 

a. Creates rain shadows ­ mountains act as barrier/wall to prevent lots of precipitation to move past it

i. Ex: Washington State

4. Land bridge ­ land acts as a bridge between two continents

a. Ex: Latin America

b. Affects ocean currents

Recording Climate

­ instruments/records only go back so far

­ Tells us how climate could change in future

­ Air trapped in glacial ice

­ Records how atmosphere was when the ice was frozen

­ Ice cores from Greenland + Antarctica>2 miles (3300 meters)

­ Some represent > 1 million years

­ Main way to study carbon dioxide levels

­ Proxies ­ substitute of some type

­ Different proxies record different aspects of climate at different times

* ice bubbles were NOT proxies*

­ Rules/types 

1. Consider nature of proxy

a. Ex: rings on a tree

i. Know type of tree and how they grow

2. Biogeography ­ study of where plants/animals live

a. Finding fossils in different areas

i. Can give data very different from today

1. Ex: Canada has crocodile fossils

16 O17 O18 

­ Stable isotopes (ex: types of oxygen O , , )

18 O16 

­ Measure as ratio (O / )

­ Bigger # always on top

­ Different atomic weights: different amounts of each isotope get incorporated into molecules

­ Ratio in some materials changes with climate variables

­ Oxygen isotopes

­ Many invertebrates/plankton shells

­ Can provide quantitative paleotemperature data

­ Very precise

­ Able to see temp change

18 O16 

­ Ex: O / in fish bone reflects water temp when fish was alive fish ­ Fish equation: T = 111.4 − 4.3 * (Df − Dw)

­ Df = ratio in fish bone

­ Dw = ratio in seawater (1.0)

­ T = water temp (degrees C)

­ Some trace metals in shells

­ Ex: Mg/Ca replace each other

­ Depends on temp

­ Why do we want multiple temp proxies?

­ Confirm other calculations

­ Stable carbon isotopes ­ good for plants/construction of environment 13 C

12

­ C / : ratio in animals skeletons reflect type of plant in ecosystem ­ Both isotopes form carbon dioxide

­ Plants take in both types of carbon dioxide for photosynthesis

13 C

12

­ Amount of C / depends on photosynthesis style

­ C3 vs C4 plants: both doing photosynthesis, just in different ways

* C3 and C4 do NOT refer to isotope; they refer to plant type

­ C3: cooler, wetter climates; C4: hotter/drier climates

Lecture 10:​Global Warming

Is Earth Warming Up?

­ Must consider different locations, daily/weekly measurements, graph methods, etc ­ Simple proxy to test: glaciers

­ Are they getting smaller?

­ As seen in pics, it looks like they are

­ Since we have reached this conclusion, we now ask why

Why is the Earth Warming?

1. Earth is currently naturally warming 

a. Coming out of most recent ice age

b. Natural processes account for ~50% of warming for past few centuries

i. Ex: Milankovich cycles

2. Unusual warming pattern 

a. Warming is occurring faster than ever before and with greater magnitude

i. Humans have been adding lots of greenhouse gases to atmosphere since

Industrial Revolution in 1800s (greenhouse effect)

­ Specifically carbon dioxide, methane, and nitrous oxide

­ GGs are steadily decreasing amount of insolation that earth has

­ Scientists have ‘concluded’ that ~50% of temp increase for the

past ~200 years is a result of GG buildup

­ Is the GG buildup anthropogenic (man­made)?

­ Increase in world population can lead to increase in GG buildup

­ Carbon dioxide buildup­ Mona Loa Curve 

­ Shows that carbon dioxide has increased over years, but

no indication as to why/how

­ Higher now than ever in past 400K years

­ Where is the carbon dioxide coming from?

­ Carbon isotopes

­ Different sources release different

isotopes

­ Volcanoes emit C­13, forest fires

release C­14 and C­12, etc

­ Suess effect ­ decline in atmospheric C14/C12 ratio

­ For there to be a decline, that means that either less C14 or more C12

­ Unlikely that C14 has changed, since it is created at a relatively constant

rate

­ Therefore ,C12 must increase

­ Fossil fuel burning can cause this; it emits a lot of C12

without any C14

* the Suess effect strongly supports anthropogenic hypothesis because burning fossil fuels is the only thing that accounts for the C14/C12 drop

** for those that don’t believe in GW, you must find an alternative to the Suess effect ­ Summary: humans are increasing carbon dioxide levels, and carbon dioxide helps increase temp, so it is concluded that humans are responsible for some of the current warming

­ Regardless of whether or not you believe in it, we still have to deal with the results ­ Possible effect of GW:

­ Ice sheets melting

­ Rising sea levels

­ Aridity in mid latitudes

­ Stronger hurricanes/El Ninos

­ extinctions

Seven Global Warming Myths 

1. Flooding Coasts

a. As glaciers melt, water will flow into oceans and cause sea levels to rise i. Although true, it will happen on decadal­century timescale

ii. Threat is not imminent

2. Planet is burning up

­ ‘An Inconvenient Truth’ movie ­ shows accurate data but makes it seem worse ­ Although accurate, some maps are designed to make you agree with message

3. Record low temps disprove GW

­ Data is accurate but does not support a disproving of GW

­ Temps from one area instead of around the world

­ Reflect one small length of time

­ Data about record highs/norms is not included

­ We don’t base climate trends on data from one area

­ People using this are typically talking about weather instead of climate 4. Who cares if its only 3 degrees?

­ Scientists predict a 3 degree increase © for the next century

­ 3 degrees C is 5.4 degrees F (slightly larger difference)

­ 3 degrees is on a global scale: temps in specific areas will change much more ­ Last ice age was only ~4.5 degrees C lower global temp then today ­ Imagine what 3 degrees hotter would be

­ Many organisms (some of which we rely on) would not

survive

5, Scientists can’t decide between GW or cooling

­ 1975 ­ National Academy of Science Report stated that warming or cooling is possible, but was inconclusive

­ Also in 1975 ­ a reporter stated that global cooling data was in high volume ­ Reporters often mess up words and thus become unreliable sources 6. Scientists profit from GW

­ Grant money does not go into a scientist’s pocket

­ All spendings are monitored and documented

7. Professionals

­ anti­GW people tell you to not trust the scientists that study this change ­ Why would you not believe them??

Lecture 11: ​Deserts

Desert Basics and Processes

­ Why do we care?

­ Deserts cover a lot of area on earth and are growing

­ 20% of land is desert

­ 15% is semi­arid

­ What is a desert? 

­ Temp is NOT criteria

­ Lack of rainfall is key (<10in/yr)

­ There are a lot of deserts, and some are even larger than the USA

­ Found in specific latitudes (~30°N or ~30°S)

­ Atmospheric Hadley Cells

­ Also found in other areas

­ Shadow zones do not get a lot of rain

­ Size of land mass can cause less rainfall as well

­ Central EurAsia ­ large area away from

Coast

­ Polar Regions also considered deserts

­ Very little precipitation per year

­ Glaciers built slowly over time

­ Weathering in deserts

­ Little chemical weathering (due to little rainfall)

­ Slow process

­ oxygen/iron oxides

­ Causes characteristic red/brown rock color

­ Erosion

­ Water still important

­ More of a flash­flood scenario

­ No vegetation to restrain rainfall

­ Arroyo ­ shallow ditches that represent day streams, but

during thunderstorms can fill up quickly and cause fast

erosion

­ Why hikers are advised to not hike in

Them

­ Wind erosion

­ Can only move relatively small particles

­ Wind has low density/viscosity

­ particles>~0.06mm in diameter hard to move

­ Unless in tornado (but unlikely)

­ Can STiLL add up to a big volume

Ex: Sahara Desert: 250­500 million tons of dust transported to

Atlantic each year

­ Deflation ­ erosion by removing only tiny particles

­ Pavements ­ result of deflation

­ coarse , grainy surface

­ Another misconception: only 20% of deserts are

actually covered in sand

Desert Features

­ Ventifacts ­ any object altered by exposure to wind erosion

­ More than just rocks; plants, trash, etc. are still ventifacts

­ Alluvial fans ­ fan­shaped sediment formed at bottom of arroyo

­ Arroyos carry a lot of sediment and builds up at its end

­ Found in other, non­desert areas, but those are formed different ways

­ Playa lakes ­ aka playas ­ isolated lakes in desert (no rivers/streams leading to it) ­ Depression filled with water (even empty at times) that fill during storms ­ White ring around playas

­ Saturated mineral deposits that were left behind when water started to

Evaporate

­ Halite = good example

­ Inselberg ­ large body of rock randomly in a desert

­ Like icebergs

­ Plutons do not weather easily

­ Arches ­ columns of rock that support an arch/bridge

­ Result of localized erosion

­ Arches National Park (Utah)(2000+)

­ Form by cracks seeing a lot of erosion

­ Erosion is typically centered on/around cracks

­ Do not last forever; the arches can fall/crack

­ Dunes ­ wind deposits of sand

­ Dunes move over time

­ Started by surface of irregularities (rock on ground, stick, etc)

­ Saltation ­ jumping/skipping action as wind pushes sand

­ Types of dunes 

­ Important factors: wind direction, sand availability, and vegetation

1. Barchan Dune ­ crescent moon shape

a. Stereotypical dune

b. Horns ­ point toward direction the wind blows

2. Transverse Dunes ­ string of Barchan Dunes attached by horns

a. Must have a lot of sand supply

b. One dominant wind direction

3. Linear Dunes ­ aka longitudinal ­ long, relatively straight

a. Crests are parallel to wind, NOT perpendicular (unlike 1&2)

b. Not a lot of sand available

4. Star Dune ­ star­shape from above

a. Wind direction constantly changing

5. Parabolic Dune ­ U­ or V­shaped (not crescent)

a. More vegetation present

b. Coastal areas (not always in deserts!)

c. Horns point toward where wind is coming from

*Know how to identify Dunes by picture, know how to see which way the wind is from/towards, and how to differentiate between each type

Desertification 

­ Process of an area becoming a desert

­ Sahara expanding south ~30mi/yr

­ 1 billion people in high­risk areas

­ Why is is occurring? 

1. Tectonics

2. Climate Change ­ increasing temps/pressures can cause greater/lesser areas of precipitation

3. Human Activity ­ livestock grazing, over farming, etc

­ How can we prevent? 

1. Not able to change tectonic movement

2. Difficult to change climates…

3. Less grazing, less clear­cutting crops, less over­cropping, etc.

Lecture 12: ​Glaciers

**Geology in the News:​amount of water flowing into Earth’s interior strongly correlates to active faults

Effects of Glaciers

­ Why do we care?

­ Problems with melting causes issues in ecosystems

­ Sea level change

­ If all glaciers melted, sea level would rise 200ft (65 m)

­ Enough to completely cover florida

­ Glaciers trap large amounts of water

­ Coastline during ice age was much larger

­ Isostatic depression ­ crust warping downward due to ice

­ East Antarctic ­ 7.5 km deep

­ Isostatic rebound (crustal rebound) ­ glaciers melt and crust morphs back

­ Changes thermohaline circulation

­ Slows down process

­ Drinking water and irrigation

­ Ex: Washington gets ~470 billion gal/yr

­ If glacier melts, there will be less over time

* melting glaciers does NOT provide more drinking water*

Glacier Basics

­ Glacier ­ large amount of ice that moves

­ Ice currently covers ~9% of land area

­ Antarctic = 85%, Greenland=10%

­ Antarctic exceeds 4200m thick

­ Formation 

1. Granular snow ­ slightly more dense snow; melted snow refreezes 2. Firn ­ denser ice pellets

3. Glacial ice ­ compressed firn; high density

a. ~ 50 m is when a ‘glacier’ can be used as a term

­ Requires time, coldness, and precipitation

­ Glacier Types 

1. Valley ­ ‘mountain’, ‘alpine’, ­ form in/around mountains and in valleys a. Can be very long and very thick , but are restricted to a specific area b. Found all around the world

c. Ex: Mt. Kilimanjaro (Africa, ca 2000 ft)

i. Ironic, because on equator

2. Continental ­ ‘ice sheet’ ­ much larger than valley glaciers

a. Cover entire landscape (entire continent)

­ Glacial advance and retreat

­ Obvious in an ice age

­ Accumulation ­ more material produced (advance)

­ Higher elevation, colder temps, etc

­ Ablation ­ where more melting occurs than freezing (retreat)

­ Firn line ­ ‘equilibrium line’ ­ not always in middle

­ Glacial movement

­ Speed varies

­ Ex: South pole flag post moving over time

­ Types of movement 

1. Plastic flow ­ >50m thick ­ small crystals at base of glacier start moving individually a. Very slow process

2. Basal slip ­ under right temp and pressure conditions, you can form a small layer of water under base of glacier which causes slipping

a. Faster than plastic flow

b. Ex: slip n slide and ice skating

­ Crevasse ­ large cracks that form at top of glacier

­ Breaks at top due to cold temp and low pressure (brittle behavior)

­ Can be very hazardous

Glacial Erosion

­ Lots of sediment trapped in glaciers

­ Abrasion ­ material caught and ground up and carried with ice

­ Plucking ­ glaciers pick up larger bodies/objects

­ Glacier moves over bump/hill and breaks up the hill as it goes over

­ Mainly affects downhill side

­ Features of movement 

­ Striations ­ thin, straight, parallel lines carved into rock

­ U­shape valleys ­ glacier moved through area and left shape

­ Hanging valley ­ u­shape valley leads into another valley

* to identify, look for waterfalls, rapids, etc

­ Cirque ­ large, carved out area

­ Tarns ­ formed permanent lakes that develop

­ Horn ­ sharp, peaked mountain

­ Form when multiple glaciers slide down different sides

­ Arete ­ ridge that separates horns

­ Roche mountonee ­ formed by plucking

­ Large rock with one steep side

­ Able to tell where from/where going glacier is

Glacial Sediment Deposit

­ Erratics ­ carried boulder left in an area by a glacier

­ Till ­ extremely poorly sorted

­ Outwash ­ sediment being washed out by melted glacier

­ More sorted than till

­ Loess ­ very well sorted, small particles

­ Very good landscape for agriculture

* STUDY HINT: don’t get depositional features and erosion features mixed up ­ Depositional features 

­ Moraine ­ large pile of sediment formed around edges of glaciers

­ Eskers ­ wavy pattern of sediment deposit

­ Formed by outwash process at base (or underneath) glacier

­ Drumlin ­ asymmetrical shape (look like mountonee)

­ Difference between drumlin and mount. Is formation

­ Drumlin is pile of sediment, mount. Is solid rock

­ Can also get ice flow direction, but is reversed (ice came from steeper

side)

­ Kames ­ small, low hill of sediment

­ Formed by broken up glaciers melting

­ One kame means lots of kames in area

­ Kettle lakes ­ bodies of water formed in kames process

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