2240 exam
how are gyres formed
result of initial push of winds on ocean surface and of CORIOLIS deflection of moving water
project stormfury
an attempt to weaken tropical cyclones by flying aircraft into them and seeding with silver iodide
carbonaceous chondrites
high volatile content and carbon compounds - most primitive of all chondrites
asteroids have a ___ composition, analogous to early Earth
primary
does evidence support uplift weathering hypothesis?
YES - more than others, but cant explain one period of glaciations
impacts from Wilkes crater relation to Siberian Traps
Asteroids impacted the moon and mercury - shock waves travelled through and around the surface on opposite sides Fractures produced in one terrain deep enough to go to the other side
what effect does angle of impact have?
craters round regardless of impact
Paleocene-Eocene Thermal Maximum (PETM)
56.5 mya; atmospheric carbon dioxide was higher than it is today and the Earth was free (or nearly so of polar glaciers). It was a time of natural global warming
snowball earth
650 million years ago, earth's surface was at or close to freezing point - low reliability
the younger dryas event
A cold episode that took place about 11,000 years ago, when average temperatures dropped suddenly and portions of the Northern Hemisphere reverted back to glacial conditions.
positive feedback
interactions in climate system already in operation initiate responses that may amplify whatever forcing is going on
why are we most concerned with the troposphere
it controls weather
why does warm air rise?
its less dense than cold air
holocene mass extinction
largely due to the disruptive activities of modern Homo Sapiens
when is energy consumed?
more to less ordered, EVAPORATION
BLAG hypothesis
most CO2 in atmosphere comes from volcanoes - during times of rapid ocean floor spreading there are many volcanoes, so high CO2 (warmer climate)
what drives surface circulation
most driven by winds
what conditions are required to result in cooling
much fresh rock exposed, sufficient precipitation, abundance of time
what are jet streams?
narrow bands of strong winds
NEO
near earth objects, classified as PHO (potentially hazardous objects) - must be at least 150m diameter
what did we learn from Andrew? (spin-up vortices)
new whirlwinds, producing hurricanes most powerful winds in small areas
emissions from siberian traps - cause extinction?
no
can we predict hurricanes?
no; can predict path after formed though
is project stormify suucessful?
not really
does evidence support polar position hypothesis?
not really - doesnt explain absence of ice sheets or changes in atmosphere CO2 content
hypervelocity created created when
objects come in so fast, means not affected by atmosphere
climate change hypotheses
polar position, BLAG, uplift weathering hypothesis, ocean heat transport hypothesis
With forest canopy reduced, decomposition increases so soils can no longer absorb CO2 and we have ________ feedback system strengthening the greenhouse and accelerating the house process
positive
2 important points about forcing and response:
- ***rate of response of climate system is fastest when the climate system is farthest from the equilibrium it seeks - the system has many components, with different RTs
consequences of chesapeake
- 300m high tsunami - 50km debris blown into atmosphere, started filling hole
3 possible scenarios why climate is warming
- more atmospheric greenhouse induced by humans - slowly happening anyway; human contribution small - slow natural cooling trend, so human contribution huge
How does the thermostat of chemical weathering help explain the faint young sun paradox?
- Chemical weathering removed CO2 slowly, thus keeping greenhouse strong during paradox while energy was weak
permian triassic era
- Pangaea formed, climate dry, life gradually disappearing, climate was warming
how does a glacier become an ice sheet
- accumulations of snow exceed ablation (removal of ice) - cold climate for extensive period, stable platform
weathering reaction.process that removes carbon from reservoir and stores it in rocks
- acidic rain break down any rock containing calcium - Ca stays dissolved in water and combines with CO2 to form calcium carbonate
tunguska event (siberia)
- huge fireball covering the sky, then became dark - air shocks circled earth twice, gases reached 20km high - destroyed forests and friction caused fragments to breakup
consequences of 4x CO2 (5)
- ice free - dry land, new ocean currents - animal populations devastated - winter shortened 2 months - unable to provide basic accommodation
cause of millennial oscillations
- ice sheets break off, move across oceans cooling climate
why does climate vary - albedo
- light colours have high albedos, and more light is reflected back to space - % of radiation reflected rather than absorbed
snowball earth extinction?
- may have been several icehouse stages rather than one - argued would have ended life completely - showed life may have flourished during the Proterozoic
chesapeake bay crater
- not much evidence others than tektites until deep sea drilling project
how can plants speed up cooling process
- pull CO2 from air and add it to soil - breakup the rock with roots, providing more SA for reaction
benefits of mining an asteroid
- raw materials used as resources for building in space - minerals worth a lot of money - comets rich in water - liquid hydrogen and oxygen to create rocket fuel
what is a sonic boom and when does it occur?
- result of violent compression of air - occur if traveling at speed of sound or greater
what conditions are required for a hurricane to form
- severe cyclonic tropical storm in North Atlantic Basin - comes from belt of tropical trade counterclockwise around an eye with minimum speeds of 119km/h
how will future climate change affect frequency and location of hurricanes
- since added water vapour decreases air density, more upward air convection, encouraging hurricane development
what evidence do we have for past glaciations
- temp obtained from oxygen isotope data of ocean floor deposits - ice sheets from deposits left behind
why (and how often) do we oscillate between glacial and interglacial periods within the icehouse?
- will probably be in icehouse for several million years - for cycle to be regular, must be an orbital one - greenhouse effect weakening - harder to get out of glacial period once in it
predictions of polar position hypothesis (2)
1. ice sheets should appear on continents when they are located at or near polar positions 2. no ice sheets should appear anywhere on earth if continents dont exist near the poles
sequence of end cretaceous extinction
1. 160mya: asteroid collision in belt sent 10km into earth 2. hole through atmosphere 3. touch surface in 5s in Mexico 4. 3m deep into earth (flat disc) 5. blew hole 15km deep in crust 6. created much dust 7. fragments --> fireballs --> firestorm --> fireball layer - all forests burned 8. sulfur producing acid rain - night like conditions for 6 months 9. huge tsunami throwing debris 10. mich material added to atmosphere; greenhouse effect raising 15 degrees
5 factors affecting sea level (do they rise or fall?)
1. changes in volume of ocean ridges (higher) 2. collision of continents (lower) 3. construction of volcanic plateaus on ocean floors (higher) 4. water storage in ice sheets (higher) 5. thermal expansion of water (lower)
different types of thunderstorms (3)
1. multicell - hours, hail, damaging winds, floods, tornadoes 2. squall line - miles long in a line for hours supercell - clockwise winds, changing speeds, huge single-cell producing high winds and hailstones
thunderstorm stages
1. towering culumus - cloud grows vertically, air moves up with turbulence 2. mature stage - storm grows higher, most dangerous 3. dissipating - air moves down, cumulus dissipates, light winds and weak rains (anvil shaped top)
how does the size of the meteoroid affect the size of the crater?
15-20x larger
Permian-Triassic event age (mass extinction?)
251.4 Mya - most catastrophic mass extinction ever
earliest life forms
3.8 billion years ago - no free oxygen; oceans only supporting anaerobic simple life forms
storm surge
A dome of water that sweeps across the coast where a hurricane lands
the little ice age
A period of cooling temperatures and harsh winters that lasted for much of the early modern era 1.5 degrees lower and huge impacts
Isotopes
Atoms of the same element that have different numbers of neutrons
what did comets/asteroids bring to earth that contributed to life?
Building blocks of life (amino acids) coming from rain of comets and carbonaceous chondrites
what will cause collapse of rainforests?
CO2 rises, transpiration reduces, and so does plant growth - Without rainfall, temp at ground level will soar
what gases did the deccan trap eruptions contribute to the atmosphere
CO2, SO2
what drives deep water circulation (density but how?)
Density of ocean water can be increased at low latitudes when the atmosphere evaporates water vapor, leaving the remaining water saltier (more dense)
Ordovician Period (1 of the big 5)
ENVIRONMENT - Formation of supercontinent, glaciers forming, volcanoes due to subduction à greenhouse and waters warming EXTINCTIONS - Due to intense, short-lived glaciations and lower sea levels
cambrian period (environment and extinction)
ENVIRONMENT - break up of Rodinia, shallow seas, breaking triggered snowball earth, nothing living on land, seas started to become habitable EXTINCTION - intense competition, global cooling and lowering sea levels, anoxic ocean waters
Triassic period (4/5)
ENVIRONMENT: Pangaea breaking, shallow seas, no glaciations, age of reptiles, mammals appearing EXTINCTIONS: CO2 from volcanism, warming oceans, methane, anoxic oceans
cretaceous period (5/5)
ENVIRONMENT: Pangaea broken, lots of shallow warm seas, marine life, dinosaurs, mammals EXTINCTION - ended with horrible one
Quaternary Period (the 6th?/our period)
ENVIRONMENT: continents drifting, icehouse climate with glacial/interglacial periods, mammals and flowering thriving, holocene mass extinction in progress
permian period (3/5)
ENVIRONMENT: pangaea formed, dry climate on land, high biodiversity in oceans EXTINCTION: 90% in ocean, 70% on land
devonian period (2/5)
ENVIRONMENT: warm shallow seas, few glaciers, lots of fish, life moving onto land, plants using CO2 EXTINCTIONS - first (impact), second (anoxic ocean water)
Bedout Crater
End-permian crater off the northwest end of Australia, same size as Chicxulub
some limitations of proxies
Erosion and tectonic activity decreases chance that very old sedimentary records will be preserved as time passes
positive/negative feedback example
Ex. decrease in heat energy from the sun; ice and snow grow and because they reflect more sun than ground, any increase should then decrease because of heat absorbed (positive feedback) Negative feedback: increased temperatures resulting in increased evaporation; formation of more clouds results in muting effect as will reflect sun's energy and reduce warming
why are there gaps in the asteroid belt
Gaps related to orbit frequency of Jupiter - gravitational pull draws asteroid away, sending it into wide elliptical orbit
What potentially caused the release of methane clathrates from the ocean floor?
Global warming; clathrates on ocean floors warming and breaking down releasing much methane, killing most marine life
hurricane Katrina
Louisiana, category 3, $75 billion in damage, grew as it passed (warm water evaporates and lends latent heat to fuel hurricanes)
hurricane Andrew
Homestead/Miami, category 4, 25 billion in damages, 50 deaths
methane and holocene extinction
If temperature is increased (probable), the icy solid will begin to breakdown, releasing colossal volumes of methane into the atmosphere (stronger than CO2)
evidence of large amount of organic decay: (so methane production)
Increase in 12C isotope of carbon (normally marks process of rotting organisms
how was the moon formed
It was formed by debris from a collision between Earth and a Mars-sized protoplanet - 4.5 billion years ago - splashed molten material
deccan traps
Largest basalt flows on earth, possibly contributed to the mass extinction at the end of the cretaceous
expanded linear scale vs logarithmic scale
Logarithmic scale method compresses the longer periods of time and expands the shorter ones
does evidence support ocean heat transport hypothesis
NO records show opposite trends
where do hurricanes form
North Atlantic, Northeast Pacific, South Pacific
What are adiabatic processes?
Occur without addition or subtraction of heat from external source
Why did oxygen build up in earth's atmosphere?
Once the ocean became saturated the oxygen the prokaryotes were synthesizing went into the atmosphere
importance of impacts in formation of earth
Possible the carbon-water based earth materials were brought together via collisions of asteroids and comets with earth
scale used to classify hurricanes higher numbers _____ severe (less or more)
Saffir-Simpson Scale Higher numbers less severe
shatter cone
Small, cone-shaped fractures formed by the shock of a meteorite impact.
how/where do changes in density result in deep water circulation?
Some of the salty water is carried north by Gulf Stream where it cools and sinks, water mass called north Atlantic deep water
two largest impact features on earth
Sudbury creater and Chicxulub, Mexico
PHA scientists are most concerned with
TOUTATIS - crosses earths orbit every for years - killing potential of 75% of species; called doomsday asteroid - looks good for 500 years
Coriolis effect
The effect of Earth's rotation on the direction of winds and currents
great oxygenation event
The time in Earth's history, about 2.4 Ga, when the concentration of oxygen in the atmosphere increased dramatically.
What caused the Younger Dryas cooling event?
Thermohaline circulation mixes oceans and spreads out heat. It can be interrupted by large runoff of freshwater due to melting glaciers.
negative feedback in holocene mass extinction
This is negative feedback for global warming; could override the 'super interglacial' condition, and plunge us into a glacial period - collapse of rainforests
why are costs of hurricanes increasing?
Too many governments allow people to inhabit land doomed to recurring storm damage
layers of the atmosphere
Troposphere - surface to 12-20km; Stratosphere - up to 50km (Ozone rich layer); Mesosphere - up to 80km (Asteroids or meteoroids first begin to burn); Thermosphere - up to 500-700km
how could warming ocean temperatures increase anoxic ocean waters?
Warmer whole ocean becomes, the less oxygen is dissolved and the slower the flow pattern - more oxygen-poor bottom waters - bottom waters become oxygen starved (anoxic)
when do hurricanes form?
When sustained light winds blow over warm oceans
are we in danger of another space impact event
YES - 1km diameter every million years (ZHAMANSHIN size)
negative feedback
a mechanism of response in which a stimulus initiates reactions that reduce the stimulus
torino scale
a system that allows scientists to rate the hazard level of an object moving toward Earth and inform the public
how do we seed hurricanes to reduce energy/wind speeds?
adding silver iodide or dry ice with airplane to produce ice crystals, reducing some latent heat and widening eye to spread energy
types of meteorites (3)
aerolites/stones - silicate materials, most primative siderolites (stony irons) - mantle-core siderites/irons - metallic core of large asteroid
how do convection cells (Ferrell and Hadley) affect climate?
air movements associated with the boundaries lead to formation of jet streams
latent heat
amount of energy absorbed during a change of state
what is a comet, where are they found?
an object made of gas, ice, and dust that orbits around the sun - surround planets called oort cloud
apollos vs amors
apollos - actually intersect earths orbit amors - intersect orbit of mars
what names describe asteroids travelling close to earth and mars? (2)
apollos, amors
Barrington Crater
arizona, famous meteorite - simple crater, 45m rift, 1km acorss
negative feedback in uplift hypothesis:
as CO2 is pulled from the atmosphere, climate will cool to the point that the factors essential for weathering will slow
why do meteorites slow as they plumet to earth
as you go down, the atmosphere density increases and so does friction, objects slow - can be melted
Permian extinction hypothesis
asteroid impact - materials found but not crater
why does climate vary - latitude
because of amount of increasing sunlight is different at the equator vs the poles
polar jet stream
bring down cold weather conditions from the north - aids in development of storms
subtropical jet stream
bring up warm weather conditions from the south - help develop and steer storms
***negative feedback mechanism
chemical weather is the active thermostat
tektites
consist of glass of the same composition as rocks hit by space objects
tertiary period
continents drifting to present location, climate cooling to icehouse, mammals and flowers thriving, background extinctions
inward spiral flow in cyclone
convergence, leads to cloud cover and rain, counterclockwise
What were the consequences of oxygen buildup in the atmosphere
deadly to most abundant organisms - positive: many oxygen-containing minerals were created
effects of vegetation (destroying it)
destroyed a biomass carbon sink
what causes air to rise? (3)
differential heating, cold fronts, terrain
outward spiral flow of anticyclone
divergent, cold air drawn down, clockwise
Did the climate warm or cool as a result of the Deccan Trap formation
dropped/cooled
deformation twins
due to applied stress as a mechanism for accommodating strain
why are humans concerned with hurricanes?
effects: heavy rain, strong winds, large waves which can result in storm surge
what assumptions are in the 4x model
emissions would not decline until after 2100, having been controlled some decade or two earlier by strong regulation
immediate consequences of barrington impact
energy --> heat; dust darkened the sky, all life around destroyed by wildfires
knietic energy & formula
energy of a moving object - 1/2 mass x velocity2 - larger = more = bigger craters - transformed to heat upon impact
two options for dealing with imapct
evacuate, destroy/deflect
characteristics of fireball layer and ejecta layer
fireball: 3mm thick, 1500 cubic km of carbon-rich debris ejecta layer: lower, 2cm, - tektites and many minerals
relationship between "forcing factors" and "responses"
forcing - factors that cause climate changes response - variation in climate produced by the forcing event
how is the ejecta blanket formed/what is it
formed following impact when hot gases in crater expand explosively and material hurled out of the crater
how we use isotopes of fossil materials to determine past temperatures
fractionation is larger at lower temperatures
fractionation vs temperature
fractionation: the variation in isotopes among materials temperature: factor fractionation varies
what two factors increase weathering rates?
fresh rock surface area, finer grain size
how/where do hadley and ferrell cells form?
from Coriolis effect breaking up flow of air between equator and poles
density is low...
high elevation, hot days, when atmosphere pressure is low
how meteoroids break up before impact
high pressure air seeps into pores and cracks, pushing the body apart and causing it to explode
high pressure vs low pressure zones
high: pressure is increasing - air is cooling and sinking, outward spiral low: pressure decreases - air heating and rising, inward spiral
what kind of climate are we experiencing now?
ice house; in an inter-glacial cycle
PETM effects
ice sheets forming, leading to icehouse - temp rose 6 degrees - tons of carbon released to oceans and atmosphere - sea levels rose - warming oceans changed circulation directions - extinction of deep ocean life
icehouse vs greenhouse
icehouses are major cold periods; greenhouses are other extremes
faint young sun paradox
if sun's energy decreased by a few %, all water on earth would freeze - weak sun, yet earth warm enough to have water
strength of sun has slowly ____ through history (increased or decreased)
increased
when is energy released?
less ordered to more ordered; CONDENSATION
identifying features of ejecta blanket
light in colour, weathered rocks
slushball earth
liquid oceans at equator and oceans of tropics would have been more slush
why might life have flourished in snowball earth/Proterozoic
lots of theories, with little proof - cold periods may have killed off some predator species - may have promoted reproduction across species to survive
density is high when
low elevations, temp low, and pressure high
silurian period
mild, shallow seas, not much happening
3 things needed to make a thunderstorm
moisture, atmospheric instability, lifting mechanism
features used to identify impact crater
overturned rim, ejecta blanket, breccia floor
Jurassic period
pangaea breaking, lots of volcanism, hot, no glaciations, golden age of dinosaurs, mammals hanging in there only background extinction
where did oxygen come from?
photosynthesis; prokaryotes
two types of climate models
physical models - emphasize things like atmosphere and ocean current variations geochemical models - track movement of distinctive chemical tracers through the climate system
uplift weathering hypothesis
process of weathering rocks reduces CO2 in the atmosphere and cools climate - weather is the active driver rather than thermostat of climate change
ex. of climate proxy record
quality of wine harvests (poorer climate = poorer harvest = higher price)
what hypothesis would need to combine to explain the permian extinction?
rapid global warming release of CO2 from Siberian traps - distribution of ocean flow and beginning of deep water anoxia - dissolution of methane hydrates
what is a climate proxy record
record of some natural event that is so closely controlled by climate, it mimics climate
significance of storing carbon in rocks for long periods
reduces CO2 content in atmosphere
how is the rim of the crater formed?
rocks at the rim are turned upward and even overturned
NEA
same as NEO but near earth asteroids specifically
the ocean heat transport hypothesis
sea levels control long-term icehouse-greenhouse climates: high sea levels cause warmer climates, low sea levels cause colder climates
thermocline
separates warm, shallow water from cold deeper water
hurricane
severe tropical storm producing violent winds, high waves, torrential rains, and floods
simple vs complex craters
simple: under 4km, rounded with uplifted rims complex: over 4km, larger rims with walls slumping inward
whats a chondrule and how does it form?
small spherical object with crystallized molten
sea swells (effects on oceans)
smooth long period waves that move out in all directions from the storm center ; Can be 6-12 hours ahead of the eye
storm-center velocity
speed of entire storm (pushed by regional winds)
positive feedback in holocene mass extinction
strengthening the greenhouse and accelerating the house process - methane release from seafloor
where can we find a constant supply of fresh rock surfaces?
striped-sided mountains, high plateaus, high terrain
differential heating
surface doesn't heat evenly creating pockets of warm air called thermals that tend to rise
natural causes of climate change
tectonic activity, orbital factors, millennial factors
3 main external forcing factors
tectonic, orbital, sun strength
climate data archives - what do we have?
temp and air pressure for about 200 years, increasingly use balloons and satelites
convection cells are formed as a result of changes in ______
temperature
thermohaline flow
the flow of deep-ocean waters made denser by coldness (thermo) and saltiness (haline)
relationship between impact size and frequency
the large a meteor, the less frequently it impacts
response time
time it takes for the climate system to react fully to some factor
examples of extinctions recently
toad and pigeons
stages of hurricane formation
tropical disturbance, tropical depression, tropical storm, hurricane
time span different proxies can cover
up to 100 million years
terrain (storm)
upslope storms form as air moves laterally across landscape
Orbital (Milankovitch) Cycles
variation in position of Earth's axis and orbit around the sun - tilt changes, wobble changes
the relationship between water vapor (humidity) and the density of the atmosphere
water vapor has lower mass than other molecules; adding it replaces some of the heavier molecules, decreasing denity
where does energy for a hurricane come from
water vapour condenses, releasing latent heat energy
cold fronts
when two air masses of different temperatures meet - uplift of moist, unstable air results in thunderstorms
global scale
where Hadley and Ferrell cells return cool air towards the surface we have high pressure zones with little rain
hurricane-wind velocity
winds travelling fast, counterclockwise around an eye
does evidence support BLAG hypothesis
yes, climate cooling noticed as sea-floor spreading slowed - limited as rocks have been subducted
how does the weathering process act like a thermostat
· CO2 in atmosphere would be reduced and climate would cool · Should also work the other way - cool climate with little CO2 in greenhouse would have much less rain, rivers, and streams
