Earth Science Exam #1 (10/14/24) Flashcards
(78 cards)
1
Q
earth system
A
atmosphere - air
hydrosphere - water
geosphere - land
biosphere - life (outlier - limiting the human influence on the Earth system so that Earth can last)
2
Q
definitions: system
A
- an entity composed of diverse but inter-related parts that function as a complex whole
- coordinated or related sets of processes and components through which material or energy flows, characterized by continual change
- dynamic, constantly changing
- different states of Earth through time
3
Q
definitions: earth model
A
includes all the biodiversity, atmosphere etc
4
Q
definitions: components
A
- individual parts of the system (the ocean, the atmosphere)
- component within components (friction is part of the atmosphere)
5
Q
definitions: state
A
- attributes that characterize the system at a particular time
6
Q
Earth photo: Blue Marble (1972)
A
- represents Earth as a small dot in a sea of black
- marks a point in earth science in which people started to reexamine the earth system of interconnected parts
- people started to run models that included all the different components of the earth system so they could make projections of the future and scenarios of the past
7
Q
systems approach in human physiology
A
- homeostasis: when everything is in balance
- when everything is wrong in one system, it’s not always clear what the problem is
8
Q
Global average temp 1850-1990
A
- temp has gone up 0.8 degrees
- in 1988 the IPCC Was started to provide the world with a clear scientific view on the current state of knowledge in climate change and its potential environmental and socio-economic impacts
9
Q
IPCC report style
A
- policy relevant, not policy prescriptive: climate scientists aren’t deciding policies but are giving the facts so that policies can be made keeping them in mind
10
Q
IPCC 1st report questions (1990)
A
- is global warming occuring?
- are human activities responsible?
- can we quantify the factors responsible?
11
Q
Fingerprinting Challenge (1st report)
A
- attribution science
- identifying changes in the earth system and figuring out what is causing them
- requires knowledge of the Earth System and its history
- thought that the increase in temp was related to the sun
- observed change in solar luminosity over time but it only gets brighter 1% every 100 million years
12
Q
Jean-Baptiste Joseph Fourier (1820s)
A
- hypothesized the idea that the atmosphere acts as an insulator for the earth: greenhouse effect
13
Q
John Tyndall: 1862
A
- certain gases opaqaue to IR: greenhouse gases
14
Q
Svante Arrhenius: 1890s
A
- CO2 as Geologic temp control
- thought about what would happen if we doubled the amount of CO2 in the atmosphere
- theory that volcanic eruptions had been increasing
- found more evidence of CO2 going into the atmosphere due to volcanic eruptions but there hasn’t been an increase in very big global eruptions
(more likely that as population increases, more abilities to observe things)
15
Q
Keeling curve
A
- made lots of observations about CO2 concentration in Hawaii because the atmosphere there is very well mixed due to Pacific winds
- In Russia they drilled to 800,000 years ago and found lots of variability in amount of CO2 but nowhere near as much as we have now
16
Q
4th IPCC report (2007)
A
- earth is warming
- unequivocal that it is human-caused
17
Q
6th IPCC report (2022)
A
- what’s the rate of change?
- what are the tipping points?
- how can we mitigate?
- how can we adapt?
18
Q
definitions: couplings
A
- components do not exist in isolation, they are linked
- describes the relationship between components
- can be positive, negative or nonexistent
Ex:
CO2 → temperature + (positive, CO2 goes up, temp goes up)
Temperature ―⚬ sea ice - (negative, temp goes up, sea ice goes down)
19
Q
definitions: feedback loop
A
- self-perpetuating mechanism of change and response to that change
- a linkage of 2 or more system components that form a round trip flow
- can be positive (self-reinforcing) or negative (self-diminishing)
Ex:
Temperature ⟺ water vapor + (as temp increases, WV increases, as WV increases, temp increases)
Temperature ⟺ low-level marine clouds (temp increases, clouds increase which deflect sunlight causing temp to go down)
20
Q
definitions: stability
A
- characterizes how a system of components will react to small perturbations in any or all of the system’s components
- achieved if negative feedback in a system is stronger than positive feedback
- a system is unstable if positive feedbacks are stronger than the negative feedbacks
21
Q
definitions: perturbation
A
- temporary disturbance of a system
- for example, volcanic injection of SO2 into the stratosphere
22
Q
definitions: forcing
A
- persistent disturbance of a system
- for example, increasing solar luminosity through time
23
Q
planetary energy balance
A
Energy absorbed by planet → planet → energy emitted by planet
- some of the energy from the sun is absorbed by the earth and some of it is emitted back into the atmosphere/space
24
Q
Formula for energy absorbed
A
= energy intercepted - energy reflected
= Πr2 x S - Πr2 x SA
S = a constant
A = albedo, set amount of radiation that automatically reflects and never enters the earth system
= Πr2S (1-A)
25
formula for energy emitted
= 4Πr2 x σT4
σT4 = S/4 (1-A)
26
Gaia hypothesis
- living organisms increased with their inorganic surrounding to form self-regulating complex system that helps perpetuate habitable conditions on Earth
Criticism: Biota would need the capacity for foresight to prevent large fluctuations in the surface environment
27
Daisyworld properties
- tells us things about planetary systems with varying levels of complexity
- white daisies and grey soil
- no atmosphere
- no clouds
- solar luminosity rapidly increasing
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Daisyworld pertinent properties
- Albedo: measure of the reflectivity of the surfaces
- Daisies are sensitive to temp
29
relationship between daisy coverage and SFC temp
- as daisy coverage increases, average surface temp decreases
- negative coupling has a negative slope
- Daisy coverage ―⚬ average surface temp
- as average surface temp increases, daily coverage increases until the optimum point is reached and it's too hot for daisies, then begins decreasing (upside down parabola)
- optimum point identifies where the relationship in the coupling
- Average surf temp → daisy coverage | average surf temp ―⚬ daisy coverage
30
Daisyworld small perturbation feedbacks
- At P1 we are in a stable equilibrium state because the temp allows for daisies to thrive and reflect which decreases the average temp = Negative feedback loop
- At P2 there is an unstable equilibrium state because we are above optimum temp, so daisies are killed and therefore there will be nothing reflective =positive feedback loop
31
Daisyworld climate history
- threshold behavior identified - lifeless case
- if we add daisies the temp evolution of the planet will dip
32
lessons of daisy world: planetary climate system
- the planetary climate system is not passive in the face of internal or external influences: feedback loops respond to perturbations and forcings
- negative feedback loops can counter external forces
- daisies live longer than expected
33
lessons of daisy world: intelligence
- daisy world is seemingly intelligent
- the daisies' response is exactly what was needed
- no foresight or planning involved
- Biota not sentient, but components of the climate system
34
lessons of the daisy world: threshold
thresholds exist in systems
- daisies only held off demise for so long until the collapse
35
radiation
- sun emits electromagnetic radiation, primarily in the visible portion of the spectrum
- intensity of radiation depends on the sun's temp raised to the fourth power (Stefan-Boltzmann law)
- surface of the sun is about 5800 K and emits about 64 million watts per square meter
36
intensity of solar radiation
- reduced as it is distributed over a larger area
- radiation intensity decreases in proportion to the distance squared
- calculating this using Earth's average distance from the Sun yields a solar "constant" of ~1367 W/m^2
- perfect amount of radiation for life to thrive
37
Earth's tilt - obliquity
- Earth’s axis is tilted 23.5 degrees
- Alters distribution of radiation over latitudes to create seasons
- Spring Equinox (March 21-22) - sun vertical at the equator
- Summer solstice (June 21-22) - sun vertical at latitude 23.5 N
- Autumnal equinox (September 22-23) - sun vertical at the equator
- Winter solstice (Dec 21-22) - sun vertical at latitude 23.5 S
38
earth's orbit - eccentricity
- Earth revolves around the sun once every 365.25 days
- Earth revolves around the sun on an ecliptic plane
- Distance from the sun varis
- Perihelion (closest) - Jan 3: 147 million km
- Aphelion (farthest) - July 3: 152 million km
- Eccentricity enhances seasonality
39
composition in terms of radiation
- Gases - nitrogen, oxygen, argon
- Liquids - H20 (clouds, rain)
- Ex. cloud fraction - sometimes liquid sometimes solid
- Solids - ice in clouds, airborne sand, ash aerosols
- Ex. black carbon, sea salt, dust
- Currently 422.71 ppm of CO2 in the atmosphere as of August 2024
40
overall atmospheric composition: water vapor
- must abundant variable gas, added or removed via the hydrologic cycle
- concentrations of nearly 0% over desert and polar regions, nearly 5-6% near the tropics
- contributor to Earth's energy balance and many important atmospheric processes: most abundant greenhouse gas, keeps planet habitable
41
overall atmospheric composition: carbon dioixde
- carbon dioxide is a trace gas
- important to Earth's energy balance
- added through biological respiration, volcanic activity, decay and natural and human-related combustion
- removed through photosynthesis and chemical weathering (generally done naturally, but now designing geo-engeineered solutions
42
overall atmospheric composition: ozone
- tri-atomic form of oxygen essential to life on Earth
- ozone near the surface is a pollutant but very good in the upper atmosphere (stratosphere)
- essential absorber of UV radiation
- chlorofluorocarbons (CFCs) specifically chlorine atoms, react with ozone and destroy it
- ozone destruction peaks over the southern hemisphere and persists through spring
43
overall atmospheric composition: ozone hole
- decline in amount of ozone in the SH due to chemical reaction caused by AC and refrigerators
- because of the Montreal Protocol, the hole has started closing
44
overall atmospheric composition: aerosols
- any solid and/or liquid particles, other than water, that exist in the atmosphere
- both natural: sea salt, dust, combustion
- and human
- due to small size they can easily remind in suspension for longer periods
- contribute precipitation processes and Earth's energy budget
45
overall atmospheric composition: pressure
- decrease in pressure as we go upwards in the altitude of the atmosphere
46
thermal layers: troposphere
- lowest layer, promotes atmospheric overturning
- virtually all weather processes
- warmed from below through solar radiation at the surface
- contains 80% of the atmosphere's mass
- due to thermal expansion, roughly 16km over the tropics but only 8km at poles
- most clouds exist here
47
thermal layers: stratosphere
- area of little weather
- temp increases with height
- inversion is caused by the absorption of ultraviolet radiation by ozone
48
thermal layers: mesosphere
- characterized by decreasing temp as you go up
- coldest atmospheric layer
49
thermal layers: thermosphere
- uppermost layer
- slowly merges with interplanetary space
- increasing temp with height
50
thermal layers: mesosphere and thermosphere
- only account for 0.1 percent of total atmospheric mass
51
atmospheric influences on solar radiation: absorption
- gases, liquids and solids in the atmosphere reduce the radiation intensity by absorption
- energy transferred to the absorber
- atmospheric gases are overall poor absorbers of radiation
- Earth's SFC is a fairly good absorber
- amount of radiation absorbed by the SFC depends on the angle of influence
52
atmospheric influences on solar radiation: reflection
- radiation redirected by objects through reflection without being absorbed
- albedo is the percentage of energy reflected by an object
53
atmospheric influences on solar radiation: scattering
- Rayleigh: reason for our blue skies and pretty sunsets
- Mie: enhances reds in sunsets, esp from pollution aerosols
54
atmospheric influences on solar radiation: transmission
- the percentage of radiation transmitted through the atmosphere to the surface
- transmission is dependent on the atmosphere's ability to absorb, scatter and reflect
- transmission of radiation varies across the Earth
55
Fate of solar radiation
- various things that can happen to radiation once it enters the atmosphere
1) radiation comes in from outer space and right off the bat some is reflected by clouds and the atmosphere
2) some makes it to the surface but is reflected back
3) some absorbed by the atmosphere: short-wave radiation
4) radiation coming from the Earth is no longer short-wave, long-wave (red) and is emitted back into the atmosphere
5) greenhouse gases put back radiation into the surface
56
Fate of solar radiation: latitude
- top of the atmosphere: poles receive radiation
- earth's surface: very similar
- reflected by clouds: less common in the South Pole
- reflected by Earth's surface: relatively low in most places, except in the poles because of ice
57
Fate of solar radiation: annual radiation budget
- surplus of radiation at the equator because it receives more direct sunlight throughout the year
- surplus heat energy is transferred by the atmosphere and oceans to higher latitudes
58
general circulation of the atmosphere: pressure gradient
- at the equator, there is max incoming solar radiation
- at surface air is lifting up and vacating mass
- surface has low press at equator
- air mass is uplifted through the atmosphere and eventually enters circulation cell
- cools at high elevations
- stacks up mass, surface has high pressure at 30 N-S due to sinking air
- return flow: at SFC we want to move mass from high press to love press from 30 N-S to equator
59
general circulation of the atmosphere: mositure
- water is evaporated and enters the updraft
- as it rises it cools and condenses
- 30 N-S very dry
- water droplets get big enough and then fall back into the atmosphere as rain
- most of it rains out before it gets to the top of the cell
60
general circulation of the atmosphere: Intertropical Convergence Zone (ITCZ)
- where the two Hadley cells converge in the tropics
- mitigates with the seasons
- non-continuous, discrete circulation
- not continuous over land, usually over the ocean
61
general circulation of the atmosphere: meridional circulation
- really cold air from the poles meets up with really warm air from the tropics
- steep temp gradient means that the temp changes the fastest and there is the most pressure: causing strongest winds (jet streams)
- lowest pressure at the equator, high pressure in the middle, low-high near the poles, high pressure in the poles
- mass wants to move from high pressure to low pressure: wind
62
general circulation of the atmosphere: coriolis effect
- due to spinning of the Earth
- object in NH is deflected to the right
- object in the SH is deflected to the left
- consequence of differential rotational speeds of the planet, spins faster a the equator
63
wind
- meterologists refer to winds in terms of the direction from which they blow
- Westerlies: blow from west to east
64
general circulation of the atmosphere: global precipitation distribution
- a combination of temp and precipitation forms climate and results in vegetation patterns
65
polar front zone
- relatively warm air from the tropics meets relatively cold air from high latitudes
- creates the strongest temp gradient
- 60 N-S
- also very steep pressure with stronger winds like jet streams
- creates instabilities that lead to storms
66
circulation of the ocean: mixed layer
- 100-200 m
- SFC circulation
- not stratified
- mixed by buoyancy fluctuates and winds
- photic zone: where light penetrates
67
circulation of the ocean
- wind exerts force on water and pushes it along
- wind angle down towards south, ocean current goes west due to Coriolis
- current moves until it interacts with a continent, some of it goes north some goes south
- water that went north is now in the Westerlies zone
- ocean current now moves east, opp direction from before
68
circulation of the ocean: gulf stream
- takes very warm water from the Caribbean and sends it across the atlantic to europe and keeps UK warmer than it would be
69
ekman spiral
- discovered that while the wind blows in a certain direction, they were transported 20-30 degrees to the right (NH)
- wind has kinetic energy and it gives that energy to the water
- each layer of water below the surface operates somewhat discreetly, not moved all at once, friction interaction with each layer
70
ekman transport
- current moves from West to East
- ekman transport shifts the flow of the water into the center of the gyre, results in the dome
71
deep ocean
- 5 km
- stratified by density
- densest at the bottom
- hard to have buoyant circulation in the deep ocean
72
downwelling
- mass convergence going inwards
- water piles up and creates a hill (convergence)
- surface layer thickens
73
upwelling
- 2 gyres side by side
- mass diverging outwards
- water from deep ocean comes up to surface
- surface layer thins
74
equatorial upwelling
- Northern and southern trade winds causing surface water to go away from the equator so cool water upwells from below
75
coastal upwelling
- warm surface layer blows off shore and cool water upwells from below and comes to shore w nutrients
76
salinity
- low at the surface and increases all the way down
- cold, salty water is very dense
77
north atlantic deep water formation
- gulf stream brings warm water to higher areas
- moisture is evaporated in the Caribbean and carried to Pacific where it rains (no salt)
Atlantic:
- water interacts with Westerlies, cooling stream and evaporating more water, increasing salinity as it goes north
- area north of Iceland is even saltier bc of sea ice and sinks to the bottom
78
antartic bottom water formation
- ice sheets range from 2-3 miles thick
- air on top is very cold and dense
- gravity and winds pull on it (katabatic winds)
- water is super cold and salty so it sinks to the bottom
- bottom water is colder and denser than the North Atlantic deep water
