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EAS 1540 PRELIM 1
Terms in this set (124)
What creates and destroys ocean basins?
How do ocean currents move?
Clockwise in the North; counterclockwise in the South
How has carbon dioxide concentration changed?
It increased about 3ppm each year; it will reach 40ppm in 20 years
What is the widely accepted safe limit of warming expressed by the international community
2 degrees; we're already at degree; 4 degrees is the difference between now and an ice age
How do we stay below 2 degrees warming?
We reduce the global energy system to net zero carbon emissions by mid century
How do we keep island nations alive?
We have to stop warming above 1.5 degrees (the global energy system to net zero carbon emissions in 13 years)
What role do wealthy nations play in warming? What barriers exist?
Wealthy nations have to bear the financial burden of this transition for themselves and also for poorer countries;
the only barriers are political restrictions
Describe the Big Bang
Super hot, ionized gas cooled; all mass contained in a single point expanded outward; universe went through dark age of hydrogen and helium; gravity compressed and heated interior so greatly that hydrogen and helium thermonuclearly fused; essentially a hydrogen bomb; stars popped off like popcorn; explosion created starlight; even atoms have gravitational effect
Where did carbon come from?
It did NOT come from the Big Bang; it came from later formed stars
How did heavier elements form?
Large stars exploded when they got old (became nebula); when lighter elements were fused, C, N, P, Fe formed, eventually Au and Cu; constant birth of stars (heavy elements form) and death of stars (when gravity collapses)
What generation is our sun?
How long ago did the Big Bang occur?
15 billion years ago
How did the Solar System form?
A diffuse, roughly spherical, slowly rotating nebula begins to contract (hydrogen, helium, and star dust - heavier elements formed in previous stars); terrestrial planets form from collision of planetismals; gas planets form from gas accretion (same composition as the sun)
How old is the sun? How long is its lifespan?
The sun is 4.5 billions years old and in about 4 more billion years the sun will run out of hydrogen fuel and die. It will expand in size beyond the orbit of earth and in so doing will vaporize the earth.
How was the moon formed?
Moon formed when earth was hit by a mars-sized object > debris was knocked out of earth and aggregated > this mass got into orbit - earth was also hit so hard that it tilted.
Describe the early atmospheric conditions of the earth
Consisted of hydrogen and helium.
Describe how earth's atmosphere evolved
Out-gassing from volcanoes released water, carbon dioxide, sulfur dioxide, nitrogen gas, hydrogen gas, and chloride gas. Water vapor condensed to form oceans and then anaerobic life developed. Billions of years later, photosynthetic organisms developed and oxygen was introduced
Where did water come from?
1. Water formed in place by condensation
2. Water was brought to earth by comets
3. Water was brought to earth by asteroids
4. Volcanic emission
What are the officially named oceans?
Southern (bottom, not the Antarctica ocean)
What is the average depth of the ocean?
Where is 0 and 180 degrees longitude?
0 = England/Prime Meridian
180 = Japan/New Zealand
It travels from england to california to japan
How do you depict an abrupt change in contour, a rapid change and a gradual change?
Abrupt change: rapidly changing colors
Rapid change: closely spaced lines
Gradual change: broadly spaced lines
How did the core develop?
How do we determine the age of rocks?
Look at meteorites
Where did the first fossils come from?
Archaean stromatolite from Western Australia
What are algal stromatolite?
What is a trace fossil?
evidence of behavior left behind in a rock record
When did LUCA occur?
When was the first sign of life?
Eubacteria + Archaea
Small, simple cells
No internal divisions
Archaeans slightly bigger
Halfway through the earth
Red rocks - iron rusted
When eukaryotes first evolve?
When did the Cambrian Explosion occur?
~530 mya: most animal groups appeared in this time, trilobytes (first exoskeletal organism)
Single or multi cellular
What is sea floor bathymetry?
Ocean floor topographic map
How do you measure bottom depth?
- single beam: creates a tracklines as ship moves forward
- multi beam: creates a swath of bottom depth (more detailed and high resolution)
- towed multi beam (highest resolution)
Which coast has a broad shelf and which a narrow a shelf?
East coast: broad
West coast: narrow
Where are most continental shelves?
What did Alfred Wegener contribute?
Theory of Continental Drift
Did NOT discover plate tectonics
Fit of continents
Paleobiography (fossil and mineral belts across continents)
What is extensional faulting?
When two rocks pull apart and the middle part slides down between
In mid ocean ridges
What evidence do you use for seafloor spreading?
- magnetic field has reversed many times
- bands represent flips and are used to date rocks
- white band (north faces antarctica)
- proxy measure of geologic time
- new molten rock splits other rocks
- gets older as you move away from center
What forces move plates?
Mantle convection and Slab pull
How will the continents be arranged in the future?
Super continent again
What are the 3 types of plate boundaries?
What some examples of divergent plate boundaries?
Mid atlantic ridge
- north american plate and east african plate or eurasian plate
What some examples of ocean -continent convergent plate boundaries?
Nazca and South American
Fuca and North American
Mount Saint Helens
Cascades and Andes
What some examples of ocean - ocean convergent plate boundaries?
Pacific and Eurasian
Japan and Indonesia
What some examples of continent - continent convergent plate boundaries?
Indian and Asia
What is an example of transform plate boundaries?
San Andreas fault
Where are mantle hot spots?
Hawaii (Big Island is the newest)
thin, high density, basalt
thick, low density, granite
Why do we want to study marine sediments?
It records different kinds of earth changing events
Similar to looking at tree rings
Where are the thickest marine sediments found?
What are 3 kinds of marine sediments?
terrigenous sediment, red clay (slowest to accumulate), biological oozes
What is proxy?
What are isotope ratios used for?
Used to get proxy temperatures (certain ratios point to certain times in history)
What is the purpose of deep sea drilling?
Examine fossils in sediment core - more popular way
Proxy Measurements of Past Ocean Conditions
How do you measure a wave?
From crest to crest
How do you measure wave speed?
The distance a wave crest travels per unit time
How do you measure wave period?
Time it takes for a wave to travel one wavelength
Number of crests passing a fixed location per unit time
What determines wave speed?
Wavelength and bottom depth
What makes waves move faster?
Longer wavelength and deeper waters
What is considered a shallow water wave?
When bottom depth is shallower than 1/20 wavelength
Describe the duck being moved by a wave
Waves propagate energy but not mass (wave orbitals - waves start and end at the same point)
self sorting of deep water waves
occurs because longer wavelengths travel faster
occurs in long distance oceans
bending of shallow-water wave fronts due to change in bottom depth
crest moves slower than other end of wave bc it hits shallower waters faster
Consequence of wave refraction
headland: high energy waves
bay area: outward bend, less erosion to bay
How does longshore sediment transport occur?
When wave strikes the beach at an angle, waves push sediment up a shore and then move laterally
Obstructed by jetties and groins
Describe the spillover effect
wave crowding > wave height increases > surf zone, top moves faster
Describe summer beach conditions
gentle waves push offshore sandbar shoreward to create wide and gently sloping sandy summer beach
Describe winter beach conditions
storm waves drag sand off the beach to be stored in offshore sandbar and frequently resulting in a rocky winter beach
What can sand tell you about waves?
Coarse sand means rough waves, high energy waves
Fine sand means gentle waves
Large waves push water onto elevated beach face, beached water is funneled back through narrow breaks in sand bars (accelerated water)
How do you get out of a rip current?
Swim parallel to the beach for 10-20 meters and then swim back
How is wave height determined?
Wind speed (sets upper possible limit)
What is wind fetch?
the distance over which wind can blow without obstruction
Waves in a storm?
Once a wave is generated under the center of a storm region it begins to propagate outward and away (lateral spreading)
Where are tsunamis generated?
convergent plate boundary and land slides
What is the equilibrium model of tides?
Idealized view of tide
no interference, infinitely deep, no continent obstruction
one high tide
one low tide
- moon orbit tilted 28 (tidal bulge tilted)
two equal high tides and two equal low tides (explained by earth rotation)
two unequal high tides
Latitudes and tides?
high Latitude - diurnal
mid Latitude - mixed tides
low Latitude - semidiurnal
What is a tidal day?
24h + 50 min
What force creates a bulge?
centrifugal - bulge opposite to moon
gravity - bulge facing moon
point at which both masses are rotating around
moon pulls along the same line as the sun (new and full moon)
moon pulls at 90 degrees to the sun (first and last quarter moon)
What do you do if you're camping on a full moon?
stay away from shore
Why ocean tides and not lake tides?
Tides are pulled laterally (lakes don't have enough lateral dimension)
Dynamic theory of tides?
continents block, coriolis, bottom friction slows
point of rotation of tide, no tidal range
Where is tidal range largest
at the poles
tidal bulge, continents, coriolis
larger tides occur where?
Global surface wind patterns
3 primary 30 degree alternating wind belts
ocean surface temp
east equator: tongue of cold water
atlantic ocean temp
warm thin surface layer, cold, thick, deep
atlantic saltier than the rest
north pacific freshest
Ocean surface currents
subtropical gyres: clockwise in north hemi and counter in south hemi
subpolar gyres: counterclockwise in north hemi, absent in south
antarctic: east around antarctica
rule of coriolis
point nose in direction of current and stick hand directly out from side (right hand for northern hemi, left for south)
What type of air column would weigh less?
Air with high amounts of water vapor
Idealized Hadley circulation
creates an oscillating low high surface pressure
Describe every 30 degrees
low pressure at equator and alternates, creating pressure gradient, bands aren't linear
what determines seawater density
where is the thermocline
shallow in summer
disappears in winter
due to wind force, friction force, coriolis
slab of water moves right of wind direction in north, left in south
follow lines of constant pressure
central high pressure and circular geostrophic currents develop
warm equator waters to high latitudes (western currents - swift and narrow)
high latitudes to warm equator waters (eastern currents - broad and slow)
samples of temp and salinity fall into 2 categories
NADW, AABW, AAIW
where are the oldest sea waters
path of water
north atlantic > south atlantic > indian ocean > pacific (slow process)
how deep is deep water?
half wave's wavelength
why do coastal regions get bigger tides
coastal regions get bigger tides bc amphidromic points - range increases away from these pts
what causes alternating wind bands
high low pressure and coriolis
what are the 3 wind bands
westerly, north east trade, polar easterly
what happens to thermocline during summer of large seasonal variation
during summer/ large seasonal variation causes seasonal thermocline to become more shallow
fully developed geostrophic currents around mound
steady circular motion fully developed geostrophic currents
western boundary currents
western boundary currents bring warm water from tropics to high latitudes
how long does it take for deep waters to move
2000 years for deep waters to move from north atlantic to pacific
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