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LSU OCS 1006 exam 3 Chemical
Oceanography practice exam update
questions and answers
what generates a seismic sea wave? - vertical movement of earth along faults (underwater earthquakes) what are some characteristics of a tsunami? what does "tsunami" mean? - "Harbor wave" long wavelength, shallow water wave, speed is proportional to water depth; very fast and can go undetected in open ocean, only deadly if they hit the coast where did the tsunami in 2004 hit? - indonesia, sri lanka, area besides the movements of tect. plates, what else can cause a tsunami? example when this occured? - a volcanic eruption Jan 2022 Tonga What is a tidal wave? - periodic, short term changes in height of ocean surface at a particular place caused by a combo of gravitational force of the sun and moon and motion of the earth longest of all ocean waves always shallow water waves Describe the equilibrium theory of tides? - examines the force balance that allows the planet to stay in orbit around the sun/ the moon in orbit to earth (bc the moon is closer to earth, the moon has more influence than the sun) describe the dynamic theory of tides - takes depth, (bathymetry) seabed contour, water viscosity, and tide wave inertia into account what are tides forced by? define these terms - gravity- pulls the earth and moon/sun toward each other
inertia- tendency of a moving object to continue in a straight line, keeps them apart (rotation of the earth) what maintains the balance bt inertia and gravtity? how does it work? - orbits
- if planet wasnt moving, gravity wouldnt pull it to the sun
- if planet is moving, inertia of planet will keep it moving in a straight line
- in a stable orbit, gravity and inertia cause the planet to move in a fixed path explain the relationships of the variables of the tide generating force equation - (m1 * m2) the heavier the mass the more force of the tide (mass/ r^3) the larger the distance the weaker the tide generating force what creates the two tidal buldges - "lunar tides" - the pull of the ocean closer/ towards the moon and the factor of inertia causing the opposite side of earth to bulge how do gravitational bulges cause high tide and low tide? - the earth spins, maintaining a fixed position of the two gravitational bulges, meaning that a position of land will pass through these bulges as earth rotates (when its not in the bulge= low tide, when in the bulge= high tide) what does the varying position of the tidal bulges tell us? - that the moon moves what is a lunar day? - Time between two successive overhead moons at their highest position in the sky 24 hours, 50 minutes what is a solar day? - 24 hours what are solar tides? how do these compare to lunar tides? - the ocean tides that are caused by the sun's gravity conceptually they are the exact same, they are just smaller and change slower since the sun is further away and earth only rotates around it once
how does the shape of a basin influence tidal movement? - wide, symmetrical basin= mini amphidromic system narrow, restricted basin= tidal wave crest cannot rotate around an amphi. point. (bay of fundy) what is tidal datum? - reference level to which tidal height is compared (avg of all low tides) what is tidal range? - The height difference between high and low tide (largest tidal ranges occur at edges of largest ocean basins- esp basins or inlets) what is a tidal bore? - "tidal wave"- a high, often breaking wave generated by a tide crest that advances rapidly up an estuary/ river how do tides affect the earths rotation? - friction has slowed the earths rotation by a few 1/100th of a sec every century how do tidal patterns affect marine organisms? - organisms at the top of the intertidal zone deal with sub/emergence desiccation animals at the bottom deal with predation What is a nuisance flood? examples of where this happened? - as global sea levels increase spring tides can flood coastal infrastructure at given meterological conditions cocodrie, la- terrebonne bay-jan 10, 2020; venice, italy what is strange about water's MP and BP? - its expected values based on the periodic table do not line up with the observed values What is cohesion and why is it important? - one water molecule forms hydrogen bonds with nearby water molecules which gives water its strong SURFACE TENSION
- is why water droplets are round why is water wet? - adhesion- attraction to other molecules/objects
what happens to waters density as it cools? freezes? - it increases but if it freezes it decreases and floats what is latent heat on the temperature diagram? - heat of fusion and heat of vaporization (larger than fusion) what is the thermostatic effect? - the moderation of the temperature of earth's surface, moderates climate what is sea breeze circulation? - the land heats faster than the water, creating a vacuum of cool air from the water, causing air to rush onshore (causes lots of thunderstorms bc of the circulation of warm and cool air) what does water do to solar radiation? how does this relate to transparency? - it absorbs (red, orange) some wavelengths and let others pass thru easier (blue- why the ocean is blue and a cup is not) in deep ocean, the colors are skewed bc the wavelengths of colors are absorbed-- to see vibrant fish colors, must bring a flash/source of white light What is salinity? - total amount of dissolved inorganic solids in seawater (parts per thousand) (per mL) What is a colligative property? - properties of a solvent that depend on the concentration of solute particles being dissolved
- freezing point
- heat capacity
- evaporation rate what are the six elements that most commonly make up seawater? - cl, na, so4, mg, ca, k what trace elements are dissolved in seawater? - Gold, mercury, zinc, iron where does the ocean's salinity come from? - - outgassing
- weathering of rocks
- hydrothermal vents
how does solubility influence gas exchange bt the atmosphere and the ocean? - increasing temperatures, decreased gas solubility (warmer temps cause gas to be released into atmosphere) how does gas concentrations change with depth? - epipelagic (surface layer)- highest amount of dissolved oxygen because of sunlight and photosynthesis (respiration) mesopelagic- at the oxygen minimum bc there is no replenishment deep ocean- stablilization of ox levels how does el nino affect gas composition - decreased levels of oxygen levels bc an increase in water temp how does co2 levels change in the ocean? - it is inverse with oxygen, CO2 is more soluble in water than oxygen at the surface layer- low co2 levels at deep later- high levels what is an acid? a base/alkaline? relative pH's of each? - acid (low pH)- proton donor (releases h+ in soln) base(high pH)- proton acceptor (oh- ion) what is the pH of ocean water? - about 8 (7.8-8.3) what is the carbonate buffering system? - 3 step process that is the ocean's way of maintaining it's acidity (amount of hydrogen atoms it releases) (step one acidic- --> step 3 basic) CO2 in the ocean forms the acid H2CO what is ocean acidification? how does it affect shells and coral? - a reduction in the ocean pH due to the uptake of anthropogenic co (little co2 in atmosphere, a lot of oxygen in the ocean) affect- since shells are made of calcium carbonate, when mixed with an acid, it dissolves
what are coastal shapes and locations driven by? - erosional processes, depositional processes, biological processes what is offshore? - point beyond low-tide breakers what is eustatic sea level? - The global sea level; sea level rises when glaciers melt and sea levels fall when glaciers grow, vol of basin can change due to plate tectonics, and increased temps expand vol of water what is local sea level? - land rises or falls due to local plate motion, ice changes, and subsidence due to delta sediment compaction, winds and currents what is relative sea level rise? - Caused by a combo of eustatic rise and/or subsidence (coastal louisiana, grand isle) what are erosional coasts? - dominant processes REMOVE material straight shores, cliffs, caves limited new river sediment What are depositional coasts? - dominant processes ADD material beaches, deltas (broad and flat) ample new river sediment what dominant forces shape a delta? - river (Mississippi) , wave (san francisco) , tide how many deltas did the mississippi river delta have throughout history? - 6 what is the role of barrier islands? how are they formed? - protect bays and wetlands by "taking the bullet" of the effects of erosion; create calm waters behind them relics of old deltas what coast is la jolla, california? - erosional
