L18: Oceans Flashcards
Oceans cover ______ of the earths surface
71%
What is the oceans maximum depth? What is this area called?
11 km, Marianas Trench
What is salinity
which measures the proportion of dissolved ions in ocean water – is ~3.5% or 35‰ (‘per mil’ or parts per thousand)
What are the primary constituents of an oceans salinity?
Chloride, Sodium, Sulfate, Magnesium, Calcium, Potassium, Bicarbonate
Define sources
Ions enter into the oceans primarily from the dissolved load delivered from land from rivers, and from submarine volcanic activity, primarily at mid ocean ridges
Define sinks
Ions are removed from seawater by the precipitation of minerals (sodium, chloride, sulfate), sequestration by living organisms to produce shells (primarily calcium, bicarbonate), sorption to clay minerals (potassium and sodium), being removed in sea spray, and in reactions with basaltic seafloor rocks (alteration)
Where is salinity high and where is it low?
Salinity is high in regions of high evaporation, and low where river water enters into the ocean
Changes in composition over time on earth?
The bulk composition of seawater likely stays fairly constant over time, but salinity was probably lower early in Earth history. Iron concentrations (as Fe2+) were higher in Proterozoic seawater, and thick banded iron formations were deposited as atmospheric oxygen increased and iron oxidized
Where are temperatures highest? Where do they decrease?
Temperatures are highest in tropical Pacific and Indian Oceans, decrease poleward
Temperature decreases with _________. Cold water is denser, therefore it _________.
- Depth
- Sinks
Thermocline
the zone of rapid temperature change
Salinity increases with _________. Why?
- Depth
- because saline water is denser and sinks
Halocline
the region of rapid salinity change
Seawater density increases with _________. Why?
- Depth
- both due to decreasing temperature and/or increasing salinity
Pycnocline
the zone of rapid density change
What cause ocean currents?
- Air currents (wind) interacting with the surface of the oceans
- The sinking of denser (colder or saline) water
- Effects resulting from rotation of the Earth
Dense, cold, high salinity water __________ at the poles to drive deep ocean ____________
- Descends
- circulation
Define thermohaline circulation
- the result of density- driven movement of water in the oceans.
- This deep circulation network plays a critical role in controlling global climate
The sun heats the planet __________, which results in . . .
- Unevenly
- resulting in energy differences which lead to prevailing wind directions
How are surface currents created?
The friction caused by winds resulting in energy differences which lead to prevailing wind directions passing over ocean water
Surface circulation is dominated by _______ driven by the Coriolis Effect.
Gyres
The coriolis effect leads to major westward drift at the equator, and sustains the 5 major gyres on the planet. Name these gyres.
N. and S. Atlantic, N. and S. Pacific, and the Indian Ocean
Surface of solid Earth is rotating about its vertical axis to some degree, everywhere except at equator. Name the directions these travel in.
- Counterclockwise (CCW) in northern hemisphere
- Clockwise (CW) in southern hemisphere
Objects moving in a straight line appear to curve relative to solid Earth beneath them. What directions do these travel in?
- Right in N. hemisphere
- Left in S. hemisphere
