Lec 2 Flashcards
The solid Earth is composed of plates floating
on liquid mantle
Oceans are formed when
2 plates separate from eachother
In the middle, ascending mantle material makes a
mid ocean ridge
subduction zones
In areas where two continents are pushing against each other, one sinks underneath the other producing these that create deep trenches
what displaces more volume? solid or liquid water
solid water (ice) displaces more volume (therefore it floats)
Water can dissolve more things than any other natural substance, including
salt, gases, and organic molecules
Seawater contains
many solutes, mostly salts in the form of ions (1 kg of seawater has approximately 35 grams of dissolved salts)
whats heavier? seawater or pure water
sea water
seawater also contains
dissolved gases that are exchanged with the atmosphere: gas exchange (vital for living organisms)
the ocean is usually
stratified/layered
The number of ocean layers vary with
environmental conditions and is determined on the physical properties of water masses (density - temperature and salinity)
ocean layers are separated by
thermoclines (transitional areas in which there is a sudden change in temp) and haloclines (…sudden change in salinity)
3 ocean layers
- surface layer (mixed) down to 100-200m (mixed by wind and currents)
- Intermediate layer: down to 1,000-1,500 m (separated by the main thermocline)
- Deep layer: below 1,500 m (very stable conditions)
Ocean circulation and movement is caused by:
The Coriolis effect and wind patterns
Thermohaline circulation
Tide forces
Wave action
Coriolis effect is caused by
curvature and rotation of the Earth
The Coriolis effect creates
circular movement of water and air particles
(Currents rotate in opposite directions in the northern and southern hemispheres)
wind is caused by
heat energy
ekman transport/spiral
The movement from the surface layer of water is transmitted to the water below, but also at a 45 degree angle caused by the Coriolis effect
most visible result of Coriolis effect
ocean surface circulation
thermohaline circulation
& produces
Because denser water sinks (colder and saltier), it leaves a void that it is filled in by less dense water
& produces great ocean conveyer
The tidal force
produced by the Moon and the Sun on the Earth’s ocean is the vector difference between the gravitational force exerted by the Moon or the Sun on water particles, and the gravitational force that would be exerted on water particles if they were located at the center of mass of the Earth
spring tide
During new and full moon the Sun, Moon and Earth line up – tidal forces due to the Sun reinforce those of the Moon
neap tide
When the Moon is at first or third quarter, the Sun and Moon are separated by 90° – the forces due to the Sun partially cancel those of the Moon
types of tides
- Semidiurnal: two high tides and two low tides each day
- Diurnal: one tidal cycle per day
- Mixed. (most places) Because of the diurnal contribution, there is a difference in height (the daily inequality) between the two high tides on a given day
Waves are caused by
winds but in some rare cases by earthquakes and landslides
The size of wind waves depends on the
fetch, the span of open water over which the wind blows
