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Earth And Space 2 > Oceanic Processes > Flashcards

Oceanic Processes Flashcards

1
Q

Why is the ocean important?

A 
Absorbs CO2
Regulates stabilises earths temp
Contains most earths volcanoes
Drives weather and climate
Shape earths chemistry
Abundance of living things 
Produces 70% oxygen
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2
Q

How much of earths surface is covered by the ocean?

A

70%

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3
Q

What is latent heat?

A

The amount of heat energy absorbed or released when 1kg of the substance changes phase/state

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4
Q

Waters properties

A

High specific heat capacity
Water has lower density than solid
Melting and boiling points unusually high
Good solvent

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5
Q

Three zones of the ocean

A

Euphotic (sunlight) zone
Disphotic (twilight) zone
Aphotic (midnight) zone

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6
Q

Euphotic zone

A

Layer nearest surface
Extends from the surface to 200m
Photosynthesis occurs because enough sunlight
90% all marine life lives in this zone

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7
Q

Disphotic zone

A

Minuscule amount of light
Extends from a depth of 200m-1000m
Plants do not grow, only animals with adaptations

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8
Q

Aphotic zone

A

Extends beyond 1000m, completely dark

90% of the ocean in this zone

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9
Q

What is a thermocline

A

A layer of water where temp changes rapidly with depth, separating warm surface water from cool, deeper waters

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10
Q

Thermoclines and latitude

A

Vary with latitude, high latitudes and equator no thermocline as water isothermal
Mid-latitudes coastal water warmed during summer cooled during winter developing a thermocline

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11
Q

Thermoclines and seasonal changes

A

Thermoclines are seasonal in mid-latitudes forming during spring and autumn
Mixing distributes heat energy, amount of mixing determines how quickly temp changes
Winter: no thermocline-water well mixed stormy conditions
Spring: thermocline starts- less mixing less wind, surface warmer
Summer: strong thermocline- no mixing very little wind, water warm
Autumn: thermocline decays- surface water cooling, winds increase mixing

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12
Q

Factors that increase salinity at the surface

A

Evaporation, sea-ice formation

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13
Q

Factors that decrease salinity at the surface

A

Precipitation (rainfall), river runoff, melting icebergs, melting sea ice

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14
Q

Haloclines and latitude

A

Salinity varies with latitude, high latitudes water less saline as melting icebergs, precipitation, runoff. Temperate regions warm dry air descends because of circulation increases evaporation, water more saline.
Equator temp higher evaporation is greater increase salinity but greater precipitation and runoff offset evaporation

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15
Q

What is a halocline

A

A layer of water where salinity rapidly changes with depth

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16
Q

Halocline and depth

A

Salinity varies with depth, at equator halocline not as prominent as tropics and poles

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17
Q

What is density

A

How much mass is contained in a given volume (density=mass/volume)

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18
Q

Density of pure water at 4 degrees

A

1 g cm-3

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19
Q

Density of seawater

A

1.022 g cm-3 to 1.030 g cm-3

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20
Q

Salinity of the ocean

A

Between 32 and 37 ppt

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21
Q

How does temp, salinity, pressure determine water density

A

Temperature increases, density decreases due to thermal expansion
Salinity increases, density increases due to dissolved material
Pressure increases, density increases due to compression effects of pressure

22
Q

Three layers of ocean water on density

A

Surface mixed layer
Pycnocline/transition layer
Deep layer/bottom layer

23
Q

Surface mixed layer

A 
Top layer (2%), less dense water 
Temp changes with weather (higher temp) 
Salinity changes evaporation or dilution of water (lower salinity)
24
Q

What is a pycnocline

A

The layer in water where density changes rapidly with depth due to either change in temp or salinity

25
Q

Transition layer/pycnocline

A

Occurs 300 to 1000m below surface. Forms strong barrier that prevents mixing of low density and high density water between surface layer and deep layer

26
Q

Deep layer/bottom layer

A

(80%) cold dense water

Temp does not change much as depth increases and becomes nearly constant at about 0 to 3 degrees Celsius

27
Q

What is pressure

A

The ratio of force to the area over which that force is distributed

28
Q

Two types of ocean currents

A

Surface currents

Deep water currents (thermohaline)

29
Q

Surface currents driven by:

A

Winds

30
Q

Deep water currents/thermohaline driven by:

A

Density

31
Q

What generates ocean currents

A

Solar radiation
Gravity
Winds (westerlies and easterly trade winds)

32
Q

What is the coriolis effect

A

The apparent deflection of objects (aircraft, wind, missiles and ocean currents) moving in a straight path relative to the earths surface. Rotates clockwise NH and anticlockwise in SH

33
Q

What is a gyre

A

A large system of rotating ocean currents

34
Q

How much of the earths surface is covered by the ocean?

A

75% or three quarters

35
Q

West boundary currents

A

Large deep fast ocean currents moving warm water/heat from equator to poles

36
Q

Eastern boundary currents

A

Shallower broader slower currents that transport cool water from poles to equator

37
Q

3 factors that affect wind wave growth

A

Wind strength
Wind duration
Fetch

38
Q

4 factors that affect wave speed and direction

A

Wave refraction, defraction, reflection, interference

39
Q

Ekman transport in NH

A

Moves water 90 degrees to the right

40
Q

Ekman transport in SH

A

Moves water 90 degrees to the left

41
Q

What is Ekman transport

A

Surface water moved by winds drags deeper layers below. Each layer moved by friction of upper layer. Deeper layers slower as energy lost, tend to twist. Layers deflected by Coriolis effect, each successively deeper layer moves to right or left.

42
Q

Coastal upwelling in SH

A

Southerly wind causes upwelling

43
Q

Coastal downwelling in SH

A

Northerly wind causes downwelling

44
Q

What is a wave

A

A cycle that travels through water transferring energy through its motion

45
Q

Types of waves

A

Capillary waves (gentle breezes)
Wind waves (wind)
Tsunamis (landslides, earthquakes, volcanoes)
Tides (gravitational attraction)

46
Q

Tides

A

Regularly rising and falling sea levels caused by combined effects of earths rotation and gravitational forces of moon and sun

47
Q

Spring and king tides

A

Sun earth and moon in line (new and full moons) combined gravities exert greatest pull on oceans causing highest highs and lowest lows.
Moon closest to earth causes king tides.

48
Q

Neap tide

A

Sun and moon at right angles to each other (1/4 and 3/4 moons) gravitational pulls on ocean in two ways gives low high and a high low tide.

49
Q

Thermohaline circulation

A

Deep ocean currents carry warm and cold water at a speed of a few cm’s per second around the globe by density differences. A mixture of temp and salinity determine density.

50
Q

Physical pump

A

CO2 dissolved into oceans –> transported down to deep ocean stored in currents and sediments –> upwelling CO2 released back to atmosphere

51
Q

Biological pump

A

CO2 used by marine organisms to synthesise other C compounds –> die or eaten drift down as marine snow –> buried on sea floor, bacteria assist decomposition, CO2 back into water from respiration

Earth And Space 2 (2 decks)

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