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EAS 212 > Lecture 4 > Flashcards

Lecture 4 Flashcards

1
Q

Why is the ocean salty

A
  • the ocean is salty because of dissolved chemicals eroded from the Earth’s crust and washed into the seas
  • there are also ejections from volcanos, particles being swept to the ocean by winds, and materials dissolved from sediment deposited on the ocean floor
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2
Q

What is the biogeochemical cycle consist of

A
  • weathering and erosion of continental rocks
  • > these are then transported to the oceans
  • > this is all part of a large, slow cycle
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3
Q

What is the definition of biogeochemical cycle

A

-pathways by which a chemical susbtrate moves through the biotic(biosphere) and abiotic(litrosphere, atmosphere, hydrosphere)

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4
Q

Do the compounds or solids dissolved in the ocean remain in the ocean

A
  • no
  • > they cycle into and out of the ocean by various processes
  • > in by processes such as river discharge, volcanic eruption or hydrothermal activity
  • > out by processes such as ocean precipitation and biological processes
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5
Q

Is the ocean in steady-state

A
  • yes we assume the oceans are in steady state and the average amounts of various elements remain constant
  • > quantity in= quantity out
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6
Q

What is the residence time

A
  • the average length of time that a substance resides in the ocean
  • > long residence time leads to higher concentrations of the dissolved substance

-residence time is essentially the time taken to replace all of the given substance in the ocean with new material of that substance from other sources

  • R=M/I=M/O
  • > no units because kilograms cancel out
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7
Q

What is the definition of salinity

A
  • it is the total amount of dissolved material in grams in 1 kg of seawater
  • > it is dimensionless and has no units
  • salinity of seawater is about 3.5%
  • > it is about 220 times saltier than freshwater
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8
Q

What is salinity expressed as

A
  • it is expressed as: grams of dissolved salts/kilogram of seawater
  • > can be expressed in parts per thousant
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9
Q

How do chemicals in seawater appear as

A
  • they usually appear as compound ions rather than actual raw elements
  • > so phosphate for example

-chemicals in seawater include most elements, a variety of radionuclides and numerous organic compounds

  • they are designated as major, minor or trace
  • > this just reflects their concentrations
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10
Q

How are dissolved chemicals in the ocean measured

A
  • in parts per million
  • > eg; 1 teaspoonfull in 5000 litres of water
  • > parts per million is used for compounds that are designated as major
  • in parts per billion
  • > eg; 1 teaspoonfull in 5,000,000 litres of water
  • > parts per billion is usually for compounds that are designated as trace or minor
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11
Q

What are the six major consitituents of seawater

A
  • chlorine
  • sodium
  • sulfate
  • magnesium
  • calcium
  • potassium

-these six make up together 99.28% of all salts in seawater

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12
Q

What are the minor constituents in seawater

A
  • bromine
  • carbon
  • strontium
  • boron
  • silicon
  • fluorine
  • concentrations range from 1 to 100 parts per million

-note some are very important for biological processes

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13
Q

What is the major process to remove major constituents

A
  • it is through the precipitation of salt deposits
  • > which mainly occur in marginal seas with high evaporation
  • the residence times for major constituents are very long
  • > the associated river/erosion inputs are very slow
  • > thus the concentrations of these ions vary little to little from time to place
  • the concentrations of minor and trace elements are so low
  • > the sources are also often localized
  • > so the concentrations of trace elements can vary significantly in different parts of the ocean
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14
Q

Can minor and trace constituents change in distribution in a location over time

A
  • yes

- >not something you would see in a major constituent

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15
Q

Describe the differences in freshwater from seawater

A
  • since seawater is 96.5% water
  • > many of its physical properties are shared with that of pure water
  • > except that of freezing point, boiling point, pH and density
  • the dissolved substances in sea water decrease the freezing point of sea water in comparison to pure water
  • > while at the same time increase the boiling point of seawater

-seawater is more alkaline than pure water and has a higher pH

  • seawater is slightly more dense than pure water
  • > this is due to increasing salinity
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16
Q

How does salinity vary in terms of percentage in the open ocean

A

-in the opean ocean, far from land, salinity varies from 33%-38%

17
Q

Is the salinity variance more extreme in the coastal areas

A

-yes

Baltic Sea

  • > 10 parts per billion
  • > because lots of freshwater inputs such as rivers produces brackish water

Red Sea

  • > 42% salinity because of high evaporation
  • > also there is limited open-ocean circulation producing a hypersaline environment
18
Q

Why is sea surface salinity pattern more complex than temperature

A

-because evaporation and precipitation have a complex pattern

19
Q

Describe the patterns in sea surface salinity

A
  • SSS is generally highest in sub-tropical regions
  • it is generally lower at the equator and in high-latitude regions
  • > because of more precipitation
  • SSS differences in some regions also heavily influenced due to runoff and or ice melt
  • North Atlantic’s salinity is higher than the Pacific because of the circulation
  • salinity is very high in marginal seas like the Red Sea where evaporation dominates
20
Q

What are the six processes that affect the salinity by changing the amount of water

A

1) Evaporation
2) Precipitation
3) Runoff
4) Icebergs melting
5) Seaice melting
6) Sea ice forming

21
Q

Is there more runoff in the northern latitudes

A
  • yes

- >as a result, the salinity there is lower

22
Q

Does Atlantic Ocean have higher SSS than the Pacific

A
  • yes

- >because of the proximity to land

23
Q

Describe the salinity in terms of depth between the low latitudes and the high latitudes

A

Low latitudes
->curve begins at the surface with high salinity

High-latitudes
->curve begins at surface with low saliniity

-at depths, curves converge since processes affecting salinity mainly occur at tthe surface

24
Q

What is the halocline

A
  • the region of rapidly changing salinity with depth

- >it separates the layers of different salinity in the ocean

25
Q

What drives the atmosphere engine

A
  • variations in solar radiation drive the global ocean-atmosphere engine
  • > creating pressure and density differences that stirs currents and waves both in the atmosphere and the ocean
26
Q

What is the composition of dry air

A
  • it is almost entirely nitrogen and oxygen

- >with other gases like argon, carbon dioxide and water vapor in trace amounts

27
Q

What is the triposphere

A
  • it is the lowest layer of the atmosphere
  • extends from surface to about 12 km up
  • this is where all the weather occurs
  • > note temperature decreases with altitude
  • > at higher latitudes, air temperature is below freezing
28
Q

Is warm air more dense than cold air or vice versa

A
  • warm air is less dense than cold air
  • > so warm air rises
  • > cool air is more dense so it sinks
29
Q

Is there a limit on how water vapor the atmosphere can hold

A
  • yes
  • > the atmosphere holds water vapor up to a certain amount
  • > with the amount that can be held increasing with temperature
  • > that is why warm air is typically moist and cold air is typically dry
30
Q

Define the saturation water vapor pressure

A
  • this is the maximum amount of water that can be held as vapor in air is the saturation vapor pressure
  • > note amount of water vapor influences the density of air
31
Q

What happens to water in the atmosphere during evaporation

A

-as water evaporates, water molecules which are lighter than air molecules are added to the atmosphere

  • this means moist air is less dense than dry air
  • > thus moist air tends to rise
  • > if the water vapour is removed, the air gets more dense and sinks back
32
Q

Does atmospheric pressure depend on the weight of the column of air above

A
  • yes
  • > thick column of air produces higher atmospheric pressure than a column of air
  • this is why pressure decreases with altitude
  • > higher up there is less air above you
  • > so less weight/area pushing upon you
  • > similar analogy to a swimming pool
33
Q

How does a column of cool dense air compare to a column of warm air in terms of atmospheric pressure

A

Column of cool dense air

  • > it is associated with high pressure at the surface
  • > because of the fact that cooler air is sinking

Column of warm less dense air

  • > it is associated with low pressure at the surface
  • > because of the fact that warmer air is rising
  • > rising is due to expansion
34
Q

Does air flow in a pressure gradient

A
  • yes it moves down the pressure gradient

- >from regions of high pressure to regions of low pressure

35
Q

Connect the dots wit solar heating, density of air and the direction that wind would move

A
  • solar heating causes air to rise at the equator
  • > then this air spreads towards the poles
  • rising air also creates low pressure at the surfface
  • > so the surface winds flow towards the equator
  • > rising air is moist but cools as it goes higher releasing it’s moisture as rain
  • sinking air at the poles creates high pressure at the surface
  • > sinking air is quite dry because cool air can’t hold much water vapor
  • > poles experience clear and dry weather
36
Q

What do the terms surface convergence and surface divergence mean in reference to the pressure at the equator and th epoles

A

Surface convergence

  • > it occurs at the equator
  • > this is resulting in low pressure

Surface divergence

  • > it occurs at the poles
  • > this is resulting in high pressure

EAS 212 (7 decks)

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