Earth and ocean Flashcards
1
Q
What did the greeks thinks about the solar system?
A
*Geocentric - earth-centered universe (false)
*The stars are fixed relative to each other and rotated about a fixed point
2
Q
What is retrograde motion
A
retrograde motion occurs because outer planets have slower orbits. This means it looks as if the other planet is moving backward
3
Q
What did the renaissance think about the solar system?
A
*Heliocentric - sun-centered universe (true)
*Copernicus published evidence for heliocentricity in 1543
4
Q
What is the ecliptic?
A
The ecliptic is the plane of the Earth’s orbit around the sun
5
Q
What is the axis tilt?
A
Also called axial obliquity. The significant angle between the axis of rotation and perpendicular to the ecliptic. this causes seasons are important as without there would be lots of uninhabitable areas. Also, some crops require different temperatures throughout the year to grow and germinate. Current tilt angle = 23.43°, however, it varies from 22.1° to 24.5° over a 41,000-year cycle
6
Q
What are the characteristics of the earths orbit?
A
*The Earths orbit is eccentric - so distance from the sun varies
*Aphelion is when earth is furthest from the sun (152 million km)
*Perihelion is when earth is nearest to the sun (147 million km)
7
Q
What is the rotation of the earth centered on?
A
The pull star which is currently Polaris
8
Q
What is the importance of the moon?
A
*Stabilises the angle of axial tilt to 22.1° - 24.5°
*Generates lunar tides. Spring tides - when the moon and sun are aligned. Neap tides - when the moon and sun are at 90°. Tides are important as the intertidal zone is key for biodiversity and the survival of lots of species and evidence they allowed for the evolution of land-walking animals
*Slows earth’s rate of rotation
9
Q
What are characteristics of the lunar orbit?
A
*Eccentric (distance from sun varies)
*Apogee is when the moon is furthest from the sun
*Perigee is when the moon is nearest to the sun
*A complete orbit of the earth is from one new moon to the next
10
Q
What is an eclipse?
A
The Sun has approximately the same angular diameter as the moon of 0.5 degrees so when the moon passes in front of the sun, it can cover it completely causing a total solar eclipse. There are typically 2 - 3 lunar eclipses per year.
11
Q
What is the doppler effect?
A
Doppler Effect works on both light and sound objects.
When a sound object moves towards you, the frequency of the sound waves increases, leading to a higher pitch.
if it moves away from you, the frequency of the sound waves decreases and the pitch comes down.
12
Q
What is redshift?
A
The movement of light to the red end of the spectrum due to an increase in the wavelength of waves emitted by a star or galaxy due to its motion away from us. Hubble observed that all galaxies were “red-shifted” so moving away from the earth, so he deduced that the whole universe was expanding
13
Q
How long ago was the big bang?
A
Around 13.8 billion years ago space expanded rapidly by a factor of >10^28
14
Q
What was the universe before the big bang?
A
A “quantum gravity epoch” where everything was tiny and lasted 10^-43 seconds
15
Q
What formed after the big bang?
A
A soup of subatomic particles
16
Q
What are quarks?
A
Elementary particles that make up the protons and neutrons that in turn make up the atomic nucleus. Quarks are the most basic known constituent of matter.
17
Q
What are composite particles?
A
Subatomic particles that are made of more than one quark. Baryons are made of 3 quarks e.g. proton and neutrons. Mesons are made of a quark and an antiquark
18
Q
What are the 6 types of quarks?
A
up
down
top
bottom
strange
charm
19
Q
What where the first elements?
A
The first elements made where hydrogen and helium due to their low atomic mass
20
Q
What are the 4 forces?
A
Gravity
electromagnetic
strong
weak
21
Q
How did light form in the universe?
A
380,000 years after the Big Bang the earth and its plasma sea of subatomic particles cools enough to allow neutral hydrogen atoms to form. Photons decoupled from the matter and light escaped.
22
Q
What evidence is there for the big bang?
A
*Expansion of the universe. Redshift and Hubble’s law (space itself is expanding)
*Cosmic microwave background. Marks cooling to allow neutral hydrogen to form and the universe to become transparent
*Big Bang nucleosynthesis. Big Bang model predicts abundances of primordial elements and dominance of H and He
23
Q
How do stars form?
A
Stars form when outward pressure from nuclear fusion of H to form He balances gravitational collapse
24
Q
What is the life cycle of small stars?
A
When all the hydrogen is used a red giant is formed. Then when all the helium is used it turns into a white dwarf.
25
What is the life cycle of large stars?
Stellar fusion uses up iron and cause the core to collapse which causes a supernova.
26
What is nucleosynthesis?
Supernova nucleosynthesis releases lots of energy and forms some of the most heavy elements. Forms most Li, Be, B
27
What is the nebular theory?
It explains the formation of the Solar System. A giant swirling cloud of gas containing mainly H2, He and dust with heavier elements generated by stellar nucleosynthesis. This situation was very unstable. A shockwave triggers instability of the Nebular and it collapses under its own gravity creating heat and a faster rotation. The collapse triggers star formation.
28
How did the solar system form after nebular theory?
Infalling material then falls onto a disk and the sun forms in the center of the disk. Planets form in the rest of the disk all orbiting in the same direction. There are distinct zones of planet formation with decreasing temperature as the further away from the sun the colder the temperature
29
How did rocky planets form?
*Dust particles slowly aggregate by electrostatic attraction
*“pebbles”(≤ 1 m) are concentrated by aerodynamic processes
*Then there is a gravitational collapse which forms 10km+ planetesimals
*Plantesimals clump into lumpy proto-planets. The interior heats soften and forms a sphere under gravity. Exterior differentiates into a nickel-iron core and a stony silicate mantle
30
How did the moon form?
A Mars-sized planet impacts Earth and vapourises itself and some of Earth. Moon forms from silicate vapour. The moon starts to move away from the earth allowing for the formation of water oceans on earth
31
How can we date the solar system?
Long lived radioactive isotopes are the most useful for dating the solar system and the earth.
32
What are the 3 types of radiation?
*Alpha radiation consists of two protons and two neutrons
*Beta radiation is high energy electrons
*Gamma radiation is high energy photons
33
What are the types of radioactive decay?
*β- electron emission is where a neutron turns into a proton+electron+antineutrino
*β+ positron emission is where a proton is converted into a neutron+positron+neutriono
*Electron capture (EC) is where a proton turns into a neutron+neutrino
34
What are meteorites?
They originated as planetesimals and protoplanets but the brutal gravitation of Jupiter caused collisions so instead of accreting further they were shattered
35
What are the 2 types of meteorites?
*Differentiated - 6% of earth falls and consist of irons. They show the differentiated cores of protoplanets smashed to pisces in the asteroid belt
*Undifferentiated - 86% of earth falls and consist of chondrites. They contain chondrules and show the aggregation from the solar nebular
36
How do we work out the structure of the earth?
P-waves - compressional, travel through solid and liquid
S-waves - shear, travel through solid but not liquid
37
What is the radius of the earths core?
3471 km
38
What is the formation of the earths magnetic field?
The earths magnetic field is like a giant dipole bar magnet. Molten iron in the core circulates in columns in north-south direction generating an electrical current. The N pole is near the Earths geographic S pole (opposites attract). Magnetic field lines extend into space. Weaken with distance. Form a shield around Earth (magnetosphere)
39
What causes the nothern lights?
Some charged particles make it past the Van Allen belts and are channeled along magnetic field lines. They ionise gases in polar regions causing a glow
40
What are the layers of the earth?
*The crust consists of the oceanic crust (7-10km) and continental (land) crust (35-40km). The oceanic crust is more dense than the continental crust so floats lower
*The mantle is separated into upper, transitional and lower. It is dictated by changes in density
*The core consists of the oute liquid and inner solid. These layers are identified by seismic waves
41
What is Pangea?
The supercontinent where all the continents originally connected. Pangea was supported by glacial evidence and some glaciers are now found on 4 continents. There is also fossil evidence with certain species found on many continents
42
How was the seafloor mapped?
Echo-sounding allowed for rapid sea-floor mapping.Bathymetric maps revealed:
*A mid-ocean mountain range runs through every ocean
*Deep-ocean trenches occur near volcanic island chains
*Huge fracture zones segment the mid-ocean ridge
43
How does sea floor spreading occur?
Upwelling mantle erupts at the mid-ocean ridges. New crust moves away from ridges, get the ring sediment. At trenches, the sea-floor subducts back into the mantle.
44
What are periods and groups in the periodic table?
*A period is represented by a row and is determined by number of electron shells an atom has
*A group is represented by a column. The number of electrons in the outer shell determines the group
45
What is the equation for wave speed?
Wave speed = wavelength x frequency
46
What is the plum pudding model?
1904 plum pudding model. An atom consisted of positive ‘dough’ with a lot of negative electrons
47
What was Rutherford experiment
1911 Rutherford’s experiment where particles were directed at gold. A small number of particles were scattered back. This suggested that there was a lot of empty space in an atom however the positive charge must be concentrated in a small nucleus.
48
What was Bohrs experiment?
1913 Bohr suggested that’s electrons orbited the nucleus in different energy levels to explain why chemicals burn with certain colours
49
How are electrons distributed in atoms?
Light is not a continuous wave, it is a series of separate wave packets. Due to wave packets we cannot give electrons an exact location instead we use probability distribution. Orbitals are represented as probability densities. Nodes are areas of zero electron possibility
50
What are crystals?
Crystals are homogenous solids formed by repeating 3D pattern of atoms, ions or molecules and form most of solid earth
51
What are molecules?
Molecules are a group of of 2 or more atoms of the same or different elements held together by chemical bonds.
52
What are minerals?
Minerals is an element or chemical compound that is normally crystalline and that has been formed as a result of geological processes
53
What is a chemical compound?
A chemical compound is formed by joining of 2 or more atoms of different elements held together by chemical bonds
54
What is electronegativity?
Electronegativity is the ability of bonded atoms to “pull” electrons ( and become a negatively charged anion)
55
What is ionic bonding?
one or more electrons from one atom are taken & attached to another atom resulting in +ve &–ve ions that attract each other
56
What is covalent bonding?
One or more pairs of electrons shared by two atoms
57
What are the characteristics of ionic compounds?
*Crystalline solids
*High melting and boiling points
*Conduct electricity when melted
*Many soluble in water but not non-polar liquid
58
What are characteristics of covalent compounds?
*Gas, liquid or solid
*Low melting and boiling points
*Poor electrical conductors in all phases
*Soluble in non-polar liquids but not water
59
What is metallic bonding?
the force of attraction between delocalized electrons and positive metal ions. It is why metals conduct electricity so well.
60
What is hydrogen bonding?
Hydrogen bonds is an attraction between a hydrogen atom in one molecule and a negatively charged atom in another. E.g. water. It give water its high melting and boiling points.
61
What is an exergonic reaction?
A reaction that releases energy
62
What is an endergonic reaction?
A reaction where there is an input of energy
63
What is an atmophile?
Molecules that are volatile, form gases and are mainly found in the atmoshphere
64
What is a lithophile?
Molecules that form rocks and dominate the crust and mantle e.g. silicates and oxides
65
What is a chalcophile?
Molecules that have an affinity for a sulphide liquid phase
66
What is a siderophile?
Molecules that have an affinity for a metallic liquid phase
67
what elements determine the size of a planets lithophile silicate layer, chalcophile layer and siderophile layer?
* lithophile- oxygen content (crust-silicates dominate crust)
*chalcophile- sulfur (mantle)
*siderophile- excess metal (core)
68
What are the two main allotropes of carbon?
Diamond and graphite
69
What are characteristics of diamond?
Diamond is the strongest mineral. Each carbon atom is covalently bonded to 4 other carbon. It forms a giant covalent structure
70
What are characteristics of graphite?
Graphite is one of the softest minerals. Each carbon is covalently bonded to 3 other carbon atoms. The spare electron becomes delocalized. It forms in sheets.
71
What methods are used to see inside crystals?
* x-ray crystallography by diffraction
*transmission electron microscopes
72
How are minerals classified?
Minerals are classified by their dominant anion
73
What are the 6 mineral classes?
*oxides e.g. hematite
*sulfides (S-) e.g. pyrite
*sulfates e.g. gypsum
*halides e.g. halite
*carbonates e.g. calcite
*native elements (pure masses of a single element e.g. gold)
74
What are silicate minerals?
Made up of oxygen and silicon with other atoms.The “silica. tetrahedron” is the building block of silicates.
Silicates are divided into several groups based on how silica tetrahedra are arranged. The groups vary by how silica tetrahedra share oxygen. The amount of shared oxygen determines the Si:O ratio.
75
Why is the Si:O ratio important?
It can control:
*Melting temperature.
*Mineral structure and cations present.
*Susceptibility to chemical weathering.
76
what are 4 Si:O ratios?
1:4 - independent tetrahedra e.g.olivine
1:3 - single chains e.g. pyroxenes
1:2 - framework silicates e.g. feldspars
2:5 - sheet silicates e.g. micas
77
What are the 2 types of crust?
Continental crust is less dense so it “floats higher.” Oceanic crust is more dense so it “floats lower.”
Continental crust is less dense due to crystals irregular lattice structure.
78
What is the crust rich in silica?
continental crust
79
What is metamorphism?
Metamorphism is a process of mineral variation that results from the physical-chemical changes of solid rocks, caused by factors such as crust movement, magma activity, or thermal fluid change in the earth.
80
What are physical/mechanical weathering techniques?
* Abrasion occurs from friction through rocks or other materials such as wind and water
*Root wedging occurs when Roots force their way into cracks. They exert tremendous pressure on the rocks as they grow, widening the cracks and breaking the rock.
*Exfoliation is spalling of surficial layers due to the release of lithostatic pressure.
81
What is chemical weathering?
The main type of chemical weathering is dissolution.Rain water contains small quantities of carbon dioxide from the atmosphere, which dissolves into the rain water making it into a weakly acidic solution (carbonic acid) which can chemically break down rocks which the rain water falls on. Other techniques include:
*hydration
*hydrolysis
*redox
82
What do soils contain?
Soil contains weathered rock, water, air, and humus (organic matter derived from the decay of plant material)
83
What are different grain sizes?
Sand varies from 1/16mm to 2mm. Sediments smaller than sand are mud and sediments larger than sand are gravel
84
How does transport impact sediment sorting?
Initial sorting (from alluvial fans/ mountains) is very poor. As it is transported, erosion occurs so it becomes better sorted.
85
What are the 2 measures of grain shape?
*roundness
*spherity
86
What are causes of changes in grain size and shape with transport
*Splitting
*Crushing
*Grinding
*Sand blasting
87
How are sedimentary rocks layered?
They are arranged planar (flat) due to gravity. The boundary between two beds is a bedding plane. Several beds together constitute strata.
A sequence of beds is called bedding or stratification.
Bedding reflects changing conditions during deposition.
88
What are causes of bedding formation?
*Changes in transporting medium (velocity, volume per time).
*Changes in sediment source
89
What are clastic sediments?
Clastic sediments are made up of different clasts e.g. mineral grains or fragments of rocks
90
What are biochemical sediments?
Biochemical sediments are made for biological processes and are skeletal parts e.g. shells
91
What are chemical sediments?
Chemical sediments are made from chemical processes e.g. salt
92
What are organic sediments?
Organic sediments are remains of once-living organisms
93
How are clastic sedimentary rocks formed?
*weathering
*erosion
*transportation
*deposition
*lithification
94
What is current deposition?
Water flowing over loose sediment creates bedforms.
Bedform character (e.g. ripple mark size) is tied to flow velocity and grain size.
95
How are glacial environments formed?
Glacial environments are caused due to movement of ice. Ice carries and dumps every grain size so creates a poorly sorted area with gravel, sand and clay.
96
what are the key depositional environments?
*glacial environments (poorly sorted grain size)
*breccia (angular rocks)
*arkose (feldspar)
*conglomerate (rounded rocks)
*fine clastics (quiet water settings e.g. floodplains and often has organic matter)
*delta (sediment accumulates as velocity drops when river enters the sea)
97
How do sediments reach the deep sea?
Down slope turbidity currents and graded beds move sediment into the deep sea. Sediment moves on a slope as a pulse of turbid water which is often caused by earthquakes. As the pulse wanes, water loses velocity, and grains settle. The coarsest material settles first, medium next, then fines. This process forms graded beds in turbidite deposits.
98
What are different biochemical sediments?
*Limestone is made of CaCO3
*Chert is made of opaline silica
99
Hat are different classes of chemical sediments?
*Evaporites (e.g. halite, they are rocks evaporated from seawater)
*Travertine (calcium carbonate precipitated from groundwater)
*Dolostone (limestone altered by Mg-rich fluids)
*Replacement chert (e.g. flint, jasper)
100
What are the two ways to date geological materials?
* Relative ages - based upon order of formation. (Qualitative)
* Numerical ages - the actual number of years since an event. (quantitative)
101
What are the physical principles?
*uniformitarianism - processes observed today were the same in the past.
* original horizontality. Sediments settled out of a fluid by gravity. This causes sediments to accumulate horizontally.
*superposition - In a sequence of layered rocks each bed is older than the one above and younger than the one below
*cross-cutting relations - younger features truncate (cut across) older features. Faults must be younger than the material that is faulted, intruded, or eroded.
*baked contacts & chilled margins - an igneous intrusion cooks the invaded country rock. The baked rock must have been there first (it is older). A chilled margin is formed at the contact from the rapid cooling
* inclusions (a rock fragment within another) - Inclusions are always older than the enclosing material
102
What are eons? Eras? Periods? Epochs?
eons- largest subdivision of time
era- subdivision of an eon
periods- subdivisions of an era
epochs- subdivision of a period
103
What are the characteristics of carbon?
* can form polar or non-polar covalent bonds
* 4 electrons in outer shell so can form 4 bonds
104
What are different carbon based organic compounds?
* Sugars & carbohydrates
*Fatty acids & lipids
*Amino acids & proteins
*Organic bases & nuclei acids
105
What are carbohydrates?
Carbohydrates are molecules that consist only of carbon, hydrogen, and oxygen and they are long chains of sugar units called saccharides. There are three types of saccharides - monosaccharides, disaccharides, and polysaccharides. Monosaccharides can join together to form disaccharides and polysaccharides by glycosidic bonds which are formed in condensation reactions. Functions of carbohydrates include energy storage and structure formation e.eg cellulose.
106
What are lipids?
Lipids consist of carbon, hydrogen, and oxygen. Triglycerides are lipids made of one molecule of glycerol and three fatty acids joined by ester bonds formed in condensation reactions. Functions include storing energy, forming part of cell membranes, and signaling. Lipids are biological molecules that are only soluble in organic solvents and are insoluble in H2O. Phospholipids are composed of 1 glycerol, 2 fatty acids, and a phosphate group. Phosphate heads are hydrophilic and the tails are hydrophobic so face inwards.
107
How is cholesterol used in the phospholipid belayer?
Cholesterol can be added to a phospholipid bilayer in order to reduce fluidity and increase rigidity. Cholesterol makes the phospholipids pack closer together making the bilayer less permeable
108
What are amino acids?
Amino acids are the monomers from which proteins are made. Amino acids contain an amino group, a carboxylic acid group, and a variable R group which is a carbon-containing chain. Amino acids are joined by peptide bonds formed in condensation reactions. Amino acids may be polar or non-polar depending on composition of the variable R group.
109
How are proteins formed?
Proteins are polymerized from amino acids by peptide bonds. One H atom from the amino group combines with the OH in the carboxylic group. Polypeptides contain less than 50 amino acids, proteins contain over 50 to several thousand.
110
What are the functions of proteins?
Functions of proteins include acting as enzymes (catalysts) for reactions, acting as channels in membranes, and can be used for cell signaling e.g. in the immune response.
111
What is the primary structure in proteins?
The primary structure of a protein is the order and number of amino acids in a protein.
112
What is the secondary structure in proteins?
The secondary structure is the shape that the chain of amino acids takes – either alpha helix or beta pleated sheet. The shape is determined by hydrogen bonding.
113
What is the tertiary structure in proteins?
The tertiary structure of proteins is the 3D shape of the protein. It can be globular or fibrous and is caused by the formation of hydrogen, disulfide, or ionic bonds.
114
What is the quaternary structure in proteins?
The quaternary structure occurs in proteins with more than one polypeptide chain where further bonds are made and prosthetic groups can be added.
115
What is collagen?
Collagen is a fibrous protein of great strength due to the presence of both hydrogen and covalent bonds in the structure. Collagen is a main component of tendons that connect muscles to bones.
116
What is keratin?
Keratin's hydrogen bonds and disulfide bridges make it strong. It is found in hair, nails, and hoofs.
117
What is ATP?
ATP (adenosine triphosphate). Adenine pentose base, three phosphate groups, and a ribose sugar. When ATP is converted to ADP by a hydrolysis reaction energy is formed
118
What is a purine?
Purine nitrogenous bases contain 2 rings in their structure e.g. adenine and guanine
119
What is a pyrimidine?
Pyrimidines have 1 ring in their structure e.g. thymine, cytosine, and uracil
120
What is the structure of DNA?
DNA is formed from 2 antiparallel polynucleotide strands, which twist to form a double helix. The 2 strands are held together by hydrogen bonds between the nitrogenous bases. The nitrogenous base pairing is complementary, where A and T and C and G pair. This is so a pyrimidine and purine always pair to keep a constant distance between the sugar-phosphate backbone
121
What is the “central dogma”?
The “central dogma” is the process of DNA replication which includes transcription and translation
122
What is transcription?
Transcription produces mRNA in the nucleus. Hydrogen bonds between complementary bases break and DNA uncoil. RNA polymerase lines up free RNA nucleotides alongside the DNA template (antisense) strand, with their complementary bases. RNA polymerase then joins adjacent nucleotides by forming phosphodiester bonds. RNA polymerases reach a stop codon and a strand of mRNA is formed. The mRNA moves out of the nucleus through a pore and attaches to a ribosome in the cytoplasm
123
What is translation?
Translation produces proteins in the cytoplasm on ribosomes. The mRNA attaches itself to the ribosome. A tRNA molecule attaches to the start codon with its complementary anticodon. A 2nd tRNA attaches to the next codon and a peptide bond catalyzed by rRNA is formed between the amino acid attached to the two tRNA molecules. The 1st tRNA molecule detaches from the amino acids leaving them behind. Another tRNA molecule attaches to the next codon and the process continues forming a polypeptide chain until a stop codon is reached.
124
What is the difference between eukaryotes and prokaryotes?
Eukaryotes have DNA enclosed in the nucleus.
Prokaryotes have no membrane-bound organelles so have no nucleus, instead, their genetic information is stored in the form of a circular strand of DNA
125
What are the steps of glycolysis?
link reaction, krebs cycle and then oxidative phosphorylation
126
What are the steps of glycolysis?
During glycolysis glucose is phosphorylated to hexose 1-6 biosphosphate by 2 ATP. Hexose bisphospahte is then split into two triose phosphate and also forms 2 NADH. The 2 TP are then oxidised to form 2 pyruvate whilst forming 4 ATP.
127
What are enzymes?
Enzymes are formed from proteins and cofactors. They act as biological catalysts by speeding up reactions
128
What is a cofactor?
A cofactor is a non-protein compound required for the enzyme’s activity to occur. They can be organic or inorganic.
Inorganic cofactors are mainly transition metals and iron. Organic cofactors are mainly small organic molecules. Cofactors aid reactions by transfer of chemical groups such as electrons and functional groups.
129
Why are transition metals good cofactors?
Transition metals make good cofactors and catalysts because they exist in a range of oxidation states, can easily coordinate (link) to an organic substrate and can act as a ready source or sink for electrons.
130
What are black smokers?
Hydrothermal vents at high temperatures (over 350’C) which erupt at high flow rates. Iron and other metals in the fluid precipitate as they mix with seawater, forming ‘black smoke”
131
What are white smokers?
Hydrothermal vents at lower temperatures (below 200’C) which seep through small cracks. Lower metal concentrations and particles of anhydrite, barite, or talc forming “white smoke”
132
What are requirements of microfossils?
* Found in rocks of known provenance
*Found in rocks of established Archean age
*Demonstrably indigenous
*Syngenetic with deposition of enclosing rock
*Of assured biological origins
133
What is the equation for photosynthesis?
6CO2 + 6H2O = C6H12O6 + 6O2
134
What are chloroplasts?
Chloroplasts are composed of an outer membrane and inside there are grandmas, steaks of thylakoids, connected by lamellae. There is also stroma, a fluid-filled matrix which contains DNA.
135
What are photosystems?
Photosystems are found in thylakoids and contain chlorophyll which traps photons and passes their energy to a primary pigment reaction center, a molecule of chlorophyll a.
136
What is the light dependent stage of photosynthesis?
During the light dependent stage light energy is absorbed by chloroplast pigments and used to synthesis ATP and reduced NADP, taking place in the thylakoid membrane. It converts light energy into chemical energy. The stages are photolysis, cyclic photophosphorylation and non-cyclic photophosphorylation
137
What are the steps of photolysis?
*PSII absorbs photons of light and a pair of electrons are excited and leave.
*½ O2 is produced which can be used for respiration
*2H+ is produced and released, moving towards NADP reductase
138
What are the steps of cyclic photophosphorylation?
*The excited electrons are captured by an electron carrier
*They release energy by making ATP
*The electrons arrive at PSI which absorbs photons of light, exciting the electrons again
*If the plant requires more energy the electrons return to the electron carriers, producing more ATP
139
What are the steps of non-cyclic photophosphorylation?
*The electrons travel to NADP reductase
*2H+ from photolysis in PSII also travel to the NADP reductase, having a;lready passed through ATP synthase producing ATP
*The electrons and protons produce reduced NADP
140
What is the light independent stage of photosynthesis?
During the ligh independent stage ATP and reduced NADP are used to reduce carbon dioxide to sugar, taking place in the stroma. The stages are carboxylation, reduction and regeneration.
141
What are the steps of carboylation?
*Carbon dioxide and RUBP reacts with the enzyme RuBisCO in order to produce 6C.
* 6C is unstable so breaks down to form 2GP.
142
What are the steps of reduction?
*The 2 GP are reduced into 2 TP
*This requires energy in the form of ATP from the light dependent stage which forms 2 ADP + pi
*And 2 reduced ~NADP for hydrogen which forms 2 NADP
143
What are the steps of regeneration?
*5 out of6 TP molecules are reduced to form RUBP which requires energy in the form of ATP which forms ADP +pi
*The 1 out of 6 TP molecule leaves
144
What evidence do we have for type original oxygenation of the earth?
*sulfur isotopes
*sedimentary rocks in equilibrium with the atmosphere
*paleosols - banded iron formations with change from Fe 2+ to Fe 3+
(no evidence for significant o2 before 2.5 billion years)
145
What is the snowball earth hypothesis?
The Snowball Earth hypothesis proposes that, during one or more of Earth's icehouse climates, the planet's surface became entirely frozen
146
What is the positive feedback loop of ice albedo?
Initial cooling causes ice formation
Increase albedo (reflectivity) of the ice surface reflects solar radiation and enhances cooling
147
How did we return from snowball earth?
With negative temperature during the snowball earth there is no rain to scrub CO2 from the atmosphere and little weathering to produce alkalinity. Consequently CO2 emissions accumulate in the atmosphere causing an increased greenhouse effect. Increasing temperatures.
148
What happened to life during snowball earth?
Phototrophs survive through cracks or in “slushy” tropics
Creates evolutionary pressures - survival of the fittest
When ice melts, possibility of new niches due to exploit massive input of nutrients to oceans
Also increased oxygenation as more dissolved O2 in colder water
149
What are the advantages of water in all 3 forms?
*Water vapor evaporated from the ocean helps transport heat from warm low latitudes to cold high latitudes.
*Liquid water helps transport heat from warm low latitudes to cold high latitudes via ocean currents.
*In polar regions, both ice and water moderate climate.
150
Why does water have high melting and boiling points?
Strong covalent hydrogen bonds
151
How does water freeze?
Water is less dense when a solid than as a liquid which allows ice to float and why ponds freeze top first forming an insulating layer for organisms below
When water freezes all 4 hydrogen bonds are formed creating a lattice causing particles to be further apart
152
Why is water a good solvent?
It’s polar covalent bonds and hydration properties
153
How is earths surface temperature determined?
The radiative energy balance between:
*incoming short wave radiation which is affected by reflection
*outgoing long wave radiation which is affected by absorption by greenhouse gases
154
How do greenhouse gases work?
Greenhouse gases can absorb and emit radiation through vibrational or rotational states. The radiation is emitted in all directions, so some is emitted back to earth causing the greenhouse effect
155
What is ozone?
Ozone is found in the stratosphere and absorbs UV radiation, particularly the more harmful UV-b and UV-c types, however this is an exothermic reaction so it does lead to warming.
156
What is steady state?
Inputs = outputs
157
What is MORT
Mean ocean residence time tells us how long between an element enters the ocean and then leaves the ocean.
158
What is the MORT equation?
MORT=Ocean conc. x Ocean vol. / River conc. x River water flux
159
What is the density of seawater?
The density of water increases as the salinity increases. Density is mainly derived in oceans by temperature. Pure water has its maximum density at about 4 degrees. The maximum density of seawater occurs at lower temperatures as salinity increases.
160
Why has saltwater got a lower freezing point than pure water?
Na+ & Cl- ions disrupt H-bond formation. So delay freezing to lower T. Most seawater freezes at -2 degrees.
161
What is the pycnocline?
Pycnocline is a steep density gradient in body of water
162
What is the layering of fluids?
Less dense fluids rest above denser fluids.The boundary between the fluids of different densities forms an interface. Interfaces act as barriers to exchange of properties
163
How is the troposphere layered?
it is inversely stratified. Denser, colder air lies above warmer less dense air. This is why we have weather and convection.
164
What are convection cells`?
Convection cells are found in the mantle, oceans, and atmosphere. When the fluid is heated the density lowers and rises to the top where it reachs an equilibrium level surrounded by fluid of equal density and spreads out. it then cools and reduces density enough to sink back down At the earth and ocean surfaces mantle and ocean convection cell convergences are downwelling zones and divergences are upwelling zones.
165
What is a temperature inversion layer?
A temperature inversion is a layer in the atmosphere in which air temperature increases with height. E.g. frost in winter as the ground temperature is lower than the atmosphere temperature
166
How does the angle of incidence impact incoming radiation?
The higher the angle of incidence the more radiation taken in by the surface . At latitudes, e.g. Antarctica, there is less heating as less energy is absorbed
167
What is the coriolis effect?
the deflection of moving objects to the right in the Northern Hemisphere, and to the left in the Southern Hemisphere due to the earths rotation.
168
what does the convection cells of the earth look like?
each hemisphere is split into 3 cells, the polar, ferrel and hadley - where the polar and hadley move in the same direction (thermally direct) and opposite to the ferrel (thermally indirect).
169
Why is the balance between evaporation and precipitation important?
Causes the salinity of the ocean to vary - affecting circulation
Determines the location of rainforests and deserts (affects albedo) rain occurs at convergences. evaporation occurs at divergences
170
What is a centripetal force?
Centripetal force keeps orbiting object from falling off tangentially
171
What is a centrifugal force?
Centrifugal force causes an object moving in a circular path to move out and away from the center of its path
172
What are the basic steps of coriolis?
Earth rotates faster at the Equator than it does at the poles. Earth is wider at the Equator, so to make a rotation in one 24-hour period, equatorial regions race nearly 1,600km per hour. Near the poles, Earth rotates at a sluggish 0.8 x 10^-4 km per hour.
173
What shape is earth?
oblate ellipsoid
174
What is vorticity?
The “spin” of a parcel of water to air
Like the Coriolis force vorticity is maximum at the poles and zero at the equator
175
What is planetary vorticity?
vector that is parallel to axis of Earth’s rotation. Everything on Earth (ocean and atmosphere) rotate with the planet so are subject to planetary vorticity
176
What is relative vorticity?
E.g. Stirring a barrel of beer will impart an additional Rotation in the beer relative to the Earth
177
What is absolute vorticity?
The sum of the relative vorticity and planetary vorticity
178
What is a water mass?
Volumes of water that have the same properties (salinity, temperature etc)
179
How are water masses transported?
Water masses are transported via ocean currents
distinguished by different densities, so flow over each other in layers along density interfaces
As water masses flow past each other, slow mixing occurs by diffusion, may be enhanced by turbulence and activity of eddies
180
What is a baroclinic condition?
when lower layers of water masses move in a different direction to the surface current
181
What is a barotropic condition?
when all layers of water masses move in the same direction as the surface current - current affects the direction all the way to the seafloor e.g. western boundary currents (technically no layering)
182
What is the Ekman layer?
the surface current that carries drifting ice does not flow in the direction of the wind because it is deflected by the Coriolis effect. It is at an angle to the wind between 20-40 degrees to the right.
183
What is an Ekman spiral?
the surface current is deflected 45 degrees to the right (northern hemisphere) or left (southern hemisphere) of the wind direction. and as speed decreases with depth and the lower level currents are also deflected by the coriolis effect a spiral shape forms. overall the net movement of water is 90 degrees to the left or right of the wind direction.
184
Why can currents flow after the wind stops?
The frictional force between moving layers of water is small
While they blow, winds cause the sea surface to be sloped and the slope remains when the wind stops blowing
The pressure gradient causes the water to flow from high to low pressure to restore the surface to a flat horizontal plane.
185
What is geostrophic flow?
It is steady-state equilibrium between coriolis acceleration and horizontal pressure gradient
186
How is the direction and speed of a current changed?
Friction
Deflection by the Coriolis effect
Blocking and deflection of current flow by coasts
The presence of horizontal pressure gradients
187
what is the only circum-global current on earth?
the antarctic circumpolar current
188
What are geostrophic gyres?
continents block the E – W and W – E currents (except around Antarctica) so they are deflected to form geostrophic gyres.
189
What is the difference between western and eastern gyres?
Currents are stronger on westward boundaries of continents because the strength of the Coriolis effect varies with latitude
Western boundary currents are narrower, faster, deeper, and warmer than eastern boundary currents. Western boundary currents tend to be barotropic. Eastern boundary currents tend to be baroclinic
190
What are the strongest currents?
Western Boundary Currents, Antarctic Circumpolar Current, Equatorial Currents
191
What is ocean circulation at the equatorial pacific?
No Coriolis effect at equator so currents can flow directly E-to-W or W-to-E
Complicated because southern hemisphere trade winds extend over equator as their is more land mass in the northern hemisphere than southern. This results in the atmospheric convergence being north of the equator - the inter-Tropical Convergence Zone (ITCZ)
192
What is the Bjerknes tropical feedback loop?
*Increased trade wind speed
*Equatorial upweling. High sea level and deep thermocline in the west. Low sea level and shallow thermocline in the east
*Zonal tropical SST difference
*Increased trade wind speed
193
What are monsoon requirements?
* Prevailing wind shifts 120°
*Average frequency of prevailing wind > 40%
*Speed of mean wind exceeds 3 ms-1
*Pressure patterns satisfy a steadiness criterion
194
How do monsoons occour?
Air rises due to higher daytime temperatures leaving a parcel of air. The ocean is a more stable temperature so is colder than the land, causing an onshore sea breeze. This is reversed at nighttime due to colder land air temperatures creating an offshore breeze.
Monsoons a have this pattern but on a larger scale
195
What are eddies?
A zone of swirling fluid motion including a component of reverse flow. Ocean eddies with radius 10 – 500 km are called “mesoscale eddies”
May be associated with upwelling (cyclonic) or downwelling (anticyclonic)
196
How do eddies form?
Form due to instabilities – e.g. shear between different water masses such as temperature
197
What are the roles of eddies?
They can carry saline waters helping to regulate thermohaline circulation.
198
What is thermohaline circulation?
Beneath the pycnocline currents are driven by density differences between water masses. Density differences cause water masses to sink or rise to the appropriate density and then move outward to flow between lower density water above and higher density water below along surfaces of equal density - isopycnals. Thermohaline circulation is driven from the North Atlantic (NADW)
199
What are the phases of open ocean deep convection?
Preconditioning sets up conditions required for deep ocean convection. For example evaporation may occur to increase salinity or cooling perhaps by winds.
There is then violent mixing due to denser water
When denser water reaches same density as surrounding water convection stops and the chimney decays and some may chip of during restratification
200
What can oceanographers measure from space?
Sea Surface Temperature (IR scanning)
Ocean Color/Optics (visible)
Sea Surface Height & Currents (radar)
Surface Wind Stress (surface roughness) (microwave)
201
What is the geostationary orbit?
36,000km altitude (wide view)
Stays over same location
Can document evolving systems
High temporal resolution
No polar coverage
202
What is the polar orbit?
850-1000 km altitude
Travels nearly over poles
Lower temporal resolution
203
What is a chlorophyll-a sensor?
It is a visible light sensor. Sunlight is absorbed by the sea and scattered depending on pigments in the sea. It is then measured by a sensor. The “color” is the wavelength that is not absorbed. Blue and red are absorbed by chlorophyll-a, green and IR are reflected.
204
What are diatoms?
Diatoms - have a siliceous frustule (hard external “shell”) made of opal, include the largest phytoplankton and are desirable as food.
205
What are dinoflagellates?
Dinoflagellates - smaller than diatoms and weakly motile, and many have a readily decomposable cellulose cell wall but none have hard parts. They tend to dominate the phytoplankton when silica is unavailable for diatom growth.
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What are coccolithophores?
Coccolithophores have a mosaic of calcite plates covering the cell wall. Secrete CaCO3. Less abundant than diatoms or dinoflagellates, tend to favor warm open ocean waters
207
What is the Redfield ratio?
C:N:P 106:16:1
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What is the compensation depth?
Depth at which the respiration consumption of oxygen exceeds the photosynthetic production of oxygen
209
What is the biological pumps?
Phytoplankton utilise dissolved carbon for photosynthesis
Some phytoplankton is eaten by zooplankton and then excreted
Most of this is decomposed by bacteria into dissolved organic carbon
Some sinks as particles to the seafloor
Death of zooplankton can also cause sinking particles, most are skeletal material as microbes can decompose soft tissue more easily.
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What are nekton?
Organisms that live in the water column and that are able to swim actively so they are not just swept along by currents
211
What are the two main types of falling particles?
fecal pellets and marine ‘snow’. Marine snow is particles of biogenic debris in the upper water column. Some is soft tissue, so is sticky and can quickly grow in size increasing the rate of sinking to the sea floor
212
What are the 3 types of ocean pump?
*Organic carbon pump
*inorganic calcium carbonate counter pump
*solubility pump
213
How are different parts of the weather measured?
Atmospheric Pressure - barometer (mean sea-level atmospheric pressure on Earth 1013.25 mbar)
Air temperature - thermometer
Wind speed and direction - anemometer
Humidity - hygrometer
Rain fall - rain gauge
Clouds:
cloud ceiling - instrumental
cloud cover - visual estimate
Cloud type
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What is the behaviour of rising air?
A rising air parcel will always expand due to decreasing pressure (less air in column above). Loses energy as molecular speeds slow so loses temperature
215
What is the behaviour of sinking air?
As pressure increases air parcel contracts again, molecular speeds increase – T increases
216
What is the equation for specific humidity?
Specific humidity =mass of water vapour / total mass of air
217
How is specific humidity changed with latitude?
Lowest in high polar latitudes
This is because – the warmer it is, the more water evaporates.
218
What is actual vapour pressure?
an estimate of the total amount of water vapour in the air.
219
What is saturation vapour pressure?
The maximum amount of water vapour that can be in air at a given pressure & temperature
At boiling point saturation vapour pressure = atmospheric pressure
220
How does boiling point change with latitude?
Boiling point lower with lower pressure/higher altitude
221
What is the equation for relative humidity?
actual vapour pressure / saturation vapour pressure
222
How does relative humidity change?
Increases with increase in vapour content. Decreases with increase in temperature (because warmer air has higher saturation vapour pressure).
223
What is the dew point?
temperature to which air needs to be cooled (with no change in air pressure or moisture content) for saturation to occur. This can form clouds, fog and frost
224
How is water a greenhouse gas?
water vapour contributes about 60% of warming effect. water vapour content of the atmosphere is controlled by temperature. Sustained greenhouse effect is driven by non-condensible gases – mainly CO2. These gases cause temperature to rise – this then leads to increase in water vapour that further increases temperature. Positive feedback
225
What are cloud condensation nuclei (CCNs)
They are “water seeking” nuclei. Sulfate aerosols are the major source of CCNs in the atmosphere
226
What is the CLAW hypothesis?
*Oceans warm
*Enhanced phytoplankton growth
*Enhanced DMS production
*Elevated DMS concentration
*Elevated SO2 concentration
*More cloud condensation nuclei
*Enhanced cloud formation
*Increases earth albedo so more sunlight is reflected cooling oceans
227
How does radiation fog form?
Forms best on clear nights when thin layer of moist air near ground is overlain by dry air – thin moist air does not have much “greenhouse effect” so cannot trap much outgoing longwave (IR) radiation
Moist layer chilled rapidly by cooling ground – saturation – fog forms
228
How is advection fog formed?
When warm moist air moves over a surface sufficiently cooler in order to cool air to dew point
Typically forms on upwelling coasts in summer when upwelling strongest
Warm moist sea air is carried advected) over the cold coastal upwelled waters forming fog
229
How is valley fog formed?
Air cools at higher elevations. Cold air drains downslope into valley. Cold air drainage reduces air temperature in valley to dew point so fog forms.
230
How does upslope fog form?
Moist air slows toward the slope. As air rises up the slope it cools to the dew point forming fog.
231
How do clouds form?
Clouds form when moist air rises and cools. Clouds form in the troposphere.
232
What are the different types of lifting?
Convective lifting - warmed air is buoyed upward
Convergence lifting - converging winds force air upward
Orographic lifting - air must rise to pass over mountains
Frontal lifting - air is carried upward along fronts
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What is the type of lifting controlled by?
Air stability.
Elevation at which moisture condenses.
Wind conditions
234
What are the different types of shape used to describe clouds?
Cirrus - wispy, thin, feathery
Cumulus - puffy, cottony
Stratus - stable, layered
235
What are the different prefixes to narrow down cloud type?
Cirri - high altitude
Alto - Mid altitude
Nimbo - Rain producing
236
What is lapse rate?
Rate of change of T with altitude
237
What is a diabetic lapse rate?
no heat exchanged from air parcel
238
What is Environmental lapse rate
Actual air temperature as measured
239
What is dew point lapse rate?
approx. 2 oC / km
240
What is Dry adiabatic lapse rate?
As long as air parcel is unsaturated it expands & cools by 10 oC per 1,000m
241
What is m oist adiabatic lapse rate?
If air is saturated, as it cools further get condensation and cloud formation, but latent heat of condensation is released so T-loss rate decreases (6 oC/ km)
242
What does the height of a cloud depend on?
Height depends on relation of Environmental lapse rate to Dry/ Moist rates
Env lapse rate less than Dry & Moist rates air parcel stops rising/ sinks
Env lapse rate greater than Dry & Moist rates air parcel may continue rising
243
What is the Föhn Effect?
Occurs with strong air flow over topography. a change from wet and cold conditions one side of a mountain, to warmer and drier conditions on the other side. This is because strong winds at the top of the mountain draws moisture out of the air and forces it downwards where it is further heated by the sun
244
What is air pressure?
The mass of air above a given level
245
What are sea-level pressure charts?
They are called constant height charts because they represent atmospheric pressure at a constant level
Since cold air is denser than warm air, it causes pressure surfaces to be lower in colder air masses, while less dense, warmer air allows the pressure surfaces to be higher. Thus, heights are higher in warm air masses and lower in cold air masses
246
What are geostrophic winds?
Just like geostrophic currents in the ocean – direction changes until pressure gradient force and coriolis force balance.
247
What is an air mass?
Large body of air with similar temperature and moisture characteristics in any horizontal direction
Found in areas that are flat, uniform and extensive with light winds e.g. subtropical oceans in summer and snow and ice covered arctic plains in winter
248
What are mid-latitude maritime zones
transition zones where different air masses clash e.g. UK
249
What are jet streams?
narrow bands of strong wind in the upper levels of the atmosphere. Coriolis deflection can lead to westerly jet streams. Jet streams tend to occour around boundaries of circulation cells and usually have wave like patterns
250
What is an atmospheric front?
boundary or transition zone between two air masses of different densities, temperatures, pressures and also humidities. These differences produce a reaction E.g. rain
251
What is a stationary front?
E.g. Polar Front, Arctic Front
252
What is a cold front?
Marked by a relatively narrow band of precipitation
Cumulonimbus clouds – may include thunderstorms
May feature intense winds as front approaches
253
What is a warm front?
Very broad belt of cloud and precipitation
Includes temperature inversion
Frontal surface much smaller slope than cold fronts
254
How does a mid latitude cyclone form?
An instability develops, creating a cold and warm front which together create the cyclone
255
What are Rossby waves?
Rossby waves are formed when polar air moves toward the Equator while tropical air is moving poleward. Because of the temperature difference between the Equator and the poles due to differences in the amounts of solar radiation received, heat tends to flow from low to high latitudes; this is accomplished, in part, by these air movements.
256
How do Rossby waves travel?
As the parcel of air moves south it gains relative counter clockwise spin from the coriolis effect, creating convergence as it is sped up. As the parcel of air moves north, it gains relative clockwise spin, creating divergence as it slows down.
257
How many Rossby waves are there?
There are 5 moving slowly eastward
258
How are Rossby waves blocked?
Atmospheric blocking occurs when a jet stream ridge becomes especially large and forms a separate anticyclonic eddy in the flow, which creates a large-scale persistent weather pattern that “blocks” the propagation of Rossby waves
259
What are thunderstorms?
Thunderstorms are convective storms that form with rising air
260
What are triggers for thunderstorms?
Unequal heating at surface
Terrain effects that lift air locally or along mountain barriers
Diverging upper level winds & converging surface winds & rising air
Warm air rising along frontal zone
Random turbulent eddies
261
What are the stages of a thunderstorm?
Cumulus growth stage
Mature stage
Dissipating stage
262
What of the steps of the growth stage of a thunderstorm?
*Drier air causes some rain drops to evaporate
*Adjacent drier air is drawn in by entrainment
*Latent heat of vaporisation warms air so keeps rising
*The air condenses to form the cloud
263
What are the steps of the mature stage of a thunderstorm?
*Drier air causes some rain drops to evaporate
*Air now colder and heavier descends as downdraft
*As air descends ice particles melt
*A circulation cell forms
*Intense turbulence, lightning, thunder and heavy precipitation
264
What are the steps of the dissipating stage of thunderstorms?
*Gust front moves away
*Downdrafts dominate through most of cloud
*No more humid rising air so clouds dissipate
*Only cirrus remains
265
What are supercell thunderstorms?
When a single violently rotating updraft forms and the downdraft never undercuts the updraft – a supercell forms causing a tornado
266
What are hurricanes?
Surface winds spiral counterclockwise (N. hem) to reach max. (e.g. 105 gusting 120 knots) in Eye wall that contains a ring of intense thunderstorms
267
What is relative mean sea level?
average value of sea level measured every hour over a period of at least 1 year
268
What is bench mark?
reference land level for tide gauge
269
What is a geoid?
shape of the surface of equal gravitational potential around the Earth. Shape of mean sea level in absence of winds, currents, tides variations in water density, atmospheric pressure
270
What is steric sea level change?
changes in water volume due to changes in temperature or salinity thermosteric – driven by temperature change
271
What is isostatic sea level change?
change in level of land/ crust (due to changing load e.g. ice, sediment)
272
What is eustatic sea level change?
change in global ocean level due to change in volume of water or change in configuration/ age of the ocean basins (e.g. ridge volume)
273
How can deglacial sea level rise be estimated?
determine of age and altitude/ depth of fossil corals because as sea levels rise corals die and new corals develop higher up
274
What is a flood current?
As the tide rises, water moves toward the shore
275
What is an ebb current?
As the tide recedes, the waters move away from the shore
276
How are tides formed?
Gravitational forces from the sun and moon. The Moon contributes ~ 70% to the tides, while the Sun contributes ~30% to the tides
277
What are the steps of a tide?
At every point except directly under the moon and exactly on the other side of the Earth, the tidal pull has a component that acts parallel to the Earth’s surface.
This component of tidal pull cannot be compensated by the Earth’s gravity and therefore causes water to flow in the direction of the force. This movement creates bulges of elevated water surface at these points, and a depression of the water surface in a ring around the Earth halfway between these points.
The bulges move around the Earth as the Earth rotates and the Earth and moon rotate around each other
278
How long are lunar tides?
12 hours and 26 minutes as the moon orbits Earth every 27.3 days (sidereal month). By the time the Earth has made one complete. rotation (24 h),
279
What is a diurnal tide?
Because of the declination of the moon:northern and southern high latitudes commonly face only one high tide and one low tide in a day
280
What is a semidiurnal tide?
normal 2 tides a day
281
What’s a mixed tide?
unequal tides
282
What are spring tides?
Spring tides occur when the sun and moon are aligned (syzygy) they are th biggest tides
283
What are neap tides?
Neap tides occur when the moon and sun are at 90oC (quadrature
284
What factors impact tides?
The Earths landmasses
The shallow depth of the oceans in relation to the wavelength of tides
The latitudinal variation of orbital velocity
The coriolis effect
285
How do the continents impact tides?
N-S oriented Landmasses prevent the tide wave from traveling around the world
When the tide wave meets a continent, its energy is dissipated or reflected, and the wave must be “restarted” on the other side of the continent.
286
How does the coriolis effect impact tides?
Water moving in a tide wave is subject to the Coriolis effect.
As the wave travels from east to west it is deflected to the right in the N. Hem. and to the left in the S. Hem.
May lead to unique form of standing wave, “an amphidromic system” in some ocean basins with the correct dimensions
In an amphidromic system the high- and low-tide points (the wave crest and trough) move around the basin in a rotary path. counterclockwise in the Northern Hemisphere, clockwise in the Southern Hemisphere
287
How can humans use tidal energy?
Constructions of semi-permeable tidal barrages (dams/ barriers)
Offshore underwater devices (tidal turbines)
288
What are the advantages of using tidal energy?
Non polluting energy source
Reducing of greenhouse and acid gasses emissions (but CO2 still locked up in the actual fabric of the machinery & produced while constructing)
Predictable
Renewable
289
What are the disadvantages of using tidal energy?
Environmental impacts (Affects the biology of the area)
High cost of construction
Reduce tidal flow
290
What are electromagnetic waves?
Electromagnetic waves consist of varying electric and magnetic fields and can move through a vacuum
291
What are mechanical waves?
Mechanical waves that require a medium for their transmission (sea)
292
What are transverse waves?
Transverse waves (those with particles oscillating at right angles to the direction of their advance. E.g.
Water waves
Seismic S waves
Light waves
293
What are longitudinal waves?
Longitudinal waves (those with points vibrating in the same direction as their advance). E.g.
Sound waves
Seismic P waves
294
What is a wave period?
the time the wave takes to move a distance equal to one wavelength (λ)
T=1/f
295
What is wave frequency?
the number of wave crests (or troughs) that pass a point on the ocean surface in a given time.
296
How is wave speed calculated?
c=λ/T or c=fxλ
297
How do wave move?
Only the wave energy and waveform, and not the water, move forward with the wave
298
How do waves move in deep water?
In deep water, the water molecules within waves move in circular orbital paths and only energy, not water, is transported forward
Orbits within which individual particles move decrease in diameter exponentially with depth
299
What forces act to restore waves in the ocean?
Surface tension
Gravity
300
What forces create waves?
Wind
rapid displacement of ocean water (e.g. earthquake)
Gravitational attraction between the Earth, moon, and sun (tides)
passage of vessels or animals through the sea surface (wake)
301
What is a capillary wave?
Light winds over a flat sea surface first create capillary waves
Capillary waves have a maximum wavelength of 1.74 cm, rounded crests, and V-shaped troughs. They disappear quickly if the wind stops due to surface tension.
302
How does wind impact waves?
As wind energy is absorbed by waves, their height, speed, period, and wavelength are increased.
303
What are whitecaps?
Breaking waves in deep water are called whitecaps. Waves break because they have become too steep. When the steepness of a deep-water wave reaches 1:7 (wave height equals one-seventh of wavelength) the wave becomes unstable and the crest tumbles down the forward slope of the wave, creating a breaking wave
304
What factors affect wave height?
*wind speed
*wind duration
*fetch
305
What factors limit fetch?
the presence of a coastline
where the storm is completely over water by the dimensions of the storm itself.
306
What is interference of waves?
When wave trains of similar wave heights but slightly different periods arrive at the same time, the sea surface will appear to alternate between periods of low and high waves
307
How is swell formed?
As the waves become separated by wavelength the sea becomes a swell—smooth undulations without sharp or breaking crests
308
What is wave refraction?
Waves usually approach a shoreline at an angle.
Because one end of the wave crest line enters shallow water and slows while the rest of the wave is still in deeper water and traveling at its original speed, the wave is refracted, or bent.
Wave refraction tends to concentrate wave energy on headlands and spread it out in bays
309
What are internal waves?
Waves also occur on density interfaces within the ocean – mainly on the thermocline or pycnocline. E.g. Rossby waves
310
How do kelvin waves form?
A combination of gravity and Coriolis force that also depends on the existence of a wave guide. They occur at coasts or the equator which is the wave guide.
311
What is North Atlantic oscillation?
The North-South pressure difference determines the strength of the westerly winds across the Atlantic
312
When is NAO in positive mode?
*strengthened pressure difference
*no waves in jet stream
*Strong westerlies
313
When is NAO in negative mode?
*weakened pressure difference
*large Rossby wave meander in jet stream
314
How do weather bombs form?
When upper level divergence is stronger than lower level convergence. This means more air is taken out at the top than is brought in below.
315
What is ENSO?
ENSO = El Niño + Southern Oscillation
El Niño indices - based on SST, anomalies in the equatorial Pacific
Southern Oscillation indices - based on air pressure differences between Tahiti and Darwin.
316
How is El Niño measured?
It is measured by the Tropical Ocean-Global Atmosphere observing system
317
What are possible reasons for El Nino?
Weakening of the trades winds
Westerly wind bursts in the western Equatorial Pacific
Gives a slackening of the force piling water up in the W. Pacific
Results in eastward – propagating Kelvin wave
318
What is pacific decades oscillation?
El Niño has envelopes of fluctuations which is the PDO. It is calculated by looking at temperature anomalies between the NE and tropical Pacific
319
What is The Quasi-biennial Oscillation?
Oscillation in tropical stratosphere from westerly to easterly and back again. Winds alternate with period 22-34 months. The easterly phase – faster/ stronger, persists longer at higher levels.
The westerly phase - more rapid and regular downward progression; less intense and shorter lived but persists longer at lower levels
320
what is The stratospheric polar vortex?
Temperature contrast between heated tropical stratosphere & cold, unheated winter stratosphere. As the air moves to the north and descends, it is deflected to right (coriolis) in N. hem. This forms cyclonic polar vortex
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How does volcanic action impact climate?
Volcanic eruptions have caused major short term cooling as they increase water vapour, carbon dioxide and sulfur dioxide levels in the atmosphere.
More radiation can then be reflected by clouds and the aerosols in the atmosphere
