What does the term spreading the risk mean, with regard to natural disasters?

Insurance may be the best example.

As the document you linked to describes in some detail, there are lots of ways of spreading risk. Traditional insurance is one common mechanism. I think their point is that with a functional insurance model, the effects of a natural disaster may be less profound and/or less protracted (see page 27 of the report).

Think of risk as the possibility of something unpleasant happening — say, something resulting in a financial cost. For example, there's a small risk of a hurricane destroying my house. I couldn't afford to rebuild it if that happened. So I buy indemnity cover for some small fixed monthly fee. Now there is essentially no risk to me, just a small definite cost. In effect, I have transferred my risk to the insurer.

The risk hasn't gone away. In exchange for my monthly fee, or premium, the insurer has assumed the risk of having to pay me a lot of money at some point in the future. It has been pooled with lots of other people — the insurer's other clients — so there's also the grave risk of everyone claiming at the same time. Weighing these risks and setting the premiums accordingly is what insurance companies have to be really good at. Read up on the insurance consequences of the San Francisco earthquake, the September 11 attacks, or Hurricane Andrew.


What is the best way to split strike and dip data on the image provided into "domains" in order to interpret folding on a stereonet?

I think you may have more than 2 domain based on satellite image. Maybe you have three limbs of folds (green) and a fault (red). Please consider this interpretation carefully, I don't know where your study area is, what are its geologic units and structures and plutonic intrusions may deform other rocks (sedimentary, metamorphic and vulcanic), which its satelite images will look like your area, specially in old terrain (Archean ones as part of Brazil, Australia, Canada, United States, Russia, Sweden, among others).

I recommend:

Try to draw the morphostructural lineaments in the topographic raster of your area. You should use the shadow relief to help you in this task. Then, based on its directions, you can have a ideia about the spacial distribution of the domains.
The relief texture (I don't know if these are right words) can also be used to define domains. The roughness of the mountain terrain is the highest in your area.
The units with similar ages as Paleoproterozoic ones and Neoproterozoic ones define two domains, at least. It can also improve or subdivided your domains.
Plot all data of a specific structure* in some stereogram program as Stereonet, OpenStereo or Georient. The Georient has an advantage, you can enter the data by clipboard. The similar structures will be plotted nearby. Based on the clustering, you may improve the domain boundaries.

*Please, do not plot foliation (Sn) and bedding (S0) in the same stereogram. Each structure should be interpretate individually.
About stereogram interpretation, you should see the book of Marshak & Mitra (1988) that show excelent description about this.

Marshak, S. & Mitra, G. 1988. Basic Methods of Structural Geology. Enlewwod Cliffs, Prentice Hall

However, the best way is observed the relationship between foliations of different order (Sn and Sn+1) and/or foliation and bedding (Sn X S0) in field. This relationship will indicate the vergence. And then, you must proceed to the interpretation of stereogram.
I don't think there are easy way to split. You should to do this manually. I commonly import the data to Excel and classify by domains following the dip direction (or strike), location and, more important, vergence.
And, please, read about the geology of your area before you start. This help a lot. I hope that I could help you. I have listen what I wrote to you several times from my teachers during my graduation :). Best luck in your studies.


How much area in the world is under SemiArid climate?

According to this link is 14% for Köppen classification.

The precise cite is:

"BS - dry semiarid (steppe). Is a grassland climate that covers 14% of the Earth's land surface."


What amount of permafrost carbon release could be expected with the IPCC worse-prediction of a 4.8C temperature rise?

Schneider von Deimling et al. in Estimating the near-surface permafrost-carbon feedback on global warming Biogeosciences, 9, 649–665, 2012 evaluated carbon dioxide and methane release under four senarios, the worst being RPC8.5.

Under RPC8.5, they calculated release of carbon from permafrost through 2100 of 63 gigatons (Gt) as CO2 and 0.5Gt as methane.

Through 2200 (cumulatively): 302Gt as CO2 and 5Gt as methane.

Through 2300: 380Gt as CO2 and 12Gt as methane.

Other estimates and nice figures are in the UN Environmental Program report Policy Implications of Warming Permafrost


How to calculate or find the compressional stress wave velocity, Cp for a rock

See page 2 here for example: https://pangea.stanford.edu/courses/gp262/Notes/8.SeismicVelocity.pdf .

What you refer to as Cp (as far as I can gather from your linked paper), is in the geophysics world generally referred to as the P-wave velocity (P stands for the primary/pressure/compressional wave; separating it from the S-wave which is the slower secondary/shear/transverse wave mode). It kind of depends on the specific mineralogy, compaction, depth, ... to determine exactly what the velocity is for any given rock. Note that the range of velocities is not particularly great (all values lie within one order of magnitude for typical rocks), so if your method is not particularly dependent on getting the P-wave velocity exactly right, you shouldn't have too much of a problem taking some average value for your rock! If, on the other hand, it is very sensitive to this value, you'll have to make an accurate measurement on your sample (which is not a trivial thing to do at all!).


Well, I can only agree that it is indeed amazing and it doesn't get less amazing when some geology, hydrology and geomorphology is added to the the amazement.

All precipitation that falls on land must flow back to the oceans somehow, and unless it evaporates it will flow in rivers or as groundwater towards a lower hydrostatic level. Water can not flow uphill, so it follows (and crafts) the slope in topography. Water will flow from mountains towards the ocean and due to geometric and morphological reasons, rivers joint to a drainage pattern due to the geology and topography.

Mountain ranges are often formed from orogeny, where tectonic plates collide. Rivers starts at high altitude, radiating out in all directions from mountains, but as collisions in the present continental settings are often on the rim of large plates (e.g Andes, Alps, Himalaya), and the rivers can't cross the range, it will have to travel the whole continental plate to reach ocean level. In the case of Asia, most large rivers starts in Himalaya (or other tectonic active regions, as Altai), in Europe large rivers starts in the Alps. In Africa, they start in the tectonic active rift zone.

This map shows the ocean drainage dividers. The border between the drainage areas are the line where rivers start.

Lakes could be understood as temporary stop in the flow, and it will quickly fill up with vegetation and sediments as the velocity of the water decreases. In a geologic context, lakes are never very old, Baikal being the oldest, 25 million years. Drainage patterns are often much older.

So why are some rivers so long? Because of tectonic uplifts and orogenies. The answer to your question 'Did the rivers make the downhill paths themselves?' is yes, as erosion works toward the peneplain (low relief).


Where and how can seismic data for earthquakes and volcanoes be downloaded?

The easiest way to look at earthquake data that you would like in a data set you can work on (filter,plot,process,etc.) is three steps.

Get yourself a copy of Matlab
Go to the iris website and download a program called IrisFetch.m (see http://ds.iris.edu/ds/nodes/dmc/manuals/) .
Next you need a list of events and a list of stations from which to download the event, both of these can be gained simultaneously with a program from iris called Jweed. Just download both lists into a cvs file and import to Matlab and run through IrisFetch. This requires a very basic understanding of programming in Matlab but its not hard to figure out at all. Later on you will learn that you don't need Jweed at all to do this but instead can do it all through IrisFetch. Jweed is popular and easy to use though.

If this is too complicated, you can use the web-based part of iris to look at specific earthquakes at specific stations. But I don't think you get to interact with the data this way.


What is the current equilibrium surface temperature of Earth, i.e. without the sun?

Assuming a thermodynamic equilibrium between heat from below and heat escaping into outer space, and assuming an energy from below of 44 to 47 terawatts (the Earth's current internal heat budget), that means the surface temperature would be about 35 or 36 kelvins by the Stefan-Boltzmann law: $$\varepsilon \sigma A T^4 = \phi$$
where $\varepsilon$ is the surface's emissivity in the thermal range (which I assumed to be one), $\sigma$ is the Stefan-Boltzmann constant (5.670367×10-8  W/M2/K4 in SI units) , $A$ is the Earth's surface area, $T$ is the surface temperature, and $\phi$ is the energy supplied to the Earth's surface from below.

Note that atmospheric effects are a non-concern for this very low temperature. The Earth would have no atmosphere except perhaps some trace helium and hydrogen gas.


converting SU file to ASCII format in seismic unix using OpenSeaSeis

The number of samples in the input binary header from the SEGY file does not match the NSAMP trace header.  I would first confirm:

What # of samples is in the binary SEG-Y header.
The number of samples you expect in each trace
Dump the su trace header for     number of samples. You can use
SUGETHW and the keyword for # of samples is "ns".

If the error is in an individual trace header, you can overwrite that with SUSETHW.


How to determine the number of bytes in the SEGD Revision 1 interblock gap

There are no bytes in an IBG. SEGDrev1 is a tape format, and the schematic you are referencing in the standards document is a map of how the data is physically stored on a tape. Tape gaps are actual physical spaces on the tape between blocks of data. An IBG is, quite literally, a gap between blocks of actual data.

If you are reading a tape, you should be able to advance the tape to the next block as needed. If you are working with a SEGD file that has been copied to a hard disk, then gaps are nonexistent and you can pretend they are not there.


What is the lowest latitude for which if the ideal solar energy received each day for a year is graphed, the graph would contain one peak?

Any area south of the northern polar circle will have one peak per day,and the same goes for the southern polar circle any area north of this will have one peak per day,the polar circles is at 66,33 north/south.

The areas whitin the polar circles will have only one peak per year but it will last for half a year.

A solar panel will only produce significant power for a maximum 12 hrs even in the area of the midnight sun,This is due to the very low angle of the sun during the "night",or at the poles it will produce energy for 24 hrs but due to the suns angle a solar panel will produce a lower level of power than if the solar panel was at the equator.

Solar panels will be most effective if placed close to equator and less effective as you move away from equator,The suns rays have to penetrate less atmosphere at equator and a lot more closer to the poles.


Main sources of $\ce{CO2}$ emission to the atmosphere

These are from the EPA's site for 2013. The top is USA emissions and the bottom, global.  I guess that's the most recent year for which they have complete results. And you're right; electricity and transportation account for 58% of total CO2 emissions.

The site is available here.


What are the hottest temperatures ocean life can survive at

The previous record-holder, P. fumarii, could live at temperatures as high as 113 °C (235 °F), well above the boiling point of water. But the new microbe, for now called “Strain 121,” thrives at 121 °C and can even survive for two hours at 130 °C.


I think what you mean by thermo-electric nitrogen fixation is the nitric oxides created by lightning discharges. This is absorbed by the raindrops as they form and as they fall to earth, and helps to fertilise the soil. You won't get this effect with sprinkler irrigation to any great extent, because the water droplets are exposed to the nitrogen oxides for far less time. In addition, sprinkler use is not usually accompanied by lighting flashes, whereas rain sometimes is.

If your crops are watered mainly by sprinklers and you would like them to have more nitrogen, you should practice rotation of crops. Some years you plant legumes, which fix nitrogen by means of the nitrogen-fixing bacteria which live in the nodules in their roots. In the tropics, a kind of acacia called mimosa, though not related to legumes, has the same nitrogen-fixing capability. This acacia is sometimes called 'the sensitive plant', as when touched its leaves rapidly fold themselves away.


Specific humidity range in tropical lowlands?

Referring to a research article "The Role of Temperature and Humidity on Seasonal Influenza in Tropical Areas: Guatemala, El Salvador and Panama, 2008–2013" by Soebiyanto et al, 2014 DOI: 10.1371/journal.pone.0100659, the authors investigate a few regions in tropical wet and dry (savanna) climates in Central America, some of which are lowland. The authors state that Panama and El Salvador study locations have less varied topography and are at lower elevations than Guatemala. They give the following Specific Humidity values and standard deviation i g/kg:

Lowland Panama province in Panama: 17.66 +/- 1.04 g/kg
Chiriqui province in Panama: 15.38 +/- 1.47 g/kg
West-central departments in El Salvador: 14.29 +/- 2.14 g/kg
San Miguel, El Salvador: 14.84 +/- 2.32 g/kg

So, a specific humidity in the 10-20 g/kg seems like a reasonable range for seasonally dry and humid lowland tropical regions in Central America.


From what you wrote, you are assuming several things:

The mantle is made up of molten rock,
Faults can go deep enough to reach the mantle.

Both are not exactly accurate.

  lava starts flowing out

The mantle of the Earth is mostly solid. It has areas where it's partially molten, and that's where the lava in some volcanic eruptions comes from. But mostly, it's solid. Even if you did get a fault line deep down there, it would not release any lava because it's not there to begin with.

  ...fault line would get deeper and deeper...

Faults can not go too deep. As you go deeper in the earth, rocks stop being brittle and become ductile. They don't break, the flow. Think of chocolate - if you take out chocolate from the freezer you can shatter it to pieces. If you put it in the sun, it bends instead of breaking. Same thing with rocks.

  I know that some earthquakes are caused by volcanoes

The movement of molten rock (magma) underground is the cause of volcanos and earthquakes associated with volcanos. Note that these kinds of earthquakes are usually very weak and their destructive power is very small, at least compared to the actual volcanic eruption.

  some earthquakes can trigger volcanic eruptions

Not really - only if it's a big earthquake you had molten rock around. Which brings me to the next point...

Having said that - actually most of the volcanic eruptions on Earth in fault lines where decompression of mantle occurs. These are the mid ocean ridges that look like this:

Source: Pearson Prentice Hall (?)

And are located here:

Source: USGS

In the case of mid ocean ridges, you basically have mantle rock melting because of decompression, and this is occurring at fault lines with earthquakes. However, the location where all of this is known and it's all pretty expected. It's also in mid ocean ridges (except Iceland) so the danger to us humans is negligible.

Other than those cases, the chances of having a surprise magnitude 8 earthquake with a volcano erupting after it are very low.


Do we know how large deposits of methane clathrates were formed in permafrost regions?

Rotting vegetation generates methane, or marsh gas as it is sometimes called. The most obvious method by which clathrates were formed in Arctic regions is that many years ago during summer and autumn, rotting vegetation produced methane, which combined with water at cold temperatures to produce methane ice, otherwise known as clathrates. Extremely cold temperatures are not necessary to form clathrates. They form at the bottom of deep seas, where the temperature even in the tropics is a constant 4 or 5 C. There are huge deposits of clathrates on the deep ocean floor, and there has been talk of exploiting them commercially.

A theory to explain the Permo-Triassic extinction event of 250 million years ago hypothesises that super-eruptions in the Siberian Traps super-volcano raised temperatures enough to release vast quantities of methane from tundras and ocean beds, so that with the additional greenhouse gas the average temperature rose by about 10 C, causing the extinction of nearly 90 percent of all large animals, a greater mass extinction than the better known event at the end of the Cretaceous.


Do normal modes of oscillation cause permanent deformation?

These are visco-elastic oscillations that cause virtually no permanent deformation.

Following the Tohoku 2011 earthquake, this gravimeter in Metsähovi, Finland, measured a radial oscillation mode amplitude of 0.06 mm. The Earth's radius is 6371 km. So the resulting strains would be extremely small.

All but the lowest radial mode decays after a few days because the energy of the oscillations gets converted to heat by dissipative processes.


Can aerostats be used for fine-grained control of the weather

No, the idea is quite impractical. Lack of helium is no obstacle because unmanned balloons, whether tethered or remote controlled could be filled with hydrogen, but to affect the climate you would need millions of them, which is too expensive and impractical. Geo-engineering projects are generally the stuff of science fiction and not practical in the real world. One way climate could be modified on a local scale is to refill places like the dried up Aral Sea with water from the ocean. Apart from other beneficial effects, this would probably produce enough evaporation to affect local rainfall. Rainfall is also locally affected by the presence or absence of trees, so if you want to increase rainfall in arid areas, one way to achieve it is large scale tree planting. That might be difficult in semi-desert environments, but nevertheless it has been done. Sometimes tree roots can reach down to a water table, which is how enormous cypress trees are in some places  able to grow in the sand seas of the Sahara Desert.


When did wildfires start to occur on earth?

A definitive statement comes from the abstract of Scott and Glasspool1, 2006:

  Charcoal, a proxy for fire, occurs in the fossil record from the Late Silurian (≈420 Myr) to the present.

One of the tired old truisms you learn is that fire needs three things: Oxygen, fuel, and a source of ignition.

There is little doubt that there has been lightning since Earth's formation. (Wikipedia:Paleolightning). There appears to be evidence of the fossil fulgurite from the Proterozoic Eon.

Oxygen levels were probably sufficient around 470 Myr. (Wikipedia:Fossil record of fire)

So as soon as plant-based fuel appears on land, there is evidence of fire.

Although there is evidence for land plants for as far back as 850 Myr, and some evidence for land-based bryophyta (moss) appears in the Ordovician Period, evidence of widespread plant colonization of the land, and plants with vascular tissue that can dry out into fuel, do not appear until the Silurian period with the appearance of Cooksonia and other early tracheophytes. (Wikipedia: Evolutionary history of plants)

The level of oxygen in the atmosphere does appear to play a role, as there is a gap in the Mid-Devonian period, apparently coincident with a dip in oxygen levels (to about 13%), but there doesn't appear to be a consensus on that. At any rate, fossil charcoal picks up again in the late Devonian as oxygen levels rise again.

1 Andrew C. Scott and Ian J. Glasspool, The diversification of Paleozoic fire systems and fluctuations in atmospheric oxygen concentration,Proc Natl Acad Sci U S A. 2006 Jul 18;103(29):10861-5. Epub 2006 Jul 10.
(Abstract at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1544139/#!po=0.694444)


Detecting seismic waves using Software Defined Radio

I hope I understand your question right, I think there are some confusion about frequency range and wave-types.

Seismic waves are acceleration of matter that transfer kinetic energy from a seismic source (e.g. an earthquake, an explosion or ambient noise) to heat.

It's similar to sound waves, vibrations from the surface of e.g. a music instrument set the air in motion and compress the molecules of the air to transfer a wave that eventually reach e.g the eardrum. However, to add to the complexity, in solid matter some additional elastic properties are in play, as you notice. Waves can progress not only as pressure waves (P) but also as shear waves (S) and at boundaries special surface waves can form, often of high amplitude. The progression of the seismic waves depends on the elastic properties of the Earth.

A large part of the terminology used for seismic waves are similar to how we describe electromagnetic waves. E.g. frequency, damping and resonance are relevant for seismic waves as well. However, the ranges are very different and electromagnetic waves and acoustic waves behaves different. The earth is a efficient filter, and even transient energy, that contains high frequencies, is limited to low frequencies as it progress through the Earth. Ground wave propagation, as know from radio signals, are different from the properties of seismic surface waves.

An interesting coincidence is that wavelengths can be in the same magnitude, but that is because radio waves progress about 100.000 times faster than crustal seismic waves.

A figure, prepared by Professor Charles J. Ammon, shows the ranges of frequency and amplitude. Source here. The amplitude and period have a large range, that's why prefixes as milli or micro can be used and a logarithmic scale is used for amplitude.

In shallow active reflection seismic surveys, we sometimes can use frequencies up to maybe 200Hz, but in the range the penetration depth is very small. For very local events, e.g. in mines and infrastructure frequency range up to 500-1000Hz might be used.

Most energy for P and S waves used in teleseismics are in the range of a few Hertz and maybe up to 10-20Hz.

Surface waves have the interesting property that the velocity depends on the frequency because low frequency content is affected by deeper elastic properties whiles high frequency content is more affected by shallow geological features. This is used for lithosphere tomography with rather good vertical resolution. The frequency range is 0.005Hz and up to 0.5Hz. This is the frequencies that you can actually see in ground motions caused by earthquakes, if you take resonance in consideration.

Normal modes are often in the range 0.3 - 1mHz. (m, as in milli, not M, as in Mega). That is frequencies about one billiard times lower than some radio frequency bands.

Another thing to remember in the context of Software defined radio, is that there is no carrier wave for seismicity. When seismologists talk about frequency, we mean energy content of a signal. We are looking at the convoluted wavelet, not continuous signals.

If you are interested in working with earthquake detection and to improve algorithms of signal processing of seismic waves, I'd suggest you to take a look at the Obspy package, there are some nice examples and tutorials that can get you started. There are also some project where people are constructing open architecture seismometers, eg the Raspberry Shake. For less than $100 or so you can build a seismograph and start to monitor local seismic events. Most geophones work by transfering ground acceleration to an induced electric current in a coil.

It's very possible that inspiration from other fields of signal processing, as in Software defined radio can improve seismic techniques in future. It is always great to get inspiration from other fields of research.


How to solve libnetcdf.so.12: cannot open shared object file in pyferret?

You need to uninstall netCDF4 as it is not compatible with pyferret library as of now.

pip uninstall netCDF4

should do.


Why is it colder in the mountains than at sea level?

The traditional answer basically comes down to the physics concept of adiabatic cooling, a description of which is:

There is less pressure as you go up in the atmosphere (basically due to less air weighing down)
Air takes up more volume at lower pressures
Since there's nothing else to supply the energy needed to expand, the air employs the energy that was in the temperature (which is the amount of air molecule movement).  The result is that air higher up is cooler by about 10 C per km (for dry air... moisture releases heat, reducing the cooling to about 6 C per km)

But, in summary, air is cooler higher up in the atmosphere.
And that is certainly the dynamics explaining why air temperature decreases as you go up throughout the troposphere (the only layer of the atmosphere we generally encounter in our lives... other things do come into play in other layers... such as ozone collecting and rereleasing energy from the sun in the stratosphere, actually causing warming with height there).
However, it seems that this typical explanation actually falls short.  Because if you pay attention to the wording of that "because air higher in the atmosphere is cooler" phrase, it doesn't actually answer the question.
Because all locations you're considering are surface locations, whether they're at sea level or in the mountains.
And the surface layer basically does all the absorbing of the troposphere's sunlight (the solar radiation absorbed by the troposphere is negligible).
And after all, mountainous places receive the same amount solar energy as lower elevation sites (in fact, technically a tiny bit more, that tiny tiny bit I mentioned that the troposphere takes out for sea-level locations).
Where am I going with this?
If the ground gets the same energy.  And if it's made of the same material and has the same color, it would therefore gain the same amount of temperature.  And then the air's heating comes up from the ground below.
So then, once again, why are mountains cooler?!?
Because of their EXPOSURE.
Air predominantly flows horizontally rather than vertically (basically consider this an effect of gravity and the resultant air density distribution).
And it's that horizontal wind that changes everything.  Because most sites on mountains are generally quite proximate (at least regionally) to places where winds will blow in air that was higher above the lower elevation ground surface, and thus colder.  The air on mountains, with limited protection (and because winds are higher aloft) is mixed strongly with the neighboring adiabatically cooler air that's sitting above the sea-level sites.
Just for more convincing this is vital, I invite you to look at these climatographs comparing two cities in the US.

What are these towns?
Red: Wendover, Utah (elevation 4,291', latitude 40.73° N)
Blue: Latrobe, Pennsylvania (elevation 997', 40.32° N)
Over a km difference in height.  So you'd expect Latrobe to be about 18°F warmer.
But it isn't.  Instead it's cooler (especially during summer afternoons, which average up around 10 degrees apart).
Why?  Because a lot of the intermountain west is actually quite a wide flat elevated basin\plateau.  So in the central part of this area, there isn't as much exposure to the colder air coming in from places with lower topography.
Rest assured, it was very hard to find examples like this.  You need a very wide flat elevated area, which is fairly uncommon.  Plus just the right place to compare to for emphasis.
There are other common factors that do enhance the cold predilection on mountains, including the lower moisture content at elevation, the often lighter land color of raised terrain, and the increased cloud coverage due to air rising orographically.
But the fundamental reason it is colder on mountains is adiabatic cooling and the exposure of raised locations to that colder air.


What divides Hydrological Unit Code areas of the same level?

I'm confused about your misunderstanding as the answer to your question is in the Wikipedia link you posted:

  Regions receive a two-digit code. The following levels are designated
  by the addition of another two digits.[8] The hierarchy was designed
  and the units subdivided so that almost all the subbasins (formerly
  called cataloging units) are larger than 700 square miles (1,800 km2).
  Larger closed basins were subdivided until their subunits were less
  than 700 square miles.[7] The 10-digit watersheds were delineated to
  be between 40,000 and 250,000 acres in size, and the 12-digit
  subwatersheds between 10,000 and 40,000 acres.[6] In addition to the
  hydrologic unit codes, each hydrologic unit was assigned a name
  corresponding to the unit's principal hydrologic feature or to a
  cultural or political feature within the unit.[7]

So, once you are outside of the 2 digit regions, HUC boundaries (or dividing/outlet points along a continuous stream) that separate an upstream watershed from one a downstream one (that should incorporate the upstream HUC using the classic definition of a watershed) are set to evenly divide up the larger (or containing) HUC.


Why are there so many "horseshoe lakes", and are they really mostly in the US?

Let's get rid of a red herring from the Wikipedia page linked to in the question!
Horseshoe Lake, Arizona - is a reservoir created by the Horseshoe dam. Nothing to do with actual horseshoe lakes.
The other's lakes listed might be genuine horseshoe lakes, but there are no aerial photographs of them.
Generally, horseshoe lakes are oxbow lakes which is

a U-shaped lake that forms when a wide meander of a river is cut off, creating a free-standing body of water. In south Texas, oxbows left by the Rio Grande are called resacas. In Australia, oxbow lakes are called billabongs.

A resacas is a

former channels of the Rio Grande and are naturally cut off from the river, having no inlet or outlet
The Rio Grande's water moves from Colorado to the Gulf of Mexico. Every year during spring, melted snow would flow into the Rio Grande, bringing seasonal flood waters to the most southern tip of Texas.3 Given the overflow of the river's main and distributary channel banks, the Rio Grande would carve new river channels, resacas. When the seasonal flooding ended and the river retreated, the newly formed oxbow lakes remained, creating resacas all throughout the Rio Grande Valley.

In Australia, billabongs are

an isolated pond left behind after a river changes course. Billabongs are usually formed when the path of a creek or river changes, leaving the former branch with a dead end. As a result of the arid Australian climate in which these "dead rivers" are often found, billabongs fill with water seasonally but can be dry for a greater part of the year.
Billabongs were significant because they held water longer than parts of rivers; it was important for people to identify and name these areas.

In general,

An oxbow lake forms when a river creates a meander, due to the river's eroding bank. After a long period of time, the meander becomes very curved, and eventually the neck of the meander becomes narrower and the river cuts through the neck, cutting off the meander and forming an oxbow lake.
When a river reaches a low-lying plain, often in its final course to the sea or a lake, it meanders widely. In the vicinity of a river bend, deposition occurs on the convex bank (the bank with the smaller radius). In contrast, both lateral erosion and undercutting occur on the cut bank or concave bank (the bank with the greater radius). Continuous deposition on the convex bank and erosion of the concave bank of a meandering river cause the formation of a very pronounced meander with two concave banks getting closer. The narrow neck of land between the two neighboring concave banks is finally cut through, either by lateral erosion of the two concave banks or by the strong currents of a flood. When this happens a new, straighter river channel develops—and an abandoned meander loop, called a cutoff, forms. When deposition finally seals off the cutoff from the river channel, an oxbow lake forms. This process can occur over a time from a few years to several decades, and may sometimes become essentially static.

The naming of oxbow lakes as horseshoe lakes might just be American terminology. When such lakes were being "discovered" and "mapped" most people would have known about horseshoes, but maybe not oxbows so they got named after what they knew.
Oxbow lakes do exist elsewhere, they're just not named as horseshoe lakes.
The Kanwar Lake Bird Sanctuary in India is one of the largest oxbow lakes in Asia. In the United Kingdom they also occur in the Gower Peninsular of southwest Wales and there is also the Bole and Burton Round in Nottinghamshire.
Celestially, there has also been a possible oxbow lake postulated in Saraswati Flumen near Ontario Lacus on Saturn's moon Titan.


If the earth is a globe, what causes temperature differences across lines of latitude?

Polar regions are colder than equatorial ones for a simple reason - geometry.

More specifically, it is caused by the greater angle of the Sun's rays to the surface of the Earth. As you go farther north, the Earth's (mostly) spherical surface bends back from the direction of the Sun's rays, and the same amount of photons are spread over a larger area.

What's more, the closer you get to the poles, this already-attenuated sunlight has to go through more of the Earth's atmosphere, and so more sunlight is scattered, and consequently less will reach the ground.

Here's an image (Thanks, Pont) to show the difference:

Source: Wikimedia Commons. License: CC BY-SA 3.0

The sun's angle is more important to climate differences than the modest variation in Earth's distance to the sun, because the atmosphere is kept warm by the greenhouse effect. It's not the direct light that matters: Air is more or less transparent to the visible light that makes up most of the Sun's spectrum. Instead, the ground absorbs that light and reradiates it as infrared and microwave radiation. That longer-wavelength radiation is absorbed by the atmosphere, but if the ground is not radiating as much infrared because it absorbed less sunlight, the atmosphere above it doesn't get warmed quite so much.

Granted, if the Earth's orbit were much more eccentric then the variation in distance to the Sun would matter more to climate variation. But it doesn't.

This would happen even if Earth's axis weren't tilted. Polar regions would still be cold and equatorial regions would still be hotter. In fact, the difference would be greater because there'd be less mixing.

The image below shows the what happens to the energy the Earth receives from the Sun:

Source: NASA

That shows an average over the entire Earth. As you approach the poles, the percentage "reflected by clouds and atmosphere" goes up while total energy "absorbed by surface" per unit area goes down. And since ice has a high albedo, this is reinforced by the percentage "reflected by surface".


What would happen if we removed Earth's moon?

This has sat untouched for a while, so I did a quick search and found this article which sums it up nicely.

They key factors with regard to earth science would be:

1) Less extreme tides. The tides would only be linked to the sun and would not be as strong. They would also peak at noon. This has obvious implications for any coastal processes that rely on the tides. Many industries would be impacted. For one, the Bay of Fundy wouldn't be quite the tourist attraction it is.

2) Day length would potentially shorten at a greater rate. Our tidal lock to the moon helps to stabilize the slowing rotation of the Earth. In terms of Earth Science, this would have implications on any diurnal processes (weather), with compounding long-term effects (the climate).

3) The axial tilt of the Earth would change quite a bit. The moon helps to maintain our reasonably stable tilt. Greater tilt would result in more extreme seasonal changes, which in turn would affect all sorts of processes.

Those are the bigger ones from an Earth Science perspective.


Are coral reefs a Biochemical Sedimentary rock?

Yes, limestone indeed is "biochemical".

The main categories of non biochemical sediments are sandstone, mudstone, shale, conglomerate,.. if you put the Sahara for example under lithification it will become sandstone, since it consists mostly of quartz.. almost all continental sedimentary rocks are "non-chemical" they just vary by the components, whilst most marine sediments are biochemical, as you say..they consist mostly of carbonate and aragonite skeletons (shells in most cases) of dead animals.. that's what makes up limestone.. the main corpus of coral reef is a good example for mostly pure limestone.. The carbonate classification is based on the amount (and form) of the skeletons.. You should have a look at it, if that's interesting to you.
Coal, as you mentioned, would be another biochemical sediment but it's not only made of skeletons but the pure organic matter of dead animals, but it's genesis is rather complicated..

So to answer your question: Yes, coral reefs are biochemical sediments and very important ones, too, since they grow really fast!
As noted in your quotation: Biochemical sedimentary rocks are created when organisms use materials dissolved in air or water to build their tissue!
That's exactly what the mentioned polyps do.. You can also have a look at stromatolithes build by cyanobacteria.. that's a nice and understandable example to understand how that works.


Quartz is a silicate at the most used Dana and Strunz classifications of minerals.
Several websites and mineralogists classify it as silicate.
The structure of quartz is similar to other silicates with Si-O tetrahedres.

Quartz structure. quartzpage.de


How to calculate gps location based on direction and distance?

The answer in a plane you linked works rather well in a sphere provided that the distance you want to measure is tiny compared with both the radius of Earth and the distance to the nearest pole - and 2.67 chains is that tiny.

For the remaining of the answer I'll be assuming that the Earth is an sphere, which quite accurate unless you need great accuracy - that is, enough accurate for nearly anything except for surveying.

The first step is to convert your distance and direction to easting and northing distances - as the linked answer tells.

The second step is to convert those two distances to degrees latitude and longitude, and you only need to know that one degree latitude measures $R_{Earth}\cdot\frac{\pi}{180}$ and a degree longitude measures $R_{Earth}\cdot\frac{\pi}{180}\cdot cos(latitude)$.

As a final step, you just need to sum those angles to the latitude and longitude of your position.

With your data:

> # Earth radius in chains
> (r <- 3958.8*80)
[1] 316704
>
> #bearing, latitude and longitude in radians
> (br <- -52/180*pi)
[1] -0.907571211
> (latr <- 37/180*pi)
[1] 0.6457718232
> (lonr <- -91/180*pi)
[1] -1.588249619
>
> #1 Distance to North and East in chains
> (east <- sin(br)*2.67)
[1] -2.103988712
> (north <- cos(br)*2.67)
[1] 1.643816139
>
> #One degree in chains
> (deglat <- r*pi/180)
[1] 5527.527554
> (deglon <- r*pi/180*cos(latr))
[1] 4414.479788
>
> #2 distance in degrees
> (dlat <- north/deglat)
[1] 0.0002973872356
> (dlon <- east/deglon)
[1] -0.000476610793
>
> #3 arriving point (GPS coordinates)
> (lat <- 37+dlat)
[1] 37.00029739
> (lon <- -91+dlon)
[1] -91.00047661


Relative Humidity approximation from Dew Point and Temperature

The equation for relative humidity is $$RH=100\times \frac{e}{e_s(T)}=100\times \frac{e_s(T_d)}{e_s(T)} \tag{1}$$
Where $T_d$ is the dewpoint temperature and $T$ is the temperature, $e$ is the water vapor pressure, and $e_s$ is the saturation vapor pressure, which is also known as the Clausius Clapeyeron equation. While the previous link has a decent definition and equation, my preferred equation (particularly because it is derivable) is the low temperature approximation:
$$e_s(T)= e_s(273 \mathrm{K})\exp\left[\frac{L_v}{R_v}\left(273.15^{-1}-T^{-2}\right)\right] \tag{2}$$
where $T$ is the temperature or dewpoint temperature in Kelvin, $L_v$ is the latent heat of vaporization,$e_s(273 \mathrm{K})=6.11 hPa$, and $R_v$ is the specific gas constant for water vapor. Note that $(2)$ is for liquid water. You may be able to replace $L_v$ for $L_s$ for sublimation/deposition. Also note, that this is the "pure" form of the relative humidity equation. The presence of solutes (Cloud condensation nuclei) may lower the saturation vapor pressure, increasing the actual relative humidity. I'll let combining $(1)$ and $(2)$ be an exercise left for the reader.


Cumulonimbus clouds are thunder clouds, they are heavy and dense clouds that come in large heaps, these clouds produce precipitation or rain, Cumulonimbus clouds also produce hail and tornadoes.


How can methylmercury in the ocean be reabsorbed into the atmosphere?

Much of the methyl mercury that enters the atmosphere may be dimethyl mercury, $\text{(CH}_3\text{)}_2\text{Hg}$.  This is a very volatile compound which, if it were pure, would have 50 mm mercury or more vapor pressure at 20°C.  Complexes involving more electronegative ligands, such as the chloride $\text{CH}_3\text{HgCl}$, are significantly less volatile, but still have more vapor pressure than purely inorganic mercury compounds.


Does the moon have any affect on earthquakes being created?

The forces involved in the New Zealand earthquake are not amenable to precise evaluation - at least not without detailed geotechnical evaluation, but we can use the peak ground acceleration as a proxy. For a magnitude 7.5 earthquake the peak ground acceleration is about 0.4g. Compare this to the normal moon's gravitational acceleration on Earth's surface of about 3.318 E-5 g. 'Super-moons' are about 16000 km closer than usual, yielding a gravitational acceleration of 3.783 E-5 g. Therefore the differential gravitational acceleration of a super-moon, compared to a normal moon, is about 4.65 E-6 g. Or to put it another way, the effect of a super-moon is to create about a 0.001% of the acceleration (and hence force) required for the accumulated strain energy to overcome friction, and hence cause the earthquake. This assumes that all of the moon's gravity was aligned in such a way as to exacerbate strain along the slip plane - which is never going to be the case.

I suppose that one could argue that the miniscule gravitational force of a super-moon could have been the 'straw that broke the camel's back', but the accumulated strain energy in the ground must have been so great that the earthquake was about to happen anyway, with or without the moon's gravity.

Afterthought: With the boot on the other foot: The Earth's much larger gravitation has an effect on the Moon. There are moon tides which cause regular, small but measurable moon-quakes. See Moritz and Melchior (2013), Tidal Interactions in the Earth-Moon System.


What kind of rock or stone is this? Where did it come from?

Quite an interesting stone.  I cannot identify all of it but given its location, and the patterns it is primarily Agate, a type of crypto-crystalline quartz.  The fourth picture down shows a layer of lace agate across the top of the stone at that location, it is underlain with a more massive translucent agate.  In the Oregon area there are many areas with volcanic rock.  The silicas have dissolved from the volcanic material in the past and this silca has been slowly deposited to form the rock you found.  The following links give you an idea of the types of agate you can find.

Types of agate

A more detailed description of types and formation.

I would warn you that there are a number of names for the various types of agates and the naming doesn't seem to follow any convention.


Can anyone recommend a good college level meteorology textbook?

So meteorology is unique in that it changes depending on the scale and process. For a general taste of meteorology, I suggest Wallace and Hobbes. You may note similarities among most of my recommendations, but that may just be a bias from my personal experience.

One of the most problematic elements of meteorology is atmospheric dynamics. A common resource is Holton's book.

For thermodynamics, a common book used in my undergraduate studies was Bohren and Albrecht. Although you may have experience in thermodynamics, atmospheric thermodynamics is often treated differently, with different quantities. You may recognize some of the equations used, but the variables derived are used throughout atmospheric science.

For mesoscale (medium-sized) meteorology, Markowski and Richardson have a good book.

For atmospheric radiation, Petty has a basic book.

In my synoptic meteorology class, we were assigned this book, but I don't recall ever really using it. This book looks more comprehensive (in fact, I might get it for myself).

For boundary layer meteorology, try Roland Stull's book.


Why do Euler poles for plate motions not stay fixed in time?

I think I can do an OK job explaining, but I could not find a proper diagram to illustrate this. Perhaps, if you could locate a professor at your university to draw this out and explain it would be best, as doing an illustration on computer is a bit time consuming.
Lets start out with a two plate system, plate $A$ and $B$.

${}_{A}E_B$ is the relative plate motion of $B$ with respect to $A$, meaning that $A's$ motion is fixed while $B$ is free to rotate.

Since this is only a two plate mode, $A$ and $B's$ relative plate motions are always the same, no matter where they are in time, you can always go back and forawrd in time, as nothing changes the relationship between  $A$ and $B$. IE, there is nothing to interfere with their relative plate motions.

Only 1 Euler pole is needed to fully describe the motions of two plates, in general. Lets now add a 3rd plate, plate C:

${}_AE_B$ is the plate motion of $B$ with respect to $A$

${}_BE_C$ is the plate motion of $C$ with respect to $B$

${}_CE_A$ is the plate motion of $A$ with respect to $C$

These three motions describe the 3 plate system.  So now lets imagine we are standing on $A$ looking at $B$ and $C$, what happens? Since we are on $A$, we move relative to $C$, and $B$ moves relative to us. But wait, a problem occurs, because $C's$ motion is dependent on $B$ being relatively fixed, and $A's$ motion is dependent on $C$ being relatively fixed, meaning if two poles are fixed, the third and final pole must wander to accommodate the reference frame. IE, because All of the plates are moving relative to each other (depending on the reference frame), the Euler poles are changing over time. This gets more complex as we keep on adding plates into the system.


How can linear oceanic ridges (like the East Pacific Rise) be explained by single point mantle plumes?

Hot spots and ridges are two different things.

Hot spots stay in one place while the earth crust above them drifts and thus create a line of dormant volcanoes, they are a point features so to say.

Ridges are places where the mantle convection wells up and spreads in two directions, gently pulling the earth crust with them and creating new crust where the magma wells up. Ridges may be described as linear features.

So, without convection and thus without ridges, which form new earth crust, the hot spots wouldn't create a chain of volcanoes.


It depends on what you want to use them for.

If you might someday want to extract DNA from them, or do some other chemical analysis, then it's probably a bad idea.

If you only want to display them, and you like the way they look after acetone treatment, then it should be OK.

Test on some samples you don't care about first.


Why don't lightning strikes cause a lot of injury or damage to property?

Annually, about 51 people die from lightning strikes per year in the United States. Part of the reason is the low probability of being hit by lightning. Tornadoes, hail, and straight line winds sweep large areas, while one lightning bolt covers a rather small area, and may even be harmless if it doesn't make contact.

Think of it this way: if you were struck by lightning, a person 500 feet away may not be harmed by it, but if straight line winds cause your house to collapse, you can say with relative certainty that your neighbor will have some damage.

Another factor is the reliability of protection. Major hail can total a car. Strong straight line winds and tornadoes can collapse or remove your house. A lightning bolt will cause property damage, but you will be safe inside, provided you aren't touching metal.


Not being a winter precipitation expert by any stretch (we avoid such silliness in Florida!), I think a significant key may be the "the humidity is low (40%)" part.
When winter precipitation falls through warm air, it certainly gets heated by the air.  But if the air is dry, some of the outer fringes of the precipitation will melt\sublimate, taking away energy and thereby cooling the flake, helping it to survive longer.  http://www.sciencebits.com/SnowAboveFreezing looks to have a pretty great detailed page about the nitty gritty of it.
Certainly precipitation starting at colder temperatures gives the particle a little reserve.  The low conductivity and high specific heat capacity of water\ice are also notable.  But the latent heat of sublimation is over 10 times as great as the specific heat capacity, showing that losing a little ice on the surface can really counteract quite a bit of warming.

But it's important to note that at the values you gave, the ScienceBits calculator doesn't give any hopes of snow.  So what's going on?
First, it's important to impart that the temp\humidity values aren't far off (try RH=30% and T=7°C or RH=40% and T=6°C and you'll start to get values).
So I am indeed convinced that your local values were off by around that amount.
You can reasonably expect that the temperature that an app or website gives typically has error of a few degrees (with similar errors in most other variables) unless you happen to be right at the location of a reporting site.
This is due to variations over space and time.
Even small elevation changes  cause significant impact on temperatures, and the current data for a relatively flat place like New Jersey shows how other microscale effects (like surface color, roughness, wind blocking, and water\plant moisture) typically lead to at least a degree or two variation between even well-sited representative locations (not even broaching the bigger changes things like concrete, buildings, trees, rock formations, etc cause).
In addition, most weather sites only give full reports once per hour... and we certainly know how things can change in an hour, especially in the morning\evening or near fronts.
In addition, there are three ways your app\website will give you the temperature and other variables:

They just give the reading at the closest official weather reporting station.  For instance weather.gov, the US Weather Service page, will do this.  Full ASOS reporting stations are about 60 miles apart on average in the contiguous US.  You can peruse this site to see the stations in the UK or other parts of the world, but in general they're reasonably far apart.  Mesonets and private weather stations offer more options, but are usually not available to apps\weather service use, and often inconsistently calibrated\sited.

Some websites give a weighted average of nearby values... but this still won't generally include elevation effects at all.

And some use weather models to fill in the gaps and estimate to a higher degree for your location, properly incorporating some elevation data along with the fundamental meteorological equations.  However the resolution (and initial data) is often still poor enough that it doesn't match reality.  I believe the highest resolution forecast\analysis models right now is only 3km, and those are only in limited spots like the US (HRRR, NAM)).  Most models only offer values three hours apart as well, and are only run every 6-12 hours, so the data is far from precise.  Here is the Global Forecast System model forecast for 4 PM BDT (1500 UTC):

You can see some hints of the terrain in a few spots, but nearly the fine variation reality has.
This model only has a 10 km resolution, so many of the smaller hills around your area aren't included at all.
Here's a topography image for a similar scale model, the European ICON model (13 km res):

You can see the North Downs fairly well, and certainly some hint of the hills and valleys around your area.  But they likely aren't well enough represented to truly incorporate the differences in weather in such complex areas.
Likewise it looks like your closest site on Met Office's observation map is Charlwood (though an international list suggests siting at Gatwick... perhaps they're really the same site?)
Remarkably the Gatwick observations from that day actually indicated 9°C at 1600 BST.  Still it's a good 6+ miles away.  And there's also about 70 meters elevation difference between East Grinstead and Gatwick\Charlwood.  It's worth noting that in confirmation at Gatwick there were only rain reports until it got down to freezing after midnight.

Finally as you asked about the vertical profile, here is the model forecast sounding from about that time:

Additionally you can get the SkewT or a table of the actual UK data from the Camborne launch site from 12Z (1 PM BST) at this website to compare. [Here's a site with a bit of info on reading such diagrams].
I originally opined that I didn't think a high lapse rate should be likely since those tend more towards deep convection\thunderstorms.  However the data shows I'm sufficiently wrong... looks like over the lowest km, there's a remarkable 11.2°C decrease, the rare superadiabatic lapse rate.
Still, even that profile only leads to an LCL temperature of around -5°C (calculated as -4.5°C on the Camford sounding, -6.2°C on the GFS sounding using Gatwick surface pressure), which represents the cloud base of a lifted surface-based parcel at those locations (obs at Gatwick are similar).  However with such a lapse rate, by the time the parcel tops out near equilibrium level (which is a rough idea of the maximum cloud top height for a surface parcel)... it's nearer -20°C.  Certainly colder, though perhaps not what I'd think of as extreme.
But you were clearly right to think that the lapse right could be high... in retrospect it makes sense as for surface air to rise air enough for precipitation to fall despite a stout T\Td spread it'd need to rise a fair bit, likely needing decent lapse rates.  My mistake was that the instability (a rough proxy of the rate air would rise at freely [so not including the impacts of the dynamical lift of the storm system]) such great lapse rates produce is tiny (only a few J/kg on this sounding, compared to hundreds or thousands in severe thunderstorms typically)... this is because such cold air doesn't hold nearly as much moisture.
So it's quite possible to indeed get big lapse rates in cold weather and get the types of clouds you saw.  That just may not mean cloud temperatures are particularly extreme, in part because cold weather clouds tend to be more shallow due to the reduction in moist adiabat temperature gains.

In the end, I really believe the temperature was likely a few degrees lower in East Grinstead than in those surrounding areas.  Not only because of the resolution of data... but also in particular because of the weather: a persistent decent northwest wind most of the day, which flows roughly into the sharpest larger-scale terrain gradient in your area.  That would tend to force a lot of ascent, likely developing initial clouds which gradually precipitated down but not reaching to the surface... evaporating fully, but at the same time reducing the air temperature and increasing the dew point below (a process called wet bulbing), until the low-level values became more reasonable for precipitation around the hills.  I'd expect you know this type of pattern very well from the many foggy rainy days that are likely near moors like yours.  That localized process, coupled with the fairly cool temperatures deeper within the cloud, likely were enough to get the sporadic snow showers.


Could evidence of a signal from an exocivilization be found in the geologic record?

No, it is not possible.

The only thing I could think about is re/de/magnetisation of magnetic minerals. Even then I'm not sure it's feasible, because you to form a magnetic field you need an electric current in motion, but that's a question for physics, not here.

So far, the major magnetic signals recorded in the geological history are well understood. There are many small scale signals that are less well understood, and are believed to be the result of internal processes within the Earth. You can look at my answer here for examples of these signals. Anyway, even if an extraterrestrial civilisation could somehow affect the geological record, it would have to be sustained for very long times (hundreds to thousands of years) for us to be able to see something, and even then we probably wouldn't be able to distinguish it from noise.

As an example, think of a river with rocks in it, constantly getting moved and tumbled. Then you go and throw a rock inside. There would be absolutely no way to know which rock was it (and even that someone threw a rock inside), even a day later, let alone 100 million years. The only way to distinguish something would be a huge amount of rocks, not just one. And then there's the question, of why would someone spend this enormous amount of energy of throwing rocks in the river or sending EM beams towards planets?


What are the approximate dimension of this iceberg? Any chance the ratio is 1:4:9?

Not likely.

Quoting Kelly Brunt, an ice scientist with NASA and at the University of Maryland, from What the Heck Is the Deal with This Weird, Square Iceberg? at LiveScience.com:

  What makes this one a bit unusual is that it looks almost like a square,

which does not rhyme with anything in your suggested 1:4:9 ratio.

The article mentions the obvious

  And, as with all icebergs, the part visible above the surface is just the top 10 percent of its mass.

but that only tells you that 90% is under water, nothing about its absolute height above sea level.


Start with my answer to this very highly related question here:

https://earthscience.stackexchange.com/a/2742/725

The melting point of minerals in isolation, or a pure substance is higher than mixtures of minerals. For example - a (well-mixed) mixture of quartz and pyroxene will melt at a lower temperature than pure quartz or pure pyroxene. The exact temperature is dependent on the proportions.

In general, the more different kind of components (i.e. "things": minerals, elements, molecules, etc) you add to a mixture, the lower the melting point of the mixture as a whole.

For example, sea water melts at -2 °C because it's a mixture of water (melts at 0 °C) and all kinds of salts. Steel melts at a lower temperature than pure iron because it's a mixture of iron and carbon.


The documentation linked from the datasets page states:

  Air Temperature (all units in Fahrenheit on PDF monthly form and tenths of degrees Celsius on CSV or text)
  EMNT - Extreme minimum temperature *
  EMXT - Extreme maximum temperature *

The Petersburg data looks plausible under this interpretation (EMXT −3.9°C to 33.9°C over the year).


What causes intra-plate faults, such as the New Madrid fault?

Good question!  I'll lay out the prevalent idea, originally (I think) put forward by Sykes, 1978 and supported by a large body of subsequent work by many authors. There are other models, however.

In the most general sense: Intra-plate faulting is due to old, pre-existing weaknesses that are reactivated due to the plate interiors being very close to critically stressed.

In other words, they're weak points in the interior of the plate.

However, we don't fully understand why some old fault zones get reactivated while others in the same orientation don't.  (It probably has a lot to do with pore pressure and fluid movement at depth.) There's a lot we don't completely understand about intra-plate earthquakes.

Also, please don't use the term "fault line". It offends my geologic sensibilities! :)  (Faults are 2D surfaces, not lines, thus the nitpicky objection.)

Most of the crust is close to being critically stressed (breaking)

There's a lot of evidence that the continental crust everywhere is close to being critically stressed -- in other words, failing in an earthquake.  (e.g. see the various Townend and Zoback papers.) The crust isn't just critically stressed near the plate boundaries, but also away from them. This may also be true for oceanic crust, but we don't have as much data there.

Another way of saying this is that the plates are being pushed along as hard as they can without crumpling.

Basically, this is why things like building a dam or deep fluid injection trigger small earthquakes.  The crust is already close to failure, so adding load or increasing pore pressure often triggers small fractures.  (However, these sort of things can't trigger a major earthquake unless they're on an already active fault.  You need continuous slip along a very large surface for a large earthquake.)

The plates being critically stressed is actually is what we'd expect. We see deformation at plate boundaries whenever they collide. Therefore, we know that the stresses driving the plates are greater than the "breaking" strength of the crust.  Because stresses from a collision at the boundary will be transmitted to the interior, it intuitively makes sense that the interiors should be close to, but just below (otherwise they'd be deforming), the failure threshold. (For the complete argument, see Zoback and Townend, 2001)

Continental crust is full of old zones of weakness

The continents are very old. Much older than the oceanic crust. The continents are like rafts that keep bumping into each other. Therefore, they have lots of "scars" (i.e. old fault zones).

There's a saying in structural geology: "once a weakness, always a weakness". Fault zones are typically much weaker than the crust around them.  Once a fault breaks through, it tends to be a permanent weakness that will be reactivated even if it's not in a perfectly favorable orientation.

Critically stressed crust + weak zones --> intra-plate earthquakes.

But why don't we see activity on all old fault zones?

Short answer, we don't really know.  It probably has a lot to do with pore pressure and fluid movement.

Some old fault zones have intra-plate earthquakes, while others don't, even if they're in the same orientation.  Pore pressure plays a huge role in faulting (it make rocks much easier to break).  There's a lot of speculation that active intra-plate fault zones may have more fluids at depth, though explaining why is difficult.


What happens to global temperature when we stop all the vehicles for a year?

Not much at first. The damage has already been done. Humanity has added at least 100 gigatonnes of carbon to the atmosphere since the start of the industrial age. Natural sequestration of that excess carbon is a slow process. Suppose all human production of carbon ceases (and note that vehicular production of CO2 is but a fraction of the total). It will take centuries to return to pre-industrial levels, and temperatures will continue to rise for decades to come.

Humanity will not countenance a decree to stop using vehicles. You would somehow need to magically dispense the laws of physics, at least those that pertain to internal combustion engines. Food shipments would stop. Riots would ensue within a week of your use of your magic wand.  Your magic want is a death sentence for a huge portion of humanity. People will die in droves. Killing off 90% of humanity is of course one long term solution to the anthropogenic warming problem. It's not a very nice solution.


Can someone help me identify this rock please?

It is quartz. The whiter parts are larger crystals that have grown together and the tan is agate. It formed like a completely filled geode.


You are correct in your intuition regarding the signs of the forces.  The reason for two terms is due to the direction of the force.  The y-direction is not aligned with the face AB (it is aligned with y') so the force on this face is a combination of the forces normal to AB ($-\sigma_{x'x'}AB$) and the force along the face ($-\sigma_{x'y'}AB$).  Because the question wants only the force in the y-direction, we need to find the projection of these forces along that direction.

If the angle between the coordinate axes is $\theta$, then the contribution of $-\sigma_{x'x'}AB$ in the y-direction is $-\sigma_{x'x'}AB\sin\theta$ and the contribution of $-\sigma_{x'y'}AB$ in the y-direction is $-\sigma_{x'y'}AB\cos\theta$, thus the total force in the y-direction is the sum of these contributions:

$$-\sigma_{x'x'}AB\sin\theta-\sigma_{x'y'}AB\cos\theta$$

Here is a quick figure to help visualize the geometry:


According the an Oregon State website,

  Volcanism far from the edges of tectonic plates, such as Chaine des
  Puys, is rare. Changes in the mantle may have led to volcanism at
  Chaine des Puys. Several lines of evidence indicate thinning of the
  crust and upwelling of the asthenosphere. The rising mantle "diapir"
  was probably a total of 30-60 miles (50-100 km) in diameter.

Chain des Puys is the 40km long chain of volcanic features to which Puy de Dome belongs. It sounds like the causes are not completely understood. Unfortunately, all the papers I could find on the topic are in French (understandably), so if you can read French you can try Google Scholar to see if there is more info there.


Is the Mauna Loa CO$_\mathsf{2}$ record affected by the nearby mantle plume?

How is ist possible that Mauna Loa Observatory is the International Reference Observatory for CO2 Global Meassurments

I don’t know that it is ‘the International Reference Observatory’. The Mauna Loa record is almost certainly the most-cited decadal-scale CO2 record, but as far as I know the observatory hasn't been accorded any special status: the record is used on its own merits. Googling for the phrase ‘International Reference Observatory’ gave me precisely one hit, which strongly suggests that it's not a well-defined term. The hit comes from Roussel-Debet et al. (2006), and appears in the following context:

  … the atmospheric CO2 values measured at the international reference observatory at Mauna Loa (Fig. 5)…

Note the lack of capitalization. I don’t think that this implies the existence of a single, officially defined ‘International Reference Observatory’ at Mauna Loa. Rather, it's like writing ‘the solar observatory at Mauna Loa’: there are many solar observatories, and this clarifies which one we're talking about. Similarly, there are several observatories which produce internationally used CO2 data, and this specifies which one we’re talking about here.

  if it is placed above the most important earth thermal plume that is heating the ocean all the year?

It’s true that there is a posited mantle plume below Hawaii, so it seems likely that there might be increased thermal heat flux at the sea-floor. (Incidentally, I’m not sure what would make this mantle plume ‘the most important’, or even how one would quantify the importance of a mantle plume.) However, Von Herzen et al. (1989) found that

  … even though there is a small increase in heat flow with age along the swell, when compared with the off-swell heat flux, the anomalous heat flow associated with the Hawaiian Swell is probably of the order of 5–10 mW m−2 and arguably may not exist at all.

But more to the point: even if there is slightly increased heat flux here, why do you think it would affect the CO2 readings? What mechanism are you suggesting by which a small amount of conducted heat, several kilometres below sea level, is able to perturb atmospheric CO2 concentrations several kilometres above sea level?

Finally: even if there were such a mechanism, the mantle plume operates, as you point out, ‘all the year’ – year in, year out, for millenia before the Mauna Loa station even existed. So at worst it would produce a constant offset, and wouldn't affect the trend of the measured CO2 concentrations.

  How reliable can these data be?

Very reliable indeed! Look at this comparison with records from Samoa, Barrow, and the South Pole.

Source: NOAA

Naturally, the shape of the annual cycle varies depending on the measuring station's latitude (you can see that the South Pole record is out of phase with the northern hemisphere records, as you'd expect), but the trends are an indisputably excellent match. If there were some confounding local influence at Mauna Loa, we certainly wouldn't see it reproduced at other sites thousands of kilometres away.

  Is it due to the 3000 m altitude of the Observatory?

That's certainly one factor that makes Mauna Loa an excellent site for this kind of study. This Skeptical Science page lists some others:

  Early attempts to measure CO2 in the USA and Scandinavia found that the readings varied a lot due to the influence of growing plants and the exhaust from motors. Mauna Loa is ideal because it is so remote from big population centres. Also, on tropical islands at night, the prevailing winds blow from the land out to sea, which effect brings clean, well-mixed Central Pacific air from high in the atmosphere to the observatory. This removes any interference coming from the vegetation lower down on the island.

For more detail on how measurements are taken at Mauna Loa, and how the data is checked to make sure that it’s not contaminated by local influences, see this detailed NOAA page on measurement procedures. The section on ‘Data selection for background air’ is particularly relevant to your question. (Thanks to jeffronicus for providing this link in the comments.)

As to your final question:

  Does not affect the geological Hawaiian situation?

I assume that you meant to write ‘Does the Hawaiian geological situation not affect the readings?’. I hope I’ve made it clear that it doesn’t, and that Mauna Loa is so widely used precisely because of the absence of local influences on the readings.

References

Sylvie Roussel-Debet, Gilles Gontier, Françoise Siclet, Marc Fournier, Distribution of carbon 14 in the terrestrial environment close to French nuclear power plants, Journal of Environmental Radioactivity, Volume 87, Issue 3, 2006, Pages 246–259, ISSN 0265-931X, doi:10.1016/j.jenvrad.2005.12.002.

Von Herzen, R. P., M. J. Cordery, R. S. Detrick, and C. Fang (1989), Heat flow and the thermal origin of hot spot swells: The Hawaiian Swell revisited, Journal of Geophysical Research, 94(B10), 13783–13799, doi:10.1029/JB094iB10p13783.


If the earth's surface is negatively charged, why aren't objects close to the surface polarized?

Think of the electric current as a fluid, and a battery or some other source of current as a pump. Change the earth for the ocean.
I don't know about the negatively charged earth's surface, but those -500,000 coulombs are an absolute measure of charge. That charge is distributed over some surface, and the earth's surface is pretty big.


According to page 86 of Exploring the World Ocean:

  In December 1989, ODP scientists drilled Hole 801C
  and recovered Jurassic-age rocks and sediments, about
  170–165 million years old, from the Pigafetta Basin in
  the western Pacific, near the Mariana Islands. Sediments
  of nearly identical age had been found previously from
  the Deep Sea Drilling Project Hole 534A, located on the
  Blake-Bahama basin in the central Atlantic. These sediments
  and the rocks on which they rest are among the
  oldest oceanic crust found in the world ocean.

There is a more-detailed discussion at Site 801: Sedimentology and Biostratigraphy


Golden and red colored light even after sunset

This is a result of Rayleigh scattering, the same reason the sky is blue.  As the sun sets the optical path for a photon passing through the atmosphere to your eye  increases.  Because of this increased distance through the atmosphere, more scattering occurs and the shorter wavelengths are scattered away, leaving the longer wavelengths.  This results in light that is reaching your eye tending toward red and the yellow to orange and gold hues are produced on the way to red.

The reason you can still see this persist after sunset is because the sun below the horizon can still reach you through scattering though clouds can enhance this effect (because clouds are good at scattering all visible wavelengths and clouds you can see can be illuminated by a sun you cannot see).  This is the same principle as above, with the addition of the scattering by the cloud.  You'll have Rayleigh scattering on the way to the cloud through the atmosphere, uniform scattering off the cloud and then more Rayleigh scattering between the cloud and your eye.  The longer these distances become, the more red the light reaching your eye has become, and thus the sky will take on the reddening hue (with the yellow/orange/gold colors in the transition to red).


Has anyone driven under, or received camera footage from, the Great Artesian Basin in Australia?

Groundwater is stored in the porosity of rocks, that is space between clasts or cracks. Larger cavities, e.g. karsts, is usually only a minor contribution to ground water reservoirs and are only common in limestone.

The Great Artesian Basin aquifer is made up of Mesozoic sandstone. It is covered by impermeable rocks that allow pressure to build up within the aquifer so that as rainwater enters at high elevation it will keep the hydrostatic pressure, even when the topography is lower.

The only way to see the rocks at great depths is by drilling and, if the budget allows, also keep core sample to be able to analyze it. Important information also comes from borehole logging when geophysical instruments are lowered into the borehole to measure e.g. porosity and density of the rocks. One can also see the continuation of the formation on the surface and study the rocks to understand how they look at great depths.

This informative document explains some of the features of The Great Artesian Basin rather well, but don't be mislead to think about the aquifers as caves, it is only water soaked rocks.


Diamonds are expensive. Really expensive. Even "cheap" synthetic diamonds are orders of magnitude more expensive than conventional fossil fuel. By using them as fuel, you will increase demand, thus increasing their price even more. And synthetic diamonds have to be made somehow, and you need energy for that.
Diamonds burn, but they don't burn well. For example, look at this video of diamonds burning in pure oxygen. The burning sustains for about a minute after the heat source is removed, but then it stops. So then, you need to apply a constant source of heat, and this requires energy. You will probably have to put in more energy than you get from the combustion of diamonds. Kinetically, diamonds just don't burn as well as other things with carbon (like fuel or wood or coal).
One of your arguments is that diamonds burn "cleanly" (let's not forget that CO2 is a pollutant as well). Burning of natural gas emits only CO2 and H2O, so it's a much better alternative when pollution is a consideration.
Diamonds are so much more useful for other things. Don't waste diamonds on energy production!


Severe storm predictions: What meteorological considerations go into hazard assessments?

The SPC's changeover announcement webpage offers very useful information on the change, and is central to this answer...

Correction:
There were actually 4 categories prior to the change.  The SPC used the "See Text" area for what is now designated as a "Marginal Risk".  These did not have colors or outlines, but instead just the words "See Text" on the map.

Note that the "See Text" area actually did have a "hidden" outline, in the tornado\hail\wind risk percentage contours that went in hand with them, as in:

Reasoning for changes:

For the shift from "See Text" to "Marginal", SPC indicated that the trouble was the lack of a precise areal outline.  There were also concerns that the "See Text" area could be overlooked or confusing to the public.

For the implementation of the "Enhanced" designation, SPC asserts that the "Slight Risk" covered too large a range of potential weather.  It definitely is true that "Slight" was by far the most used forecast.  I chose a random month prior to the changeover - July 2014... there were 23 days topping at slight risk, 3 days of moderate risks, and 5 see text days.

There were also slight realignment by weather type, and downward shifts in a couple spots.  The overall changes are summarized in this table of risk criteria:

Old data taken from archive.org

Other Countries:
It's important to note that the US is on the forefront of focus on severe weather and especially tornado forecasting.  Many parts of the world have minimal forecasts.  One key cause of this is that the US averages over 1,000 tornadoes per year, while Canada only about 100, all of Europe about 300, and most of the rest of the world even less (see Wikipedia or this article from ustornadoes.com).

The UK looks like it uses a three color scale of yellow, amber (orange), and red for notices on all weather hazards, which is a combination of how likely the event is with impact table levels of very low, low, medium, and high for how destructive it will be.  It appears that they only issue warnings for thunderstorms, hail, and wind, not for tornadoes directly.  A more straightforward scale... though some concern that the words very low and low suggest a lack of danger... I believe the US avoids these terms for this reason, and instead strays into the words you find more confusing.

Canada appears to only have watches and warnings similar to the basic US versions.

South Africa seems to have a yellow, orange, red scale which is a mix time and intensity.  Yellow can be either up to 5 days in advance, or a lesser weather event in the short term.

A quick look around the met office pages for Australia, France, Argentina, Italy, and Bangladesh show no evidence of clearly defined outlook scales beyond equivalents of watches/warnings.

My familiarity with such sites is incomplete, but the fact that tornado warnings in Australia seem to be a rather notable curiosity, and that the Bangladesh main met office page has a counter suggesting only 160,000 visits highlights that the US may well be in a very unique situation in terms of regular supercellular weather and heightened attention to its threats.  And so detailed scales for such weather may be without comparison.  However, though many other nations certainly have threats to cause great consideration, be it blizzards, tropical cyclones, or sand storms... there doesn't appear to be widespread usage of scales with as many levels as the SPC convective outlook.

Validity:

I believe you're right to question it...

A small study in the dissertation entitled Communicating Natural Hazard Risk: Warnings, Decisions, and Precautionary Behavior by Robert Drost (which likely overlaps the subsequent journal article Severe Weather Warning Communication: Factors Impacting Audience Attention and Retention of Information during Tornado Warnings, which is still unavailable except to subscribers, so I have not read)... found that 37% of the participants were unable to distinguish between a watch and a warning.  (Given that the study is of young college students, this probably greatly underestimates overall misunderstanding in the public... though the use of such a small selective sample means the value could be quite inaccurate in any direction).  If we're struggling with fundamental terminology important to direct life-or-death decisions, changes like these do seem hindering to the public.  I spend a lot time on Facebook tv station livestreams during severe weather, meeting and talking through questions with the public... and in my experience you're right that more people are struggling with the new categories.

There is one perspective that may help offer some understanding and even support the SPC changes; there has always been a loose pattern suggesting that the SPC and other NWS specialized offices aim slightly more at meteorologists and emergency managers than the general public.  This is reflected in the extensive usage of complex terminology throughout the site, the conspicuous citation of journal articles, the presentation of statistics and percentages that really wouldn't have much grounding to the general public, and the rather unadorned pages and overloaded navigation menus that all make it very hard for people unfamiliar with the sites to know where to find what they need.  The new categorization may be quite confusing to the general public, but for an active meteorologist, they were quickly adapted to.

However, the SPC and its brethren at the same time puts a great deal of emphasis on mediums like Twitter and Facebook and does television interviews in key weather events.  So it could reasonably argue that in reality, they are also trying to be public-facing entities.  And in the end they wind up having multiple competing personalities/goals (perhaps true of all of the NWS?)

In the end, the goal of course goes back to prewarning the public.  The SPC may wish the broadcast media can consolidate the messages they put out, perhaps down to just a simpler "there is a chance of tornadoes today".  But the reality is that people clamor for exact values and maps, even at times when they aren't that useful.  And so it typically ends up that the outlook map does make it on to the public (or, more troubling yet, presenters create their own competing scales).  And so we wind up back at the issue that the scale probably confuses the public.

We all know that at some point, information overload is a problem.  And that too many terms will confuse people.

So indeed it may well be after all that the relatively minor severe weather events don't need an outline and term to show it as less than "Slight", but rather just a little hint on the image like "See Text" offered.
And whether or not "Enhanced" helps better warn than confuse people is a very legitimate question.

In the end, the SPC page did note that "the NWS has a strong commitment to engaging the social sciences in evolving our services, and this community has helped inform our decision making for this change."  That's where we must look to.  No studies were published on this change that I know of.  But we have to hope they'll continue to look into it.  Social science is definitely still rather nascent and under-explored in meteorology.  Here's to hoping that greater attention and resources can be dedicated to weighing terms and categories like these.  You've raised a good, helpful point... and one that hopefully filters back to the people making these decisions, encouraging some more firm answers and data.  It's something we definitely need to be thinking about more!


The axis of rotation of the earth passes through the geographical poles or is there a true axis?

Geographic axis is NOT fixed.

North and south poles are NOT fixed.

Ideology is reverse of what you are thinking.

First suppose that Earth is rotating about some arbitrary axis => Then this axis intersects on Earth's surface at two points => Now, if you see earth from above and observe earth rotating in counter-clockwise direction then this point is defined as North pole and hence other will be south pole.

In short, first we see earth rotating about an axis and then north and south poles are defined according to it.

Also, the axis of rotation wobbles and as a result north and south pole wanders a bit. This is known as Chandler wobble.

Note: It is very important to realize that according to chandler wobble axis of rotation wobbles with respect to Earth. Earth itself is NOT wobbling due to chandler wobble, it is only changing the axis of rotation.

So, there is no concept of true axis here, but only one axis -> geographic axis which wobbles.


Are there plants or bacteria that perform NO2 fixation and how relevant are they for improving local/regional air quality?

NO2 uptake by plants

It has been observed that plants can lead to a reduction of atmospheric NO2 concentrations [Breuninger et al, 2013]. Currently, it is assumed that NO2 is taken up through stomata of plant leaves when the atmospheric NO2 concentrations are above a certain threshold. However, when the atmospheric NO2 concentrations are below this threshold, plant leave stomata act as sources for NO2. Therefore, this process is not fixation in the sense as N2 is fixed by legumes.

See Breuninger et al. [2013] and refernces therein for details

Canpoy reduction

Plants do not only take up (excess) NO2 actively but they decrease the concentrations of several air pollutants by providing a lot of surface for dry deposition as Christoph stated in his comment. After deposition they may revolatilize or be washed down by rain. See e.g. Grundström and Pleijel [2014] for details.

Impact on air quality

The presence of plants/trees in urban environments can reduce ambient NO2 concentrations. However, this effect is not due to NO2 fixation but due to the canopy reduction/enhanced dry deposition rate, which also yields a reduction of other air pollutants. See e.g. Grundström and Pleijel [2014], Yang et al [2005], or Yang et al. [2008] for details.

The canopy reduction is also considered in recent regional modeling studies - see e.g. Arndt et al. [2016] (Disclaimer: I was member of that working group until recently). It can be seen like increasing the surface roughness.


Soil moisture conditions and air temperatures - literature needed

If you're after "basic" academic work, I suggest the following 2003 textbook from the Utah State University entitled, "Rainfall Runoff Processes", chapter 2:

Runoff Generation Mechanisms

It looks like a pretty good compendium of what you're looking for with easy-to-understand text and clear diagrams. Further detail, if needed, can be found by hunting down the references within. The entire textbook can be downloaded here:

Rainfall Runoff Processes


Both are relatively small secondary effects on global temperature, but at the same time, both are worth studying.

Ice acts like a heat sponge.   It takes heat to melt ice (that's kinda obvious) and less obvious, forming ice releases heat.   Large blocks of ice cool the air when it's above freezing and warm the air when it's below.   Even as ice changes from solid to liquid, without changing it's temperature, the energy change is significant.   This is called it's latent heat of fusion or LHF.

By this article about 2% of the trapped heat goes into melting ice.   A 2% variation on heat that would otherwise, warm the air or oceans or escape into space is almost small enough to ignore, but the effect grows much larger locally near glaciers (perhaps as high as 25%, but the source I found for that isn't one I'd call credible), but certainly, the effect is significantly higher than 2% in the arctic and antarctic.

Latent heat of fusion is also important in calculations for the total energy balance and here's an article from IPCC AR4 that discusses LHF.

As pointed out in the comments, melting sea ice also changes ocean albedo and can lead to a rather quick change in absorbed heat and a reduction in the light reflected back into space.  This also happens on land, mostly snow cover, (as glaciers melt too slowly for that kind of year to year effect), but I don't think that's what the question is asking.

The 2nd part, the change in salinity is (to my knowledge, and I invite correction from anyone who studies this professionally), but from what I've read, it's much more complicated to model than LHF.   It's certainly something that researchers are aware of, both the warming arctic and changes in salinity might effect ocean currents.   Unlike air, where temperature drives density and that leads to low and high pressure and updrafts and basically, weather, oceans have two factors that can effect water density - temperature and salinity.   Warm water is lighter than cold water, but lower salinity water is also lighter than warmer, more salty water.

Small changes in salinity in ocean surface water doesn't have any real effect on temperature directly, but the effect on ocean currents is worth studying because changes in ocean currents can effect temperature significantly, certainly on a local scale, and globally too.

Modelling this, like modeling the rate of future glacial melt, may be close to impossible and when it's written about, it can sound more alarmist than science, so it's a subject that has 2 key problems, difficult to predict (even in the hard to predict climate change models the effect of salinity changes on ocean currents are especially tricky), and it's the kind of thing that might invite shouts from the other side, like Wiesław Masłowski's infamous study that suggested the arctic might be ice-free by 2013.   He was a graduate student, not a climate scientist and his was a good study and preliminary.  It should have been subject to peer review, instead, (in part because Al Gore used his study in a speech), it became a famous example to alarmism and was subject to much ridicule that persists to this day.

Scientists are certainly aware of the possible effects of salinity changes and the effect that might have on ocean currents, but it's very difficult to model and mostly written about observed effects in the present, and mostly not written regarding future forecasts.   Predictions like "the Atlantic current could shut down" may be based in science, but low probability predictions like that tend to invite criticism.

Fresh water/ice melt is discussed in Wikipedia here and here's an article where the opposite is happening.   As arctic sea ice recedes, the lighter, less salty water on top isn't present as much as it used to be and the arctic-ocean stratification is going away.   Article on that here.

It's also worth noting that glacier fed rivers will affect the ecosystem down-river, putting less or more water into the environment leading to less or more greening and less or more water evaporating off the river into the atmosphere.   It's more common for rivers to be fed by snow melt than glacial melt, but the glacial melt should be studied too.   Changes in greening down-river and in atmospheric water vapor also effect climate, so, as someone said in the comments, there are a lot of moving parts to the climate picture.

Generally speaking, scientists are aware of all of this and as much as possible, study it and include it in models.


"Five of the Solomon Islands disappeared" due to sea level rise, how is this possible so quickly?

The sea is not the only thing that rises, the sea floor can also rise and fall in accordance with the underlying geology. Oceanic tectonic plates sink as they age (and thus get colder and denser), the Solomon islands happen to be on a  sinking section of the ocean floor and at the same time the sea level is rising. Keep in mind many of those islands have a very shallow slope, so a few rising millimeters are many feet of inland horizontal motion. Of course once the wave base reaches  new "virgin" sediment (often loose sand), it often washes it away moving the tide line even further inland.
Storms cause a storm surge which can wash away sediment. A rising sea level means the storm surge is reaching sediments they could not reach before, so they are causing faster erosion. In addition, salt water kills a lot of plants further eroding the sediment, so a higher surge means more dead plants and more settling of sediment. Storms can cause a tremendous amount of erosion on unprotected soil, a single storm washed away two entire city blocks in the Atlantic City history.
I am not entirely sure, but prevailing winds can cause some displacement of water (the ocean is not completely leveled because it is moving) so a change in the trade winds could lead to a minor effect of local sea level, how much this contributes, I have no idea.

Note: the OP started with a numbered list and specifically asked about the highlighted numbers, hence only 2-4 were referenced in my answer (the first one was a normal sea level rise).


Why is McMurdo Station in Antartica more hostile than Longyearbyen (Norway), while Longyearbyen is closer to the pole?

The lack of oceanic and atmospheric currents going into and around Antarctica from equatorial latitudes means that much less heat is transported from the tropical latitudes to Antarctica compared to Svalbard. Therefore, at equal latitude (i.e. equal solar isolation), temperatures in the south are much colder.

In Antarctica, at 75°S latitude most of the land has permanent snow cover.

As for the flights, in addition to the fact regarding the distances mentioned by Erik, also consider that the only landing strip in McMurdo that can be used by planes with wheels is over an ice shelf (a floating platform of ice). Therefore, installing proper airport instrumentation is impossible, and landing is performed mostly by visual navigation. This is something that can not be done safely in the permanent darkness of winter months or in bad Weather.

There are scheduled commercial flights in summer from Punta Arenas to Union Glacier (latitude 80°S and more hostile than McMurdo). But they are extremely weather dependent. Most flights gets delayed, and waiting a week to fly is not unusual (it was even more common when the landing strip was some kilometers south in Patriot Hills).
Therefore, an Ilyushin 76 plane is waiting in Punta Arenas the whole summer just to fly once a week at most. All that added to many other logistical complications makes the round trip ticket to Union Glacier about USD$22,000. It wouldn't be much cheaper to McMurdo, so you can imagine that few people will be able to afford it. Therefore it is kind of a niche business that is not attractive for commercial airlines.

The only landing strip that is on solid ground in Antarctica and is large enough to receive commercial planes (medium size, nothing big) is on King George Island (latitude 62°S). DAP airlines also has scheduled commercial flights there, but they are also extremely expensive.  Tourist flow in winter is minimal; Auroras generally aren't seen there, and  therefore there is little draw for tourists to visit during the winter.


Is weathering of rock a primary means of $\text{CO}_2$ scrubbing on primordial Earth?

NO, it's not a very major sink on our planet, red is the extra carbon from human activities: https://jancovici.com/en/climate-change/ghg-and-carbon-cycle/wont-the-carbon-sinks-absorb-the-extra-co2/

Cool theory about Venus. It lacks a strong magnetosphere, so the solar wind carries away more light elements like hydrogen, and water vapor, the solar wind has carried away all the seas of venus since about 2 billion years ago, probably aided by the sun being 30% bigger and hotter there.
So, if Venus had kept it's CO2 levels in check, it would probably have sunk them in limestone, and also weathering if there was tectonic activity. Weathering does account for 0.2 to 1 gigaton of CO2 sink every year, compared to 30 gigatons released every year from fossil fuels.
The primary store of carbon in the earth's surface is in limestone, comprising about 60,000,000 gigatons of carbon, and coal and oil. the total amount of carbon near the surface of the earth is source 120 million GtC. Life exists on our planet since about 3.8 billion years, so it could have survived in Venusian oceans until about 2 billion years ago. That's the same time that the first major limestone layers appear on earth about 2.4-2.8 billion years ago. https://www.skepticalscience.com/weathering.html#significance


Velocity gradient of surface ocean current in dephts

Yes, the speed of currents varies with depth.

In the case of shallow, coastal water, the flow is retarted by friction at the seabed, so it is slowest at the seabed and usually has a curve of increasing speed towards the surface.

This curve can theoretically be calculated, but in practice it is very sensitive to things like the material and shape of the seabed, wind and waves near the surface, and so forth, so while estimates can be made from theory, it's usually better to measure it.

Approximations are often made using a "power law" such as

$u_1 = u_2 \left( \frac{z_2}{z_1} \right)^{\frac{1}{\alpha}}$

where $u_1$ and $u_2$ are the speeds at distances $z_1$ and $z_2$ above the seabed respectively, and $\alpha$ is an arbitrary value often between 5 and 7.
This figure, from Lewis et al. 2017 (creative commons licensed), illustrates a number of such theoretical curves with different values of $\alpha$.

In deeper oceans this mechanism will only apply close to the seabed; however, far more complex systems can come into play, with different water bodies moving in (potentially) different directions. Possibly others with more expertise in ocean dynamics can address that case.