What is the characteristic time of the loss of the Earth atmosphere, how can it be calculated?

Even in the exosphere, at 1800 deg centigrade, the only components of the Earth's atmosphere that can currently attain escape velocity are hydrogen (3 kg per sec), and and helium (next to nothing). The notion that the Earth's atmosphere would be stripped away by solar wind but for the protective magnetic shield, is a myth. So there is no 'characteristic time of loss of the Earth's atmosphere' in the sense of slow decay. There is certainty that, as the sun approaches the red giant stage, several billion years from now, there will be catastrophic heating of the atmosphere such that oxygen and nitrogen will be stripped away, leaving Earth to overheat in runaway carbon-dioxide. Unless, that is, if gravitational mayhem, caused by galactic collision with Andromeda, flings Earth substantially further from the sun.

Oxygen, nitrogen and inert gasses can escape from bodies the size of the moon, Venus and Mars because the thermal process, 'Jeans Escape', in less massive bodies incurs substantially lower escape velocities.


How do the different densities of the oceanic and continental crust affect earth's outer shape?

The two confusions have everything to do with Isostasy as mentioned by Gimelist. I advise you to read the Wikipedia page because it will explain everything to you! But maybe this helps:

The continental crust is made up of relatively light-weight material compared to oceanic crust. That's really all that the authors of your book should have said.

The fundamental idea of isostasy is that from a certain depth onwards to the center of the earth, the pressure is identical no matter where you are. This 'compensation point' is usually taken at about 100 km depth. This is an assumption about the physical state of the Earth -- it is thus an assumed reality!

This means that you can take any single column from 100 km depth (say, a cylinder, or a square meter) and extend it all the way to the surface, and all the columns that you could choose must weigh exactly the same (such that they cause the same pressure at 100 km depth). Mathematically, this is an integral over the densities(!) that you encounter as you move towards the Earth's surface: $\text{Pressure}=\text{mass}/\text{area}=\int_{100 \text{km depth}}^{\text{surface}(x)}\rho(x,z)\Delta z=\text{constant}$. It is the density that varies with $x$, i.e. your location on the earth, that makes the exact location of the $\text{surface}$ variable with $x$ also!

So you're moving up in your column and summing all the densities you encounter every meter. Density is always positive, so your sum is always growing. You also know that the solution has a fixed, constant, solution. We could thus just keep integrating from 100 km depth towards the surface, and when our integral reaches the constant, we know that we are at the earth's surface! That's a useful bit of information, because...

If the material in your column is relatively dense, the distance from 100 km depth until the $\text{surface}$ must then also be relatively small, because you're reaching the integrated constant faster! And vice versa, if the material in your column is relatively light you know that the surface extends out relatively far. It then follows that the oceanic crust has its surface at a lower level than the continental crust, because it is about 20% denser.

Effects of buoyancy only make the matters worse, as continental crust tends to be much thicker than the oceanic crust, and correspondingly it 'floats' higher on the fluid-y astenosphere below it. This is much like an iceberg floating on the sea: a larger iceberg both sticks into the sea more and sticks out of the sea more. The continental crust does the same: it has a deeper base and higher surface than the continental crust, because it 'floats' on the more dense 'fluid' underneath.

There are thus roughly two effects (although of very similar physical principles) that make the continental crust rise above the ocean crust: it is less dense and it is thicker! Therefore, continental crust rises above continental crust to produce the same pressure at depth, and its base lies below the oceanic crust because it is thicker (and floating like an iceberg).
So the missing piece of information in your book was the perspective of a constant pressure. I hope that helps :-)


What is the difference between a geologist and a geophysicist?

First of all you have to think about that both geology and geophysics are huge fields and even people that think of themselves as a geologist or geophysicist can have vastly different research topics.

If a geologist and a geophysicist are interested in the same topic, e.g. the lithosphere, they will have a lot in common. In this example I think the main differences would be methodology. While a geophysicist would rely on the analysis of seismic waves, numerical simulations and modelling, a geologists would work more with lithospheric scale cross sections, and geologic data that he or she can gather on the surface.

In summary I would say: The fields have much overlap, many differences, and when approaching a question more calculations and modelling will be done in geophysics and more field work and lab work (petrology, age dating, stratigraphic age, ...) will be done in geology.


Sea water is all very corrosive; the precise composition is not significant. Steel structures are cathodically protected with impressed current and/or sacrificial anodes, usually aluminum. For equipment to be cooled with seawater there are a few choices ;However, for the Navy where reliability is more important than the cost , titanium would be the material of choice ( Type 2 , but types 1 and 3 or the Pt alloy - forgot the number- are also good).The variables for sea water corrosion are : temperature, velocity, sediment, and marine growth, not composition. Inco/Huntington probably evaluated every possibility for sea water corrosion at the La Que labs in Wrightsville Beach NC. Work done before Harvard MBAs' in management eliminated "research" from "research and development". Papers will be published under "Seahorse Institute" and NACE ( National Association of Corrosion Engineers). NACE will have various current publications available for sea water corrosion ( located in Houston TX). Most of this R & D was done before the internet so it won't be available on-line.


Are there any sulphides, sulphates, carbonates that cannot be dissolved by aqua regia?

This was also asked in Chemistry Stack Exchange, where it was noted that barium sulfate is insoluble in water and generally insoluble in acids.  A quick check reveals that indeed the otherm minerals can be dissolved in nitric acid and so should yield to aqua regia.  Thus barite is the troublemaker.
Barite can be dissolved in hot alkaline chelating solutions, as described here[1].  This, of course, is not compatible with the acidic solvent you intend to use to dissolve and measure the gold.  It is not clear from the reference whether a pretreatment with such a chelating agent to remove the barite before placing in aqua regia would work when the barite is intermixed with the alkali-insoluble sulfides listed in the question.
Reference
1.
Bader Salem Ba Geri, Mohamed A. Mahmoud, Reyad A. Shawabkeh,  Abdulazeez Abdulraheem, "Evaluation of Barium Sulfate (Barite) Solubility Using Different Chelating Agents at a High Temperature", Journal of Petroleum Science and Technology 7(2017), 1, 42-56.


Geomorphology of Mountains With Wind only Erosion

You do have an earth analogue for this. The Namib Desert in Namibia has been a desert for the past 2 million years with very little precipitation. Also the Atacama Desert is hyperarid since more than 25 million years.

Mars is probably a planet that has below freezing temperatures for million of years, with only wind as an erosional process (apart of a few gravitative processes).

Granite is weathering in roundish forms, as it takes no clear direction from crystallisation. Usually the granite erodes in arid landscapes because of temperature changes and tiny differences in moisture and salts. In a completely frozen plant without a strong atmosphere you would probably still get round forms like Inselbergs.
Furthermore there are of course different kind of forms of wind erosion resulting in strange looking shapes.

High mountain ranges on earth are always limited by erosion from water or glaciers (frozen water) in their growth, as there is more precipitation with altitude.
To get sharp mountains you will need plate tectonics, which will result in the formation of an atmosphere and the release of heat and water (I assume the formation of an atmosphere since platetectonics are associated with volcanismn, which will lead to water and other chemicals like CO2 being released). Thus you will get erosion from water. If the plate tectonics stop and the atmosphere disappears, the mountains will stop growing and there is no moisture left for erosional processes. Then erosion by wind will be the primary geomophological process and the planet could look like Mars.

(I admit this is highly speculative, but the question is speculative in itself.)


Aligator or Dinosaur Fossil skin type rock

I agree with commentator @John, this is a fossil coral.  The coral animal (the polyp) builds a column, and as it ages it closes off the bottom and extends the upper lip.  In some of the views you see the column structure.  In others you see the arrangement of polyps.  It looks like the cells of the coral are filled in with calcite, which probably made the fossil harder than the surrounding rock.  When the rock weathered the fossil coral broke apart.  It looks like this piece is a rounded pebble from a stream bed.  Or possibly the coral broke up and was rounded by wave action.

Compare this picture http://www.fossilmuseum.net/fossil-art/cnidaria/tabulatecorals.jpg


What type of fossil is this found at northern Ohio?

Of course 5 minutes after I post the question, I find the answer myself:
Halysites (Chain Coral) fossil extinct coral from the Silurian period.


It depends on what type of test. If you just want simple identification this site offers a tentative one and any museum with a mineralogy section will have someone on staff who can do identification and they are usually happy to do it. Ditto for an college with a geology class/program. you might want to call/email the professor in question first to make sure they are willing. All these are usually free, although for the museum you should at least pay the admittance fee out of courtesy. You can also look for a local rockhound club.


Now you see, humidity and rainfall are connected, but not in the way that you'd expect...

Let's suppose that their are rain clouds already in the air, maybe a couple hundred meters to a kilometer or so. Now imagine two scenarios:

1) Humidity of the air is low

2) Humidity of the air is high

Oh, and there is one more thing you need to understand before we move on. As raindrops fall, some of the water will evaporate into the atmosphere, increasing the humidity; but the air can only absorb the water if it has low humidity. Okay, back to our example.

1) Humidity of the air is low

Air can absorb a lot of water
As the rain drops fall, most, if not all of the water will be absorbed (evaporated) in the surrounding air

2) Humidity of the air is high

Air can absorb little to no water
As raindrops fall, the water will not be absorbed into the air

The second example is called rain. The first example is called virga. And yes, when virga happens, some of the rain drops don't even reach the ground! Crazy, right?

But now to answer your question...

I'm assuming that your clouds are relatively low to the ground, maybe no more than a kilometer. Also in April, the sun isn't that strong, so it doesn't have a chance to evaporate that much water.

Just remember, all scenarios are different, but as a general rule of thumb, the less humidity, the more rainfall.

EDIT:

This doesn't mean that places with less humidity must get rain. No. Rain cloud formation and humidity are completely unrelated. Rain clouds can form in whatever condition and in any place at any time. Humidity on the other hand affects whether or not the raindrops actually touch the ground.

It'll still rain with low humidity, but the raindrops might get absorbed into the air before they hit the ground. In some cases with low humidity, the sun isn't strong enough to evaporate all the water, so there'll only be a light shower. Sorry for the confusion.


How would the Earth look without water in the oceans?

National Geographic made a documentary called Drain the Ocean, this is You Tube link to part one. the other three parts are there as well.


The subtropical jetstream
The subtropical jetstream can be explained with angular momentum arguments.  In an idealized circulation model of the atmosphere, there is a hadley cell that circulates upward at the equator, poleward along the tropical tropopause, downward around 30 N/S and equatorward at the surface.  Parcels rising at the equator have a fair bit of angular momentum from the rotation of the Earth.  As these parcels move poleward they tend to conserve this momentum and this manifests as a westerly wind.
The subtropical jet is weak in the summer (ITZC and maxmium solar heating disrupt the hadley cell in that hemisphere), strong in the winter and is generally fixed at around 30 N/S and at a higher altitude than the polar jet.
The polar jetstream
The polar jetstream draws its energy from horizontal temperature gradients in the lower troposphere as a consequence of the thermal wind.  To understand the thermal wind, consider a temperature gradient at the surface, cold toward the pole and warm toward the equator.  Over the cold air, heights of pressure levels will be lower than normal and over the warm air the heights will be higher than normal.  If you look at any pressure level this will result in a height gradient with higher heights toward the equatot.  This gradient will increase with height.  The geostrophic wind is proportional to the height gradient and thus increases with height.  The polar jet exists where these surface temperature gradients are strong but above them around 250 mb.
You will find the polar jet wandering around and associated with the strong surface fronts that come out out of the poles and into the mid-latitudes.  It will be stronger in the winter when the fronts are stronger.  During the summer the jet will remain at higher latitudes and in the winter can dip well into the mid-latitudes.


Hypothetical: Can we rehabilitate arid/desert landscapes through the artificial precipitation from exhausts of hydrogen powered airplanes?

Rough calculations: A 747 burns about 10000 kg of fuel an hour. Assuming it burned hydrogen at the same rate it would produce about 100000 kg (or litres) of water an hour. Flying at 1000 km/hr that means it produces 100 litres of water per kilometre of flight, or 0.1 litre of water per metre.  Lets assume all of this water drops vertically below the plane in a path 100 metres wide. That means that we have 0.001 litres/m$^2$ of water, equivalent to 0.001 millimeter of rainfall. The plane could then turn around and repeat the pass, so in a 10 hour working day we could have 0.01 mm of rainfall
If we take a threshold of desert very conservatively at 200 mm rain per annum, and fly our plane backwards and forwards along a 1000 kilometre path for 10 hours a day, 5 days a week, it would only create 2 mm of rainfall a year. So to get 'non-desert' along our 100 metre wide strip of desert we would need to fly 100 planes every day!
Looked at another way. The Aswan dam in Egypt irrigates an area of 300,000 square kilometres. The dam releases about 50 cubic kms of water per year. 50 cubic kms  is 5 x 10$^{13}$ litres of water. Our plane produces 10$^5$ litres per hour, so we would need 10$^8$ , or 100 million, hours of flight to produce the same volume.  That would be 100,000 jumbo jets flying 24 hours a day, 365 days a year to irrigate an area equivalent to 3% of the area of the Sahara.


How to plot a Hovmoller diagram in MATLAB?

Here is an example using contourf. The trick is in sampling the 3D arrays appropriately:

    x=linspace(0,pi,20);
y=linspace(0,pi,10);
t=0:10:120;
[X3d,Y3d,T3d]=meshgrid(x,y,t);
[X2d,T2dx]=meshgrid(x,t);
[Y2d,T2dy]=meshgrid(y,t);

dat3d=7*sin(X3d)+5*cos(Y3d)+T3d/max(T3d(:))+rand(size(X3d));
dat2dx=7*sin(X2d)+5*cos(y(5))+T2dx/max(T2dx(:))+rand(size(X2d)); % at y(5)
dat2dy=7*sin(x(12))+5*cos(Y2d)+T2dy/max(T2dy(:))+rand(size(Y2d));  % at x(12)
%%
figure(1);clf
contourf(X2d,T2dx,dat2dx);
shading flat; colorbar
ylabel('Time (days)')
xlabel('X distance (km)')
%%
figure(2);clf
contourf(Y2d,T2dy,dat2dy);
shading flat; colorbar
ylabel('Time (days)')
xlabel('Y distance (km)')
%%
figure(3);clf
subplot(221)
contourf(squeeze(X3d(5,:,:)),squeeze(T3d(5,:,:)),squeeze(dat3d(5,:,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('X distance (km)')
title('Hovmoller at y(5)')
subplot(222)
contourf(squeeze(Y3d(:,12,:)),squeeze(T3d(:,12,:)),squeeze(dat3d(:,12,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('Y distance (km)')
title('Hovmoller at x(12)')
subplot(223)
contourf(squeeze(X3d(8,:,:)),squeeze(T3d(8,:,:)),squeeze(dat3d(8,:,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('X distance (km)')
title('Hovmoller at y(8)')
subplot(224)
contourf(squeeze(Y3d(:,17,:)),squeeze(T3d(:,17,:)),squeeze(dat3d(:,17,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('Y distance (km)')
title('Hovmoller at x(17)')


CO2 density, is it really a greenhouse gas?

Yes, carbon dioxide truly is a greenhouse gas.

With regard to the immediate greenhouse effect, 99.96% of the dry atmosphere might as well be vacuum. Nitrogen (N2), oxygen (O2), and argon are extremely weak greenhouse gases at the temperatures present in the atmosphere. The only greenhouse gases in our atmosphere are trace gases. (The most powerful greenhouse gas is water vapor, and that, too is a trace gas in our atmosphere.)

The 99.96% of the atmosphere that doesn't directly participate in the greenhouse effect is however present. At sea level, a molecule of carbon dioxide will travel freely for about a tenth of nanosecond before colliding with another gas molecule. This mean time between collisions increases to a few tens of nanoseconds at the top of the troposphere. A greenhouse gas molecule such as CO2 that has just absorbed a thermal infrared photon will very quickly transfer that absorbed energy to the non-greenhouse gases that comprise the vast majority of the atmosphere.


How does Vertical Electrical Sounding Work?

The diagram is perhaps a little mis-leading.
Think of the ground/rock between the electrodes as a big resistor. The surrounding rock can be modeled as a set of parallel resistors. Most of the electrons will take a direct straight line route between the electrodes, but some of them flow through this surrounding rock, so increasing the current and reducing the measured resistance.

In theory this parallel resistor model could go off to infinity (or the other side of the Earth), however if the probes are close together, then the resistance for the electrons to go down and then back up counteract any reduction in overall resistance. Yes there's a contribution but it is vanishingly small.

Move the probes further apart and rock of varying depths (and widths) can add effective current carrying capacity - as per the diagram. Just remember that for the outer probes, the electrons are also moving horizontally, as well as in the deeper tracks.

So what you measure is a composite effect of many depths. By moving the electrodes further apart, you can sample deeper, but you are still measuring a composite resistance.

This makes interpretation difficult! In fact, the only time I've seen or known a Schlumberger or Wiener array being used, was in a student demo that I participated in.

Resistance is much more practical in the archaeological domain. Here, two electrodes are left at a base station, and two are moved around in a sampling frame (rather like a zimmer frame or walker). Then you are sampling shallow variations localized to the frame-mounted electrodes. Eg. shallow stones, charcoal, etc. The resulting images are much easier to interpret and often appear on TV shows like Time Team, Discovery Channel, etc.


How do mantle plumes travel from the core of Earth to the crust?

The high values obtained when estimating the Rayleigh number for the mantle indicates that convection there is vigorous, and that convection is responsible for almost all the heat transported from the deep interior to the surface. Similar systems set up in the laboratory can develop 'plume-like' patterns of convective flow, and so mantle plumes are a physically plausible model of mantle convection too.


Can the clouds on Venus and Titan be categorized in the same way as clouds on Earth?

Clouds on Venus

After a quick search, it appears the clouds found on Venus are different than Earth's:

  Venus is covered by a thick layer of clouds. These clouds are made
  mostly of sulfuric acid and are very fast moving, going up to 220
  miles per hour (350 km per hour). The clouds rotate 60 times faster
  than the planet rotates. The clouds circle Venus in four Earth days;
  the planet rotates around its axis in 243 Earth days. These
  quickly-moving clouds distribute the heat around the planet, making
  the night side hot also. V-shaped cloud patterns are visible in the
  middle latitudes when the clouds are examined in ultraviolet light.
  The clouds rain sulphuric acid (extremely acid rain), but this
  corrosive precipitation does not reach the surface. The high heat
  beneath the clouds (up to 220°C) evaporates the rain drops about 10
  miles (30 km) above Venus. SOURCE

Clouds on Titan

According to this release by NASA, Titan has "cirrus-like" clouds:

  Now, thin, wispy clouds of ice particles, similar to Earth's cirrus
  clouds, are being reported by Carrie Anderson and Robert Samuelson at
  NASA's Goddard Space Flight Center in Greenbelt, Md. The findings,
  published February 1 in Icarus, were made using the Composite Infrared
  Spectrometer (CIRS) on NASA's Cassini spacecraft.


How much energy does the Moon transfer to the Earth, does this affect the Earth's surface temperature?

According to a slightly old estimate, the total power input from the tides is approx 3.7 TW [1]. Of this about 3.2 TW is from the moon (the rest is from the sun). Most of it goes into moving the oceans around, and some of it into doing the same with the land - but both ultimately end up as heat.

The question of how much this power affects the temperature of the earth is beyond my expertise, but it's a small amount of power at a planetary scale. Some very approximate comparisons:

Tidal power from the moon: 3.2 TW [1]
Total global electricity consumption: 3-4 TW
Geothermal heat flow from the earth's interior: 30 TW [1]
Total sunlight hitting Earth (outside the atmosphere): ~175,000 TW [1,2]

[1] Munk & Wunsch 1998; http://www.sciencedirect.com/science/article/pii/S0967063798000703 - probably paywalled.

[2] https://www.e-education.psu.edu/earth103/node/1004


Unwarranted claim of higher degree of accuracy in zircon geochronology

I can't be entirely sure but I'll make an informed guess:

That value doesn't come for a single measurement. Therefore, if the error in the age of a single sample is $\pm125$ kyr, you just need to average 16 samples to get it down to $\pm31$ kyr.

The uncertainty in the addition (or substraction) of two or more quantities is equal to the square root of the addition of the squares of the uncertainties of each quantity (assuming they arise from random errors). For example, if we have quantity A with uncertainty $\sigma_a$ and quantity B with uncertainty $\sigma_b$, the error in the quantity $C=A+B$ would be:

$\sigma_c=\sqrt{\sigma_a^2+\sigma_b^2}$

And if we call M to the average between A and B. The uncertainty in the average is

$\sigma_m=\frac{\sqrt{\sigma_a^2+\sigma_b^2}}{2}$

So if we average 16 samples with $\sigma=125$ kyr, the uncertainty in the average would be

$\sigma_m=\frac{\sqrt{16 \sigma^2}}{16}=\frac{\sqrt{16 \times 125^2}}{16}=31$ kyr

Uncertainty propagation can be seen in the abstract of the article you refer to:

  The extinction occurred between 251.941 ± 0.037 and 251.880 ± 0.031
  Mya, an interval of 60 ± 48 ka.

Where the ±48 ka comes from?

$\sqrt{37^2+31^2}=48$

This treatment of uncertainties assumes that uncertainties are independent of each other. As @Mark pointed in the comments, this won't be the case if the uncertainty comes from "the length of your measuring stick (the half-life of U-238)".

This is: if you measure something with a "yard-stick" that have the wrong size, you can't reduce the resulting error by just averaging many measurements.

I don't know enough of geochronology to understand all the different errors they report. But the simple example in the abstract cite I presented above shows that they are indeed treating those errors as independent. Otherwise the reported interval error (±48 ka) would not make sense.

If one significant source of error is indeed the uncertainty in the half-life of $^{238}$U. However, it would be wrong to treat these errors as independent only if there exists an exact value for this half-life. Alternatively, maybe there is no exact value of the half-life, and what they meant is that the half-life value can truly vary a 0.05%. This is something to look into if you want to figure out if the treatment of errors they do is correct. However, after a quick google search I found that radioactive half-life can indeed vary by a small fraction due to environmental conditions, this article explains pretty well the phenomena. Here a short excerpt:

  ...radioactive half-life of an atom can depend on how it is bonded to
  other atoms. Simply by changing the neighboring atoms that are bonded
  to a radioactive isotope, we can change its half-life. However, the
  change in half-life accomplished in this way is typically small. For
  instance, a study performed by B. Wang et al and published in the
  European Physical Journal A was able to measure that the electron
  capture half-life of beryllium-7 was made 0.9% longer by surrounding
  the beryllium atoms with palladium atoms.

If the 0.05% uncertainty on the half-life of $^{238}$U comes from random environmental factors, it would indeed be acceptable to consider them as an independent source of error for each sample.


This may not answer your question, but it indicates that erosion is extreme at high altitudes.

  More than 60 percent of the sediment delivered to the world's oceans in the prehuman world originated from erosion in mountainous areas with elevations greater than 3 km above sea level.
  Muddy Waters -
  More sediment is entering rivers, but less makes its way to the sea
  - Sid Perkins

Only about 1% of Earth's area is above 3 km.

  (Fig. 2.4 of Deep-Sea Biology: A Natural History of Organisms at the Deep-Sea Floor) (via DavePhD)


Earthen dam with rock fill and clay core

Okay have a look at this article it may be some use, it's the Journal of GeoEngineering, Vol. 8, No. 1 April 2013 Pgs 27-32 so you may be able to get a hard copy if the link fails, it talks about clay core dams and seepage calculations thereof, including phreatic pathway estimation.

If I remember correctly rock fill in earth dams is treated as earth for the purposes of working out seepage lines etc... as it is generally small enough (particle size), relative to the dam as a whole, to have little or no effect on total mean permeability.


Please identify- no origin known but given to me by a geologist

The block is quartz. The green staining could be anything, from copper-bearing minerals, to clays, to silicates like epidote, actinolite, serpentine, etc.


Simply put, the amount of iron in the solar system/universe is higher than nickel due to a process called nucleosynthesis.

Basically at it's origin the universe comprised only of hydrogen, through nuclear fusion heavier elements were/are being created. Fundamentally, hydrogen is fused into heavier elements in the star, our sun is currently turning massive amounts of hydrogen into helium through the proton-proton chain.

Eventually as a star gets older you start seeing fusion of heavier elements, helium, carbon, nitrogen, etc up until you hit iron at which point you hit what is known as the iron peak  where fusing iron atoms together requires more energy than is release. Heavier elements are all formed during supernovas and thus we see lower level of abundance. That being said the abundance of nickel is still higher than all the other heavier metals.

https://en.wikipedia.org/wiki/Stellar_nucleosynthesis

http://physics.info/nucleosynthesis/


I think it is important to think of the El Niño as just one of the components of a large scale global atmospheric-oceanic phenomenon known as the El Niño and the Southern Oscillation (ENSO). ENSO takes shape as fluctuations of the rainfall, wind, ocean currents and waves. They are by nature very irregular.

The Southern Oscillation (SO) was first discovered by Sir Gilbert Walker who conducted seasonal averages for pressure and rainfall at a number of stations around the world. He found that a single spatial pattern was dominant where regions of high pressure in the central South Pacific Ocean and low pressure near Australia and India reverse and the highs turn into lows and the lows into highs. The SO is an atmospheric phenomenon, on the other hand, the El Niño is an oceanic process. Nonetheless, the interconnectedness between both phenomena is significant such that they cannot be considered alone, as pointed out by Bjerknes (1966). The combined action of ENSO is known to cause drought in Australia and the reduction of upwelling in the western coast of South America (which has disastrous consequences for nutrient delivery).

There is general agreement that one of the necessary ingredients for the initiation of the ENSO event is the reversal of the general equatorial Trade Wind pattern, an easterly steady wind due to a Walker cell. Westerly wind bursts spanning thousands of kilometers and acting over days or perhaps weeks at a time set off internal waves that transport energy westward and eventually poleward along the western coast of South America, some of that energy bounces off and radiates back east. See sketch below:

The equatorial isopycnal depression moves eastward along the equator as a Kelvin wave until reaching the western coast of South America relatively unchanged. These are shallow water waves so the speed is just $c = \sqrt{g'D}$ where $D$ is the depth and $g'$ is the reduced gravity, so they travel at about $c = 2.5$m/s plus 10-20% because they are literally advected by the Cromwell Undercurrent. They transport large amounts of energy over vast distances, depositing it far away from the generation zone in the western Pacific Ocean. Namely, after arrival on the east Pacific coast the equatorial Kelvin wave energy degenerates into two coastal Kelvin waves propagating poleward, and into new diffuse equatorial Rossby waves radiating towards the west Pacific. It is this removal of energy from the Western pacific through the development of these complicated wave motions and other more subtle processes that eventually brings an ENSO event to an end (chicken and egg?). Because the energy is removed, the SST drops, the trade winds resume thus ending ENSO.

I like the quote from the link in @DavePhD's answer:

"An El Niño event contains the seeds of its own demise."

Source:

Regional Oceanography: An Introduction By Matthias Tomczak


Does nitrogen fixation plants consume nutrients from soil

I'm not familiar with the plants you mention, unless they are the ones whose leaves rapidly move away from you when touched. I saw some in Malaya. However, the plants well known for fixing nitrogen from the air and enriching the soil are legumes, belonging to the same group as peas, beans, alfalfa and clover. There are hundreds of them, and they all have similarly shaped flowers, though of many different colours.

They all have nodules on their roots which harbour the bacteria which do the actual nitrogen fixation. Like any other plant they also extract minerals from the soil, so the soil will be enriched with nitrogen but depleted in minerals. Farmers get round this difficulty by rotation of crops.

If the flowers of the plants you mention are similar in shape to the flowers of peas and beans they probably enrich the soil, and it is unlikely they remove enough minerals to harm your coconut palms. In England, farmers sometimes sow a legume like clover or alfalfa, then plough it back in so that the soil is enriched with nitrogen but not depleted in minerals. Perhaps you could do the same with your mimosa plants.

Most fertilisers contain nitrogen, and if yours contains anything else your mimosa will probably use a bit of it, but not enough to worry about. If your plants are indeed a kind of legume, that should enable you to use less fertiliser. If your touch-me-not plants have thorns on them, that's the only ill effect I can think of.


Are thunderstorms normal at the end of a heat wave?

Ingredients necessary for the formation of thunderstorms are

... moisture, rising unstable air (air that keeps rising when given a nudge), and a lifting mechanism to provide the “nudge.” (source)

as well as

... MOISTURE, INSTABILITY, and LIFTING. Additionally, there is a fourth ingredient (WIND SHEAR) ... (source)

and they depend on the local, regional or overregional weather situation, can have seasonal aspects, may be be bound to one or more circulation patterns or just depend on the weather ;-)
Thunderstorms can form isolated, e.g. in the afternoon when during the day the conditions have built up and labilization took place from different ground types, orography, sunshine duration/intensity/angle or "drops" of cold air high up in the troposphere. These are Orograhic thunderstorms or air mass thunderstorms. They are usually (but not always) short lived (hours), local and occur in the afternoon and last until the early night.
Or thunderstorms can form along a frontal line that separates cold from warm air mass and that moves into the warm, moist air, causing it to rise to great height where it starts to condensate. This phenomenon is called a cold front or in a special form a squall line (radar image) and labilization is here the result of the difference in air temperature and moisture on a relatively narrow frontal line. Frontal system have considerable length (100s or rarely thousands of km) and moves swiftly over long distances. These frontal systems can be part of the cylones in the temperate zones (not the tropical cyclones, those are different and I leave them out here, though they house embedded thunderstorms as well) and move with the prevailing western drift there. Such a frontal passage usually doesn't last long, comes with a significant drop in air temperature when passing overhead and a significant weather change and veering wind, on the northern hemisphere.
All these forms are expressions of convective weather, vertical movement of air caused by labilization.
Otoh, heat waves are frequently simply the result of dry and hot air being transported by advection, which is not bound to a local scale alone. For example the Sahara air to central Europe. This air is hot and very dry, and it simply lasts until the weather situation changes and different airmasses come along, e.g. of Atlantic origin. There won't be thunderstorms, then, because there's not enough moisture. Such a weather situation frequently happens on the Canaries (just as an example), it leads to a hot and extremely dry atmosphere until great height, with a cool layer underneath, for example 23°C at sea level, ~30° at 500m ASL with an inversion in between, and 35°C around the summits between 2,000 and 2,500m ASL. This is absolutely stable and not even slightly conducive for the formation of convection or any kind of precipitation (except sand :-/).
tl.dr: No, it is not normal, but it can happen. There is no general rule and it is not the absolute temperature that causes thunderstorms, but differences in temperature and moisture that cause labilization and thus convection.


How can the 'abiogenic oil' hypothesis be disproven?

One possible key is isotopic fractionation via biological processes - see dating the development of the C4 photosynthetic pathway, and specifically isotopic fractionation between carbon-13 and carbon-14. δ13C from volcanic degassing is markedly different to that from biological sources; the arguments for human involvement in climate change (see e.g. the IPCC) rely on the changes in δ13C since the beginning of the Industrial Revolution: the value has shifted markedly towards that of the hydrocarbons we've been burning from its pre-Industrial value. (As for how we know atmospheric δ13C for CO2 prior to the Industrial Revolution - the answer is polar ice cores!)

Thus the arguments for/against abiogenic oil rest on (1) isotopic ratios, and (2) other geochemical indicator ratios; see e.g. Jenden et al. (1993).

Höök et al. (2010), in a review of the arguments for biogenic and abiogenic formation processes, say:

  However, theoretical studies, laboratory verification and discoveries of trace amounts of abiotic oil do not imply the existence of commercially significant deposits. [...] The lack of a clear and irrefutable success in locating abiotic petroleum in commercial quantities is problematic.

This year, Ahmed et al. (2014) advances the argument that Siljan Crater oil is unambiguously of biogenic origin due to the copresence of molecules of "known" organic origin (specifically terpane and sterane biomarkers). As for a definitive answer, [Wang et al. (2014)7 say:

  Whether abiotic (inorganic) process can form oil and gas resource is a difficult question that has been explored continuously by scientific community for more than a century but has not yet been solved.


Does a geomagnetic storm visibly deflect a compass?

You can definitely see a large geomagnetic storm with a compass, if you have the timing to catch one and the patience to sit and stare for a few minutes.

If you look at these minutely measurements from Lerwick observatory for one of the more recent large storms (the 2003 Halloween storm), you can see a roughly 4.5 degree swing in declination (labelled "D", the horizontal magnetic field angle to geographic North) over about 15 minutes at about 07:00. "I" is inclination, vertical field angle to the horizontal plane, "F" is total intensity of the field.

  Lerwick (LER) based on 1-minute definitive data 2003-10-29 shows plots for D and I in degrees and F in nT. D shows a dip to -2 degrees in the hour before 07:00 UT and then a sudden rise to about +1.5  degrees at about 07:00 with spikes to +2 degrees.

It will depend on where you are as to how big this change in the magnetic field is, and how big the storm is. For this storm, the UK geomagnetic observatory network gives a good idea of how the effect seen depends on where you are.

  Compass angles (positive West, negative East) measured at BGS Lerwick, Eskdalemuir and Hartland observatories during 2003-10-29 and 2003-10-30. The the biggest change is seen at Lerwick, a smaller change is seen at Eskdalemuir further to the south (further away from the auroral zone where the field changes are occurring), and a smaller change still at Hartland.


What produces these amazing 3D structures in Tibet?

The terrain examples show some striking similarities to what is referred to in the United States as "Badlands" - a type of terrain formed by layered sedimentary strata of rock that is soft enough to be eroded by wind and water into recognizably similar features. For example, here is South Dakota Badlands National Park:

Anecdotally, I have seen similar terrain in numerous areas of the Western United States, some appearing almost identical to the examples in the question. Furthermore, as mentioned in the updated question, the terrain examples shown for Zanda County, Tibet, are also referred to as the "Earth Forest"; further research of this specific location indicates that it was likely formed by similar erosive processes acting on "sediment stratum [...] mainly composed by sandstone and clay", comparable to the processes forming the various areas of Badlands in the United States.


Is Desert Sandstone a chemical sedimentary rock?

No, it's not.

The overwhelming majority of the material in the rock is clastic, not chemical. Chemical sedimentary rocks are rocks where (almost) all of the material was precipitated, such as travertine, evaporites, etc.

Cementation is a chemical process. As a clastic sedimentary rock has to be cemented somehow, otherwise it would be a sediment rather than a rock, all clastic sedimentary rocks have undergone some chemical process. This does not mean that they are chemical though.

As diagenesis progresses and the rock undergoes more chemical changes it may become a diagenetic clastic sedimentary rock of even a metamorphic one, but never a chemical sedimentary rock. This implies that most, if not all, of its initial mass precipitated out of solution.


What does the degree and order of Spherical Harmonics mean?

It's Legendre polynomials, not Lagrangian.

The zonal harmonics (the $Y^0_l$ terms) depend only on latitude. These zonal harmonics are closely associated with the Legendre polynomials $P_l(x)$, where $x$ is the sine of the geocentric latitude.

The tesseral and sectoral harmonics (the $Y^m_l$ terms, where $m\ne 0$) are closely associated with the associated Legendre functions $P_{lm}(x)$.  (Note: These are sometimes called associated Legendre polynomials, but they aren't polynomials.)

Spherical harmonics are widely used in physics, so the presentations readily found on the internet generally reflect how physicists use spherical harmonics. There are some key differences between these easily found references on the internet and the forms used to represent gravitation. One is that physicists typically use colatitude, and hence use $P_l(\cos\theta)$ as opposed to $P_l(\sin\phi)$. Another is that physicists tend to use the complex form, while gravity models are expressed in terms of real sine and cosine forms. Finally, a set of gravity coefficients is inevitably going to be fully normalized coefficients, while physicists use a form with a different normalization.


Would a volcanic winter trigger an oceanic "spring"?

I can't answer the question in detail but maybe take some of the tension, addressing the so called bottleneck hypothesis.

It was never really supported by archaeology, the mentioned article just adds to the evidence that human variety didn't suffer that greatly from the Toba eruption as the bottleneck hypothesis might suggest and that there was no decade long volcanic winter.

Example from lake Malawi after the eruption:
https://www.sciencedirect.com/science/article/abs/pii/S0047248417302750?via%3Dihub

Southe Africa:
https://www.nature.com/articles/nature25967

India:
https://science.sciencemag.org/content/317/5834/114

And to my knowledge no extinction signal in Neandertal population (they were few anyway) during oxygen isotope stage 4 in Europe.

Some think that it is time to put the bottleneck hypothesis ad acta.

There is evidence that eruptions "fuel" phytoplankton, but not necessarily connected to volcanic winters.


How stormy (wave height) does Lake Baikal get?

An article here says 4 meters. (No statistical data however, just a general information page)

  Waves on Lake Baikal may reach a height of 4 meters. Sometimes they
  evaluated as 5 and even 6 meters, but it is most likely an estimation
  “by eye”, which has a large error. Height of 4 meters obtained by
  instrumental measurements on the high seas.

Another source, The Lakes Handbook: Lake Restoration and Rehabilitation
edited by Patrick O'Sullivan, C. S. Reynolds, (pg 179) agrees with this figure (emphasis mine):

  Baikal exhibits many features of an ocean: abyssal depth, internal
  waves and seiches, tides, violent storms in which wave-height
  reaches up to 4m, and deep water luminescence of uncertain nature.


How did natural processes as we know them develop around effects of winter?

I don't know if one answer can list all the positives, but one I can think of is this: In many (not all) places of the world winter produces the most violent storms. Because deciduous trees lose their leaves during winter, they thus have less wind resistance, which in turn lessens--but does not eliminate--their vulnerability to being toppled over by severe winds.And of course, hibernating species take advantage of winter by sleeping through it and pretty much staying awake for the rest of the year. (I sometimes wish we humans could do the same.)


Canada is fairly similar to the US in how this works.  As pointed out in a comment, Environment Canada is the primary provider of observation and forecast data within Canada.  You can access plots of this data and somewhere on that site you can probably also get access to the raw data files to process on your own.

Canada also partners with other states to provide data globally that others can use, some of which provide global model products such as ECMWF and NOAA.  The data from the Euro is not completely open but the data from the GFS is freely available.

The person on TV is working with their fellow station meteorologists and often under a chief meteorologist.  They are going to look at data provided by Environment Canada observations and model output, global model data from others and perhaps private sector weather provider companies who themselves ingest all of that data and have operational meteorologists on staff.

The general flows of data will be

Observations taken by Environment Canada are ingested
Data is shared with other weather agencies, Canada ingests global weather from others
EC runs forecast models
EC makes observational and model data available

Private sector companies may use a workflow like:

Ingest data from government sources
Process data, run models, make forecasts
Make that data available to clients

TV stations will have a flow like:

Ingest data from EC, global models and possibly private sector companies
Interpret data and make local forecasts
Present forecasts to the public.


A secchi disk is basically a measurement of optical depth, and is very similar in principle to the measurements of AOD made in meteorology.  Those measurements are quantified at a particular wavelength of light (or a few discrete wavelengths), related to the Beer-Lambert law of light extinction.  Light extinction occurs due to scattering and absorption and the total attenuation is integrated.  A nephelometer, in contrast, has it's own light source which is shining on the particles, and a detector measures the reflected light (absorption is not being measured).  The nephelometer is calibrated to measure particle density by volume of a particular type of particle, based on the reflected light signature.

http://en.wikipedia.org/wiki/Nephelometer

http://en.wikipedia.org/wiki/Secchi_disk

http://en.wikipedia.org/wiki/Optical_depth


The fact that there is much less land mass in the southern hemisphere affects the climate and sea currents, but the situation is otherwise much the same as the northern hemisphere. Cold fronts tend to move north, whereas in the northern hemisphere they tend to move south. Hurricanes and typhoons are less common in the southern hemisphere, especially in the south Atlantic, and drift south, where there is less land to get in their way.

Cyclonic tropical storms form where ocean waters are heated by tropical or subtropical sun, and this heat is the source of their power. In the north, the Caribbean and Gulf of Mexico are a prime source of hurricanes because the ocean is hemmed in by land and heats up more easily than the south Atlantic. Hurricanes here do more damage and attract more attention than they would in the less populated vastness of southern hemisphere oceans. Just as hurricanes from the Caribbean tend to move north, those forming below the equator in the Indian ocean, where they are called typhoons, tend to drift south toward the vast emptiness of the Southern Ocean.


What would happen if I installed distributed water fountains in all of the ocean's dead zones?

That sounds like a method to attempt to increase the global humidity level.  I'm not sure how many areas we're talking, or who large they are, but "all of" just sounds like a lot.  It's at least going to be a massive humidifier the way you've designed it.
I would think if you want to achieve your goal without radically humidifying the air, it would probably work better to design your apparatus after aquarium aerators.
Somebody is studying this idea in the Baltic Sea. (thank you trond hansen).

A main threat for the Baltic is at first the human induced pollution through industries, agriculture, deforestation, private homes, shipping and tourism. Waste or erosion water due to these practices, contains lots of N and P that stimulate primary production. Also rising sea water temperatures due to global climate change make the oxygen availability even worse, since less O2 can be dissolved in warmer water (USGS, 2016). Moreover, also pharmaceutics or other artificial chemical substances that end up in waste water contribute for a great deal to the dead zones. Not directly by inducing primary production, but maybe even worse; the toxins they contain can either directly kill marine life or add up in the food chain and cause health troubles. Also reproductive success can be affected by certain chemicals.
In an attempt to stop the eutrophication and bring back life into dead zones, Swedish scientist came up with the idea of engineered re-oxygenation of the Baltic’s ‘dead zones’. Pumping relatively oxygen rich water from the surface into deeper anoxic layers, hereby breaking through the oxycline and allowing the water to mix again, must safe the Baltic according to the BOX project (Forth, 2015).
Facilitating nature to restore itself, instead of only focussing on banning the resources, could accelerate the battle against eutrophication in the Baltic. However, many scientists are sceptical about the idea. Prof. Conley (Lund University) mentions that there might be unforeseen consequences that could change the whole ecosystem. He also mentions that oxygenation could affect the reproductive success of some fish species. That’s indeed true, but Koster et al. (2005) found that increased O2 – levels actually improve the reproductive volume of at least cod, which thus makes it a benefit.
Apart from the costs of the BOX project, another point for consideration is the fact that treating the consequences instead of the sources might cause ignorance to obligations that try to reduce waste dumping, since it will be cleaned anyway.

In areas that are devoid of life due to a eutropic cycle (excessive nutrients in the water triggered a population explosion, which consumed all available oxygen, so everything suffocated), it would probably be helpful, so long as the aeration reaches the perimeter of the area.
However, if other pollution is involved, that changes things significantly.  Even if the initial death was due to eutrophication, developing life can be much more susceptible to toxic chemicals than mature life.  Because of this and other factors, what works for one part of the ocean may not work in other parts.
It's also worth noting that dead zones are not confined just to the oceans.  Something like this is being done in small lakes in Canada (Thank you Friddy).

Ecologically, many of these nutrient rich small lakes are classified as being in a eutrophic state. These lakes are typically shallow, with maximum depths of less than 50 ft and average depths of less than 15 ft. They are often landlocked or have only intermittent or seasonal stream connections. Because they are rich in nutrients, they are abundant in aquatic plants and invertebrates. Eutrophic lakes can be extremely productive and have the capability to grow trout and char very quickly and to large sizes. However, the same features that make accelerated growth possible in the summer can make it difficult for trout to survive over winter. Some of our most popular interior trout lakes are marginal in terms of their ability to support trout through the colder months due to a drop in dissolved oxygen levels Thousands of small trout lakes in BC’s interior freeze over for 4 to 6 months each winter. During that ice-covered period, the aquatic plants that grew through the open water seasons die off from lack of sunlight. Dissolved oxygen in the water is used up as this plant matter decomposes. As winter progresses, the volume of oxygenated water decreases to levels that become too low to support trout life, which results in a winterkill.
There are also small lakes located in the coastal regions that suffer from severe oxygen depletion during the summer months. This affects the ability of trout to survive as well as having impacts on the quality of the water for domestic use and other forms of aquatic recreation.

Their situation is quite different.  Rather than trying to resolve issues with pollution, they're using it to allow fish in ice-covered ponds to survive the winter.  There's also some lakes with issues during the summer the article doesn't go into detail about, which could be pollution or it could be natural eutrophication.  For the winter use case, it apparently works at two levels, as not only does it provide direct oxygenation of the water, but it also adds resistance to icing over directly above where the aeration is done, providing some surface that continues to be able to get oxygen from the air.
Both linked articles explicitly state this is just one tool to solve one particular issue, not a solution for all pollution, fish survival, and water quality issues.


Matan, the continents where we all live "float" on the Earth's mantle. The continents are made out of relatively brittle rock called the "Crust" and the mantle is made out of much more ductile material. The mantle, however, is NOT liquid. It is just much more ductile than the crust so, in geologic time, it can flow (like silly putty). Also, the mantle is much more dense, so the crust doesn't sink into it by gravitational/bouyancy forces alone.

Think of it as a creme brulee. We live on the little hard crust on the top. And there just happens to be a little bit of water on that crust that covers the less-elevated parts.

Now, a little more technical, the crust that makes up the continents and the crust that is under the deep oceans are actually compositionally different. This is because the magma that solidifies to form each of these crusts travels, by partially melting its way up, through different materials and different thicknesses. The consequence of this is that the crust making up the continents is less dense than that making up the bottom of the oceans.

The image above shows the process by which we get new (left) oceanic crust, (right) continental crust, and (middle) a special type of crust like that in Hawaii. Note that when two tectonic plates collide, the more dense one will tend to subduct under the other.


Can you please help me to identify this thing I found inside a rock in the Almanzora riverbed Spain

Read below for my initial response which was incorrect. My revision is: It is not an ammonite. It is a gastropod of the genus Cepaea, family Helicidae. I do not know the species, unfortunately.

My initial response, which is incorrect; I've kept it here for future reference:
What you found is a small fossilized sea creature known as an ammonite. Ammonite were a squid-like creature that had tenticles and a spiral shell. They existed from the Permian (300 million years ago) up to the end of the Triassic (65 million years ago) and are some of the most common fossils found.
The specimen you have resembles the species Simoceras.

http://www.thefossilforum.com/index.php?/gallery/image/44911-simoceras-lytogyroceras-subbeticum/


Humidity doesn't affect whether or not it rains. Rain clouds form on their own. Humidity does control whether or not the rain will touch the ground or not.

Sorry if I wasn't clear in my other answer.

Deserts. They don't get a lot of rain because rain clouds never make it to a desert. This can be due to a factor of many reasons. You can read more about it here: Why don't deserts get a lot of rain?

Rain forests. Like I said before, humidity doesn't really affect whether or not it will rain. Even though there is high humidity, rain clouds can still form, and it will still rain. Like I said in my other question, the surrounding air can't hold more water, so there will always be rain in a rain forest if rain clouds are present.

What I was trying to say in my other question, is that the surrounding humidity could play a role in whether or not the rain drops actually fall to the ground or not. But rain cloud formation is completely unrelated to humidity.

I'll be sure to edit that question to make it more concise. Sorry for the confusion.


Does negative reference evapotranspiration make sense using FAO Penman-Monteith equation?

Short answer, especially if it is about 1% of the time series and these values are just slightly negative, this likely indicates that the ET needs to be recalibrated slightly, and for practical purposes you can set the ET on those days to 0 mm/d. The ET calculations typically calculate potential ET, meaning that if there is no water available no ET will occur, and a similar concept applies to negative ET values (i.e. no demand for water -> no ET).

A couple of notes
- the reference $ET_0$ calculations were meant for ten-day or monthly time steps, not daily, which may be a reason for these results (see top of Ch 2)
- the equation seems to be for a specific type of reference grass, and they suggest adjusting the $ET_0$ based on crop type using a ratio; another potential adjustment to make

Overall if the negative values are infrequent and close to zero then likely setting to zero is not an issue, if the values are much less than zero than check the calculations and try the suggestions above to recalibrate the calculation.


Does nitrate take a particular long time to percolate from surface into groundwater?

I know in New Zealand we have a number of soils you can't raise dairy herds on because the nitrate in their urine strips too many nutrients too fast, to the point where one can tell where the cow urinated a couple of weeks ago because that patch of grass is dying from several different deficiencies simultaneously. My understanding is that dairy cows are, hands-down, the worst farm animal for this because they stand still when voiding and dump up to 15 litres of moderate-high nitrate liquid waste at a time which all goes effective straight down through the soil column robbing it of nutrients along the way. On the other hand there are also some soils, generally in more arid areas, where nitrate doesn't migrate right through the soil column at all but concentrates in the subsoil as a visible, white, salty, horizon.

As a rule the more water retentive the soil the longer water soluble compounds like nitrate will take to work down into the ground at a given water input. There are also some chemical interactions that will bind nitrate and slow it down more than you might expect we need study them in my soil fertility papers but I can't think what they are right now.

But to answer your question, usually soluble soil ions (which nitrate is) move on a timescale of days, weeks or maybe months, but not decades. We wouldn't need to apply slow-release nitrate fertilisers annually if it didn't migrate through at least the top-soil relatively rapidly.


Why is Ozone hole above single area of earth? Why that area?

Mostly temperature, leakage of CFCs(Chlorofluorocarbons), produced for early model refrigeration units thinned the ozone layer a bit all over the world but in Antarctica, and to a lesser extent over Scandinavia, CFCs were frozen into winter snowfall rather than effecting the ozone layer equally year round. Small amounts of ozone damage regenerated reasonably quickly, I understand the reaction is self catalysing but I'm not sure of that, but the flood of CFCs evaporating with the summer thaw in colder climates overwhelmed the natural increase and thus the massive hole down south. The Arctic isn't as badly effected due to the combination of fact that much of the melting ice turns to water which absorbs much of the CFC burden, continental Antarctica sees more ablation in summer months than melting, and the fact that global air currents concentrated much of the pollutant matter south of the equator in the first place.


Should Imilac (meteorite) be singular or plural?

Without knowing if there's an official statement on that, I can give my common sense opinion.

These are fragments that came from one single meteorite, or one single
"formation". Let's say that we have a basalt flow, let's call it the Michael Basalt. It's fragmented, right? So there are a bunch of pieces of it. If I collect the pieces, those are still several pieces of the "Michael Basalt". If I would refer to basalts instead, that would imply that there were several flows, not only one. But there is one. So I have several samples of the singular Michael Basalt. Therefore, there are several samples of the singular Imilac meteorite.


Lab procedure for analyzing/assessing the presence of semi-volatile solids

It seems to me you should draft an analytical procedure first in which you include the compounds (or compound-groups) you want to identify (qualitative) and what detection limits you need. Then get a list of methods or instruments you have access to. Then see which methods / instruments fulfil your analytical requirements. You might need to make aliquots and use two or more methods to cover all the requirements.

Complexity is usually the last thing to worry about, because you have to use what instruments you have, and often times the analytical requirements are only fulfilled by one instrument. The methods mentioned on the page you linked also guarantee that your measurements will be comparable to other peoples measurements.

Look for advice in books and lecture notes about "analytical chemistry" and "instrumental analytics". Personally I think infrared spectroscopy is pretty simple, but I don't know what your detection limit requirements are ("trace level" is very vague), and depending on your samples there might be a lot of overlap from the different organics (It also depends on how well you have to distinguish them).


Great Pacific Garbage Patch Equilibrium Points

Theoretically, I agree that there should be one instable equilibrium point between the two stable equilibrium points when we have a 2D current field. However, there are some additional components of the problem:

Ocean currents are not 2D but 3D currents. Considering only the sea surface might lets field lines disappear.
The wind has an additional forcing. This is not true for all items and the wind already affects the ocean currents. However, litter items which are partly above the sea surface experience an additional wind forcing (see e.g. Yoon et al., 2010)
Ocean currents are not time independent and equilibrium points may undergo a seasonal multi-annual cycling
Accumulation zones are not necessarily stable equilibrium points but the residence time of the marine litter items in the named regions just needs to be sufficient long.
The gyres are macroscopic accumulation regions. Thus, if we have regions with a higher density of particle trajectories and lower particles velocities we could identify these regions as accumulation regions from a macroscopic perspective.

About item three (Ocean currents are not time independent) I am not completely sure, but I think to remember an animation or plots in a publication which showed seasonal variations between the both garbage patches you showed.

As far as I remember the publications on that topic of global transport modeling of marine litter correctly, the eastern North Pacific Garbage patch is the actual accumulation region. It has a long tail towards west. Howell et al. (2012) writes about the North Pacific Gyre and plastic debris accumulation within it. I did not have time to read it in detail.

For further reading it might be interesting to look into these publications:

Eriksen et al., 2014. doi: 10.1371/journal.pone.0111913
Howell et al., 2012. doi: 10.1016/j.marpolbul.2011.04.034
Lebreton et al., 2012. doi: 10.1016/j.marpolbul.2011.10.027
Martinez et al., 2009. doi: 10.1016/j.marpolbul.2009.04.022
Maximenko et al., 2012. doi: 10.1016/j.marpolbul.2011.04.016
Yoon et al., 2010. doi: 10.1016/j.marpolbul.2009.09.033


Is plate tectonics a hoax theory? How can tightly packed plates move?

tectonic plates are not completely rigid they can bend, flex, and in the case of oceanic plate, get pushed under each other and melted back down.The plates move by sliding under each other, melting, or bending

Take a toffee-bar candy, hang most of it off the side of a table and put something heavy on the other end to hold it in place, wait a few hours, just under its own weight it will bend 90 degrees. However bend it fast by only a few degrees and it will snap. Rock behaves in a similar fashion, do it slowly enough and with enough force and you can bend it. Basically all solids behave like this to a certain extent. tectonic plates are not rigid on the large scale.

bending rock leaves behind traces like this and this

bend it to fast and the rock breaks creating a fault lines like this and this

plates pushed down get remelted, it helps if you think of oceanic crust as exposed mantle that has been cooled into a solid, while continental crust is much less dense and sort of floats on top of the more liquid mantle. that's why continental crust does not subduct but oceanic does. In essence there are huge gaps between the the permanent plate material, it just cools when exposed forming a hard surface skin called an oceanic plate.

we can even see that in how earth quakes behave around subduction zones getting deeper and deeper in the direction of movement until the stop indicating where there are no solids left to break.

here is an earthquake depth map for japan. notice how they get deeper in the direction of the movement of the pacific plate (west by NW) as it dives under japan.

If you look at a global map of plate movement you will notice that at then end of a moving plate (in the direction of movement) is either a mountain range or a subduction zone, or often both.


The difference of vertical advection and convection process for chemistry species

The difference between advection and convection in Chemistry Transport models (CTMs) is a question of scale:

Advection is driven by winds that are provided by the meteorological input dataset. Thus, the wind is resolved in the meteorological data.
Convection is driven by sub grid processes (e.g. temperature gradients) and is paramterized in CTMs.

See for example:

Pleim, 2007a. doi: 10.1175/JAM2539.1
Pleim, 2007b. doi: 10.1175/JAM2534.1
Rasch et al., 1997. doi: 10.1029/97JD02087


What is the technical term for spatially aggregated measures?

Count data.

Quantitative data that varies discretely and arbitrarily along some scale can be called count data.

Nick Chrisman (1995; Beyond Stevens: A revised approach to measurement for geographic information, presented at Auto-Carto; see this PDF for a transcript) pointed out that there are many more typologies of measurement than the 'classic' four proposed by Stevens and outlined in Wikipedia's Typologies of measurement article.

None of the measurement typologies are rigid or prescriptive, but Crisman is not alone in recognizing counts as an important statistical data type:

  Another class of geographic measurements consist of counts aggregated
  over some region in space. Counts are discrete, since there is no half
  person to count, but a count captures more mathematical structure than
  the other discrete levels (nominal and ordinal).

Mosteller and Tukey also called them counts (see Mosteller's book, Data Analysis and Regression).

It's clear to me that the concept is a good fit for, say, population, but your biomass example seems intuitively less clear-cut. The point is that it's a countable quantity, as opposed to a ratio scale, so it might just be a matter of being careful how you define the term.

This answer was edited after clarification in the comments.


Why don't you think calcite is forming in-situ? The saturation index does not guarantee that calcite has precipitated (or dissolved) but there are a number of reasons to think it has. First, calcite does not have a large kinetic barrier to precipitation. The kinetics are fairly rapid. Rapid is a relative term but the formation of calcite in caliche and speleothems indicates that it does not take much for it to precipitate. Secondly, are you suggesting that it is merely coincidental that the SI indicates saturation? Do you have a number of water samples from different locations that are all in equilibrium with calcite? How would that occur without reacting to form or dissolve calcite? What else could be buffering the pH to the value at equilibrium between your solution and calcite?

Have you looked at the gypsum SI? Does it remain undersaturated? If so you would expect it to be dissolving which would move calcite towards supersaturation.

One possibility is that you in equilibrium with both gypsum and calcite. In that case, they will fix the ion concentrations in solution and pH so you get no further precipitation (assuming the system is closed to carbon dioxide).


Are coral cays and coral atolls just volcanic islands?

No, they are not necessarily volcanic.

Both of these terms, along with many others like fringing reef and barrier reef, are just morphologic — to do with shape. They tend not to imply anything genetic — to do with origin. (The separation of description and interpretation is an important principle in observational sciences like geoscience.)

Cay   A low island, often of sand or coral. See Wiktionary.
Atoll   A ring-shaped coral reef. See Oxford English Dictionary.

The name Cay is sometimes applied more generally to an island or group of islands. In some cases, as in Cay Sal Bank, Bahamas, the feature is actually an atoll: a ring-shaped reef. Cay Sal Bank is one of the largest atolls in the world, and did not form on a volcano.

Charles Darwin hypothesized in his monograph The structure and distribution of coral reefs that atolls form when a fringing reef around a volcanic islands grows as the volcano subsides:

Indeed, Darwin turned out to be correct that atolls often have a volcanic origin, but Cay Sal Bank is a counter-example. I think it's fair to say that most people would assume that origin though, and lots of Internet definitions , so it's notable if an atoll formed some other way, e.g. on a non-volcanic seamount (see Keating et al., 1987, in Seamounts, Islands, and Atolls, AGU), or by island subsidence due to dissolution.


What will happen to the Indian plate after it slides under the Eurasian Plate?

It is a continent-continent collision following subduction, no subduction is taking place at the moment. The ocean floor that was attached to it has vanished into the mantle or got wedged into the thickened crust. The collision builds up immense stress, resulting in deformation, faulting, folding, crustal shortening and uplift of the Tibetan plateau.
https://www.files.ethz.ch/structuralgeology/jpb/files/English/Asiaeng.pdf
Will it become part of the Eurasian Plate?
That's a question of definition of plate boundaries, fault lines, sutures ...
Will it slide back out of Siberia?
Of course not. How could rocks even be preserved in such a process? In the process of shortening the crust is near completely consumed.
Will it get pushed into the mantle?
No. Continental crust doesn't subduct. Both sides have approximately equal density and the mantle is much denser, so they just push and shove each other. Maybe parts get pushed to greater depths (~100km) in the dynamic process and exhumed again. Shortening will continue, uplift, faulting, folding and erosion in equilibrium, and when and where uplift stops erosion will take over.
Afterwards there may probably be something like the Appalachians, an older result of a continent-continent collision and a very thick continental crust. Pop-science link depicting the principle: https://www.nps.gov/subjects/geology/plate-tectonics-collisional-mountain-ranges.htm


We are already knowledgeable about some aspects of the requirements needed to terraform Mars & the Moon. As @David_Garcia_Bodego mentions in his comments, gravity is a major factor in celestial bodies being able to retain an atmosphere.

This is because the gravity of a celestial body affects the escape velocity  of that body. The other important factor is the surface temperature of the celestial body. This is why Titan, a satellite of Saturn, has a thick atmosphere, despite having a similar escape velocity to the Moon (Luna), it is much colder and has a thick atmosphere.

Another factor that assists Titan in maintaining a thick atmosphere is its distance from the Sun and the weaker effect of the solar wind at that distance. Also, Titan is protected by Saturn's magnetosphere.

I recommend reading:

What will happen to the air released from the Moon's Surface?
Could the Moon keep an atmosphere?

and the links contained within those questions.

Yes, these questions discuss the Moon and not Mars, but the information provided in those questions is applicable to Mars.

The graph below provides a visual of the gases a celestial body can retain in a atmosphere based on escape velocity and temperature.

Factors that act in favor of Mars being able to have a thick atmosphere are:

Mars is farther away from the Sun than Earth & Luna so it experiences
a weaker solar wind.
The surface temperature of Mars is cold, which reduces the energy of
atmospheric molecules.

Factors that act against Mars being able to have a thick atmosphere are:

The gravity of Mars and subsequently the escape velocity of Mars is small.
The lack of a magnetosphere to shield the atmosphere from solar wind.


Regarding compression, shuffle filter of netcdf4

I made some pictures on my tablet to explain everything a bit better. Sorry that they are not that nice.

Shuffle

If we do not us shuffle, we store on value (float, double, integer, short integer, ...) after another. Thus, each variable itself is stored contiguously in memory. The first bit of a second value follows the last bit of the first value. If we use shuffle, the first bit of all variables is stored contiguously in space, followed by the second bit, and so on.

The figure above shows an array of six 8-bit integers (only 8-bit because it was less painting work ;-) ). The vertical black boxes split in 8 compartments represents on 8-bit integer. The orange arrows from left to right indicate how the bits would be stored with shuffling.

Now we assume some example values: We have an array with the values 4, 2, 4, 5, 7, and 6. It is shown in the figure below. The first row shows the decimal representation. The matrix below is the binary representation. Each binary column represents the corresponding decimal number in the first row. The red arrows indicates the normal storage order. The orange arrows indicate the shuffled storage order.

Now we can write down the order of bits in the memory. I wanted to use color. Therefore, you get another picture:

We have a lot of zeros in the beginning of the binary representation of each value (because we have very low values). The shuffling is favorable in this situation because we have a long contiguous memory part filled with the same number/condition (= 0).

If we had no low numbers but higher numbers, (but) which are close to each other, we would not have a long contiguous memory part filled with 0s (zeros) but it might be six 1s and then six 0s. Commonly in netCDF files we have much larger arrays. Lets say a 4-dim array with 100 x 200 x 30 x 365 values, which are quite similar to each other. Then we would have often 2.19 x 109 contiguous 1s or 0s in memory, which is quite nice for compression.

However, if neighboring values differ considerably, shuffling might not be a good idea.

Chunking

If we have an uncompressed file (= no chunking; or one big chunk), a n-dim array is stored contiguously in memory: at first all values of the first row (first index) of the array are stored contiguously in memory; then we go to the next row (increment second index by one) and write the second row contiguously into the memory; and so on.

We might also start with the last index and do it the other way around ... - depending on the programming language and on the definition of what are rows and columns. But the principle is the same.

The figure below shows an example for a 2-dim variable with one spatial and one temporal dimension. The red arrows indicate how the data is aligned in memory. The black dots are individual values in our 2-dim array.

Now, we want to extract a time slice (all spatial values at one time step) and a space slice (all temporal values at one location) from our data. In the second case we get a time series (could be a time series of model data). In the first case we get a picture of the current situation (could be for a map). The blue and green markings in the figure below indicate the time and space slices.

The difference between time and space slice is the following. The time slice is fast to extract because the values are stored contiguously in memory. The space slices takes more time because only each sixth value is extracted. Is this example the extra work/time spend is low. However, if we have a large 4-dim variable, the time-slice-extraction will be faster than the space-slice-extraction.

When we compress data, we can chunk it. That means, that we split our large array-variable in sub-arrays. For the user it looks the same from the outside. netCDF-4 does chunking automatically, when we compress data but don't define a chunking pattern.

The figure below shows an example, in which our data was split into three chunks. The red arrows indicate the alignment of our values in the memory. This is just an exemplary alignment.

Now, we extract time and space slices again (figure below). Green and blue indicate the slices, again. Here we see that the space-slice will be much easier/faster to extract then before. However, the extraction of the time slice will take more time.

In addition, the compression will differ when you change the chunk sizes. The background is similar as described in the Shuffle section: depending on which values are neighboring each other, the one or the other chunking might be favorable.

Now to your question: what's the best choice of chunk size?

focus on usage

It depends on your data usage and you access pattern. If you often extract time series at specific locations, it might be favorable to define the chunks in a way that the values corresponding to one location are close to each other aligned in memory.

But be careful, some software like cdo access the netCDF data always in the same way - independent of what you do with it during the processing. Thus, if you don't access the file directly via the C- or Fortran-netCDF4 routines but via some other software, the best chunking pattern might not depend on what you want to do but how the software does it ... . Some software might - for example - always read data along the spatial dimensions first, although you want data along the time dimension.

focus on compression:

The size of the compressed file varies with the chunking layout. The situation is similar as described in the Shuffle section. If the data are more effective to compress in time dimension, the chunking in my example figure above might be favorable for file size (e.g. high variability in space but low variability in time).

Chunking summary

The best choice of the chunk size depends on your access pattern, on the software you use, on your data itself, and on your focus on access time vs. storage space.

Compression level

The choice of the compression level depends on your aim. If you just want to store the data (in an archive or where-ever) and have it as small as possible, you might use compression level 9.

If you want to access data often and fast, you should choose a lower compression level. We use compression levels up to 4. Above that the reduction in file size is very low (for us) so that we do not have a reason to go beyond.

Example: Currently, I work with an ocean model. We have a lot of land in our model domain (roughly 1/3). Compression of level 1 is sufficient to reduce the file size by approximately 95%. However, this is a special case.

summary:

I tried to give an overview of the features you asked for. The exact choice depends on you particular use case and cannot be generalized. For you, my answer might be too late but I hope that it might help some others. For me, the document you linked helped a lot in the past.


What is the geochemical origin of carbon dioxide with the 'white smokers' of the Champagne Vent?

Observations and geochemical measurements presented in a study published soon after the article in the question, Submarine venting of liquid carbon dioxide on a Mariana Arc volcano (Lupton et al. 2006) sheds considerable light on the processes involved in the unique Champagne vent.

The key unique features of the Champagne Vent are the presence of CO2 droplets and the CO2 concentration - 2.7 moles/kg - the highest for any underwater hydrothermal vent. This concentration is also supersaturated, being considerably higher than what should be possible at the temperature and pressure present at the vent.

The proposed model, based on Lupton et al's observations and measurements, suggests that there is a subsurface layer of CO2 liquid and hydrates that is penetrated by the vent, resulting in the CO2 becoming entrained in the hydrothermal fluids, providing for the observed 'cold' CO2 droplets and also increasing the concentration to supersaturation levels.

Lupton et al. also explain that from geochemical analyses, the source of the carbon is mostly (90%) from subducted carbonate melt, with a small amount coming organic matter and mantle derived carbon.  Further, chemical measurements reported in the later research Chemistry of hydrothermal plumes above submarine volcanoes of the Mariana Arc (Resing et al. 2009) indicate that there is an absence of chemical reactions between the host rocks and the CO2 and further suggest that the magma chamber is deep within the NW Eifuku volcano (Champagne Vent source) and the gases rise into colder, older substrate.


How deep would the nitrogen and oxygen ocean be if cooled to liquid?

I'm not sure it would be entirely liquefiable as the atmosphere gets thinner and thinner, but if we ignore that, then it's a simple matter of calculating density and ocean cover.

78% Nitrogen, 0.807 g/mL  Source:  Liquid Nitrogen

21% Oxygen, 1.141 g/mL  Source: Liquid Oxygen

Ignoring the 1% of trace gases, average density of liquefied air, 0.87 g/mL, or 87% the density of water.

Mass of air, 1 ATM is equivalent to 33.9 feet of water.   Source:  link

and the Earth is 71% covered by oceans.   From there it's just math.  33.9*(1/.87)*(1/.71) = 54.88 feet.    That's quite a bit less than the oceans would rise by freezing solid (which might not happen given volcanism and warmth coming from the earth, but if even half of the average depth of 14,000 feet of oceans froze, a 9% increase in volume, we'd be looking at some 600 feet of sea level rise by freezing.

Colder temperatures might cause the liquid nitrogen/oxygen to contract a bit further but that's a ballpark answer - 54 feet, 10 1/2 inches.   Some of the air might dissolve into the oceans prior to the oceans turning to ice, cause colder water can hold more gas, so the actual answer might be a little bit less than that.


What is this (possible) fossil from the triassic/jurassic boundary?

Its definitely a flowering plant which evolved in the early Mesozoic Era. Also, Pangaea was beginning to break up, but not fully broken up so climate would be than likely be Continental-Maritime allowing for dry weather and water cycle contributions from the surrounding body of water as it broke apart. Also, this land was positioned a little closer to the equator at that time and if found in Ireland, it would have been 'attached' to northwest Africa and the east coast of North America to the west making it possible from a climate and geographical situation. Have a look at this video of Continental Drift movements of parts of the world at 200 million yrs ago in the roughly similar time period you suggest: view at 3:47 for 200 mya and 4:03 to view the recognizable formation of the British Isles. Enjoy! https://www.youtube.com/watch?v=UwWWuttntio


Organic matter affects the pH and makes the soil more acidic. The best example of this is in peat bogs, where only acid tolerant plants can live and the peat is so acidic that micro-organisms don't flourish, thus preventing decay. There is the famous Tollund Man, found in a peat bog in Denmark if I remember rightly. The body is in an almost perfect state of preservation, yet is about 3,000 years old! Tollund Man was apparently executed by hanging in ancient times and his body thrown into the bog. The principle is the same as the jars of eggs, onions, gherkins and so on which are pickled in vinegar.


A lot of stress is accumulated along the fault by the time it breaks. For example, on the San Andreas, the Pacific plate is moving north with respect to the North American plate, but the fault resists this motion. As a result, a ton of elastic energy builds up around the fault as the stress increases.

Eventually, the stress becomes so much that the fault slips. The fault slipping releases the stored elastic energy, some of which is radiated as seismic waves. (Most of the energy becomes heat.)

Seismic waves "carry" stress and motion. When a wave first arrives, the rock at that location experiences a change in stress. This causes the rock at that spot to move slightly. But then, the rock at that spot has moved with respect to nearby rock. This differential motion of the rock creates stress, which then affects nearby rock similarly. So, the wave's stresses propagates motion in the rock, and motion in the rock propagates stress.

A few types of waves exist (P waves, S waves, and surface waves, in descending order of wave propagation speed). But the general idea behind them all is the same.

The ground therefore shakes when the waves arrive.


How was it possible that CO2 levels were higher nearly 650,000 years ago?

The explanation is that human activities are not the only processes that affect atmospheric composition.

Last time CO2 levels were higher than today was 10-15 million years, during the Miocene epoch. During the Miocene, sea level estimated to be 100 feet higher and the global average surface temperature estimated to be 10°F warmer than today.

References:

Miocene Sea level graph.

Temperature over time graph.

www.climatecentral.org

Coupling of CO2 and Ice Sheet Stability Over Major Climate Transitions of the Last 20 Million Years


Why do the vast majority of the world's deserts fall on the tropic of capricorn or cancer?

At thirty to thirty-eight degrees north and south of the equator are the so-called Horse Latitudes, regions with constant high-pressure systems. These regions inhibit precipitation. The phenomenon is quite well described and illustrated on Wikipedia:
https://en.wikipedia.org/wiki/Horse_latitudes


What is the difference between subvolcanic rocks and plutonic rocks?

Main difference between a subvolcanic verses a  plutonic is depth at which the rock solidified at from its molten state.  Plutonic implies a depth greater than subvolcanic by definition but I am sure there is some overlap between shallow end of plutonic and subvolcanic.  Depth of emplacement for plutonic would mostly be much greater than 2 km.

Plutonic is an igneous rock formed by solidification at considerable depth beneath the earth's surface.

Subvolcanic rock, also known as a hypabyssal rock, is an intrusive igneous rock that is emplaced at medium to shallow depths (<2 km) within the crust.


Are Helium 3 and 4 being produced by earth's core?

tl;dr no.

The paper you are referring to has major flaws in it. Claims that should not be in any respectable scientific journal such as:

  ...the demise of the georeactor is approaching. Within the present level of uncertainty, one cannot say precisely when georeactor demise will occur, whether in the next century...

or

  At some point in time after the georeactor dies, there will be no geomagnetic field and life on Earth will never be the same.

etc., have no place in a scientific article that is to be taken seriously by anyone. This is scaremongering that belongs in tabloids. This was publish in PNAS which is a reputable venue, so I don't know how it got through. Was this even reviewed? No idea. But let's talk about the actual science presented in the paper.

I'm not an expert on nuclear reactions so I can't comment on that actual model presented in the paper, but I can comment on the assumptions that are simply wrong. His model assumes a certain volume of uranium that exists in the core. Such a "block" of uranium doesn't exist. Uranium doesn't go in the core. He says:

  The background as to why a large portion of the Earth's reservoir of uranium is expected to exist in the core, precipitate, and ultimately collect at the center of the Earth has been set forth in refs. 8–11...

But refs 8–10 are actually his own papers. So he made up a theory that uranium goes in the core, completely ignoring years of published experimental work by different groups saying that uranium does not go into any significant amounts in the core, and then bases his story on that. This is wrong. Some related questions:

Why is uranium only in the crust, really?

What percent of the Earth's core is uranium?

Also note the lack of neutrinos, as mentioned by David Hammen in one of the answers, something that should happen if this was true.

So your questions:

  Is Herndon correct...

No, he is not.

  If not, what is their origin?

Mantle sources with different 3He/4He ratios. There are many reasons for that. Mid ocean ridge basalts are mostly generated by melting of depleted mantle, that is, mantle that was already melted (at least) once. So it will not have too much of primordial 3He in it, and the ratio will be low. Hotspots such as Iceland or Hawaii tap a deeper mantle source that still has 3He in it, so the ratio will be higher. There are other factors that can modify the ratio. Episodes of depletion and recycling, metasomatism (by aqueous fluids or carbonatites, each with their own capability to transport U and Th), and some more than I can't think of at the moment. Anyway, there's no nuclear reactor in the core of the earth and we're not going to die due to its demise because it doesn't exist.


Why do climate experts from the UN/IPCC rarely mention Grand Solar Minimum?

The IPCC do mentions solar minimums and maximums, as part of extremely careful treatment they do of the reconstructions and predictions for the changes in solar irradiance. The Assessment Report 5, Working Group 1, Chapter 8, have a whole section (~4 pages) dealing with solar irradiances.

If the IPCC don't mention grand solar maximums/minumums that often, is because the research in the area have shown that solar minimums and maximums have smaller impact in climate than other factors. Therefore, such factors deserve more attention, like Greenhouse gases or land use changes. These factors deserve more attention both because they have a greater impact on climate and because we can do something about them. When it comes to solar activity we can't do much anyway.

The work of the IPCC is to combine the research of the whole scientific community, their conclusions are not based in the result of a single study but in the combination of pretty much all of them. Some studies could be contradictory, so instead of cherry-picking what suits them, they compare and combine all the studies to have the most reliable answers and a good idea of the uncertainties. If predictions of multiple models differ a lot it means uncertainties are large. If they all give the same result, we can be a bit more confident about it.

For example, the figure 8.11 compares the reconstruction of solar irradiance between years 1750 and 2000 from six studies:

You can see how the Dalton minimum shows up around 1810-1820, but the total solar irradiance change is rather small (less than 1 W for over a total of 1360 W).

Here some excerpts from the IPCC reports that are relevant to this question, and where solar minimums are mention and considered in the wider context of climatic forcing (text between square brackets were added by me for clarification):

Page 662:

  Satellite observations of total solar irradiance (TSI) changes from
  1978 to 2011 show that the most recent solar cycle minimum was lower
  than the prior two. This very likely led to a small negative RF [Radiative Forcing] of
  –0.04 (–0.08 to 0.00) W m$^{–2}$ between 1986 and 2008. The best
  estimate of RF due to TSI changes representative
  for the 1750 to 2011 period is 0.05 (to 0.10) W  m$^{–2}$. This is
  substantially smaller than the AR4 estimate due to the addition of the
  latest solar cycle and inconsistencies in how solar RF has been
  estimated in earlier IPCC assessments. There is very low confidence
  concerning future solar forcing estimates, but there is high
  confidence that the TSI RF variations will be much smaller than the
  projected increased forcing due to GHG during the forthcoming decades.
  {8.4.1, Figures 8.10, 8.11}

Page 690 (explicit mentions of grand solar minimums):

  8.4.1.3 Attempts to Estimate Future Centennial Trends of Total Solar Irradiance

  Cosmogenic isotope and sunspot data (Rigozo et al., 2001;
  Solanki and Krivova, 2004; Abreu et al., 2008) reveal that currently
  the Sun is in a grand activity maximum [a.k.a. grand solar maximum] that began about 1920 (20th
  century grand maximum). However, SC [solar cycle] 23 showed an activity decline not
  previously seen in the satellite era (McComas et al., 2008; Smith and
  Balogh, 2008; Russell et al., 2010). Most current estimations suggest
  that the forthcoming solar cycles will have lower TSI [Total Solar Irradiation] than those for
  the past 30 years (Abreu et al., 2008; Lockwood et al., 2009; Rigozo
  et al., 2010; Russell et al., 2010). Also there are indications that
  the mean magnetic field in sunspots may be diminishing on decadal
  level. A linear expansion of the current trend may indicate that of
  the order of half the sunspot activity may disappear by about 2015
  (Penn and Livingston, 2006). These studies only suggest that the Sun
  may have left the 20th century grand [solar] maximum and not that it is
  entering another grand [solar] minimum. But other works propose a grand [solar]
  minimum during the 21st century, estimating an RF within a range of
  -0.16 to 0.12 W m$^{–2}$ between this future minimum and the present-day TSI (Jones et al., 2012). However, much more evidence is needed and at
  present there is very low confidence concerning future solar forcing
  estimates.

  Nevertheless, even if there is such decrease in the solar
  activity, there is a high confidence that the TSI RF variations will
  be much smaller in magnitude than the projected increased forcing due
  to GHG (see Section 12.3.1).

Summarizing, the IPCC consider solar irradiance variations, the timing of solar minimums and maximums. However, it consider also many other factors that also affect Earth's energy budget. Then, they do predictions based on the combined effect of all these factors. In contrast, some people tend to focus on just one factor (as solar activity) and erroneously assume that it will dominate over all the others.

For the particular case of solar activity, as you can see in the cites above. The IPCC acknowledge the possible occurrence of a solar minimum in the future, but combining all the models they conclude that there is a high confidence that its effects will be much smaller in magnitude than the projected increased forcing due greenhouse gases.

Part of the reason your question might not be well received is because it starts from an assumption that is false: "climate experts from the UN/IPCC never mention Grand Solar Minimum". They do mention it, and if you follow the references in the IPCC you will find plenty of discussion about Dalton, Maunder and older Grand Solar Minimums. And part of that discussion is to estimate the real impact that those events can have in Earth's climate. Then the IPCC get those estimates and figure out how they interplay with the many other factors that conjugate to determine current and future Earth's climate.


If the distance between Earth and the moon were changed, would the effects be immediate?

The moon's orbit might have changed, but obviously it would take some time before this would become visible. The moon's position iself would probably not be that affected by the event as its inertia is too huge. So the tides would probably not be noticeably affected in the first hours.

I have no idea really how long, but it might not take too long before, depending on what point of its new, elliptical orbit the moon is now positioned - is it now approaching earth, or more or less staying at the same distance, or to the contrary getting farther away - the tides will start to be affected.


Pressure as a function of altitude above 11 km

Those formulas are based on an assumption that the pressure is hydrostatic and the ideal gas law. The example given is limited to 11km but uses the tables from the U.S. Standard Atmosphere which actually go up to $1000$ km. Starting at Page 58 one can find values for pressure density and temperature above 11km.