[I am going to preface this by saying that I am not in one camp or the other in this discussion, as I think there are pros and cons to each side]

This links to the "Gaia Theory" proposed by James Lovelock, wherein the Earth is considered a self regulating organism.

In this hypothesis, Earth is an organism in that it will try to maintain certain conditions.  These conditions include temperature (within a range suitable for life as we currently understand it), oxygen content of the atmosphere, water availability etc.

This does not mean that the ball of rock we are flying through space on is a living organism as we understand it, but rather that the various spheres of life (These are usually the biosphere (ecosystems), the atmosphere, the cryosphere (the poles, and other ice-bound areas), the hydrosphere(oceans), and the pedosphere(soil)) interact with each other in such a way that optimal conditions are maintained.

Whilst the theory as a whole is not used today, it is recognised that feedbacks and interactions between different spheres occur, and are an important part of understanding Earth systems, and is studied in an area of science known as Earth System Science

One of the initial arguments for this theory was that our atmosphere is not in chemical equilibrium, and that there must therefore be processes active to maintain oxygen levels at a steady state outside of equilibrium.

This is a difficult topic, as it is important to stress that the Gaia hypothesis does not state the Earth is some sentient being consciously doing anything, rather that a complex set of interactions, abiotic and biotic, combine to maintain and regulate the planets temperature and atmospheric composition.

An example of this regulation is chemical weathering, whereby carbon dioxide in the atmosphere falls in rain, and reacts with rocks, to form calcium bicarbonate, removing carbon from the short term carbon cycles.  The more surface rocks there are which are capable of this reaction, the more CO2 is removed from the atmosphere.
There is a hypothesis which says that at least once, the Earth has been covered largely in ice and snow, and this reaction (known as carbonation) is suspected to have played a part in the recovery of Earth.
The hypothesis (Snowball Earth) goes like this:

The Earth became cooler, whether due to Milankovich cycles, volcanic activity, or solar output changes.  As this happened, ice began to form at the poles, changing the albedo, and reflecting more radiation back to space, this caused local cooling, and allowed for the growth of the ice sheets. As they spread, the albedo became higher on a larger scale, and the ice sheets eventually covered the two hemispheres, with a band of open ocean at the equator.
The earth was now very cold, but not completely empty of life, or without volcanic activity.  Life continued to respire CO2, and volcanoes continued releasing CO2.  Without rocks to remove it from rain, or ocean to absorb it, Carbon dioxide began to build up in the atmosphere.
As it built up (over millions of years), it began to warm the planet, which in turn began to melt the snow. As the snow and ice began to retreat to the poles, rocks, and open ocean were again available to remove the carbon dioxide from the atmosphere, and more photosynthetic organisms were able to survive, and remove more CO2 through photosynthesis.

This lead to a stabilisation of the planets systems again, although, it may have gone too far, and swung back to a glacial period (although not a frozen earth), then moving back to a warm period before stabilising due to the tectonic movement of the continents northwards The break-up of Rodinia, birth of Gondwana, true polar
wander and the snowball Earth

I hope this long ramble illustrates how there are a number of complex systems which all interact with each other to maintain conditions.  Whether we consider the sum of these systems an organism is an ongoing discussion, but, all organisms have the ability to regulate via various systems, and each of these systems has the potential to lead to chaotic positive feedbacks, and spiral out of control, although negative feedbacks usually keep everything running as normal.

I have linked the Gaia theory webpage, and if you search for Daisyworld model, you will find a model which you can run to simulate feedbacks
It is up to you whether you think this collection of feedback systems is an organism, and this debate will likely run for decades more.

Gaia Theory Site


What is the origin of the dominant atmospheric nitrogen content in Earth's atmosphere?

According to the recent paper in Nature Geoscience: Nitrogen speciation in upper mantle fluids and the origin of Earth's nitrogen-rich atmosphere, $N_2$ originates from regions of the Earth where plates are converging.  Venus and Mars lack plate tectonics and therefore lack $N_2$ in their atmospheres.  In other regions of Earth upper mantle, and in Venus and Mars, nitrogen is expected to exist as aqueous ammonium and not enter the atmosphere.


Does organic decay release the same CO2 as burning?

I can't quantify the answer, but intuitively, nearly all of a burning tree's carbon is converted to $\small\mathsf{CO_2}$ - assuming the fire is hot enough. You are correct in assuming that termites and bacteria convert some of the carbon to other organic species, as do fungi, yeasts, moulds, and slow weathering. In addition, some of the rotting tree's carbon is converted to soluble inorganic ions, humic, fulvic and tannic acids. So no, organic decay would not yield the same $\small\mathsf{CO_2}$ as burning.

This would make an interesting school or 1st-year uni science experiment. Burn some wood in a sealed environment, measure the $\small\mathsf{CO_2}$ evolved, then repeat the experiment with wood in a wet organic-rich isolated biome, and compare the results. I suspect it would make for an interesting paper with potential climate change policy implications.


What is the meaning of step in ERA reanalysis data?

The "step" is the number of hours the ERA re-forecast has been run into the future from the "time" of the re-analysis.

For example, asking for ERA data with time = 12:00 and step = 0 means asking for data valid at 12:00 based on a re-analysis for 12:00. But asking for data with time = 12:00 and step = 6 means asking for data valid at 18:00, i.e. for data produced by a 6 h model run based on the 12:00 re-analysis.

To fill the gaps between the analysis times one can use steps from a forward run. Forward runs are needed to get parameters like time accumulated precipitation, which would not be available from an analysis. Sometimes a combination of steps and times might be appropriate for a joint analysis of instantaneous and time averaged parameters, i.e. to stagger them correctly in time.

Data valid 00:00 deviate less from the observations if they come from a 00:00 analysis compared to data from step 12 of the 12:00 analysis. But a series of steps from one initialization time should be more consistent in time compared to a series of independent analyses.


There has only been one chromium mine in Australia - the Coobina mine, in the Pilbara region of Western Australia. It is located 80 km south east Newman (23 deg 29' 31" south, 120 deg 16' 32" east). The resource at Coobina is 1.5 Mt @ 29.4% Cr.

  The ore deposit was discovered in 1924 and was once worked under the names of Jimblebah and Murramunda. It was mined as a series of small open cuts for several decades with most of the pits being less than 70 metres deep.

The deposit is associated with an ultramafic unit.

  Chromite deposits in this rock occurs as massive chromite with up to 150 lenses having been mapped so far. The largest around 340 metres long and 6 metres wide.

Chromium clinochlore is mined at Coobina/Jimblebah.

Other deposits of chromite occur at Mount Christie, Tomkinson Ranges and Wingella Hills, in South Australia.

Mount Christie is within the Gawler craton and Tomkinson Ranges and Wingella Hills are within the Musgrave block.

At Moount Christie,

  The best intersection was 1.5 m at 9.8% Cr2O3. Microprobe analysis showed the chromite to contain ~48% Cr2O3 and 30% FeO, which may only be suitable as chemical-grade chromite.

  Chromite has been identified within Mesoproterozoic Giles Complex rocks in the far northwest of the State. It occurs as rare veins up to 10 mm thick within layers of pyroxenite in the Tomkinson Ranges (Coats, 1956) and as grains in ultrabasic rocks of the Wingelinna Hills intrusions. A representative sample gave an assay of 16.9% Cr2O3.

Geoscience Australia has very little information about Coobina.

Some more information from Geoscience World and Research Gate.


What, if any, paleoclimate data can be derived from stromatolite fossils?

Stromatolites have indeed been used in palaeoclimatic investigations. Here are a couple of papers I found through Google Scholar:

Paul I. Abell, Stanley M. Awramik, Robert H. Osborne, Sterling Tomellini, Plio-pleistocene lacustrine stromatolites from lake Turkana, Kenya: Morphology, stratigraphy and stable isotopes, Sedimentary Geology, Volume 32, Issues 1–2, May 1982, Pages 1-26, ISSN 0037-0738, http://dx.doi.org/10.1016/0037-0738(82)90011-2.

Andrews, J. E. and Brasier, A. T. (2005), Seasonal records of climatic change in annually laminated tufas: short review and future prospects. J. Quaternary Sci., 20: 411–421. doi: 10.1002/jqs.942 http://dx.doi.org/10.1002/jqs.942

As you'll notice, though, these are both relatively young records. I don't know if similar studies have been attempted for Precambrian stromatolites.


What rate of deforestation would be needed until we run out of oxygen?

As Jan points out, there are many other factors in the oxygen balance, not just trees. But for a bit of fun, let us suppose that we burn all the trees on the planet. The global biomass of carbon is estimated as 47.4 PgC (it varies a bit according to season and inter-annual growth conditions). Of this we can estimate that the contribution from trees is about 36.3 PgC. 1 tonne of carbon consumes 2.67 tonnes of oxygen to create CO2, so the oxygen consumed is about 9.68 x 10^^10 tonnes. The total mass of the atmosphere is known to be 5.15 Petatonnes, of which oxygen is 20.95%, or 1.08 Petatonnes of oxygen. So taking the ratio, the loss of atmospheric oxygen from burning all the trees is 0.0034%. This is far less than the day-to-day fluctuations in available oxygen due to changes in atmospheric pressure - i.e. the weather.

So, there is a lot of woody biomass, but think of the partial pressure of the oxygen layer that wraps the Earth: 21.2 kPa O2 on every square centimetre of the Earth's surface. We are never going to run out of oxygen! On the other hand, pyrolysis of every tree on the planet would create so much smoke that we would probably all die of lung cancer!


Quoting from this paper: Haus R., Prinz S., Priess C. (2012) Assessment of High Purity Quartz Resources. In: Götze J., Möckel R. (eds) Quartz: Deposits, Mineralogy and Analytics. Springer Geology. Springer, Berlin, Heidelberg. https://doi.org/10.1007/978-3-642-22161-3_2

What purity level is required in naturally occurring silica in order to be used for manufacturing semiconductors?

As high as possible.

...high purity quartz with total impurity levels less than 20 ppm...

20 ppm means that the silica has to be 99.998% pure. It is extremely hard to find silica that pure in nature.
More specifically:

Specific requirements as to tolerable limiting values differ from
industry to industry. In the lamp tubing and optics industries
aluminium content in the refined quartz concentrate should not exceed
20 ppm, other metals should be less than 1 ppm, and total impurities
less than 30 ppm. For semiconductor base materials and crucibles
aluminium content should be even lower, specified to less than 10 ppm,
other metals less than 0.1 ppm, and total impurities not to exceed 15
ppm.
Feedstock for solar silicon used in the photovoltaic industry should
generally have boron and phosphorus contents in the sub-ppm range
since these elements are most difficult to remove and negatively
affect the performance of the solar cells (Geerligs et al. 2002).
For microelectronics applications, e.g. in epoxy moulding compounds,
uranium and thorium, both responsible for soft errors by alpha
radiation, should be less than 2 ppb, and in low alpha applications,
even less than 0.5 ppb.


WRF: EPSG code or spatial reference for Lambert conformal, Mercator and polar stereographic projections

Spatial reference systems are coordinate systems that can be geographical coordinate systems defined on a model ellipsoid or projection coordinate systems.

A projection coordinate system is defined by four groups of parameters:

model ellipsoid,
projection type
projection parameters
measurement unit

EPSG codes refer to complete spatial reference systems or model ellipsoids.

You are saying that you want an EPSG code for projection coordinate systems that  use WGS84 as model ellipsoids and Mercator, Lambert conformal conical, and stereographic projections. These projections require additional parameters such as the central meridian and origin latitude. Choice of parameters depends on your region of interest.

You could start with EPSG:4326 which is a geographical coordinate system with degrees as units.

Next, since your region of interest seems to be in the south of Brazil, consider EPSG:32722 that stays for Universal Transverse Mercator zone 22S and uses the WGS84 ellipsoid.

For a Lambert Conformal Conic projection consider ESRI:102015 that stays for South America Lambert Conformal Conic. This spatial reference uses a model ellipsoid that is different from WGS84, so this might be a problem for you. The standard parallel numbers for this projection are 5S and 42S meaning that the distortion would be greater for regions that lie away from these latitude, i.e. the Northern hemisphere or the Antarctic regions.

Finally for a Stereographic Polar you might consider EPSG:3031. An Antarctic Polar Stereographic projection coordinate system that uses WGS84 as a model ellipsoid.


Why don't we store carbon by storing used plastics under ground?

Some locations don't have the available space to dump rubbish underground and those that do are running out of suitable dump locations.
Similarly, the location of abandoned mines and the available dumping space is also limited. Prior to using abandoned mines, many will need to be made safe by implementing ground control measures to prevent injuring from falling rock and to prevent cave in.
Some mines, particularly coal mines have been mined to subside shortly after coal has been removed, making such mines unusable.
Some mines were constructed underneath the water table and are now flooded. Such mines would need to be de-watered and made safe. The water would need to be dumped somewhere, which and may need to be treated prior to dumping because of metals that may have leached into the water from minerals in the abandoned mine.
Once such mines have been backfilled the ground water will again flood the mine. The question of how any plastics would behave when submerged needs to be investigated to mitigate against deleterious environmental effects.
Some old mines were established using manual methods and have short height and narrow width tunnels which would require a lot of manual handling to make the mines safe and to dump plastics in them. Alternatively, the tunnels may need to be enlarged to allow the used of heavy machinery in dumping the plastics. This would be expensive and may not be practical in some cases.
The location of some mines is far from population centers which would required expensive haulage to the mines.
It would be to reuse plastics in another way, if possible, or to stop using them or significantly reduce their usage.


Addis Ababa lies 9 degrees north of the equator at about 2300 metres in altitude. Its' mean annual rainfall is about 1090 mm, with an average daily  probability of rain of about 41%. The inter-tropical convergence zone in this part of East Africa is a little anomalous, but sufficient to bring long rains in July-August, and short rains in March-April. Given the altitude, latitude and synoptic climatology, there is nothing unusual about this rainfall, though as Kwinkunks points out, if you happen to hit an unusually wet 'long rainy season' it might seem unusually wet.


I think the Southeastern Tropical Indian Ocean (SETIO) provides a better hint of what might be happening. It clearly shows a positive pattern since last November.
source

I think it might be related to the recovery from the intense 2015 El Niño. If I remember from Lau & Nath, 2003, when you have a warm ENSO, you get a reduction of the Monsoon intensity with lower wind speeds, which results in a reduction of sensible and latent heat loss. Also, the  cloud cover is reduced because of dryer conditions, which results in a larger percentage of the shortwave radiation reaching the ocean surface.

The WTIO seems pretty normal currently, so it suggest the conditions are mostly eastern Indian Ocean related. The altimetry sea surface height anomaly seems to suggest the currents are counterclockwise in the Bay, so the anomaly seems to be a regional effect.


How can oceanic Rossby waves move from East to West?

Yes it is. In fact Rossby waves always move westward in the absence of a zonal mean flow. Before going into detail lets try to explain this qualitatively. In a barotropic fluid the absolute vorticity is conserved. The absolute vorticity is composed of the relative vorticity $\zeta$ and the planetary vorticity $f$ ($f$ is also called the Coriolis parameter). $\zeta$ is the rotation of the fluid as you would observe on earth. $\zeta + f$ is the rotation of the fluid as someone from space would observe. Conservation means that the sum $\zeta + f$ must always stay the same no matter where a fluid parcel moves. I.e. $D(\zeta + f)/D t = 0.$ Notice that $f = 2 \Omega \sin \varphi$ increases the further we move away from the equator. $\Omega$ is earths angular frequency and $\varphi$ is the latitude.

Now imagine a line of connected fluid parcels that is initially at rest (horizontal line in the figure below). Lets say on the northern hemisphere at a line of constant latitude. If we displace the parcels to the sine like line, the following happens: If we move northwards to the pole the planetary vorticity increases ($f$ increases), but if absolute vorticity is conserved, $\zeta$ must decrease. If the parcels were initially at rest (as observed by someone standing on earth) $\zeta$ is now negative - inducing a clockwise rotation. If we displace parcels southward the converse happens. $f$ decreses and $\zeta$ increases, inducing an anti-clockwise rotation. If we move even further in time the rotation induced before will translate the wave to the sine like dashed wave. Think of the arrows in the figure as "pushing" the solid sine like line to the dashed sine like line. This describes a motion of the wave from east to west!

What is needed to make the wave move eastward? Imagine the horizontal line moves towards the east (i.e. we have a zonal flow), the wave itself will move eastward if the zonal flow is faster than than the westward movement of the phase which I described above. The details are a little more complicated but I will state them below.

Lets take a look at the details. Maybe the simplest setting to study Rossby waves is based on the barotropic vorticity equation (BVE) which describes the flow of incompressible, non-divergent, constant density flow on a rotating sphere. If you are not interested in the derivation here just take a look at the part denoted "Dispersion relation", which will describe the phenomenon.  The relative vorticity $\zeta$ is given by $\zeta = \partial v / \partial x - \partial u/ \partial y$, where $v$ is the the northward component of the velocity and $u$ is the eastward component of the velocity.

The equation of motion (BVE) is given by:

$\left( \frac{\partial }{\partial t} + u \frac{\partial }{\partial x} + v \frac{\partial}{\partial y}\right)\zeta + \beta v = 0.$

This equation is equivalent to $D(\zeta + f)/D t = 0$ as described above. The first term ($\partial \zeta/\partial t$) is the local change of relative vorticity, followed the advection of relative vorticity and finally there is the advection of planetary vorticity $v\beta$ ($\beta = \partial f / \partial y$), which is the contribution to the rotation of the fluid by the earth itself. Solutions to this equation can be interpreted as Rossby waves. However to admit solutions including zonal flow we must linearize the equation about a basic state plus perturbations. We do this by letting $u = \overline{u} + u'$ and $v = v'$. So we have a zonal mean flow $\overline{u}$ and perturbations $u'$ and $v'$. The perturbation vorticity is then $\zeta' = \partial v' / \partial x - \partial u'/ \partial y $. Introducing a stream function $\psi$ that is related to the relative vorticity by $\nabla^2 \psi = \zeta'$ we can write the linearized BVE as

$\left(\frac{\partial}{\partial t} + \overline{u} \frac{\partial }{\partial x} \right) \nabla^2 \psi + \beta \frac{\partial \psi}{\partial x} = 0.$

In the equation above terms involving products of perturbation (e.g. $u'v'$) where neglected because they are assumed to be small (something small squared is even smaller).

Dispersion relation:
A wave like solution to the perturbed BVE is given by

$\psi = Re(\psi_0 e^{i \phi})$,

where $\psi_0$ determines the maximum amplitude and the phase $\phi = kx + ly - \nu t $. $k,l$ are zonal, meridional wavevectors and $\nu$ is the frequency of the wave. Substituting the proposed solution into the perturbed BVE yields the dispersion relation

$\nu = \overline{u}k - \frac{\beta k}{k^2+l^2}$.

Recall from elementary physics that the zonal phase speed is given by$ c = \nu/k$. This allows to write the dispersion relation in the desired form, answering your question:

$c = \overline{u}- \frac{\beta}{k^2+l^2}$.

Notice that $c$ determines whether the Rossby wave moves eastward (c>0) or westward (c<0). In the case of $\overline{u} = 0$, $c$ is negative and therefore, the wave moves from east to west. In fact a Rossby wave can only travel from west to east in the presence of a zonal flow that is also directed eastward. More precisely if $\overline{u}>\beta/(k^2+l^2)$. This also explains the answer of gansub: long waves have small wave numbers, therefore $\beta/(k^2+l^2)$ is greater compared to smaller waves. Thus, it is more likely for the waves to travel westward.

My answer can be found almost identically in Holton, Hakim - Dynamic Meteorology, 5th edition, page 161 onwards. So credit the book rather than me.


Groundwater unloading and corresponding changes in fault zone stick-slip behavior

Changes in water level effect the pore pressure at depth around the fault. The general assumption is that the pore pressure is proportional to fault-normal stress which can be thought of clamping stress (i.e., the stress that prevents it from slipping). Basically the higher the clamping stress the more shear stress is required to make it slip. Now the shear stress on San Andreas accumulates due to plate motion between the North American and Pacific plates and that rate remains unchanged. But the normal stress can change slightly due to water level changes, so it can either advance or retard the occurrence of an earthquake in time. But under no circumstances can it stop them from occurring.

The main idea in the paper is that the normal stress on faults have slightly decreased (due to water level drop) which helps to unclamp the fault(s) which in turn increases the background seismicity rates.

So given all this, the first argument by (Holthaus) is correct. However the unclamping can also advance (in time) the occurrence of the big one. Having said that please remember that stress changes we are talking about are rather small.

With regards to the Napa earthquake: The point of an earthquake is to relive the accumulated shear strain. If there are two faults in parallel (as is the case in the region) and both are accumulating strain then an earthquake on one will decrease the 'effective shear stress' on the other fault, directly parallel to it. However at the same time it will increase the shear at the two ends. So things are slightly more complicated.


What is the global warming potential (GWP) of any gas over a 1 day time frame?

It can, but it's not very helpful. A large number of gasses (methane being one) decompose relatively quickly in the atmosphere to form other compounds. A longer time horizon means you capture all of that change in the metric (as compared to CO2), while if you did it for a day you'd end up with a figure that only really made sense for that day. The details of how it's calculated and why the time horizons are where they are is in the IPCC AR5 WG1 CH8 technical supplement (8.SM.11.1 Equations for the Global Warming Potential)


Need seismic data and digital well log data from the same area?

The SEG has a list of open file seismic data sets here: https://wiki.seg.org/wiki/Open_data

For a number of these surveys well logs are also given.


This question has tenuous links to Earth Sciences, but the answer is simply that, historically, freshwater has been used to flush toilets, and hence the sewage treatment plants have been developed to treat non-saline sewage. The water can be (and frequently is) recycled for domestic use, whilst sewage sludge can be used to enrich farmland. No such benefits accrue to flushing effluent with saline water. It is then pollution, whether it is disposed of on land or at sea.

In many estuaries and deltas around the world sewage sludge does end up in the sea where it accumulates as tidal mud flats with an unnaturally high lipid content. Give this sediment a few tens of millions of years of compression and maturation and it will doubtless yield oil shale.


Why does Earth's outer-core rotate in the opposite direction to the inner-core?

Is it true that Earth's outercore rotates in the opposite direction to Earth's inner-core?

No. You misread a badly written for-the-masses science article. The article summary is at best rather confusing and misleading. It invites a reader to misinterpret what's going on.

So what's really going on? It's simple, conceptually. The mantle, outer core, and inner core all rotate in more or less the same direction and at more or less the same rate. However, because outer core is liquid, there exists a possibility for the mantle, outer core, and inner core to exhibit slightly different rotation rates (and perhaps even rotation axes). That's apparently what is happening inside the Earth. The mantle and crust make one rotation per sidereal day. The inner core currently rotates a tiny, tiny bit faster than that, while the outer core rotates a tiny, tiny bit slower than that.

This means that when viewed from the perspective of an Earth-fixed observer, the outer core currently appears to be rotating a tiny, tiny bit westward and the inner core currently appears to be rotating a tiny, tiny bit eastward. It's a matter of perhaps confusing perspective. When viewed from an inertial perspective, the mantle, outer core, and inner core are all rotating more or less synchronously.

When you read one of those science-for-the-masses type articles, it's a good idea to jump to the underlying journal article. In this case, you should try reading Livermore, Hollerbach, and Jackson, "Electromagnetically driven westward drift and inner-core superrotation in Earth’s core", PNAS 110:40 (2013).


The initial stage of mineral exploration involves finding a site to investigate. In some situations this may result from the discovery of a surface outcrop of mineralization, which is the exposure of a mineral deposit.

Surface outcrops are becoming more difficult to find because some have already been mined or they are buried under sediments or lava flows. To get an indication where buried mineral deposits occur, geophysical exploration techniques are required. Generally this will require the use of either gravity measurements and/or magnetic surveys, usually aeromagnatic surveys. In some situations geochemical exploration methods may be used as well. This requires wandering over land taking samples of the surface rocks and assaying them for minerals and metals. The assaying method used will be determined by the metal being explored for. Fire assays, when they are used, are used for gold, not base metals.

When a prospective area has been found, exploration drilling is undertaken. Initially reverse circulation drilling may be done because it is cheaper and quicker. The cuttings from the drill holes are analyzed by a geologist to ascertain the rock types and samples of prospective rock types are assayed for their metal content.

If the mineral deposit is large enough and rich enough, diamond drilling will be undertaken. Depending on the condition of the ground being drill, this generally provides a solid core of rock that can be inspected for rock type. Usually the core is split in half lengthwise and half the core for prospective rock types are assayed for metal content.

To get an accurate understanding of the size the mineral deposit and the amount of metal present. A grid of holes, drilled on a 20 m by 20 m or a 10 m by 10 m pattern is drilled over the deposit. The length of the drill holes will largely be determined by the depth of the mineral deposit. The results of this, outlines the size of the deposit.

The assays for metal content and subsequent modelling by geologists determines the amount of metal in the deposit (its richness). This may involve the use of geostatistics.

Classifying the deposit as either a mineral deposit or orebody is done by mining engineers who evaluate the models created by the geologists by creating possible mine designs and evaluating the economics of the potential mine. If the deposit is economic to mine is called an orebody, if not it remains as a mineral deposit.

As part of the mine design and evaluation process, the mining engineers must engage with metallurgists regarding how any ore from the deposit will be processed and the costs involved. In developed countries they must also consider the rehabilitation of any potential mine, once it has been mine out, during the evaluation of the mineral deposit.


Calculating magnetic declination for a non-axial dipole field

Inclination is given by

$$I=\arctan(2\cot\theta)$$
where theta is equal to 90° minus the observer's latitude (in the Northern Hemisphere), therefore

$$I=\arctan(2\cot(90-40))=59,21^\circ$$

To get declination the following figure helps:

Declination is the angle between geographic north and magnetic north. (I suppose 80°N, 72°W are the coordinates of the North Geomagnetic Pole.) Let's do the math!

$$D=\arctan\left({{{33}\over{40}}}\right)=39,52^\circ $$


Why is Europe warmer than North America at similar latitudes?

It is true that the Gulf Stream plays a role on the different climates of each region; I would not call it an 'urban legend' as Richard Seager and other scientists put it, however it seems that how much it actually changes the climate is currently under debate.
From Wallace Broeker:

One of the major elements of today's ocean system is a conveyor-like circulation that delivers an enormous amount of tropical heat to the northern Atlantic. During winter, this heat is released to the overlying eastward air masses, thereby greatly ameliorating winter temperatures in northern Europe.

Thermohaline circulation—often dubbed "the ocean conveyor belt"—carries warm surface waters (pink) from the tropics to the North Atlantic, with the return flow at depth (purple). But contrary to many accounts (summarized by diagrams such as this), this heat conveyor plays only a minor role in keeping European countries warm during winter months.

It seems that although, as you stated, the Gulf Stream traditionally was thought to play a major role in the climate difference, new studies emerging shows that only contributes a small amount to the temperature difference.

The cooling effect could account for 30 to 50 percent of the temperature difference across oceans, the study suggests.  It also explains why the cold region is just as big for both North America and Asia, despite the continents' differences in topography and size.
The cooling depends on heating air over warm ocean water. Since the warm currents along western ocean boundaries in both the Pacific and Atlantic are similar, the resulting cold region to their west would be similar as well.  The new study adds to other recent research that found that ocean currents such as the Gulf Stream aren't capable of transporting that much heat to northern Europe, instead contributing only up to 10 percent of their warming.

There are also studies suggesting that the conveyor belt model itself was extremely oversimplified, and its role in ocean overturning cycles is being re-evaluated:

As the study of the modern ocean’s role in climate continues apace, the conveyor belt model no longer serves the community well — not because it is a gross oversimplification but because it ignores crucial structure and mechanics of the ocean’s intricate global overturning.

Based on the evidence at hand, I believe that the Gulf Stream does play a role in making Europe warmer than North America at similar latitudes; however how large a role it plays perhaps has been overestimated, and with the new ongoing studies perhaps different climate elements, such as the atmospheric elementsrather than the oceanic currents, can be modeled and brought to light in the scientific community, much as Richard Seager is doing now.

The oceans do still play an important role in keeping Europe’s winters mild, but it is nothing to do with the Gulf Stream. The winds that blow northeast onto Europe from the Atlantic carry with them air that is relatively warm even in the winter; the large heat capacity of water means that the sea cools off more slowly in the winter, and this also moderates the temperature of the air above the sea surface. This contrasts with the eastern US, where the prevailing southeast winds are cold, having lost their heat to the thousands of kilometres of land surface they’ve already passed over.
So the oceans are still involved, but it is the atmosphere that is the true key to explaining Europe’s mild winters; and in a pleasing geological twist, it is apparently the presence of the Rocky Mountains that causes the large scale waviness of atmospheric circulation that magnifies the temperature contrasts on either side of The Pond (Richard Seager explains this in more detail in this more comprehensive piece at the American Scientist).


Software for sediment transport modeling

I think the best option for sediment transport modeling is the Community Sediment Transport Modeling System (CSTMS) package that was developed for ROMS. CSTMS was created by a group of sediment transport modelers lead by the USGS. One of the many benefits is that it is open-source and, thus, free. The model was designed for realistic simulations of processes causing sediment transport in the coastal ocean (estuaries, nearshore regions, and the continental shelf). Details on the package and its implementation are found in Warner et al (2008). The people from FVCOM implemented this package.

The most up-to-date version of the sediment transport module is part of the Coupled Ocean – Atmosphere – Wave – Sediment Transport (COAWST) modeling system. A good description of the model and its capabilities is given in Warner et al. (2010). The code can be downloaded from here.

The current version of CSTMS can model both cohesive (mud) and non-cohesive sediment (sand) sediments, bedload transport and sediment deposition and erosion caused by waves and currents.


Manmade ditches in lowlands of New England

they are drainage ditches intended to drain salt marshes.
They may be old and no longer maintained, it is impossible to tell for certain from satellite but it seems likely.
https://qsr.waddensea-worldheritage.org/reports/salt-marshes


How do I convert between different east longitude coordinates?

The database with the negative longitude angles is storing longitude as eastings and westings, whereas the other database is storing everything as eastings.

It appears you prefer your data as eastings and westings. Your methodology for changing eastings greater than 180 degrees to westings is correct: where the longitude angle is greater than 180 subtract 360 from it (i.e. longitude angle - 360).


What's really happening with "stormquakes"?

The article can be found here in Geophysical Research Letters:
Fan, W., McGuire, J. J., Groot‐Hedlin, C. D., Hedlin, M. A. H., Coats, S., & Fiedler, J. W. ( 2019). Stormquakes Geophysical Research Letters, 46. https://doi.org/10.1029/2019GL084217

Abstract
Seismic signals from ocean‐solid Earth interactions are ubiquitously recorded on our planet. However, these wavefields are typically incoherent in the time domain limiting their utilization for understanding ocean dynamics or solid Earth properties. In contrast, we find that during large storms such as hurricanes and Nor'easters the interaction of long‐period ocean waves with shallow seafloor features located near the edge of continental shelves, known as ocean banks, excites coherent transcontinental Rayleigh wave packets in the 20 to 50 s period band. These “stormquakes” migrate coincident with the storms, but are effectively spatiotemporally focused seismic point sources with equivalent earthquake magnitudes that can be greater than 3.5. Stormquakes thus provide new coherent sources to investigate Earth structure in locations that typically lack both seismic instrumentation and earthquakes. Moreover, they provide a new geophysical observable with high spatial and temporal resolution with which to investigate ocean wave dynamics during large storms.
Plain Language Summary
Large storms such as hurricanes and Nor’easters generate strong long‐period ocean waves, which can interact with shallow seafloor features located near the edge of continental shelves known as ocean banks. Such interactions produce seismic sources with equivalent earthquake magnitudes that can be greater than 3.5. These seismic sources are termed “stormquakes”, and they can excite coherent seismic wave fields that are well recorded across the North American continent. Stormquake is a newly identified geophysical phenomenon, which involves interactions of atmosphere, ocean, and the solid Earth. Therefore, stormquakes can provide useful information to investigate the Earth structure and ocean wave dynamics.

At the moment the link there to the PDF works and is not paywalled.


Of course there is, and in not that complex. Is called the heat equation, and is a type of diffusion equation that can be easily solved numerically or analytically in some simple geometries.

If you don't want to get involved in the math, you can use one of mane heat transfer simulation software, there are even online version that run in your browser like Energy2D, in which you can configure the geometry and thermal properties of your materials and let the simulation run.

The screenshot below is a problem with the geometry you suggest. But you would need to set the correct thermal properties of air and basalt.

If you are looking for a customized equation, you have to constrain the geometry of the problem. For instance: the cooling of a laterally infinite layer of material at 1000 °C of thickness X with a medium (air in your case) above it, at constant temperature of 10°C and a medium below it (bedrock) at initial temperature 5°C, you can look at engineering formulas handbooks, or post the question on the Engineering or Math Stack Exchange sites.


Ions & elements, which is the correct terminology to use when discussing chemical compounds in Earth Science?

Elements are just one specific type of atom. Magnesium, oxygen, sulfur, etc. These are all elements.
Compounds are several different types of atoms (that is, elements) bonded together. For example, magnesium oxide (MgO), or iron sulfide (FeS).
Ions are charged atoms or compounds (also known as species in some cases). Ions can be monoatomic (consisting of only one atom, or element) or polyatomic (consisting of more than one type of atom). Cations are positively charged (like Ca2+) and anions are negatively charged (like O2-). Polyatomic ions that occur in geological contexts are usually anions, with carbonate (CO32-) and sulfate (SO42-) being two good examples.

All ions are elements (or combination of them). Not all elements are ions. We geologists and geochemists use these terms interchangeably all the time. I think that using ions may be slightly better, particularly in the case of sulfur. Because sulfur in minerals can be either in sulfate or sulfide form, just saying "sulfur" gives little information. The properties of sulfate and sulfide minerals are completely different, so it's actually useful to know.

  Sulfide ions (S2-) bond with a number of positive ions to form the sulfides

Not strictly correct, because the bonding in many sulfide minerals is a combination of covalent and metallic bonding, and it only has a little ionic character. Still, even in cases when the bonding is not ionic (such as in sulfide minerals), we still often talk of them of ions because it's convenient and easy.

  Sulfide minerals consist of metallic elements in chemical combination with elemental sulfur

This statement is not correct. When we speak of "elemental" elements, we mean that they are monoatomic compounds (or minerals). In the case of sulfur, it will be the yellow sulfur mineral. Gold, copper and silver and other example of "elemental" minerals. Once the sulfur is bonded to other metals, it is no longer elemental. It is part of a sulfide mineral.


Formation of flint & chert in limestones/chalk

This is not really my specialism, but in the absence of other answers so far, I'll give it a go.

Firstly, to simplify the terms of the question a little bit, flint is a form of chert, so we don't need to distinguish the two terms: we can just talk about chert in general. Also, I'll ignore chert beds formed in siliceous oozes, since you're specifically asking how cherts form in carbonate beds. Nichols (2009) gives a concise explanation, and I don't think I can do better than to quote it:

  Diagenetic cherts are formed by the replacement of other material such as calcium carbonate by waters rich in silica flowing through the rock. The source of the silica is mainly biogenic with the opaline silica of
  diatoms, radiolarian and siliceous sponges being redistributed. Chert formed in this way occurs as nodules within a rock, such as the dark flint nodules that are common within the Cretaceous Chalk, and as nodules and irregular layers within other limestones and mudstones.

If you want more detail, Maliva and Siever (1989) would probably be a good reference. (Free online reading for all, and download for many institutions, at the JSTOR page.) Here's the abstract:

  Mapping of carbonate dissolution in nodular chert-bearing strata indicates that nodular chert formation in a diverse suite of Phanerozoic limestones occurred in bulk pore waters that were at calcite saturation. Opal-CT and quartz supersaturation was achieved in most chert-bearing strata by the intraformational dissolution of amorphous silica skeletal material. Chertification occurred by a combination of force of crystallization-controlled replacement of the host carbonate, whereby non-hydrostatic stresses resulting from opal-CT and quartz crystal growth caused calcite dissolution, and the isomineralic heterogenous nucleation of new opal-CT and quartz crystal at nodule peripheries. The restriction of the solution phase at silica-carbonate contacts to thin films permitted the preservation of ghosts of micron-sized features in the chert. Heterogeneities in sediment organic matter content, porosity, and biogenic silica concentrations promote the nucleation of chert nodules in some formations.

Maliva, R. G., & Siever, R. (1989). Nodular chert formation in carbonate rocks. The Journal of Geology, 421‒433.
Nichols, G. (2009). Sedimentology and stratigraphy. John Wiley & Sons.


In the oil field, when a vertical cylinder coring sample is taken, how is the core severed at the bottom and removed from the formation?

Coring is an important method to get detailed information about the formations, however, it's very time-consuming and costive, so it's only applied when geologists and reservoir engineers need high-resolution data. It is more common in ore prospecting and mining, mapping for infrastructure and basic geological understanding of the 3-dimentional structures. Lake sediment cores are used for varve chronology. Marine sediments are cored to understand the oceanographic development, date events as slope processes and changes in glaciation and climate. Ice is cored to measure variations in the atmosphere to understand past climate and vulcanism.

To sum up, coring is a very important tool for geologists, not only in oil fields. Cheaper, and faster, alternatives to coring is mud logging, a very common practise when drilling in oil fields.

So how to get the cores up from the borehole?

There are some different systems used, depending on the rock/sediment and investment involved.

For deep drillings in hard formations, a core catcher is used in a two-barrel system. The corehead (the drill bit) is connected to the outer barrel, while the core is pushed into an inner barrel. The lower part of the inner barrel is called the shoe just above the drill. In the shoe, there is a core catcher that wedges between the barrel and the core. The core catcher is a split ring with a rough inside that holds the core. When you pull the core, it snaps off as the lower and upper shoe squeezes the catcher. The core catcher works somehow like an expansion anchor, but inverted, grabbing the core on the inside of the barrel rather than the wall on the outside. The inner barrel also protects the core from the rotating outer barrel.

For softer sediments, the core catcher is made out of springs that close inwards as the core is pulled. It is sometimes called basket retainer and can be in metal or plastic.

For smaller gravity corer, there is a valve on top of the tube that is closed and the underpressure in the tube holds the core in place. Sometimes...

Check the linked pictures, they probably explain better how it works, but I couldn't find any good CC.


I found a great paper named Remote Sensing of Particulate Pollution from Space: Have We Reached the Promised Land? and collected some remote sensing instruments doing CH4 measurement in the chart below.

It contains the information about the satellite, orbit types, instrument and the data time-range.

Satellite       Orbit       Instrument    Years

Nimbus-7        Polar       SAMS          1978-1983
UARS            L56.9       CLAES         1991-1993
UARS            L56.9       HALOE         1991-2005
ADEOS           PS          IMG           1996-1997
Terra           PS          MOPITT        1999-
AQUA            PS          AIRS          2002-
AURA            PS          HRDLS         2003-
Envisat         PS          SCIAMACHY     2007-


The significance of peak period in surface wave models

The peak period is only one of multiple parameters that is used to describe the spectral shape of ocean waves. Most commonly used parameters are significant wave height, mean period, and dominant (peak) period. Significant wave height is proportional to the square-root of total wave energy and it tells us how much bulk wave energy is there at any given location. Mean period tells us how long are waves on average, and peak period indicates how long are the waves with maximum energy. These are just statistical parameters describing the shape of the spectrum. In reality, accurate prediction of the whole spectrum is important for wave prediction.

What happens if we vary the peak wave period while keeping the total wave energy, and thus significant wave height, constant? These are some of the effects that can expect with longer peak period:

Swell propagates faster and reaches the shore sooner, as you mentioned in your question;
Because swell propagates faster, wave dissipation from swell outrunning wind will increase;
Longer waves are more dissipated due to bottom friction, i.e. longer waves will feel the bottom sooner as they propagate toward shallow water;
Longer waves induce Stokes drift that decays more slowly with depth compared to that of shorter waves, inducing stronger Lagrangian transport at depth and enhanced Langmuir circulations;
Longer waves with same wave energy are less steep, effectively decreasing the dissipation of short waves that "ride" on the forward faces of swell waves;
Different interaction with structures, as mentioned by Wolfgang Bangerth.

Because of the above physical processes, waves at peak period affect the evolution of the spectral shape both locally and along their propagation line.


Does flow banding only occur in silicic rocks?

Flow banding can occur in all igneous rocks, regardless of their composition. Any kind of molten rock that flows may eventually cause some flow banding. Sometimes the flow banding is not even obvious to the eye and can only be detected using geophysical methods such as magnetic anisotropy.

Here's an example of flow banding in a mafic rocks from Skaergaard intrusion in Greenland:

source

This looks like a sedimentary rock, but it's in fact igneous. Those are layers of minerals such as olivine, pyroxene and plagioclase that settled from a melted magma chamber.

It doesn't even have to be a silicate rock, here's a picture of natrocarbonatite lava from Ol Doinyo Lengai volcano in Tanzania:

source

Obviously, this rock exhibits flow banding and it hardly has any silica in it.


Difference between Earthquake Seismographs

An earthquake generates waves that move through the earth in different ways. Two of the principle waves are the compressional P wave and the shear S wave.  P waves move faster than S waves, so by timing the difference in arrival time of the two waveforms we can estimate the distance to the epicentre.

https://www.bgs.ac.uk/discovering-geology/earth-hazards/earthquakes/how-are-earthquakes-detected/


How can temperature be calculated given relative humidity and dew point?

To understand that formula, it's better to start from the more intuitive dependence of dew point with temperature and relative humidity, as illustrated by the following graph from Wikipedia:

As for any solvent with a solute, the higher the temperature of the solvent the more solute it can hold. That's why hot water can dissolve more sugar than cold water. Or, for a given quantity of sugar, hot water dissolves it faster than cold water.

The figure above says basically the same: Hotter air dissolves more water. Condensation happens when the amount of water in the air is more that the amount the air can actually hold. The dew point is the temperature at which condensation appears. Therefore, for a given relative humidity, the hotter the air, the higher is the dew point.

As you can see, in the Magnus approximation, the relationship is just a straight line, with a slope and constant changing for different values of the relative humidity.

I'll assign letters to each constant for simplicity, so that

$b=17.625$

and

$c=243.04$

With that, the dew point can be calculated as

$TD= \large c \LARGE \frac{\ln\left(\frac{RH}{100}\right)+\frac{b T}{c+T}}{b-\ln\frac{RH}{100}-\frac{b T}{c+T}}$

(see Calculating the dew point)

I won't do the algebra, but if you rearrange that formula so that $T$ is written as function of $TD$ and $RH$, you will go back to the formula you presented.


What does supersaturation with respect to ice mean?

The saturation vapour pressure defined by the American Meteorological Society:

The vapor pressure of a system, at a given temperature, for which the vapor of a substance is in equilibrium with a plane surface of that substance's pure liquid or solid phase; that is, the vapor pressure of a system that has attained saturation but not supersaturation.
The saturation vapor pressure of any pure substance, with respect to a specified parent phase, is an intrinsic property of that substance, and is a function of temperature alone. For water vapor, the saturation pressure over supercooled liquid differs appreciably from that over ice.

When water vapour exists over a body of supercooled liquid water, water is constantly exchanged between the liquid form and the water vapour form.  When this reaches equilibrium, there is equal phase change in both directions.  If the air becomes saturated, no more water vapour can be added to it, for it will condensate to the liquid form immediately.  At this temperature, the vapour pressure is the saturation vapour pressure with respect to water.  Remember that water can exist well below 0°C — clouds are typically not completely frozen until temperatures drop to around -40°C, although it depends on many factors and the details are subject to ongoing research.
When water vapour exists over a body of ice, there is a phase exchange.  At a certain temperature and pressure, the air is saturated, any water added will precipitate as ice.  At this temperature, the vapour pressure is the saturation vapour pressure with respect to ice.
By "Body of" you should probably not so much think of a frozen lake or liquid ocean but rather of small cloud droplets or ice particles.
This graph from Vermont State College shows the saturation vapour pressure over water or ice:

Source: Vermont State College
As your source stated, this difference is important for meteorology as it affects the formation of clouds and precipitation.
Now as to why the saturation vapour pressure is different with respect to water than with respect to ice is another question.  You may find more expertise for that on Chemistry Stack Exchange than here on Earth Science.  My atmospheric science textbooks in any case don't go into detail there.


Why is it still day in Mumbai at 6:47 PM?

This image from https://www.timeanddate.com/sun/india/mumbai shows that daylight ended at 6:44, so 6:47 was three minutes into civil twilight and pretty much close to daylight.

Notice the orange light in the back - I'm assuming that this is a street lamp, which are only turned on at twilight.

Most likely the image appears relatively bright because of camera settings, not because it is full daylight outside.


What is the correct way to report historical daily Max / Min / Avg Temperature by City?

Yes, daily minima, maxima and precipitation totals are calculated simply as you suggested in your question. Take care that there aren't missing values,, but that's more of an issue calculating means. Also check whether the reported values for precipitation are in fact a null value, it's unlikely that it could be measured in such small units.


How to locally identify a cold front passage?

A cold front lies in a trough of low pressure and separates air masses.  As you mention in your question there are differences in temperature and the winds on either side of the front, though these can be subtle depending on latitude and season.

A "classic" (mid-latitude NH) cold frontal passage might be recorded as southerly or southwesterly winds, increasing in in strength, temperatures rising and pressure falling.  As FROPA occurs the pressure will bottom out and start to rise, winds shift to northwesterly or northerly, temperatures start to fall and skies clear.

A "classic" (mid-latitude NH) warm frontal passage might be seen as temperatures stable, calm or weak southerly or easterly winds, high clouds with bases lowering over time and pressure falling.  The FROPA will see pressure at its minimum and starting to rise, winds shifting to southerly and temperature warming.

The common factors the changes in pressure, wind and temperature and can be used to determine frontal passage.  Look for a pressure minimum, a change in temperature trend and a shift in wind.  A cold frontal will also generally bring drier air, and a warm front humid air, so this can also be used.

Here is a meteogram from SLC:

In this plot, cold frontal passage occurs around 7Z, marked by a minimum pressure trending upward, dropping temperatures and dew points, winds shifting to northerly and skies starting to clear once the precipitation ends.

Individual frontal passages will be different in exact details, but these general set of trends should help you out.


What causes the Earth to have magnetic poles?

Well, firstly it's important to recognise that the poles are merely the extremities of the shape of a magnetic field - the earth's magnetic field.  All magnetic fields have polarities as such.

However, you're asking why the field itself even exists, I gather.  In this case it's generated by electric currents in the conductive molten iron (and other metals) in the core of the earth, as a result of convection currents generated by escaping heat.   This is known as a geodynamo, and is one way of generating a magnetic field.  However, exactly why this occurs is still under investigation.

More is available in this Wiki piece - specifically on the physical origins of the earth's magnetic field.


What kind of lava tube feature is Cleopatra's Grave?

It's just average ropy lava called pahoehoe by geologists. It's similar to dough so it easily forms ropes like the ones around the side and bulbs like the central area which is similar to a pillow except that it's called a toe.

The colder black lava flows like ropes and the hotter red lava is smooth.

This is also from Cleopatra probably: https://media.gettyimages.com/photos/ropey-lava-from-volcanic-eruption-picture-id200432059-001

Another good image of a toe:

Source: Oregon State University


Where can I find a list of active mining claims in my area (Northern Nevada)?

You may want to check this out ESRI open data http://opendata.arcgis.com/ if this is what you were looking for.

One another thing is that you might want to contact BLM's Nevada State Office.

http://www.blm.gov/nv/st/en/prog/minerals/mining.html

They may have the data if they are on the Public lands. I am not sure about the private lands for that.


The presence or absence of a large number of massive buildings has no bearing on where and when earthquakes occurs, or their magnitudes; particularly along major fault systems such as the San Andreas Fault.

Earthquakes mainly occur on tectonic plate boundaries, such as the San Andreas Fault, near San Francisco, or the fault systems through Turkey, Italy, New Zealand, near Japan and the Rift Valley in Africa. However, this does not preclude earthquakes from occurring elsewhere, such as in the middle of a tectonic plate.

For many decades some Australians thought that Australia was immune to earthquakes because it lies in the middle of the Indo-Australian plate; then a number of large earthquakes occurred in the latte half of the 20th Century causing people to have a rethink.

The fact is geological faults occur everywhere: some are major, others are minor; some are active, others aren't. If ground movement occurs on a fault an earthquake or tremor will happen regardless of any extra weight on the Earth's surface at any location.

The San Andreas Fault, like many major faults, is not one single fault, but a fault zone of sub parallel faults of varying lengths. The accumulation of stresses along the individual faults are not uniform throughout the entire system. There is no precisely predictable pattern to when an earthquake will occur or where along these major fault systems

There is a picture on the following website showing the system of faults in the San Andreas Fault in the San Francisco bay area.

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

The size and occurrence of a earthquakes along tectonic plate boundaries is dependent on the speed at which the plates are moving past each other and how much they snag on each other and the strength of the rock at the snag points. With very strong rock at the snag points a lot of pressure can build up over a long time and when that pressure is eventually released when the rock breaks or slips a strong earthquake will occur.

Many earthquakes will occur within the San Andreas Fault system, but it doesn't necessarily mean that San Francisco will be affected any time soon or how badly it will be affected.


The influence of special emissions (possibly coal mining activity) on particulate matters

The first thing to consider is, if it is not the adjacent coal mine, what other nearby sources could produce such a result. Is there a coal fired power station or a factory nearby. If there are no other likely sources then the coal mine is still the most likely candidate as the source of the dust and metal contaminants.

The other thing to consider is how is the coal being mined in the open pit and how is dust being generated by the coal mine.

The most likely method of mining the coal would require the use of explosives and blasting. This can create large clouds of dust that can be high and wide. If the wind was not blowing when a blast occurred the dust may have reached your sensors.

If the coal is mined by mechanical cutting techniques dust will still be generated, but not in the same quantities as blasting produces.

The other ways dust is generated is by vehicles travelling on unsealed roads - the tyres of the vehicle churn up the dust on the roads.

Dust can also be blown from trucks loaded with coal or from conveyor belts conveying coal to a dump site. The loading of trucks will also generate dust, as will the dumping of coal.

From experience, the only way to control dust is to constantly spray with water. Do you know if the mine uses any for of dust suppression?

It is well known that coal contains all types of contaminants, including metals such as cadmium and mercury. Different deposits have different types and degrees of contaminants.

From what you have presented, the coal mine is the most likely source of the dust and metal contamination.


Are there resources for determining what percentage of the earth's surface is occupied by air conditioned spaces?

I would dispute the idea that the "vast majority" of the world's buildings have air con; in fact, considering that a large proportion of the world's buildings are either (a) in hitherto cool places; or (b) in undeveloped places, I would imagine that it's probably a minority. But I don't have figures on this.

The main part of the question, though, is about the proportion of the earth's surface that is built on. That could be approached as a GIS exercise, and would be reasonably easy to do in places like the UK that have freely-available maps that show all buildings... and very much harder to do in parts of the world that don't.

This study made an estimate (from various data sources, including nighttime lighting) that about 3% of the Earth's land area is "urban". That certainly doesn't include all buildings, but it also includes urban spaces that are not buildings, so it may serve as a useful first approximation.

Depending on your objective, you might find it more useful to stop thinking specifically about air conditioning and instead ask about heat produced by buildings. All buildings produce heat, whether this is from heating, cooling, or other energy use. As a proxy for this net heat production you could simply look at the buildings' energy consumption.


Is it natural for clouds to flow near the surface?

I suppose that it had been raining before. The water had gone to the soil, but the moment you took that picture, it was already evaporating. The air was filling with such water coming from the soil, but air can hold only a limited quantity of gas water, so no more water could be in the form of gas (at so called "point of saturation"). Thus, it changed its state of matter from gas to liquid. But as we all now, liquid water can be seen (the "gas" above the boiling water that we can see is actually liquid water that rapidly cools down). Also, clouds are just such liquid water caught in the air, thus a cloud formed.
The near surface clouds can also form near the sea, with orographic clouds, or on a front, but such near surface clouds are more similar to fog (actually they are fog).


Melting basalt on the lunar surface - what would the resulting material be like?

Melting lunar dust of basaltic composition will result (unsurprisingly) in basalt lava. There might be some volatile loss - if for some reason the basalt had some H2O or CO2 trapped in the solid you will most likely lose it. It's probably not going to change its chemical properties much though.

On Earth, as lava cools down fast, for example when it's erupted underwater, or when it's the top of a lava flow in contact with air, it quenches to volcanic glass. When it cools down slower, there is enough time for small crystalline material to form in it. These are usually tiny crystals in the μm size. On the Moon, I reckon the lava would cool down slightly slower than on Earth (since there is no air to conduct away heat), but since you're talking about a lava layer which is only 2 cm thick I'm pretty sure it will cool down fast enough for the formation of glass, and any crystalline portion of it will be negligible. I am not sure whether it will crack or not. From my own experience of melting rocks, when you have a similar amount cooling down in Earth's atmosphere, they crack. But then, silicate glass does not crack when cooled down in air. I guess it comes down to the composition of the rock/glass.

The lava will not percolate down to the regolith. Lavas hardly penetrate soils on Earth, so it is probably not going to happen on the Moon where the gravity is much weaker.

If I were looking for construction materials on the Moon, I would just build a quarry. Seems easier than melting down dust.


Difference between "Geology" and "Physical(Natural) Geography"?

Physical Geography is a wide area of study - there is many sub-disciplines in this field, such as Biogeography, Climatology, Hydrology, Pedology, Geomorphology (and others as well). Often the scale interesting for the physical geographer is the recent past and future, calculated in thousand of years before today up to a few million (time scale could vary in the recent past (last few years and up to the glaciations and Pleistocene at large). Further, it is focused on surface processes, and not necessarily on rocks, there is a lot more interest in dirt, soils, looses pebbles, and their dynamics of erosion and deposition, the processes affecting the surface. A physical geographer will enjoy hunting for deposits exposure when in the field, so a wall of ancient dirt stratae.

On the other hand, the Geology field is interested in longer period of time, in rocks, often very deep rocks, the internal geodynamics (mantle, core, magma), will consider the disposition of crystals, petrology, geochemistry of rocks. Otherwise, geologist will be interested in the same topics that physical geographer do, but will use different tools, or consider those topics as a factor among many. Geologist may be mingling with the engineering world better than geographers. They will hunt for outcrops in the field, like intact, in situ rocks that can explain something about the site.

To illustrate this, when I go in the field with geologists, I prefer to bring a shovel, they bring a hammer (I bring one too but will choose the shovel over!). We will enjoy the accessibility to a drill to make boreholes, but will be happy with the first 5 meters depth where they would be interested more in deeper drilling. Further, I will be glad to drill in soils and dirt, where they would definitely prefer in rocks.


Curious natural patterns on the surface of basalt blocks that make up the sidewalk

These are most likely manganese dendrites. It is not a fossil, and not organic. These usually form in cracks in rocks, and most likely this slab was broken along an existing crack.

You can read more about it now: https://www.mindat.org/min-26645.html

One comment: this is not basalt. Basalt is black. Most likely some form of limestone.


A normal single arc rainbow is caused when sunlight enters a raindrop with a light-path refracted>reflected>refracted. A double rainbow occurs when sunlight hits a part of the raindrop at a different angle of incidence, at which the light-path is refracted>reflected>reflected>refracted. Some energy is lost with each reflection, so the double internal reflection emerges as less bright than the primary arc. Also, because there is another internal reflection the colours are inverted. So every rainbow has a primary and seconday arc. Hence the question becomes: 'Is the observer in a position to see the secondary arc', which  is a matter of geometry between the sun, raindrop and observer.

So the answer to your question is 'no', it isn't rare at all, in fact a secondary arc is always present somewhere, but is not always visible to the observer for reasons of geometry and background light intensity.


Please help me identify the inside of this stone

Your rock is chalcedony, a Cryptocrystalline variety of quartz.


How are paleomagnetic polarities determined?

This is a big question: it essentially translates to ‘how do we do palaeomagnetism’? I will try to give a brief overview and links to more detailed explanations. I'm also going to focus on the ‘how’, and leave the ‘why’ to someone else (perhaps it would be best split out into a separate question?). To record the geomagnetic field, you need three things:

A ferromagnetic mineral -- that is, one that can be magnetized like a compass needle.
A situation where grains of this mineral can have their magnetization aligned with the earth's field.
An event that locks the magnetization in place once it's aligned.

There are a surprising number of ways that (2) and (3) can happen, but for this answer I'll just describe the two that tend to be most useful: thermal remanent magnetization (TRM) and depositional remanent magnetization (DRM).

Thermal remanent magnetization is induced when a rock cools from a hot (often molten) state. Here, (2) occurs because, above a certain temperature called the blocking temperature, the magnetization of a mineral is able to change freely to align itself with the earth's magnetic field. As the rock cools, it becomes harder for the magnetization to align, and eventually it is locked in place.

Depositional remanent magnetization occurs in sediments, and is induced when grains of a magnetic mineral fall through the water column and land on the sea floor (or lake bottom). While they are in the water column, the grains are free to move and align themselves with the geomagnetic field. Once on the bottom, they gradually become buried in more layers of sediment, fixing their original orientation.

In principle, recovering the recorded field from a piece of rock is very simple: you record the rock's orientation, cut or drill it from its current situation, then measure its magnetic field in a laboratory magnetometer. In an ideal world, the field you measure would correspond to the Earth's magnetic field when the rock was formed. In practice, it's rarely that simple, and you might need to use heat treatment or alternating-field demagnetization to ‘peel off’ weaker magnetizations that have been layered on top of the original magnetization over the years.

This answer is a gross simplification and glosses over a great deal of theory, practical detail, and possible complication. For more depth, I would direct you to two excellent textbooks which (thanks to the magnanimity of their authors) are freely available online:

Tauxe, L., Banerjee, S. K., Butler, R. F. and van der Voo, R. (2014). Essentials of Paleomagnetism, third web edition. http://earthref.org/MAGIC/books/Tauxe/Essentials/ (accessed 2014-04-17)

Butler, R. F., (2004). Paleomagnetism: Magnetic Domains to Geologic Terranes. electronic edition. http://www.geo.arizona.edu/Paleomag/book/ (accessed 2014-04-17)

Tauxe et al. (2014) is more recent and more extensive; Butler (2004) is an electronic reprint of a 1992 book, but is still an excellent introductory work, and provides (to my mind) a slightly gentler introduction than Tauxe et al. (2014). (While many advances have been made since 1992, the basic theory and techniques have not changed.)

If you are interested in the nitty gritty of how the techniques are actually applied, you might want to look at:

Richter, C., Acton, G., Endris, C. and Radsted, M. (2007). Handbook for shipboard paleomagnetists. ODP Technical Note 34, Texas A&M University, College Station, Texas, USA: Ocean Drilling Program. http://www-odp.tamu.edu/publications/tnotes/tn34/TNOTE_34.PDF (accessed 2014-04-17)


Are there seamounts as close as 100 m to the water surface and not inside any Exclusive Economic Zone?

Yes, there are many. According to the seafloor topographic data of ETOPO (1 arc second resolution), and the Exclusive Economic Zones (EEZ) database of marineregions.org. There are at least 157 seafloor features higher than -100 m (closer than 100 m to the sea surface). With that data, I made the following figure that shows:

ETOPO topographic data
All EEZ polygons
All 157 -100 m contour lines that are completely or partially outside any EEZ.
A red point at the centroid of each contour line (to make even the smaller seamounts visible).

Some of them are just a few meters below sea level according to ETOPO.

But note that with this data we can only see large features. ETOPO resolution is about 2 km. Therefore, a seamount with a sharp summit just above -100 m would probably not show up on ETOPO data.

For more information about individual seamounts you can query the Seamount Catalog of EarthRef.org. There you can find high resolution multibeam seafloor topographic data for many seamounts, there are more than 1,800 seamounts in the catalog so far.

For example, for Vema seamount that was mention by @arkaia and that corresponds to the point just West of South Africa in my figure, you can find data like this:


How does CO2 contribute to global warming?

It seems that you are wondering how a chemical that prevents heat (putting out a fire) can also cause heating (global warming).  These two things happen through unrelated processes.

Fire extinguishers that use CO2 act by displacing oxygen.  The CO2 doesn't directly interact with the fire but just takes up space so that oxygen cannot interact with the fire.  There is a secondary effect that the CO2 exiting the extinguisher is cooler than the air it is displacing so it helps to remove heat from the fire (by putting it somewhere else).
These are reasons that CO2 extinguishers are not suitable for all kinds of fire suppression, particular for fires that have oxidizers and do not rely on atmospheric oxygen for combustion.

The contribution to global warming from CO2 (and all other greenhouse gases) is a radiative effect.  Every molecule has specific frequencies of electromagnetic radiation they absorb and emit.  The earth (and all things) emit electromagnetic radiation based upon its surface temperature.  This energy would be lost to space (cooling the earth) except that the greenhouse gases absorb radiation at the same wavelengths the earth emits at.  This means that, e.g. CO2, intercepts this energy headed for space and instead absorbs it, causing the CO2 to warm up a little.  This CO2 also emits radiation but will emit less than it absorbs (and some of its emission is back toward the earth, not space), so there is a net energy gain due to atmospheric GHG, which causes warming.

As you can see, the mechanisms that CO2 contributes to global warming and fire suppression are unrelated (radiative vs displacement) which is why this molecule can be used in these seemingly contradictory applications.


Is pollution a contributing factor to freezing rain?

Pollution shouldn't contribute to produce freezing rain. It might have an impact in the precipitation rate and location but not on the likelihood of freezing rain.

Freezing rain requires not only that the near-surface temperature is below freezing, but also that there is a temperature inversion that provides above zero temperature in the atmospheric layers above the surface.

Usually temperature drops as you go higher into the atmosphere. But in some areas, due to climate, geography and local weather patterns, you can often find that the temperature rises as you go up, that's called a temperature inversion (eventually as you go high enough the inversion dies and temperatures drops as you go even higher).

Such condition can melt the snow high in the atmosphere and then the water droplets enter an area near the surface that is below zero and cools them down but not for long enough to freeze solid (something that would produce sleet). Water droplets in such conditions gets below zero but remain liquid, a phenomena called supercooling. When the supercooled drops hit the surface (that is also below zero), they instantly freeze forming a thin layer of ice, hence freezing rain.

This figure from mprnews.org nicely summarize the phenomena:

Regarding why some places can be mor suitable for freezing rain, I'll highlight here the comment by @Anirudh pointing to this link that deals with the case of Guizhou Province in China.


Where did the daily temperature variation go?

There are (at least) five factors at play here:

the cold air advection from the north east has driven temperatures down
the cloud cover traps longwave radiation sort of like a blanket, keeping the night time temperatures from dropping
also, the cloud cover prevents solar radiation from reaching the surface and warming it
the relative humidity is near 100%, indicating that the dew point is nearly the same as the air temperature.  Dew point serves as a minimum possible temperature, so this also prevents the air temperature from dropping
precipitation traveling through the lower atmosphere will evaporate, having two effects: cooling the atmosphere and maintaining a high dew point

(5) is only really a factor during the day when temperatures would normally be on the rise.  The precipitation will keep the diurnal heating to a minimum.


If the study of "minerals" is covered by inorganic chemistry

The study of minerals is the field "mineralogy" In some ways it would be a subset of inorganic chemistry, restricted to crystaline materials of natural origin. However, mineralogy includes the physical as well as chemical properties, especially crystallography, X-Ray diffraction and optical properties. It also includes aspects of how the minerals were formed in nature. Minerals also may be named by their chemical formula, but some chemicals have different crystal forms so two minerals can have the same formula. For example the minerals calcite and aragonite are forms of calcium carbonate, $\ce{CaCO_3}$. So you may need to broaden your search in pubmed and they may not include data for all minerals.


Packages as Seismic Unix and Madagascar represent a different philosophy than commercial products.

The packages are open source, so any user can look at the code, understand how it works (or why it doesn't) and even produce reproducible research so other geophysicists can test the results and use the methods. A great way to learn about seismic processing is indeed by reproduce earlier studies.

A lot of new processing methods are developed within the Seismic Unix and Madagascar groups, and they are great sources if one needs a special tool for a special problem.

The packages are free and are widely used by universities, but they can also be useful for processing companies. It is easy to share or sell projects if they are built in code that everyone have access too.

If the processing capabilities are superior or not is generally about opinion, but at least the results can compare well with commercial packages. Sometimes they can be used in the same workflow, e.g. the geometry might be easier to do with a GUI but processing might be just as easy in a script.

My own experience is that the learning curve is rather steep in the beginning, but once you understand the basic tools, Seismic Unix and Madagascar are just as easy, or even easier to work with. Especially if there is a problem or you need to do something unconventional with the data.


Could pumping ocean water into desert areas help reduce sea level rise?

This is no an answer per se, just a back-of-the-envelope calculation for fun.

Lifting 1 kg (one litre) of water up a height of 1 meter uses 9.8 (let's say 10) joules of energy.

Let's say you want to lower the sea level by 1 meter. You need to pump 3.6e17 litres (3.6e14 m2 of ocean area = 3.6e14 m3 to pump * 1000 for litre conversion).

Let's say you want to lift this water up a height of at least 10 meters, so it doesn't go right back into the ocean but rather stays behind some kind of dike. We're already at 3.6e18 J of energy. That's 1e15 Wh, or 1000 TWh. That's more than what the 20 largest power stations combined produce in a year.

This also assumes an ideal, 100 % efficient pump (no energy loss)...


Why doesn't Wolfram Alpha show low gravitational acceleration for the Hudson Bay?

Wolfram Alpha reports values between 9.78 and 9.88 m/s^2 depending on the location, which is odd because it should stay within the range 9.76 - 9.83 all over the world. It also seems to be using the ocean floor as a reference elevation if the point falls in water.

Using Natural Resources Canada's tool, it reports a gravity of 981933.3 mGal (9.819333 m/s^2) for Hudson Bay at 60.9N, 94.1W at sea level, which seems more likely for that location.

Keep in mind that while the area near Hudson Bay has a negative gravity anomaly, this does not imply that it should have weaker gravity than Chicago (9.8026 m/s^2), which is much closer to the equator. It means that Hudson Bay's gravity is lower than what it should be at that latitude.  Gravity is even weaker near the equator (around 9.78) because as you get closer to the equator, the centrifugal force is stronger and slightly counteracts the force of gravity, also the mass of the Earth is slightly further away from you, thus has less gravitational pull on you. These 2 effects alone create gravity variations up to 0.5% (around 0.05 m/s^2)

Gravity anomalies are relative to a theoretical normal gravity based on an idealized ellipsoidal rotating Earth, and these anomalies are small compared to the variation caused by cetrifugal forces and the oblateness of the Earth. Anomalies range between -50 and +50 mGal (+-0.0005 m/s^2). Normal gravity at the Equator for sea level is about 9.78 m/s^2, and near the poles, around 9.83 m/s^2. Altitude also has a significant effect, at 5000 meters, gravity is about 0.01 m/s^2 weaker than at sea level.


Does climate change cause increase in CO2?

One reason is that we know exactly where the current increased CO2 comes from.  That is, we know from economic data how much petroleum, natural gas, & coal is extracted and burned.  From that simple chemistry lets us compute the amount of CO2 produced, and we find that (after allowing for factors such as e.g. some being absorbed by the oceans) that the amount created by burning fossil fuels matches the observed increase.

(There are also more subtle measurements, such as isotope ratios, which I'm not qualified to expound in any detail...)

Another reason is that for warming to have caused the observed increase in CO2, there'd have to be some other cause for the warming.  No such cause has been found.  Suggested causes such as variation in solar output have been ruled out by measurements.


This is a non-exhaustive list of factors influencing the permafrost thickness :

latitude
altitude
aspect
material type
nature of the regional climate (dry, oceans, continental)
geologic history of the permafrost (formed after the last glacial maximum, or before?)

Time is important: older permafrost can be very deep, especially in areas such as in Siberia, Yukon/Alaska where the effect of glacier was limited, thus exposing the ground to cold conditions for long time. Some areas in the Canadian archipelago are in excess of 1 km deep, and more than 500 m is not uncommon, largely depending on local and time conditions.

Yet, huge discrepancies in permafrost depth can be found between western Canada/AK, eastern Canada, Northern Europe and Siberia, given a constant latitude, and therefore isolation and thus comparable aspect. As an example at Svalbard (78N), permafrost depth was reported to be less than 400 m, while regional depth in the central canadian archipelago north of Baffin Island is more than 500 m (for 73 - 75 N) and 1500 m in northern Siberia (which is at a lower latitude than Svalbard).

To get back to your question, aspect (or solar radiation input) is pretty much uniform for a given latitude - but in this case, for the same latitude, permafrost depth vary.

On the other hand, material type vary locally. If wetlands, mosses and vegetation will contribute to cool the ground, enabling deeper permafrost in those areas. Areas were there is a lot of snow (snowbanks) will have a warmer permafrost compared to crests nearby. Lakes change how heat can be extracted from the ground (latent heat effect) so permafrost will be thin under a lake compared to around the lake (lake being a type of material in the context of your question). Desert ? Rock outcrop ?

Each type of environment behave in a certain way regarding heat extraction and ultimately heat exchanges, which have a lot to do with the nature of the surface..


How can crystal habit be determined when rock is worn and rounded?

Is there a simple instrument

A geological hammer. Seriously. Once you smash a rock, you reveal fresh cleavage planes, grain boundaries, less weathered zones, etc. The downside is that it's destructive.

  angle of a crystal, even if it is worn and rounded?

Here you're assuming that crystals that are not worn or rounded have their original crystal shape. This is rarely the case. These crystals, known as "euhedral" are the exception, not the rule. A good example is feldspar phenocrysts in granites, or some elongated amphiboles. Maybe phenocrysts of pyroxene in basalts. More commonly, crystals are just shapeless, also known as "anhedral".

A more advanced form of rock and mineral study is called petrography - this requires thin sectioning abilities and a petrographical microscope. Basic tools that exist in all geological departments at universities, but probably not accessible to amateurs.


Groundwater consists mostly of water, obviously.
Usually, "minerals" in water (for example in bottled water) are actually not minerals but rather dissolved ions. Strictly speaking, minerals are solids. Fluoride, then, is also a "mineral", and actually a dissolved ion.

Groundwater usually begin their life as precipitation: rain, melting snow, etc. These are usually clean and pure (as in distilled) waters and once they percolate through the ground they pick up ions from the rocks and from the soil.
For example, groundwater in areas rich in limestone will have high calcium contents. So yes, there are differences in different areas.

Groundwater is mostly safe. However, there are cases where it isn't. Most commonly, groundwater contaminated by man-made sources. Leaks from factories, improper water treatment, etc. Also, some groundwater may be acidic (low pH) or basic (high pH, 1). While this may be desired in natural hot spas, this is not something that would be safe to drink. Groundwater may also be contaminated with arsenic or with radium (2), a radioactive element that occurs naturally in Uranium-bearing rocks (e.g. granite).

References from my local area:

(1) Saines, M., Dickson, P., & Lambert, P. (1980). An occurrence of calcium hydroxide ground water in Jordan. Groundwater, 18(5), 503–503. doi:10.1111/j.1745-6584.1980.tb03427.x

(2) Vengosh, A., Hirschfeld, D., Vinson, D., Dwyer, G., Raanan, H., Rimawi, O., … Ganor, J. (2009). High naturally occurring radioactivity in fossil groundwater from the Middle East. Environmental Science & Technology, 43(6), 1769–1775. doi:10.1021/es802969r


How we can find hot spring genesis time?

The answer to the first question is a maybe, hot-springs often have mineral saturated water that can create layered deposits which may be datable, much like tree rings. If reasonably uniform flow and mineralisation rates can be demonstrated over time then reasonably accurate dating may be possible.

As to the second question, we have a saying "how long is a piece of string?" meaning there is no universal answer, some springs may be seasonal, only flowing for a few months at any given time, while others may flow continuously for hundreds of years then stop abruptly for no apparent reason. There are no "in general" each and every set of geothermal plumbing is unique.


Do tectonic plates "float" over the mantle and "collide" like icebergs?

you are missing a big factor, the plates are not moving due to the momentum of an initial impulse. They are being actively moved by the push and pull of mantle convection. Much like how icebergs are pulled along by ocean currents. the iceberg analog however breaks down because icebergs melt before they can do much complex interaction, where as continental plate material is more or less permanent. also icebergs are subjected to far lower forces than continents, a closer analogy would be ice in glacier.

The amount of energy the mantle is supplying is massive, far far more proportionally than an iceberg is subjected to, more than enough to drive continental plate together and build mountains.  if you are interested in the detailed mathematics you can start here.

The continents float on the mantle becasue they are less dense, but they are moved by mantle movement transferring energy.


What is a massif and what differentiates it from other types of mountains?

My interpretation is that while an individual mountain itself may be part of a mountain range that is marked out by faults and flexures, the actual mountain is demarcated by erosive processes. For example, the Alps in France are a mountain range, demarcated by faults. However, the Matterhorn, shown below, is clearly a mountain figure not marked out by faults or crustal flexing. Instead its prominence from the surrounding regions is caused by the erosion processes of glaciers.

To use the example in the massif Wikipedia article, The Mont Blanc Massif contains peaks within it (Aguille du Midi, the Mont Blanc peak etc., shown below) that are defined by erosion, but the group of these peaks is defined by faulting.


Is the Yellowstone National Park unique for its geysers?

Yellowstone is thought to be above a mantle plume, of with there are tens to hundreds on our planet, although there is plenty of debate on this matter. The exact nature of mantle plumes is a huge area of hotly contested research, but generally the are thought to be large melts originally sourced from the D'' layer (core / mantle boundary). Below the park, the plume is theorized to have resulted in magmatic intrusions overlain by a hydrothermal system. The intrusions can also be considered as magma chambers of a supervolcano, which has had several ultraplinean caldera-forming events.

The Yellowstone hotspot is the only obvious expression of a mantle plume beneath the continental United States, which may be why you consider it "unique." The other major plume / hotspot in the US is Hawaii.

Yellowstone is certainly not the only major geothermal area in the world; geothermal areas in New Zealand, Italy, Japan and Antarctica are comparable in terms of heat flow. It's unclear what you mean by "thermal power" but Yellowstone park does not have any geothermal electric power generation plants. New Zealand, on the other hand, generates 13% of their national power needs geothermally.


How high is too high for hydrogen to rise?

I had a similar question, and then I learned that at the molecular level it is diffusion what dominates, that means that despite Hydrogen is lighter, it won't rise to the top of the atmosphere. Flotation as we visualize it doesn't really work at the molecular level (because it is overcome by chemical diffusion).
Therefore, the Hydrogen in the atmosphere is evenly distributed trough it.

To clarify it further, a parcel of hydrogen would indeed rise, but as soon as it gets diluted in the surrounding air, the buoyancy of individual molecules/atoms would become negligible in comparison to the chemical diffusion that will take the atoms in any direction, not just upwards, leading to further dilution of the original molecules within the parcel throughout the atmosphere.

As for why that's the case, let's me explain how I visualize it: Imagine you put two a thousand million ping-pong balls in the middle of the Pacific ocean. Half of them with a piece of Iron inside. If you put a magnet in the coast of Mexico, you would expect all the balls with the piece of iron to end up in Mexico. However, the forces of the wind and waves hitting the balls in random ways is so much more powerful than the magnetic attraction in this case, that most likely the balls will end up all over the Pacific. In the same way, all molecules in the air are bouncing against each other with such a strength, that the fact that one is lighter than the other doesn't really play a role in the trajectory a molecule will follow on its journey trough the atmosphere.

In any case there is not much Hydrogen in the atmosphere, that only contains a 0.00005 % of molecular Hydrogen (H2).


Have two hurricanes ever merged? And what was the result?

Yes two hurricanes/tropical cyclones/typhoons can merge with each other and the effect is known as Fujiwhara effect- Fujiwhara effect.

The National Weather Service defines the Fujiwhara effect as "Binary Interaction where tropical cyclones within a certain distance(300-375 nautical miles depending on the size of the cyclones) of each other begin to rotate about a common midpoint". What really happens is that centers of both systems begin to orbit in a counter clockwise direction about a midpoint that is determined by the relative mass and cyclone intensity. Eventually the smaller cyclone may merge into the larger cyclone.
There are several examples of the Fujiwhara effect and one example would be  Hurricane Connie Hurricane Connie and Diane Hurricane Diane way back in 1955. Shimokawa et al Fujiwhara Effect Types talk about the various kinds of interactions that can take place among various typhoons(Please note that the Fujiwhara effect is not restricted to two systems). The various kinds of interactions are

Complete Merger
Partial Merger
Complete Straining Out
Partial Straining Out
Elastic Straining Out

Complete straining and complete merger interactions lead to destruction of one of the vortices. Partial merger and partial straining lead to partial destruction of one vortex and elastic straining is an interaction in which both vortices survive with their initial circulation. Partial merger and partial straining out have received less attention in the literature on binary tropical cyclone interactions as the interactions are extremely complex. Prieto et al claim that during a partial merger repeated mass exchanges occur between vortices. As these are nonlinear effects a quantification is only possible by a direct numerical integration  and precise initial condition Binary TC Vortex Like Interactions

The period of orbit maybe as small as one day or there are others such as Cyclone Kathy and Cyclone Marie Kathy/Marie Fujiwhara orbited for a period of 5 days prior to merging into each other as pointed out by Lander et al. If the period of orbit is longer then there is a greater probability of a merger.

Region wise binary cyclones are more common in the Western North Pacific than the North Atlantic as pointed by Dong et al Relative Motion Of Binary Tropical Cyclones
Regarding the predictability of the track of binary cyclones Dong et al. state that prediction of steering forces of a single tropical cyclone are replete with numerical forecasting uncertainties and the problem is accentuated by the presence of another tropical cyclone in close proximity.
Those who followed the progress of Hurricane Sandy in late October 2012 (an instance of the Fujiwhara effect but in this case a tropical cyclone merged with an extra tropical storm) will remember the ECMWF model correctly predicted the landfall location.


Reults of the glacials and interglacials of the ice age on the soil

First a comment on the number of ice ages - one could say 5 to 7 major ice ages, depending upon how one defines an ice age, and several more minor ice-ages, with some debate as to whether some are sufficiently separated in time to be regarded as two ice ages.
Most of the northern hemisphere has been emerging from the most recent ice age over the past 10000 to 12,000 years, but by no means at a constant rate, with some short-term reversals. As regards soil formation, it is only the most recent ice age that is of relevance - older palaeosols have been either eroded or lithified.

How long does it take for soil to form? That is primarily a function of climate, and secondarily a function of weathering lithology. That is, many millennia for cold dry climates, or as little as a decade or so for hot wet conditions. Soils take many years to form on limestone, quartzite, granite and some other resistant rocks, but are rapid on recent basic rocks such as volcanic ash. The weathering rate of different minerals varies over many orders of magnitude, and is a combination of chemical and biological processes which is far too complicated to discuss here. I suggest you read a good book on weathering processes.

Regarding soil fertility, this is also rather complex, but obviously continuous cropping will tend to remove organic carbon, organically available phosphate and potassium, not to mention other trace elements, thereby leaving the soil less fertile unless very well managed.

Ice ages are not 'normal' in the geological history, and it will take tens to hundreds of millennia for a normal soil quasi-equilibrium to be reached. This 'equilibrium will also be lost both by human intervention and by accelerated climate change.


How does salinity and density affects sea surface temperature?

A low salinity layer that is associated with low density (assuming the same temperature) will remain on top of the water column. As such the water will be able to get warmer and the difference in salinity and temperature will make it even more difficult to mix it down with the rest of the water column. So the combination of high temperature and low salinity results in even lower densities. You can play with the relationship using http://www.mt-oceanography.info/Utilities/density.html