Why does the ocean seem much cleaner than the bay I live near

I had the same experience when I lived in Cardiff, South Wales. When I lived there, the waters around Cardiff were always greyish and uninviting, but the further away one got, the more blue-green and transparent the sea became. Fifty miles west on the Gower coast, the water was pristine and beautifully transparent, more like the Mediterranean.

The reason for this was two fold: a lot of effluent from the city, including sewage, was discharged into the sea, and the river Taff, which runs through Cardiff, brought down a lot of industrial effluent from the Welsh valleys. It is a matter of common sense that the sea dispersed and diluted the pollution the further away from the big city one looked. I understand that the river and the city are much cleaner now, but I think the murky waters of Melbourne which you describe are due to the same sort of causes which many years ago fouled the waters around Cardiff.


Sensible and Latent Heat. how to separate them

First some definitions:

Latent heat is the heat that leaves or enters a system during a process where the temperature of the system stays constant. Phase changes are prime examples where latent heat leaves (exothermic) or enters (endothermic) a system. Ice melts (endothermic) and water freezes (exothermic) at constant temperature. Sensible heat is the heat that enters or exits a system when the temperature of the system changes. Heating or cooling water are cases that involve sensible heat. All heat flow between two systems requires a temperature difference between the systems. Convection is heat flow between two systems by movement of mass. The two other heat flows are conduction and radiation.

Now to the questions:

During a phase change, the temperature of the system stays constant. The heat gained or lost is called latent heat. To vaporize a liquid, we must supply heat. Hence vaporization is endothermic (heat enters the system). To get the heat into the system, we must set the surroundings at a hotter temperature. Otherwise the heat will not flow. The process by which the heat flows can be any one of the three modes. We can set a pot of water in a pan on an electric heater and realize conduction from the burner to the pan to the water. We can set use a hair dryer to blow hot air over the pot and realize (forced) convection from the air to the pan. Finally, we can set the pot a small distance above the glowing electric burner and realize radiation from the electric burner to the pot.

By contrast, consider the case of a day where the outside temperature is below freezing and the air is still. A duck pond in the yard is not frozen over. Clearly, it’s water temperature is above freezing. Should we jump in the duck pond to warm up? Of course not! The natural convection coefficient of stagnate water is higher than the natural convection coefficient of stagnate air (and the difference only becomes greater in flowing water versus flowing air). The water pulls heat from us by convection faster than the air does at the same temperature, and our body temperature will drop faster than when we would stay standing in the still air. Also, while the conduction coefficient of water is larger than that for air, the main heat transfer in a fluid is convection, even in stagnate cases. The heat that flows out of our body as our body temperature drops is sensible heat.


Term for the thing that shines radiation onto a black body

The Sun is also regarded as a black body. Any body that radiates energy following Planck's law of black-body radiation, and absorbes energy at all wavelengths can be considered as a black body. This is an idealization, but if Earth is approximated to a black body, the Sun can be considered one as well.

The case of the sun is not very different to that of Earth: The stuff that makes up both is mostly opaque (plasma for the sun rock for the Earth), but at some point both bodies become transparent (in the Sun when it is cold enough such that electrons recombine with atomic nucleus and form gases, in the Earth at the base of the atmosphere), the base of the transparent layer and the transparent layers themselves emit electromagnetic radiation according to their temperature following Planck's law of black-body radiation, and absorb pretty much any incoming radiation regardless of its wavelength.

The concept of black body (or gray body) only refers at the fact that a body absorb all (or a constant fraction for a gray body) the energy it receives regardless of the wavelength (color), therefore it looks black. Similarly, it must emit in all wavelength too, with the intensity at each wavelength (color) following Planck's law of black-body radiation.

Therefore a mirror is not a black body, neither is a fluorescent lamp, nor a tomato. Because a tomato reflects red light more than green. However, if the thermal balance of a tomato is mainly controlled by the exchange of infrared radiation, you can treat it as a black body, because it acts as one in the infrared spectrum (i.e. if your eyes were sensitive to infrared radiation only, a tomato would look black or gray). In the same way, despite the fact that Earth isn't black, it can be approximated to a black body and with such approximation you can get very accurate results of its energy balance.

Going back to your point. Black bodies can have internal energy sources (like the Sun), and in the absence of the Sun, the hot interior of Earth would also act as an energy source and the Earth would emit more energy than it receives, in the same way the Sun does.

So anything can shine radiation onto a black body, that is precicely because it is a black body and absorb all kinds of electromagnetic radiation. I hope this clarifies your doubt.


comparing use of Laplace equation with diffusion equation to simulate flow of fluid/water through porous media?

The Laplace equation, (d^2 Ψ)/(dx^2 )+(d^2 Ψ)/(dy^2 )+(d^2 Ψ)/(dz^2 )=0, is just a steady state 3D flow equation. It's a black box conservation of hydraulic potential. Diffusion doesn't come into it. The Diffusion equation (assuming homogeneous isotropic conditions) is (∂^2 Ψ)/(∂x^2)+(∂^2Ψ)/(∂y^2)+(∂^2 Ψ)/(∂z^2)= S_s/K  ∂h/∂t. This discretizes the time element, and is very much dependent upon the diffusive properties of the aquifer. Note that S_s/K is the reciprocal of the 'hydraulic diffusivity', hence the name of the equation.


How much did the worst volcanic eruption in human history affect global temperature?

The largest volcanic eruption in human history was the Toba eruption on Sumatra about 75,000 years ago. There is still a huge lake, Lake Toba, in the crater. It dwarfed Thera, Krakatoa and Tambora. The Tambora  eruption on the Indonesian island of Sumbawa occurred in 1815, and was the largest eruption in historical times, also dwarfing the other two. It caused bad weather and lower temperatures around the world, including Europe, for about a year. The much larger Toba eruption must have had even more drastic short term effects lasting for years, but strangely enough doesn't seem to have had any major effects on the human population of South East Asia. It may have emitted enough CO2 to have made a minute difference to the ppm figure had there been anyone around able to measure it.


Recommendations for books on boundary layer Meteorology?

Is there any particular aspect of boundary layer meteorology? Or just something general?
NOTE: I have not read all of these nor do I know anyone who has read these, but judging by the year published or level of detail, these may serve whatever purpose you want. I found these mostly by Googling. I recommend looking at the preview offered in each website.

Turbulence by John Wyngaard- published in 2010
Fundamentals of Boundary-Layer Meteorology by Xuhui Lee was published in 2017, but from the brief look inside, I don't see a large difference from Stull or Arya.
Atmospheric Boundary Layer Integrating Air Chemistry and Land Interactions (2015)
Turbulence and Dispersion in the Planetary Boundary Layer By Francesco Tampieri · 2016


If today's Earth becomes warmer, how will it compare to the Earth of the Cretaceous period?

During the cretaceous the earth was on average 4 degrees warmer, but a 4 degree average results in nearly no change at the equator but a significantly higher rise at the poles, 8 to 15 degrees warmer. Antarctica was not covered in an icecap in the cretaceous period, although smaller ones may have formed periodically. Northern antarctica was largely covered in wet forest. Ecologically you would see wet temperate forest similar to those in australia and south america.

Note however warming was not the the only factor different positions of continents leads to a significantly different ocean circulation. Higher sea levels turn lowlands into seas changing rainfall patterns significantly. So the cretaceous is not a great predictor of the near future climate.

Source 1

Source 2


Is water actually blue or is it transparent?

It is blue. But white light needs to cross a long distance through the water to actually get the blue tint.

This related question explains it for ice, but for water it is pretty much the same story.

This article, mentioned by @JeopardyTempest in the comments of the answer to the above question, tackles the case of the oceans. There it says:

  The ocean looks blue because red, orange and yellow (long wavelength
  light) are absorbed more strongly by water than is blue (short
  wavelength light). So when white light from the sun enters the ocean,
  it is mostly the blue that gets returned.


Would it be geographically feasible to store water on land to counteract sea level rise?

Using the eTopo1 data Eakins and Sharman has calculated a hypsographic curve for the earth. In the elevation span between + 6 to -6 m they found that land area will change by 396 000 km2 per meter sea level change. In the range -7 to -51 m below current sea level the land area will change by 251 000 km2 per meter sea level. Thus to get an area the size of Zimbabwe (391 000 km2) or Norway (385 000 km2) (data from the World bank) sea level will currently have to be lowered by 1 m. Since the ocean surface is about 360 000 000 km2 (e.g. The Physics factbook) this would mean a total of about 360 000 km3 of water which in turn is comparable to the Caspian Sea (371 000 km3 according to a Wikipedia compilation)

So where does that lead? Clearly adding a Caspian Sea somewhere on land is not an easy task so the question is how much land need to be gained and where? Remember that all coasts are not the same, topographically.

As a side point, the Greenland ice sheet contains enough water to raise sea level by about 7 m. Hence the ongoing warming is a far more problematic issue when it comes to sea level change and counteracting this volume would be 7 times more challenging than the calculation made above. That is a sobering perspective.

Reference

Eakins, B.W. and G.F. Sharman. Hypsographic Curve of Earth's Surface from ETOPO1, NOAA National Geophysical Data Center, Boulder, CO, 2012


How can I identify "tough" (mixed) granites?

So, the question is how can I tell if a minedat description of a plutonic rock is favorable according to the criteria of the quoted passage?

No. The description doesn't say how much feldspar is in the rock. It could be 5%, or it could be 20%. It also doesn't say anything about the iron content of the feldspar (although with some petrological hand waving you can assume by the presence of other minerals).

The nepheline syenite is going to have no feldspar (or very little), because it's usually either nepheline or feldspar, not both. But, we don't know whether nepheline is any good for the purpose.

I'm also wondering why is hornblende considered superior because it is a mineral that cleaves and breaks very easily.

One thing that is important is that they stress the fine grain size. Usually rocks with fine grain size are tougher than those with coarser.


How good were climate models of the 1990s at predicting the global temperature trends of the 2000s/2010s?

You might take a look at the Technical Summary of the most recent IPCC Assessment Report (5).
Thematic Focus Element #3 is "Comparing Projections from Previous IPCC Assessments with Observations"
It says:

Global Mean Temperature Anomaly
Relative to the 1961–1990 mean, the GMST anomaly has been positive and
larger than 0.25°C since 2001. Observations are generally well within
the range of the extent of the earlier IPCC projections (TFE.3,
Figure1, middle left) This is also true for the Coupled Model
Intercomparison Project Phase 5 (CMIP5) results (TFE.3, Figure 1;
middle right) in the sense that the observed record lies within the
range of the model projections, but on the lower end of the plume. Mt
Pinatubo erupted in 1991 (see FAQ 11.2 for discussion of how volcanoes
impact the climate system), leading to a brief period of relative
global mean cooling during the early 1990s. The IPCC First, Second and
Third Assessment Reports (FAR, SAR and TAR) did not include the
effects of volcanic eruptions and thus failed to include the cooling
associated with the Pinatubo eruption. AR4 and AR5, however, did
include the effects from volcanoes and did simulate successfully the
associated cooling. During 1995–2000 the global mean temperature
anomaly was quite variable—a significant fraction of this variability
was due to the large El Niño in 1997–1998 and the strong back-to-back
La Niñas in 1999–2001. The projections associated with these
assessment reports do not attempt to capture the actual evolution of
these El Niño and La Niña events, but include them as a source of
uncertainty due to natural variability as encompassed by, for example,
the range given by the individual CMIP3 and CMIP5 simulations and
projection (TFE.3, Figure 1). The grey wedge in TFE.3, Figure 1
(middle right) corresponds to the indicative likely range for annual
temperatures, which is determined from the Representative
Concentration Pathways (RCPs) assessed value for the 20-year mean
2016–2035 (see discussion of Figure TS.14 and Section 11.3.6 for
details). From 1998 to 2012 the observational estimates have largely
been on the low end of the range given by the scenarios alone in
previous assessment reports and CMIP3 and CMIP5 projections. {2.4; Box
9.2}

I've attached an image as well from that summary:

Estimated changes in the
observed globally and annually averaged surface temperature anomaly
relative to 1961–1990 (in °C) since 1950 compared with the range of
projections from the previous IPCC assessments. Values are harmonized
to start from the same value at 1990. Observed global annual
temperature anomaly, relative to 1961–1990, from three data sets is
shown as squares and smoothed time series as solid lines from the
Hadley Centre/Climatic Research Unit gridded surface temperature data
set 4 (HadCRUT4; bright green), Merged Land–Ocean Surface Temperature
Analysis (MLOST; warm mustard) and Goddard Institute for Space Studies
Surface Temperature Analysis (GISTEMP; dark blue) data sets. The
coloured shading shows the projected range of global annual mean near
surface temperature change from 1990 to 2035 for models used in FAR
(Figure 6.11), SAR (Figure 19 in the TS of IPCC 1996), TAR (full range
of TAR, Figure 9.13(b)). TAR results are based on the simple climate
model analyses presented in this assessment and not on the individual
full three-dimensional climate model simulations. For the AR4 results
are presented as single model runs of the CMIP3 ensemble for the
historical period from 1950 to 2000 (light grey lines) and for three
SRES scenarios (A2, A1B and B1) from 2001 to 2035. For the three SRES
scenarios the bars show the CMIP3 ensemble mean and the likely range
given by –40 % to +60% of the mean as assessed in Chapter 10 of AR4.


What other graphical methods can be used to represent weathering?

First of all, you probably used XRF, and not XRD. XRF is a method used to obtain chemical compositions. XRD is used to obtain crystal structures.

A ternary diagram would be indeed very useful in this case. Another thing you might want to try is ratios: a plot of Al vs. K/Ca or something similar. Potassium and calcium likely behave differently in different weathering regimes, so it could be useful to show it.


Does vegetation contribute to long-term carbon sequestration?

Unlikely but theoretically possible.
As the bits of tree work their way down to the sea, they are going to oxidise and release CO2. This would appear to our eyes as "rotting" and breaking down. Leaves aren't going to make it, although they might get buried in river sediments.
Trunks might. Once they reach the open sea, they are going to have to become water logged and sink to the bottom of the sea or ocean. They are going to then have to either fall into an area of anoxic bottom waters (restricted water flow => very little oxygen if any), or be quickly buried by sediment that cuts off the oxygen.

Speaking generally, when I look at ocean sediments, I have yet to see fossil wood. I do see fossil wood in places like river deltaic sediments though (eg. the Carboniferous sandstones of West Yorkshire).


Why is it necessary in seismic imaging to calculate an image of reflection coefficients when one of the inputs is the velocity model?

One of the inputs to seismic processing is a guess at a low-resolution velocity model that is just good enough to build an image. It is not a geologically useful model of acoustic velocities in the earth.

That Marmousi example is a bit misleading, because that seismic section is a synthetic seismogram, simulated from that velocity model (and assuming or modeling rock densities — we need velocity and density to get rock impedance). It is a result of solving the so-called forward problem$\dagger$ — solving a system of equations representing the seismic experiment, shown here as G, given an earth model m, and getting synthetic seismic data d:

Geophysicists spend most of their time trying to solve the inverse problem — deriving an earth model m (which is the interesting unknown), given real seismic data d (which we measured), and the parameters of the experiment, our understanding of nature, etc (G). So in a real problem, we wouldn't know that high-resolution velocity model a priori.

So what was all that about 'requiring an estimate'?

We don't go straight from the data to a high-res earth model. First, we have to build a seismic image, via a process called migration, which requires us to guess a rough velocity model to focus all the seismic energy into something we can interpret. We do this by choosing a grid of velocity-vs-depth functions that seem to focus well.

Here's a pretty typical velocity model for imaging, from a Marmousi example by Tristan van Leeuwen (2012; UBC preprint). Notice how it lacks high frequencies:

Once we have an image, interpreters and seismic analysts can use various methods to reconstruct a plausible model of the earth's impedance. This is called seismic inversion, and is a substantial area of research. It will almost never result in a model with the resolution of the Marmousi model, but we'd like it to be good enough, over enough of the stratigraphy, to be useful.

$\dagger$ Forward models are useful because we can try to figure out ways to solve the inverse problem better when we already know the answer. Inverse problems are useful because they are a systematic way of making data-constrained inferences about unknowns. Here's some reading on forward and inverse problems:

What is inversion?
How to get paid big bucks
Backwards and forwards reasoning


Why does upwards lightning use only one path but downward lightning uses multiple paths?

Upwards stroke happens when the stepped leader and the traveling spark have already connected. This path then becomes much more conductive than any other paths where the connection hasn't happened yet—because the latter ones have gaps of non-ionized air inside them. This highly conductive path shunts all the remaining stepped leaders, lets the charges quickly cancel out, and thus basically stops propagation of the leaders.


Was there once a glacier over Starcke national park in Queensland Australia?

That region forms part of the North Australian Craton and the underlying bedrock is in the order of 1.8 billion years old. The bedrock appears to be overlain by the Isa Superbasin during a period of deposition from 1.575 to 1.665 billion years ago and underwent the Ewamin Orogeny (1550 Ma) to form the Georgetown Inlier.

About 500m years ago the Eastern seaboard of what is now Australia was under water and over the next 250m years continental subduction took place and Eastern Australia was geologically analogous to modern day Japan and China with an inland sea and a volcanic arc stretching from north to south. What was once this inland sea is now part of Australias rich coal basins, which stretch from Collinsville in Quensland all the way to Tasmania and they have also been correlated to coal deposits in Antarctica.

The region you question about, Starcke, is very close to what is known as the Tasman Line, which is a geological separation of the older 1.5 billion year old events and the younger 500 million year old events. The lines in the photo appear to be parallel to where the Tasman Line is shown to be. You'd really need to be on the ground checking out the geology to see how closely your photo images line up with the Tasman Line.

While all this was taking place, there was, amongst other events NE-SW compression of the continental crust along the Tasman Line which may have contributed to the geology in your picture. While I'd take a guess and say that many of those structures are folds (and they look like them too) I'd really need to put my boots on the ground and have a good look before I could say for sure.

Here's a link to an image of The Tasman Line.

http://economicgeology.org/content/97/1/109/F1.large.jpg

A guy called Nick Direen wrote some good papers on the Tasman Line. You might find more info if you google him.

Further to what I've written above, I've looked at the QLD government geological maps online at: https://minesonlinemaps.business.qld.gov.au/

As mentioned by Gordon, the surface geology is comprised of Quaternary age sand dunes which is indicated by the yellow colours. The purple areas are strata that is Devonian age and the small patches of pink are intrusive granites, which are typical of Eastern Australia. The sand dunes overlay the older rocks.

How much the underlying bedrocks influence the sand dunes? Without further research and boots on the ground, I'd have difficulty in saying.


It actually is the common centi- prefix, but applied to temperature changes in units of Kelvins rather than absolute temperatures. The research as quoted by the Daily Mail obscures this by simplifying the results for a general audience.

The analyses and results are much more clearly described in the original refereed journal article, which clearly refers to changes in temperature - see in particular the discussion of their Fig. 1 (reproduced below), which explicitly refers to rates of temperature change of 0.1 and 0.02 °C at depths below 2000 m over the previous century, corresponding to cK contours of ~10 and near zero in the corresponding section of that figure.

So, the contours in the figure quoted by the Daily Mail represent changes in temperature between measurements made in the 1870s and the early 2000s, in units of 0.01 K (or equivalently, 0.01 °C).

Figure 1 from Gebbie and Huybers (2019), https://doi.org/10.1126/science.aar8413 - reproduced here for non-commercial use.


Does subduction of plates make them stretch and form the oceans?

Ocean plates subduct beneath continental plates. Does this make the oceanic plates stretch and become thinner so that the elevation of the sea flow is lower?

When a continental plate collides with an oceanic plate, or when two oceanic platers collide, the result is subduction of an oceanic plate. This subduction makes oceanic crust recycle rather than build up over time. When two continental plates collide, the result is the Himalayas and the Tibetan plateau. Continental crust isn't recycled to anywhere near the extent that oceanic crust is. Excluding the rather rare ophiolites, the oldest continental crust is about 20 times older than is the oldest oceanic crust.

This quick recycling of oceanic crust versus the slow build up of continental crust is the primary reason that oceanic crust currently is considerably thinner than is continental crust. The very first continents would have had have had fairly thin crusts. Continental crust has become thicker and thicker through the ages, while oceanic crust has not and cannot thanks to subduction.


Did the formation of Panama trigger the beginning of Ice Ages?

The closing of the Isthmus of Panama alone did not trigger the beginning of the Ice Age, but it is a potentially decisive step on the way of ice shield build up in the north.
The development that leads to the current Ice Age, per definition a phase in earth's history were polar and continental ice shield build up, starts much earlier. Cooling began after a greenhouse phase already 60 million years ago at the end of the Cretaceous, possibly because of declining atmospheric CO2 levels. Intense volcanism (flood basalts) and the Chicxulub impact surely have contributed to peak cooling at that time.
During the late Paleogene and Neogene, Around ~40 - 30 Million years ago Antarctica and Australia separated and the Drake Passage opened, enabling an Antarctic circumpolar current (ACC) that isolated Antarctica from global circulation. Though the role of the current is debated, it coincides at least partly with ice shield buildup in Antarctica, but declining CO2 may have played an equal or even bigger role. The uplift of the Tibetian plateau may have contributed to cooling by chaning continental circulation patterns. Reason for the CO2 carbon decline in the late Paleogene/early Neogene may be increased silicate weathering in the course of the Himalayas and the Alpine orogeny.
So, when the Isthmus of Panama closed (exact date debated), it was already pretty cold compared to the Cretaceous and an ice shield covered Antarctica. The closing is hypothesized to have steered the gulf stream farther north, enabling the transport of moisture and warm air to the north and thus ice shield build up there.
We also should keep in mind generally ice shield buildup has a feedback in itself by rising the albedo, thus reflecting more energy back to space.
It is a complicated path to the current Ice Age with a lot of facets, starting in the late Cretaceous.


Can we really travel through earth's core?

As Chris Mueller said, in short: it isn't, or at least highly infeasible. Projects to drill into the mantle, such as the Kola Superdeep Borehole, have all failed because drilling equipment can't withstand the heat at only ~15km deep. Even if we were to come up with some sort of cooling system that's able to cool to 6400km or 12800km deep (depending on whether you would drill from one side only or from both sides at the same time), pressure is the second barrier that holds us from traveling through the earth's core.

According to Lide (2006) the pressure in the inner core is 330 to 360 GPa, at which iron becomes a solid even at the high temperatures in the core. If you could drill as far as the core you would have to build a device that's able to withstand that pressure, because if you can't, the material surrounding your well would immediately become liquid and fill the hole, if not shoot up your well towards the surface.

There are no physical walls between the layers of the Earth, only transition zones where temperature and pressure combinations lead to different behaviour of the materials. An example is the Mohorovičić discontinuity, or Moho, which is the boundary between crust and mantle, below which temperatures are high enough and at the same time the pressure is low enough so that rock becomes either liquid or at least a "flowing" solid. Similarly, at the boundary between the inner and outer core the pressure is so high that even at those temperatures the iron becomes a solid.

Lide, D.R., ed. (2006-2007). CRC Handbook of Chemistry and Physics (87th ed.). pp. j14–13.


Help determining virtual geomagnetic pole

You say you're "not given the declination angle", but you also say "the horizontal direction of magnetism of these lavas is due west". That's your declination angle, right there! Since I assume (from the very round-numbered location) that this is a homework exercise or similar, I won't work through the rest of the calculation here. However, if you need more guidance on VGP calculation, I can recommend Chapter 7 of Robert F. Butler's freely available book.


How big does a lake have to be to have its own Sea Breeze?

Lake breezes(similar to sea breezes) are fundamentally a feature of mesoscale meteorology and the peer reviewed reference Small Lake Daytime Breezes:
Some Observational and
Conceptual Evaluations details both the observational studies of lake breezes and the conceptual understanding behind the formation of the lake breeze.

Since OP's question is

  How big does a body of water need to have a sea breeze?

The answer according to this book Climate in a small area which is one of the references in the first reference is that lake breezes have been observed in lakes with a width of about 4 kms(Lake Suwa, Japan ) and a width of 10 kms (Lake Constance, Switzerland). The lake breeze reached a speed of 2 m $s^{-1}$ in the case of Lake Suwa and slightly greater speed in the case of Lake Constance. But because both of these lakes are orographic lakes the presence of thermally induced upslope flows (diurnal heating and consequent upslope flows during the day)  can interfere with the formation of lake breeze.

Further observational studies carried much later for the following lakes  Lake El Dorado , Lake Okeechobee, Lake Winnipeg and Lake Eufaula have reported lake breeze speed values in the range of 2-4 m $s^{-1}$. One must remember that these lakes are much larger in size but in essence the numbers capture the range of the lake breeze values. These observations had been obtained as a result of measurements carried out over a period of few months and over different weather conditions.

The upper range for the lake breeze is around 6 m $s^{-1}$ and any lake having a width of less than 2 km is likely to have an undetectable lake breeze.

So the physics behind the lake breeze formation in essence is similar to the physics behind the sea breeze formation. A pressure gradient(density gradient) is created between the land and the lake and this gradient is primarily established in the lower troposphere. Greater the inland sensible heat flux greater the value of the pressure gradient.

The following URL shows satellite images of different stages of formation of a lake breeze during the day - Lake Breeze Satellite Imagery

In regards to the second question I believe steam devils are mesoscale vortices that have been observed to form over lakes. These vortices are no more than 50-200 meters wide and can develop in the absence of any major synoptic scale forcing. But the surface area of the lakes have to be in the range of Great Lakes of North America  in order for the strong surface heat fluxes to play a role in mesoscale vortex development. The following peer reviewed reference provides observational and modeling studies of steam devils- Mesoscale spiral vortex embedded within a lake


Would life on Earth survive without the Sun?

The answer is No, the Earth would not remain in any recognizable form without the Sun.

There would still be a husk of a dead planet with a small amount of energy coming from the residual heat of the core which might be able to sustain chemosynthetic life in small colonies.  However, this is a pretty minor amount of energy compared to what we usually receive from the sun, and without an energy input lifeforms aren't able to sustain their unusually low entropic state (i.e. entropy wins the battle with life).

Some other examples of everyday things which would no longer occur (some already mentioned by @fre0n) are:

There would be no seasons.
There would be no weather.
There would be no daytime.
There would be no liquid water at the surface.
The surface temperature would drop to near absolute zero


This indicates that there was wind shear. Wind can change direction and speed with height.

Since air is a fluid, it's wind vectors can change with height. On a large scale, this is called the thermal wind balance. In the ocean, it is Ekman balance. On smaller scales, there isn't really a term that I know of that describes the balance, because it is rather turbulent.

As far as "How could this happen": What you saw was the mean flow over the height of one cloud, followed by the mean flow over the depth of another cloud.


Why should dynamical downscaling of meteorological data be made incrementally?

The basic answer to your question is that there needs to be an overlap between the spectra of the two domains. One way to think about it is that there needs to be a connection between the Kolmogorov energy cascades (https://en.wikipedia.org/wiki/Energy_cascade) of the two domains.

Kolmogorov energy cascade (D. Newman, U. Alaska Fairbanks).

Each domain is going to be forced (have energy input) at a relatively large scale and it is going to assume that the energy that it can't resolve at sub-grid scales is going to be dissipated. If there is no (or little) overlap between the two grid resolutions, the energy from the large domain (parent) will be dissipated by viscosity at sub-grid scales that the small domain (child) cannot resolve and there is not going to be an appropriate input of energy from the parent to the child.

The reason for the odd numbers in the ratio is given in Why is WRF most often configured at 3:1 nesting ratio?


How to calculate the kinetic energy spectra from ocean current timeseries?

Do you get much different results if you do both ways?

I think if you want the kinetic energy spectrum, use your second method. Some separately compute velocity and KE spectra, e.g., figure 2 of http://journals.ametsoc.org/doi/pdf/10.1175/2009JPO4330.1 (DP Wang et al, JPO, Apr 2010). Comparing velocity and KE spectra, the KE spectra looks similar to the more powerful velocity spectrum, especially at low frequencies.

Others use your first method (e.g., http://journals.ametsoc.org/doi/pdf/10.1175/JPO-D-15-0087.1, Rocha et al, JPO, Feb 2016)


As the earth's core cools, will the size be affected?

Over the 4.6 billion years of the Earth's evolution, so far, the inner/outer core interface has "cooled" to a mere 6000 deg C. Of course, other things being equal, the core will contract as it cools, but the rate of cooling will be massively delayed by the slow radioactive decay of uranium 235, U 238 and Thorium. Delayed, in fact by many more billion years. The mantle will cool with it, and being plastic, will deform to take up the space of the thermal contraction. However, by the time the radioactive heating decays to much lesser values, the sun will have blown up into the red giant phase. Even if the Earth is not actually engulfed by the expanded sun, it will be so heated that the oceans, and more volatile fractions of the crust will have boiled off into space, to become  part of the enhanced solar wind.

If we assume that the Earth's core will eventually cool by 4000 deg C, then Earth will eventually have a reduction in radius of about 10 km (my very rough back of an envelope calculation) from thermal contraction alone. How much of the surface will have boiled off into space by then is anybody's guess.


What is the synoptic/atmospheric setup that is causing the U.S. severe weather outbreak in May 2019?

Summarizing the comments I made above in this question and in this one - Does this weather pattern have a name ? I believe significant parts of the US  are experiencing a  Stationary Front for the past one month. There has been plenty of media coverage of this event and if you google the term "stationary front" under news one will receive a lot of links to the TV news media with meteorologists giving detailed analysis of this event.

A few summarized below -

1) Week's bleak weather not an unusual spring occurrence

2)A stationary front is stuck across the middle parts of Illinois and Indiana

I will attempt to provide a synoptic scale explanation of the event from reanalysis data.

1) From JMA's site  -

an upper level look at the 200 hPa surface reveals that an equatorward trajectory of the wave activity flux vector(seen as small arrows) is seen  from the Upper North Pacific. Climatologically Rossby Wave Breaking can occur from boreal fall to boreal spring. The signal is seen at 30 day , 10 day period and 7 day period and 5 day period. The signal is present in the raw data as well as in the anomaly. Most importantly this wave activity flux is directed towards the continental USA all the way from New Mexico to the Great Lakes region.

A popular science version of the above information has been discussed over at this link - What's up with all this wet weird weather ?

2) At the surface level this "stationary front" presents itself as air masses of two different temperatures as seen from this plot and one can see the frontal boundary more or less coincides with the rising contour of the stream function plot in (1). Here the south easterlies are bringing in warm moist air from the Gulf coast and the Atlantic and the colder air masses are coming from Canada and North East Pacific. So the key question is whether the upper level influence is directing the surface level weather and that question can be answered by calculating PV anomalies when ERA 5 reanalysis data does become available.

Source - JMA reanalysis data

3) The moisture flux being pumped into the south eastern part of the USA can be seen from this plot over a seven day period - .
Again the signal is present over 30 day period, 10 day period and 3 day period and over a 1 day period. I would like to point out the moisture flux is seen at different levels of the atmosphere from surface level to the 300 hPa surface.

Source - NCAR NOAA reanalysis derived variables

4) Last year (2018) apparently a wavenumber - 7 was found to be causing weather stalls as shown in this link - Weather stalls becoming longer. This year in April  it is a wavenumber 5 pattern as seen in this site - Current Weather reports and summarized here

  From a global point of view, the weather pattern in the beginning parts of the 6-10 day (around day 7) will enter into a wavenumber 5 pattern. That's where you have 5 distinct upper-level troughs (areas where the weather is cool and stormy) around the globe. It's like a major traffic jam in the atmosphere and could lead to weather stagnation with little to no variation for days and/or weeks. This could also lead to extreme weather events such as droughts and severe weather/flooding across some parts of the world.

and I am able to pick up the wavenumber 5 or 6 as pointed by user Deditos (as well in this twitter feed - Wave number 6 planetary wave) from NCAR NOAA reanalysis data for the 500 hPa geopotential height anomaly for the month of May.


The first problem to tackle is "what is an odor"?  An odor is a chemical aerosol or gas, which are small molecules suspended in the atmosphere.  To track the odors of pizza or burning wood you would first need to identify the molecules associated with the scent.  One example is α-pinene, which is the molecule that gives pine trees their scent.  Food cooking typically gives off other volatile organic compounds (VOCs) and the particular matter associated with it.  VOCs physically and chemically combine to form more types of aerosols and there can also be increases in ozone.

Meteorology, emissions sources, and atmospheric photochemistry are combined in chemical transport models (CTMs) so that the air quality can be predicted.  One example is WRF-Chem, which is used for large regions and many sources. Another example is CALPUFF, which is better suited for near-source impacts and capturing the effects of complex terrain. The reason you want a model with chemistry is that molecules can be reactive and will change as they interact with other molecules turning them into things that no longer smell like pizza or wood burning.  The reason you need a meteorological model is so that pollutants will be advected with the wind and interact with the moisture budget, solar radiation, terrain, etc.

For large-scale plumes you can simulate your molecules as being emitted at a constant rate from a point source and see how this plume evolves with time.  For smaller scale flows like a pizzeria, you may need use a model that can accommodate small scale features like buildings that will have an effect on atmospheric flows.  Lastly, you'll also need to account for other emission sources as the perceived strength of the smell is also going to depend on what else you are smelling (e.g. car exhaust) and these other aerosols may be reactive or combined with the odors you are interested in tracking.

Once you have done this you will have a time varying plume of "smell" as output from your model.  This will likely be output as a number concentration of aerosol molecules per unit volume per grid box.  To turn this into "odor strength" is probably a harder problem and one I am not familiar with.  As a first order approximation though, wherever the plume is located, so is the smell; and the higher the concentration of molecules, the stronger the odor.


In addition to other information others have written in comments, gradients measure the rate of change of "a quantity".

For example, take a hill. As you walk up the hill your elevation increases relative to the base of the hill. The steeper the hill the more quickly your elevation changes. The slope of the hill is defined as the gradient of the hill. The steeper the hill the greater the rate of change of elevation, with respect to the horizontal component of distance traveled.

With atmospheric gradients, imagine there are two towns, each with a weather station. The distance between the two is 100 km.

Each weather station measures pressure & temperature at defined times, usually at half hourly intervals.

If the first town measures a pressure of 1011 hPa and temperature of 25 C @ 10 am and the second town, at 10 am, measures a pressure of 1008 hPa and a temperature of 20 C, then between the two towns there is a pressure gradient of 0.03 hPa/km [(1011-1008)/100]. Likewise there is a temperature gradient of 0.05 C/km [(25-20)/100].

Now, if at 11 am the weather station in the first town records a pressure of 1012.5 hPa and a temperature of 28 C, then over time, there has been a pressure gradient over the first town of 1.5 hPa/h [(1012.5-1011)/1] and a temperature gradient of 3 C/h [(28-25)/1].

So when it comes to gradients, it depends what is being measured (pressure, temperature, humidity) and what is it be measured against (distance, time, etc.), and for atmospheric quantities the distance could be lateral distance or vertical distance.


Climate consequences of very large asteroids striking the Deep Ocean

A 5km impactor would make a very, very global mess.

Here's a discussion of tsunami formation from asteroid impacts. It presents numbers for impactor size up to 2km, and posits a rule-of-thumb that indicates a 5km impactor would generate a coherent wave (one that doesn't dissipate much over great distances) as long as it impacts in water less than 20-30km deep -- in other words, in any ocean on Earth. The tsunamis would propagate right around the globe.

Here's a discussion of more general effects from larger impactors. Fireball radiation from a 5km impactor would ignite flammables within a 600km radius, and the secondary radiation from returning ejecta would cause a firestorm across a 5000km radius. Earthquakes and hurricanes would take care of whatever the tsunamis couldn't reach. The skies would be completely dark for months (once the glowing stuff finished landing).

About our best hope would be for a polar impact, where global atmospheric circulation patterns might spare the opposite hemisphere the worst effects.


Why are there waves in seas towards shore - even in night?

Ocean waves (and also in mediterranean type seas and larger lakes, but on a smaller scale) are generated by two processes:

locally generated waves ("wind waves"), which follow the direction of the wind;
waves generated further out in the sea (i.e. "swell waves"), which do not necessarily follow the direction of the wind.

During the night, you are probably seeing swell waves. Of course, some wave energy is generated also in the opposite direction by the wind blowing offshore, but one can only "see" these waves further out in the sea if the wind is strong enough (see the definition of fetch).

Also check the Figure [1] below for clarification on how swell is generated (the longer period wave energy travels faster than the energy of the shorter period waves, so the initial "random" wave field disintegrates into regular swell).

Shallow water wave processes like diffraction and refraction will curve the paths of the waves that start reaching the coast and "feeling the bottom". The waves appear to be heading almost perpendicular when they reach the coast, even if 1 km out to sea they're moving almost parallel to the long distance coast.

How the waves appear at the coast to the observer depends on the direction of the local wind. Generally, if the local wind blows in the same direction as the waves (i.e. onshore wind), the waves appear "mushy" as the wind helps to break the waves (see example image). If the local wind blows in the opposite direction of the incoming waves (i.e. offshore wind), the waves maintain their shape due to opposing wind and they break later (see example image). These conditions are favourable to surfers.

[1] Holthuijsen, L. H. Waves in oceanic and coastal waters. Cambridge University press, 2010.


"So much work"? Actually, compared to the global rate of greenhouse gas emissions, it's a case of "so little work"! From a scientific perspective the 'economists' solution' of carbon trading was always unlikely to achieve the required carbon cuts, as has been verified by their ineffectiveness over the last decade or so. As farrenthorpe points out, the rate of increase of CO2 is largely population-driven, and hence there is still an inexorable rise in mean atmospheric CO2. The acid test of human efforts to limit global warming is whether the Hawaiian CO2 monitoring graph is flattening off:

It clearly isn't going to flatten anytime soon. In fact, if anything, it is getting steeper. So all the hot air from 'Paris', and previous talkfests, is evidently too little, too late. Realistically, limiting the average temperature rise to less than 2 °C, is now effectively unattainable. We have yet to see what 'all this work' can achieve. So far, almost nothing.


Are cattle really contributing to global warming?

Let's just talk about cattle here and ignore other factors related to cattle production for now.
The current cattle number (93 million) you found is probably the total number of dairy cow and beef cattle. In your argument, it is possible that bison has much more emission than cattle on pasture. But the emission from cattle in feedlot and dairy farm is much larger than the cattle on pasture because of their diet chosen by us (human).
Typical beef cattle (steers and heifers) in the U.S. spend one year on pasture, and 5-6 month in feedlot before slaughter (unlike Argentina beef cattle which are fully raised on pasture). In feedlot, these young cattle (yearlings) are intensively fed with high protein feed in order to get them fatten up in a very short time. The U.S. dairy cows spent most of their time on dairy farm (unlike the Swiss cows who are raised on pasture). They live for about 5 years and are continuously fed with high protein forage to ensure their milk production. Both beef cattle and dairy cows have a high protein diet that result in high emission of methane (the impact of methane is 25 times worse than CO2 in terms of warming).
The closest comparable cattle to bison is beef cow which spend most of its life time (about 10 years) on pasture and are only occasionally fed with low quality hay when there is a shortage on pasture. But again, the life span of a beef cow may be different from the buffalo and beef cows may eat more because they are basically pregnant very year(!).
California has this new policy that tries to cope with dairy cow methane emission from their manure. If you are interested, there is a recent study done by University of California Agricultural Issue Center here (https://aic.ucdavis.edu/wp-content/uploads/2019/01/DairyManure-1.pdf).


The Haicheng Earthquake is the only successful evacuation of a devastating earthquakes. It's notable that the Chinese scientists thought they had figured out ot predict earthquakes, but have subsequently failed to predict many catastrophic earthquakes and many people's lives have been ended, ruined, changed.

It is news to me that this research is in decline, but there has been recent scrutiny for failing to predict earthquakes. This type of research is very hard, and probably not answerable, here is a related question:Is earthquake prediction possible?

Hazard assessment is much easier because we can model many different types of known earthquakes and infer the damage from that. There aren't as many unknowns, it seems, for what happens after an earthquake as there is during the buildup. Plate Tectonics is complex as we live in on a dynamic planet.


Large Scale lightning Strikes from Cloudless or Near Coudless Skies. How Does it Work?

Revised answer

TL;DR After having just heard from two experts who actually work in this field(firestorms and dry lightning) in Australia I believe the lightning seen is what is known as "dry lightning" comes from isolated thunderstorms and sometimes storms associated with minor troughs and fronts that come through Australia and also originating from a pyrocumulonimbus cloud. So @David Hammen and @jamesql are correct in their observations that the large scale dry lightning is indeed originating from isolated thunderstorms as well as storms associated with minor troughs and fronts. This dry lightning the experts confirm  is associated with little rain.

In addition there have also been several  dry lightning strikes from pyrocumulonimbus clouds. As an example for today over 20 dry lightning strikes have been recorded originating from pyrocumulonimbus clouds.

The major driver for the current drought like conditions over Australia is the large anomalous positive Indian Ocean Dipole (positive IOD) that has persisted well into boreal autumn/astral spring.

What the experts mention is that while the dry hot conditions are sporadic (2-4 days) they are persisting over over many weeks.

The following articles written by two researchers  Firestorms and flaming tornadoes: how bushfires create their own ferocious weather systems
 and Firestorms: the bushfire/thunderstorm hybrids we urgently need to understand provide information on the dynamics behind firestorms and the formation of pyrocumulus clouds and the associated dry lightning.

Following is a  summary of those articles and the conditions that lead to dry lightning from pyrocumulonimbus clouds.

Not all bushfires lead to firestorms. If a bushfire has sufficient area the upward movement of air causes the fire to interact with the atmosphere above it and form what is known as a pyrocloud. If in addition  there is an atmospheric instability then this process leads to the formation of a pyrocumulonimbus cloud . Normally in meteorology we are taught of heat radiating from the ground but in this case the upward movement of air is due to the heat emanating from the fire.

Again from mesoscale meteorology one hears the word "downdrafts". Similarly in this context the appropriate word is "downbursts" and these are vertical drafts of air that hit the ground and move about in all directions. The unsettled conditions cause embers to carry over large distances.

These firestorms produce dry lightning that potentially can spark new fires that may end up creating a larger flaming zone.


What are the implications of the recent discovery that huge oceans exist close to the mantle of the Earth?

I am going to assume that you are referring to recent new stories with titles like "Rare Diamond Confirms That Earth's Mantle Holds an Ocean's Worth of Water" (Scientific America).

These articles are referring to research published in Nature: Pearson, D. G. et al. (2014).  The researchers found an inclusion of ringwoodite inside a diamond.  Here is a quote from the Nature article about the paper...

  Using infrared spectroscopy, Pearson’s team found that its tiny fleck
  of ringwoodite contained about 1% water by weight.  “That may not
  sound like much,” Pearson says, “but when you realize how much
  ringwoodite there is, the transition zone could hold as much water as
  all the Earth’s oceans put together.”

This doesn't mean that there is a liquid ocean of water within the transition zone.  There are minerals that are considered "hydrated" because they contain hydroxide ions.  Examples of these are the serpentine group and micas.

Ringwoodite can contain hydroxide ions within its structure, and these ions are the "water" that was measured.  If you were to lower the pressure, and increase the temperature, the water would be liberated from the mineral.  The point is that there are not huge oceans of liquid water within the mantle of the Earth; the water is locked up in the structure of certain minerals.

There are interesting implications from this research discussed in the Nature News article about the research.

Nature News Article


According to Ultraviolet Radiation, Human Health, and the Urban Forest it would seem at least the general shape you obtained is correct:

Here they tracked the irradiance at noon over different months of the year not hours of the day, but the basic change is the same: high to low to high Solar Zenith Angle when irradiating a vertical surface leads to an irradiance graph with 2 "shoulders" on both sides of the maximum solar elevation point. The irradiance is lower at the central point because the direct rays are parallel to the target surface and the only contribution are the scattered and reflected rays from the environment and the rest of the sky, and then as the SZA progresses more and more toward 90 degrees (or elevation toward 0 degrees) the increasing atmospheric absorbance comes into play and reduces the irradiation long before the rays become exactly perpendicular to the target surface.
But if the goal of the UV Index was to provide safety data for the general public, I would say it should've been measured assuming the absolute worst-case scenario of some unprotected skin being exposed to exactly perpendicular solar rays at any hour of the day (this is possible because our bodies have complex surfaces and it's always possible to have at least a little skin that's perpendicular to almost any ray direction in all of 3D space). So they should've used a detector that is rotated to face the sun at all hours of the day, and the resulting graph I suspect would not look like the official daily UV Index graph but also not like the "2 shoulders" one we have here. It would probably look more like the "IND", "SYR" and "INL" variants in the image above: a sort of "Gaussian with a wider top".
LE: Here we go, it should look like the Direct Normal Irradiance curve, with no cosine correction for horizontal receiving surfaces: https://www.researchgate.net/figure/Direct-normal-irradiance-vs-solar-time-at-Izana-Tenerife-Kaashidhoo-Maldives-and_fig1_236314638


In this case I'd say it's a combination of Rayleigh scattering,
Mie scattering and the angle of the sun.

Rayleigh scattering is related to the chemical composition of the atmosphere and occurs when the particles causing the scattering are smaller in size than the wavelengths of radiation in contact with them (this is why the sky appears blue most of the time). The yellow sky in this question is likely mostly owing to Mie scattering. Mie scattering is caused by pollen, dust, smoke, water droplets(the most likely culprit in this case), and other particles in the lower portion of the atmosphere. It occurs when the particles causing the scattering are larger than the wavelengths of radiation in contact with them. The angle of the sun and Raleigh scattering may also be at play, when the sun is low in the sky sunlight passes through more air than when the sun is higher in the sky. More atmosphere means more molecules to scatter the violet and blue light away from your eyes. If the path is long enough, all of the blue and violet light scatters out of your line of sight. The other colors continue on their way to your eyes. This is why sunsets are often yellow, orange, and red.


When calculating a precipitation index, should it be constrained to a basin?

Normally you could calculate a precipitation index for any location with a long-term record.  A basin will have nearly the same index, regardless of which station location you use, so it can be appropriate to just calculate a single value for the whole basin, as you've suggested.  The project scope will determine what level of spatial variability you need, and sometimes political boundaries are good enough (e.g. counties). Applying this same idea to a satellite-derived product, you could use a simple ecoregion boundary (see here) to determine the spatial resolution.  You may also want to determine spatial boundaries baed on an environmental condition that can interfere with the accuracy of the satellite retrievals you are using (e.g. surface albedo or elevation).
I'm intrigued by the prospect of calculating a precipitation index from satellite imagery (instead of ground stations) and wonder which instrument(s)/products you are planning to use, especially since the calculation involves a climatological component that is difficult to build without continuous records. I suppose it is possible to train your algorithm to give results consistent with ground stations, otherwise I would worry about accuracy.  Good luck!


Traits of invaded ecosystems? Are my compost worms a threat to New York?

The native worms are not good at competing for some reason.

There's a reason for that. There are no native earthworms in New York.

  Still, before the most recent glaciers there were worms in these regions.

North America has been hammered by multiple glaciations for the last two million years. It wasn't just the areas covered by ice that lost their earthworms. The northern forest, or taiga extended to the Gulf Coast at the peak of the last glaciation. You have to drive to Ontario to see the taiga now. The Great Plains were the mammoth steppe, very cold and very dry. Most of the US is depleted of native earthworms.

Invasive earthworms are your enemy if you like maple syrup. Sugar maples take a couple of years to germinate, and only need a nice pile of duff (leaf detritus that hasn't been consumed by earthworms) in which to do so.


What keeps the different gases mixed in the atmosphere?

It's because gases also diffuse. If you separate two gases of different densities by a horizontal membrane, and then slowly remove the membrane, then the interface will diffuse. You can try this with bromine and air, for example – the bromine will stay at the bottom (easily visible because it's brown) and the air will stay at the top, but the interface will be diffuse. The bromine will largely stay at the bottom because it's significantly heavier than the air, but the diffusive mixing will be much stronger if the density difference is smaller – as is the case with nitrogen and oxygen, which are of course not very different in density.

While the effect above just considers mixing due to molecular diffusion, the atmosphere of course also vigorously convects due to the effects of thermal heating (and humidity differences). Both also turn over the atmosphere and mix it.

That said, the composition of the atmosphere does change with altitude. See, for example, here. The thing is that the thickness of layer corresponding to the blurry interface between bromine and air is about as thick as the entire atmosphere, and therefore hard to distinguish from other effects (such as ionization) that change its composition with altitude.


What would be a reasonable set of thresholds for flood severity classes?

One existing classification for return period events is minor and major flows, which basically classifies floods into those that the storm network (pipes and small conveyance network) is designed to handle, typically in the 2-10 year event range, and those more major floods which will overwhelm the stormwater infrastructure and are mainly conveyed by overland topography and larger flow channels/watercourses (>10 year event). The definition of major and minor return periods depends on the level of design in your are of study, but that is one classification. This distinction in major/minor flows is common and you can find lots of resources, one example is in the Ontario Drainage Manual.

Given that you want a small/medium/large classification, I would put minor flows (say 5 year and smaller, based on the study area) into the small category, everything above a minor flow to the 100 year event into the medium category, and everything 100 year or larger (i.e. 100 year and regulatory event) into the large flood category. The 100 year as you mentioned is a very common standard for a large flood event. The Regulatory event is typically the largest observed flood on record or similar estimate for a larger than 100 year flood event.

Hope that helps!


doubt about the 'white spaces' in the maps from satellite

Expect every daily retrieval of AOD to have many missing pixels, mostly where clouds appear.  Data is removed when the quality assurance flags do not meet some minimum criteria.  This can happen when the retrieval is contaminated (e.g. from clouds or sun glint on the surface).  If you are interested, you can obtain raw level-1 and level-2 data with all data, including arrays for quality assurance flags.

There will also be systematic gaps in the data where the satellite had no coverage.  Polar orbiting satellites will get complete coverage near the poles, but widening gaps will appear the closer you get to the equator.


Probably both but I'd expect to see more in a peraluminous melt. The more mafic the melt the more iron based mineralisation you're going to see.


Is it inevitable that a mega tsunami will hit America?

As a lecturer I had during my undergraduate put it: if you draw your information from BBC/Discovery Channel documentaries, you will believe we could get a 100-million-people-killing disaster every week.  The collapse of the Cumbre Vieja is but one of those perceived threats.

How do such documentaries get their info?  Scientists develop models, then run them.  Remember than all models are wrong, but some are useful.  Using their models, they speculate that if the substance of the mountain has a certain shape, and if the volcano erupts in a certain way, and if this causes a landslide in a particular way, with a couple of more ifs, then they speculate that there might be a huge tsuname destroying the eastern US.  Do they state this with certainty?  Absolutely not.  Do other scientists agree with them?  Not really.  Does Discovery channel care that it doesn't appear very likely?  No.

The already linked Wikipedia article Cumbre Vieja#Future threats answers this particular one better than I can do.  Don't worry and sleep well ;-).

Oh, and you must visit, it is spectacular!

La Palma, 27 December 2012.  Certainly, the inhabitants of the shores of the Cumbre Vieja are more at risk than the inhabitants of the US east coast. (P.S. I'm cheating, this is actually some 15 km north of the dangerous part of the slope.  But still, if this mega-tsunami does happen, I think the TV networks will forget about the poor islanders :()


Where on Earth does paleo-groundwater exist?

In large intracontinental basins where the main rock formations are exposed in adjoining highlands and rare deeply buried within the basin itself.  The Madison Limestone is an example.

The Madison and its equivalent strata extend from the Black Hills of western South Dakota to western Montana and eastern Idaho, and from the Canada–United States border to western Colorado and the Grand Canyon of Arizona.

From Wikipedia.

Ground-water ages vary from virtually modern to
about 23,000 yr. The 14C ages indicate flow velocities of
between 7 to 87 ft/yr. Hydraulic conductivities based on
average carbon-14 flow velocities are similar to those
based on digital simulation of the flow system (Downey,
1984).

From: Geochemical Evolution of Water in the
Madison Aquifer in Parts of Montana,
South Dakota, and Wyoming
By JOHN F. BUSBY, L. NIEL PLUMMER, ROGER W. LEE, andEWJCE B. HANSHAW


Why are there no wild fires in New England?

Its just too wet there

Generally, fires don't happen where it is wet. Here is a map of the fire regime in Pre-Columbian America:

Northern New England gets practically no fires, with a fire frequency of every 200 years or longer. Southern New England sees more frequent fires, maybe ever 40 years, but those fires are typically understory only.

For a region to be fire resistant, it must meet two criteria: it must be 'humid' and it must be 'humid' year-round. New England meets both of these criteria. Here is a map of precipitation versus evapotranspiration for the US:

Note the areas in green have more water falling from the sky than returning to it via evaporation and transpiration. New England is one of the wettest parts of the nation by this metric. There is plentiful rain/snow, generally heavy cloud cover, and relatively low temperatures to reduce evaporation.

The last piece is being wet all year. By looking at Boston's climate data, we can see that Boston's precipitation is evenly distributed throughout the year.


Earth's inner core is solid even though the temperature is so high because the pressure is also very high.  According to the Wikipedia article on the Earth's inner core, the temperature at the center is $5,700\ \text{K}$ and the pressure is estimated to be $330$ to $360\ \text{GPa}$ ($\sim3\cdot10^{6}\ \text{atm}$).

The phase diagram shown below (taken from this paper) shows the liquid/solid transition, where fcc and hcp are two different crystalline forms of solid iron.  You can see clearly from the slope of the line going off toward the upper right that iron should be solid at this temperature and pressure.


Why is uranium only in the crust, really?

(tl;dr below)

First, a correction. Siderophile elements are "iron-loving" elements, those that go in the core with the Fe-Ni liquid. Uranium is lithophile, or "rock-loving". It partitions to silicate rocky material (i.e. mantle and crust) relative to the core.

Secondly,

  But, according to this answer, the solubility of Uranium in the Earth
  Core is between 2ppm and 6ppm.

You have to understand where this is coming from. That answer is based on this paper, which experimentally measured how much U is in the Fe phase, coexisting with a silicate phase of peridotite composition (which is an approximation of the mantle composition). If you look at their Table 3 (page 14) and Figure 8 (page 17) you can see that the $D_\rm{U}$ values range from almost 0 to around 0.03. This value mean the ratio of U in the metal phase relative to the silicate phase. So even in the most extreme case, you're going to have 30 times more U in the mantle than in the core. And in their experimental setup they used wt % amounts of U in the starting material, much much more than exists in the Earth, so you eventually get a considerable amount in the Fe-metal phase. This does not mean that this is the amount that is present there now, inside the Earth.

The truth is, we do not know how much U is there in the core. And this research papers shows that whatever amount there is, there will be more in the mantle. There will be even more in the crust, because U is an incompatible element in partial melting of the mantle. See this Q&A for more information about that:

What are the high field strength and large ion lithophile (HFS or HFSE & LIL or LILE) elements?

Also related, also read the comments:

What percent of the Earth's core is uranium?

  Second, what I think: trying to mix unmixable liquids they we will
  have separate phases of solutions in the order of their density...

You have to differentiate solubility from partitioning. Solubility is how much of x (let's say U) you can put in y (let's say Fe) before you saturate a separate phase instead of one. Partitioning is when you have two phases x and y (let's say Fe-liquid and silicate), how much a third component z (let's say U) will dissolve in each. The paper linked to before was discussing partitioning. In terms of solubility, there is a complete solution of liquid U and Fe when the temperature is high enough (such as in the Earth's core). Even if there's not, a ppm amount of U in liquid Fe is not enough to saturate a separate liquid U phase, so density doesn't matter. If it's all one phase, density plays no role. If you have a solution of NaCl and KCl in water, it's all homogeneous. The K doesn't sink because it's denser.

tl;dr

We do not know how much U is in the core. We do know that whatever amount of U goes in the core, more U will be in the silicate mantle. When you melt the mantle to produce magmas that form the crust, it concentrates U even more, and depletes the mantle of U.


Because of the limitations of wartime sonar, U-boats could sometimes pass undetected into the Mediterranean through the Straits of Gibraltar, but it was always risky and avoiding detection couldn't be guaranteed.

There were many things that limited the efficiency of sonar (or ASDIC as the British called it). It is true that sea water has a tendency to separate itself into layers which sonar finds difficult to penetrate. Sometimes this layering was based on differences in salinity, sometimes on differences in temperature, and sometimes on intervening sea currents. Even ships wakes could deflect the sonar beam, so sometimes powerful curving wakes were deliberately made by the U-boat to shake off a pursuing warship.

The range of active sonar under good conditions was normally a few miles, but that could be reduced if there was a lot of background noise. The Gibraltar straits are about 12 miles wide.  Whales and schools of fish could also send back false echoes which would fool all but the most experienced sonar operators.


Structural geology, regarding cross section of two outcrops with similar characteristic but very distinct dip

Is this a homework question?

These are quite steep dips, strongly implying that substantial deformation (folding) has taken place. The interlayering of steep mudstone pretty much rules out your outcrops as being original bedding structure. Draw your examples in plan, using the normal dip and strike notation. Sketch in some possible continuation of the strike (as curved lines). Then consider what style of folding could have created this pattern. Consider also the possibility that the fold could be steeply plunging.

When you have an idea of the structure from the plan view, this should guide you in deciding the orientation of the cross section.


Esker vs. Kame vs. Drumlin - what's the difference?

Eskers are glaciofluvial deposits from sediment carrying subglacial tunnels. As the water emerges from a tunnel at the bed of an ice sheet or glacier it will slow down. Since the sediment movement depends on water velocity the sediment will be deposited. The results is a highly localised deposition. When glaciers retreat the point of emergence for the water will of course change with the edge of the glacier. Hence the deposition will occur progressively further upstream leaving a narrow trail of sediment accumulation. Much more can be said but the result is ridges sometimes hundreds of kilometres long that extend pretty much perpendicular to the past glacier edge, the way the water flows from within to the edge of the glacier.

Kames are hummocky terrain formed by material that has been transported by glacier melt water. The reasons for the hummocks is that when the sediment was deposited, chunks of ice were buried by the sediments and when that ice melted a hummocky terrain was formed. A key here is that the deposition of sediments from sediment transport would not be able to form the irregular hummocky terrain as a primary feature, there has to be other processes involved. Kames are therefore usually an extensive land form that does not necessarily have a preferred extension. As with eskers the origin of the water and sediment is the same, the base of the glacier.

Finally, drumlins. These forms are elongated land forms, in the direction of ice flow, often some kilometres in length, width of a few hundred metres and a height of tens of metres. This varies a lot though. These forms are not formed by running water and sediment transport but formed beneath the ice. In the literature they have been described as both depositional and erosional land forms, although a depositional formation seems to be most common. They seem to consist of whatever material is present beneath the ice but because the most common sediment beneath glaciers is till this is also what most drumlins consist of.

So eskers and kames have som relationship in the origin of the sediment that make them up. Drumlins are of completely different processes. Much more could be said and all details are not completely understood when it comes to many glacial landforms and their formation.

ADDED:
The formation of drumlins, and hence also their characteristics is too complex to be explained in a short answer here. Three scientific papers that will help gaining a deeper understanding of drumlin formation are (I suggest googling on the titles to find copies):

Patterson, C.J., Hooke, R.L., 1995. Physical environment of drumlin formation. Journal of Glaciology 41 (137), 30–38.

Stokes, C.R., Spagnolo, M., Clark, C.D., 2011. The composition and internal structure of drumlins: complexity, commonality, and implications for a unifying theory of their formation. Earth-Science Reviews 107, 398–422.

Roger LeB. Hooke, Aaron Medford, 2013. Are drumlins a product of a thermo-mechanical instability? Quaternary Research. http://dx.doi.org/10.1016/j.yqres.2012.12.002


Water veins underground causing health problems

In my opinion, there is no such thing as water veins as described in this article, but, it is a fact that there is water circulation underground.

In the natural environment, water can either circulate in porous mediums (like within the small spaces between sand grains in sandy soils) or as underground streams. There is also the concept of the water table and aquifer recharge and depletion.

This schematic provides a broad picture on the importance of groundwater

More info here as well.

Some regions composed of rocks, especially carbonates (karst) can have more often channelized underground streams, as the ground is not necessarily porous so water is kind of forced to flow where there is an opening (see following figure). (More info on karstic landscape here)

So that was a small overview on how water can circulate underground.

Then people getting sick from water circulating underground is not because of the veins per se, it could be because of moisture (or many other factors). But then living near a lake or any streams, any wet areas or in a badly insulated house could make people sick as well.

This is 'old wives' tale' (no offense - English is not my primary language I am not sure how to say) and is not really a thing as presented in the http://swissharmony.com/en/water-veins-neutralized site. There has been no new research in a medical paper about geopathy since 1940 (wonder why?). You are doing well in being skeptical! To conclude I am sure many people living in drylands would be more than happy to be  'sick' over a vein.


Why do we say Earth rotates from west to east?

Your confusion arise from the definition of East and West hemispheres. That's an arbitrary and confusing definition. Because East and West are relative directions. Meaning they depend on the position were they are specified.

East and West come from the proto-germanic languages, where East means dawn and West means evening. Therefore, East from any given point is roughly the direction at which the sunrise happen. And West is where the sunset happens.

That's why the east/west hemispheres definition is confusing, because if you are in the middle of the pacific, the Western hemisphere is towards the East... confusing.

So let's forget about East/West hemispheres, and consider the East/West cardinal directions. Where East is 90° to the right of North and West 90° to the left of North. These directions keep the original spirit, on which East points roughly to the sunrise, and West to the sunset.
Let's also forget about clockwise and counterclockwise, because that depends on where are you looking from. If you are on top of the North pole it will look like Earth is rotating counterclockwise, but from the top of the South pole it will be clockwise.

Now, when we say that Earth rotates to the East, we mean that each point on the surface is moving to the East of that point.

The following figure taken from pulauubinstories.com will help clarifying the point:

In the figure is clear that the fact that sunrise happens to the East is because we are moving in that direction. At dawn, as we move Eastwards we enter in the sunlit side of Earth, producing the sunrise. And as we keep moving Eastwards during the day, we enter in the night side of Earth, leaving the sunshine and the sunset to the West.

Therefore, as East means "dawn" it follows (basically by definition) that Earth rotates to the East.


How are minor tributaries of a river determined?

This is a question of topology. There are three major attempts to order streams from small to larger.

The first was established by Horton (1941) who established the concept of drainage composition. To establish the relative importance of streams in a network Horton suggested to investigate each junction and to set the stream that entered the junction at the highest angle as a stream of lower importance. By starting at the mouth of a river, one can thus establish which would be the main trunk of a river and which are tributaries of smaller and smaller significance. The order number of streams cannot be determined until the entire tree of streams have been ordered. In the figure on Strahler stream order the diagonal would be the main trunk of the river and have order three. The only order two trunk would be the one labelled two turning down from three in the figure.

Strahler, 1952 took the concept further and established the concept of stream order. In this approach the basic stream is the smallest source tributaries. When two streams of order one meet they form a stream of order two. It takes two of the same order to make a stream of a larger order so a stream of order two and one will not increase the order number, the result is still two. The following image provides an example of Strahler's stream order:

Strahler stream order concept. Image from Wikipedia commons

The stream order allows one to calculate an assortment of statistical measures that characterizes a drainage basin and it is possible to use these characteristics in, for example, flood prediction.

Shreve (1967) took the ideas of Horton and Strahler further by introducing magnitude, now called Shreve Magnitude. This concept differs from Strahler's in that all streams are additive so that as soon as one stream is added to another the resulting stream is the sum of the two tributaries. The result is that the system can be seen as reflecting discharge, assuming all first order streams are of similar size. In the figure above the largest magnitude would be six, this is also the sum of all order one streams.

So establishing the main trunk of a river is not necessarily simple. Hortons method does this but is at the same time relying on geometry and rivers may be heavily influenced by geology  to generate odd river patterns.

References:

Horton, R.E., 1945. Erosional development of streams and their drainage basins: Hydrophysical approach to quantitative morphology. Geological Society of America Bulletin, 56, 275-370. doi: 10.1130/0016-7606(1945)56[275:EDOSAT]2.0.CO;2

Shreve, R.L., 1967. Infinite topologically random channel networks. Journal of Geology 75, 178–186.

Strahler, A.N., 1952. Hypsometric (area-altitude) analysis of erosional topology. Geological Society of America Bulletin, 63 (11), 1117–1142, doi:10.1130/0016-7606(1952)63[1117:HAAOET]2.0.CO;2.


How to determine (lost) surface (km²) of a country when both population and population density have changed?

$\text{Poulation density} = \frac{\text{Population}}{\text{Surface}}$

Re-arranging

$\text{Surface} = \frac{\text{Population}}{\text{Poulation density}}$

In your case

$\text{Surface} = \frac{100,000,000\, \text{inhabitants}}{10\, \text{inhabitants}\, \text{km}^{-2}}=10,000,000\, \text{km}^2$

So something doesn't make sense, because those numbers suggests that the surface of the country is now larger than before.


Q: Is the crust getting thinner or is the mantle getting smaller

The crust is actually getting thicker very gradually as the Earth cools down. This process is well seen on Mars, where due to its smaller size and greater distance from the sun, Mars is cooling faster than the Earth. No one knows exactly how thick the Martian crust is, but what we do know is that magma can no longer find its way to the surface. All the Martian volcanoes are extinct.

On Earth, the magma ejected from volcanoes is mostly recycled oceanic crust. Sea floor spreading from the mid-ocean ridge pushes the oceanic crust on the Pacific Plate toward the continental crust on,for example, the North American plate, where it is forced to dive  beneath the continental crust and driven down into the mantle. For a number of reasons (friction, water content etc) this causes it to melt, and being lighter and more fluid than the mantle it rises to the surface, where it escapes through volcanism.

This is not the whole story, because if oceanic crust is disappearing as it is pushed below the continental crust of another plate, it must somehow be replaced. This happens at the mid ocean ridge, where a deep chasm plunges through the comparatively thin oceanic crust, enabling fresh magma from the mantle to rise up and create new ocean floor. This is constantly spreading out in opposite directions from the mid ocean ridge, hence the term 'sea floor spreading'.


Timeline of atmospheric model resolution

Europe is looking nicer and nicer every year (source):

This is a little bit out of date, since AR5 is already out - the dates for the first 4 IPCC reports were:

IPCC First Assessment Report, 1990
IPCC Second Assessment Report, 1995
IPCC Third Assessment Report, 2001
IPCC Fourth Assessment Report, 2007
IPCC Fifth Assessment Report, 2014

And an updated image for AR5 looks like this (both of these are AR5 model resolutions) (source, p145):

And that same PDF has another representation of increasing complexity, where cylinder height indicates complexity (source, p144):


Calculating/estimating volatiles based on other representative samples

If you are sure that the samples for which you have H$_2$O data are from the same intrusion than yours, then I don't see a problem for using these values for viscosity modelling, as long as it is clearly mentioned in the paper. After all, a sample is supposed to representative of the rock unit, and science is done by standing on the shoulders of giants!
If you have several historical samples with different H$_2$O contents, this gives you a range of water contents. Do you intend to use a model like Giordano et al. (2008) ? If so, you also need a temperature estimate, which you may have by geothermometry. These temperature estimates have an uncertainty, see Putirka (2008) for a review. For example, if you use the two-feldspar thermometer, it gives you $T$ to $\pm$30 °C.
So, what you could do is to model two scenarios: one "cool and dry", with the lowest $T$ and H$_2$O content, which gives you the highest viscosity; and one "hot and wet", with the highest $T$ and H$_2$O content, which gives you the lowest viscosity. This way you can be quite confident that the viscosity was somewhere between these two values. Usually a $\pm$30 °C interval will change your result by half a log unit, and a $\pm$0.2 wt% H$_2$O interval will change it by one log unit, so you'd get something like $\log \eta = X \pm 0.75$ Pa s, which is not that bad.


"Is there any interaction between the Earth's atmosphere and high velocity protons in the solar wind (e.g. protons combining with atmospheric oxygen to form hydroxide) which is capable of balancing the hydrogen loss?" I found Hydrogen ions in the solar wind react with oxygen in interplanetary dust grains to form little packets of water, potentially supplying Earth with its water, but they don't know how much.

"How big is the hydrogen loss?" 3 kilograms per second.

"Is the amount of hydrogen on Earth in equilibrium?" We are also gaining 50,000 tons of matter per year from space dust, but only a small part of that is hydrogen.


If ALL the ice melted, what percentage of the Earth's surface would be water?

As @gerrit commented, a precise calculation would need to incorporate a litospheric model to account for isostatic post-glacial rebound. But the "blurry approximation" you want, can be obtained based only on topographic data. This approximation would be reasonably accurate if the melting of the ice happens quickly.

For this, we need topographic data of the current surface, and of the bedrock topography. That's the bare ground below the ice. The only source of such data at a global scale (at least that I'm aware of) is ETOPO1, at a resolution of 1 arc-minute (roughly 1.8 km).

A visualization of current surface data from ETOPO1, using an equal-area projection (Eckert IV) and setting the sea level at 0 m looks like this:

And if we measure sea and land areas, it says that currently, a 70.97% of the global surface corresponds to oceans, pretty consistent with the figure you have. Be aware that this simple approach does not consider lakes or rivers, only oceans. It would also misinterpret below sea level dry land as ocean. However, all those factors are arguably minor contributions at a global scale.

Now, if we use the bedrock version of ETOPO1, and set the sea level at 66.5 m, consistent with the best estimates of water stored in land ice. The globe would look like this

In this case, if all the ice melts, the fraction of the Earth's surface covered by water would be 75.18%. Equivalent to an increase of 4.21% relative to the current value.


Wet and dry seasons - what are they and how do they form?

In the mid-latitudes we experience 4 seasons (winter, spring, summer and autumn) due to the large annual variation in sunlight due to the tilt of the earth in its orbit.   The tropical latitudes, however, do not see large annual variations in sunlight or temperature and instead define their seasons by precipitation changes e.g. wet and dry seasons.

Some examples of a wet/dry climate are monsoon climates and savanna climates.

The monsoon is driven by seasonal changes in wind directions.  The typical setup is offshore flow during the dry season and onshore flow in the wet season with a mechanism similar to the sea breeze (e.g. driven by temperature differences between land and sea).  During the dry season, dry  air flows out to sea and during the wet season, moist air flows inland from the sea, rises and produces rain.  The monsoon circulation occurs in parts of Africa, Asia, Northern Australia and arguably in the North America desert southwest (debatable because it lacks a true seasonal flow reversal).

The savanna climate generally have a dry season of varying intensity and length and a rainy season in the remainder of the year.  Total rainfall in savannas tends to be less than that in monsoon regions.

Both of these wet/dry climates involve interaction with the inter tropical convergence zone (ITCZ), which is a persistent band of rising air and thunderstorms near the equator.  It moves north and south with changes in location of the sun seasonally and responds to the monsoon circulations and ends up merging with them.

The other tropical climates are wet all year long (rainforest climates) and dry all year long (desert climates).  The rain forests are equatorial and dominated by the ITCZ year round.  The hot deserts are around 15-30 N/S latitude and are favored on the western extents of the continents.  The latitude preference derives from the descending branch of the Hadley cell, which suppresses precipitation and causes warming.  The western continental preference comes from the direction of the trade winds, which are easterlies in the tropics.


What are the formulae for calculating the thermal heating effect of back radiation in greenhouse gases?

As you have mentioned already, there are several physical phenomena which are responsible for heat and energy transfer. I'll just list them again for completeness, although you already addressed them in your question.

Conduction
Convection
Latent heat of vaporization
Radiation

To get to your question: Radiation is the transport of energy by means of electromagnetic waves emitted from a body of a absoulte temperature uneqal zero Kelvin.

What does that mean? Radiation does not rely on contact or a transporting fluid as do conduction and convection. Instead it is equivalent to the fourth power of its absolute Temperature. This is what we know as "Black Body Radiation".

The equation for this is:

$$ E = \sigma * T^4$$

where σ is the Stefan-Boltzman Constant and T is the absolute Temperature in Kelvin. This law is obtained by integrating Planck's law over the solid angle and wavelength, in order to determinate the energy which is transmitted not only by one particular wavelength, but the whole spectrum and in all directions. Combined with Kirchhoffs Law, which says, that the absorbtivity of an object equals its emissivity, you can calculate the radiated Energy of any object or atmospheric layer.
The emissivity (ε) of a body is a value between zero and one with one being the perfect black body. For most things you can find values in the web. It also explains why aluminum foil is such a good insulator.

$$ E = ε * \sigma * T^4$$

To put all of this in an example:
Everything around you radiates heat. Beginning with the most obvious, the sun. The sun's surface has an approximate temperature of 6000K. This means it emits radiation of the following spectrum:

As you can see, the maximum of the energy of the sun is radiated in the part which we know as visible light. Also a big part of the radiated energy is absorbed in the atmosphere (the difference between yellow and red graphs). Responsible for these are particularly Ozone (O3), Water (H2O) and (CO2) which are also our most important greenhouse gases.

What happens, is that the radiated energy of a particular wavelength "hits" the molecules and excites them into a state of higher kinetic energy. The average random kinetic energy of a substance is what we know as the temperature of this substance. Hence, also the atmosphere acts like a black body and radiates energy
back to space but also back to earth.

Unfortunately I can't really say much about the second part of your question. I don't know about the original experiments. But I suggest a read about Gustav Kirchhoff, who introduced the idea in 1860 which then has been proceeded by Josef Stefan in 1879 and Ludwig Boltzman (1884). Also Planck's works from 1900 could be helpful.

I hope I was able to point you in the right direction with your studies.


If "oblique square prism" is this, where the top and bottom planes are parallel, then yes, there are. Carbonates (members of the Calcite and Dolomite, but not Aragonite, groups) have perfect cleavages that leave them with such habit. But be warned that they do not crystallize with such habit, it is a product of an effort that forced it to break accordingly to its cleavages.

A beautifully euhedral calcite crystal.

If, however, you're looking for a mineral which crystallizes in such shape, then the answer is no. There are 14 Bravais lattices (to put it simply, a Bravais lattice is the atomic arrangement that makes the smallest unit of a crystal, and so a crystal is a repetition of it). Each vary on edge ('line') length and angular relationship and obey some rules which are irrelevant for this discussion. The point is, none of the Bravais lattices has the edge parameters a, b and c (thickness/depth, width and height edges, respectively) in equal sizes (i.e. a = b = c) and angles different than 90 degrees between them. Which means that no crystal will ever be fundamentally crystallized in such a form.

The 14 Bravais lattices. Any solid must obrigatorily crystallize in one of these 14 lattices. It's a natural rule.


Does the shear modulus of silicate minerals vary significantly with changes in P and T?

A quick Google Scholar search for the most studied mantle mineral leads to this paper, with this in the abstract:

  The shear elastic moduli exhibit non-linear pressure dependencies.

So the answer is yes. As for the magnitude and drastic changes, you will have to do some reading.


Why do clouds have areas of darkness instead of scattering light to produce a rainbow?

It really depends on the cloud. Actually, it depends on its density and thickness which is related to concentrations and type of hydro-meteors in it, the size distribution of water droplets and ice crystals, and shape of ice crystals.

Rainbows are formed by the refraction and internal reflection of light in water drops (usually rain).

But cirrostratus clouds can form a halo by refraction on ice crystals in shape of hexagonal prisms. These halos have angular radius of about 22 degrees.

Another optical phenomena that you might find interesting is a corona around the Sun or the Moon which is caused by diffraction of light on water droplets and tiny ice crystals. Angular size of a corona depends on the size of water droplets.

'Areas of darkness' are due to the density and optical thickness of a cloud. More ice crystals and water droplets cause more scattering which results in less light reaching your eyes making a cloud appear darker.


So all this leading to my question: What could have been the cause of
  the this deep divide?

Think about what animals need to travel between Islands.  It's very difficult unless the water between the islands either drops or freezes over (Deer, for example, have crossed from New Jersey to Staten Island when the Hudson River freezes over), but the ocean doesn't freeze near the Wallace line.

Or, during ice ages when sea level falls as much as 410 feet, Islands can be joined as sea level drops.   Japan, for example, a land-bridge formed through Hokaido to mainland Asia.  Likewise, the UK connects to France and the Bering Straight becomes land as well.

There's nothing particularly remarkable about the water over the Wallace line other than it being too deep for any land bridges to form during ice ages.  The relevant geological feature for land bridges is shallow oceans/seas/bays/straights/channels, etc.   The Java sea is sufficiently shallow that all the islands Northwest of the Wallace line are joined when sea level falls.

It was pointed out that it's rough water too, but that's not the primary reason.   The primary reason is simply the ocean's depth and width.  Animals have little incentive to try to cross any fairly large body of ocean.  Animals sometimes migrate across raging rivers, but in that situation the other side is clearly visible.  The islands on each side of the Wallace line, even with the sea level drop, would (I assume), appear very far away to the eye, if they could be seen at all.


Are there any saltwater rivers on Earth?

The water in any river draining the sea is infinitely recycle-able (from rain replenishment), whereas the salt from any terrestrial source is not. So salty rivers, if any, won't exist permanently. Saltwater lakes gain their salinity precisely because they have no outlet, so salt just gets concentrated by evaporation. I don't think there are any truly saline rivers throughout their entire length.

The nearest approximations I can think of are:

Rare ephemeral runoff from emergent salt domes in desert areas.
Freshwater rivers that drain into arid areas where combined evaporation and infiltration gradually reduces the flow to zero. These are more 'very brackish' than truly saline. The Amu Darya in Uzbekistan is one such example. I don't know the salinity of the Jordan as it enters the Dead Sea, but the river is reduced to almost nothing, whilst there are hypersaline springs, and sewage effluent from Amman draining into it.
The only river I can think of that is very highly mineralized from source to sea is only about 3 kilometres long. It is an unnamed river from the volcanic crater on Savo Island, in the Solomon Islands (Southwest Pacific). It is also acidic and boiling hot - quite literally, for most of it's length.


Would a gold-containing meteor cause it to "rain" gold?

As it melted, it would be broken up into a spray or even a mist by the airstream. The droplets would quickly slow down to their terminal velocity and solidify, so you would get a fine gold dust imperceptibly falling over a wide area.
I am basing this on my admittedly incomplete understanding of meteors that do not contain gold. When the one in Russia some years ago exploded, it didn't vaporize, but only so many pieces were found.