Why don't animals rot when trapped in amber?

things need to be exposed to bacteria to rot, amber produces a perfect form fitting seal and has several antimicrobial properties to boot killing off bacteria that is already present. Even microbes trapped in amber become preserved. This makes a lot of sense when you realize the resin evolved to seal injuries in trees if it did not prevent the spread of bacteria it would not work. HOwever preservation in amber is not perfect and the things do degrade, but do so so slowly that more geologically recently deposits have decayed so little is is almost undetectable, the type of resin also matters all resin is not equal and some amber resins preserves better than others.


A good estimate of the lunar tidal energy dissipated into the oceans is 2.5 Terawatts (Munk, 1997; Le Provost & Lyard, 1997). The value estimated comes mainly from two different sources: from harmonic calculations and from altimetry estimates using satellite observations (e.g., Topex/Poseidon).

The input of energy into the coastal ocean is not uniform and has a peak in the South Atlantic Ocean, while the energy is dissipated by bottom friction in the coastal ocean and mainly in the North Atlantic Ocean (Le Provost & Lyard, 1997).

Source: Nature: Egbert & Ray, 2000. Estimates of tidal energy dissipation.

Egbert & Ray (2000) showed that a fraction of the dissipation (1 TW) takes place in the deep ocean in areas of, generally near areas of rough topography. Maintaining ocean stratification and the large scale thermohaline circulation (the commonly known "Conveyor Belt") requires around 2 TW to provide enough mixing (Munk & Wunsch, 1998). Therefore, the tides provide about half of that energy with the other half coming from wind forcing.

Here is a summary figure from Munk & Wunsch, 1998.

The repercussion of this fact are given by Wunsch (2000):

  ...it was only recently recognized that the need for an energy source to sustain the vertical mixing (lifting dense water through lighter) has important consequences. The difficulties of driving fluid motions by surface heating and evaporation mean that a mechanical source of energy must control not only the directly wind-driven flows, but also the deep-water components of the meridional overturning circulation.

  ... changes in tidal distributions and the consequent mixing would need to be understood over geological time. During the Last Glacial Maximum, the sea level was about 130 metres lower than today. This configuration removed much of the present regions of shallow-water energy dissipation and changed the deep-ocean tides, presumably affecting oceanic heat transport. Over longer periods in the past, the entire continental configuration was different, with radically different tidal distributions and mixing. It appears that the tides are, surprisingly, an intricate part of the story of climate change, as is the history of the lunar orbit.


With all the rain Seattle gets, why is widespread flooding relatively rare?

Regarding climate, it does not rain in Seattle as much as people think; Seattle is in the snow shadow of the Olympic Mountains. It doesn't rain much in summer at all. Seattle gets rather dry in July and August.
Regarding flooding, the Skagit and Snohomish rivers north of Seattle flood regularly experience flooding. Some of the land in the flood plain is used for farming, and there are scattered households in the 100 year flood plain.
Regarding drought, drought severity is relative to the amount of precipitation and soil moisture levels typical for a specific locale. This means that even a rainforest can suffer drought. Because it's a relative concept, the rainfall during a drought in a rainforest would be a rainfall bonanza in arid climates.
Regarding forest fires, the Seattle area occasionally undergoes offshore flow. This occurs when the air pressure is lower in the Seattle area than it is east of the Cascades. This makes winds blow from the east, and if there's a forest fire east of the Cascades (which has a rather dry climate), that smoke can be carried westward toward the Seattle area by the offshore flow. That said, wildfires have occurred on the western slopes of the Cascades, and sometimes even in the temperate rainforest to the west of the Seattle area.


Is this particular multiple rainbow unexplained by science?

There's nothing inexplicable about that photo.  It's got a few uncommon features, but nothing unknown.  In the image below, I've drastically distorted the brightness curve to make things more obvious:

Primary arc.  This is the classic "internal reflection" rainbow that you learn about in school.
Secondary arc.  This one forms when light is reflected twice within a raindrop, broadening the bow and reversing the order of the colors.
Supernumerary arcs.  These are formed by the wave nature of light: light, even of a single color, spreads out as it passes through a raindrop.  The arcs are interference patterns formed by the spread-out light from many small raindrops, and because of this spreading, they're usually pastel colors rather than the single-frequency colors of the main arcs.  The less variation there is in raindrop size, the sharper the arcs are; these are especially sharp.
Supernumerary arcs on the secondary bow.  These are rarely seen, because they're even more sensitive to variations in raindrop size than the primary arc's supernumeraries.
Possible fifth-order bow.  This faint green patch is in the right place to be the green stripe from light reflecting five times as it passes through a raindrop.  Fifth-order bows are almost never seen because of how faint they are, and are photographed even less often, so this may just be an image artifact.
Primary glow.  Only the light passing through the edges of a raindrop forms the rainbow.  Most of the light passing through the middle just goes straight through to form the zero-order glow (not pictured), but some reflects back to form a glow in the middle of the rainbow.
Alexander's dark band.  The light making up the rainbows has to come from somewhere, and this band is where it comes from.
Reflected rainbow.  This isn't a reflection of the primary arc (rainbows aren't real objects, so they don't have reflections), it's the rainbow you'd see if your position had been reflected across the plane of the water.

All of these have been known to science for quite some time.  The primary arc was the first one to be explained, by Persian astronomers in the 1200s.  Supernumerary arcs were the last one to be explained, by Thomas Young in 1803.

The "third rainbow" the BBC is talking about is probably the first few supernumerary arcs of the primary arc.  Supernumerary arcs have the same color ordering as the arc they're attached to, but because the brightness and width of the arcs varies, and because they're usually pastel colors rather than spectral colors, it can give the appearance of a reversed spectrum.

The "third rainbow" isn't a twinned rainbow, because the second arc of a twinned rainbow (caused by two rainstorms at different distances with different raindrop characteristics) wouldn't be concentric with the first arc.


For processing large data it is a good practice to call data into RAM in slices(Either by spliting time axis or spatial domain). In the interest of earth sciences python packages Xarray, iris, netCDF4 and h5py are few of the great tools for handling huge hierarchical data. For handling data in a labeled fashion Xarray and Iris will be useful while netCDf4 and h5py are good to process in a gridded way.

My personal suggestion is h5py which is meant for processing and archiving large datasets. Documentation here explains it. If you have netcdf files and want them in hdf5 format a question at Stack Overflow might help.


What happens if a magnitude 13 earthquake occurs?

It can be problematic to use an earthquake magnitude scale for such purposes. To explain why, you have to look at the different scales how they were produced. The magnitude scales are normally used related to earthquakes on earth, resulting from elastic rebound effects from fault activity. The Richter scale (local magnitude, ML) is, easily said, measured by the amplitude of a seismograph in < 100 km distance the centre. It gets inaccurate at a magnitude greater than 6.5. From a magnitude greater than ca. 8, even the teleseismic calculated surface-wave magnitude scale (MS) gets inaccurate. For greater magnitudes, the magnitude has to be modelled in a completely different way: Here, the moment magnitude scale (MW) is used. It is defined in relation to the seismic moment:

$M_{W} = \frac{2}{3} log (M_{0}) - 10.7 $

The seismic moment M0 is defined as:

$M_{0} = D *A * m$

where $D$ is mean displacement at the total fault, $A$ is the fault and $m$ the rigidity (shear strength) of the faulted rock. It can only be modelled by visible surface offset/displacement.

So, let's come back to the question: The magnitude of an earthquake is related to the length of the fault. The problem of a magnitude 13 is, that it is not possible according to this concept due to the earth's physical limitations. Keep in mind, that with one magnitude higher, a quake has about 32 times more energy. Of course, you can compare the energy for instance to that of an impact event - which is also often done. However, it is not easy to presume the intensity.


This form of geothermal energy was investigated in Australia in the early 2000s.

A company, then called Geodynamics Australia but since renamed as ReNu Energy, constructed a geothermal power plant and during 2013 conducted a [160 day trial of a 1 MWe pilot plant] in the Hanbanero Field near the border between South Australia and Queensland(http://www.futuredirections.org.au/publication/geothermal-industry-future-australia/).

"The pilot plant used steam generated through an EGS (Enhanced/Engineering Geothermal System) that exploits thermal energy from hot rocks over four kilometres below ground level. Following the trial, it was concluded that it may be economically viable to supply heat energy to nearby gas production operations, but not the supply of electrical energy. No further work has been done on the project, and the company completed site environmental remediation works in 2016."

The pilot plant had many technical challenges:

"EGS (also described as a hot rock system) extracts heat from hot rocks deep in the earth and conveys it to surface where it is used to generate electricity (see Figure 1 above). This involves a heat exchange arrangement. In most EGS projects, water is pumped into an injection well where it takes on heat as it moves through fractures in hot rock, and is then extracted to surface from a production well. In the Habanero pilot plant trial, temperatures seen on surface from the production well were up to 215 degrees by the time the trial was finished – certainly demonstrating the capacity to extract heat. Another critical factor in how much electricity can be generated though is the rate at which the high temperature steam is produced. In the Habanero trial, up to 19 kg/s of flow could be sustained. This contrasts with (according to the 2014 report to ARENA) flow rates in the order of 80 to 100 kg/s that would be required for economic viability. Whereas the initial intention of the Habanero project was to create a network of man-made fractures to allow optimal rates of circulation, in actuality, fluid was circulated through a naturally occurring fault in the rock (a geological feature which was not anticipated). The challenge of establishing and optimising fluid circulation between wells might be addressed in future through fracturing techniques that have resulted from ongoing technology development in tight gas or oil wells."

One of the issues with developing geothermal energy in Australia, from deep hot rocks, is the remoteness of the potential generation sites from regions that could utilize the energy. This makes the use of such geothermal systems currently unviable.


Why are some theories as to the cause of glacation less popular among the scientific community?

Your question is framed as if any model of glaciation were only allowed to consider one of those influences. I think practically any palaeoclimatologist would accept that astronomical forcing, solar output, and volcanic eruptions all have effects on glaciation. It's true, however, that on long timescales (tens of kiloyears and up), Milankovitch forcing generally gets more attention than the other two you mention. There are further important drivers of glaciation which you don't mention. Perhaps the most obvious is greenhouse gas concentration: if atmospheric levels of CO2, methane, and other greenhouse gases drop, the Earth cools and glaciation becomes more likely (see e.g. DeConto and Pollard, 2003). Another influence is tectonics and geography, the best-known example perhaps being the theory that Antarctic glaciation was caused by the break-up of Gondwana, which left Antarctica thermally isolated (Kennett, 1977).

To return to your main question, there's a good reason to consider Milankovitch forcing as a (or the) dominant driver of glaciation on longer timescales: it's simply that glaciation (as deduced from δ18O records) varies in time with the astronomical cycles. Hays et al. (1976) is one of the classic papers on this, and they sum the situation up neatly:

  Over the frequency range 10−4 to
  10−5 cycle per year, climatic variance of
  these records is concentrated in three discrete
  spectral peaks at periods of 23,000,
  42,000, and approximately 100,000
  years. These peaks correspond to the
  dominant periods of the earth's solar orbit,
  and contain respectively about 10,
  25, and 50 percent of the climatic variance.

To put it another way: if you want to discount astronomical forcing and attribute those variations to (say) volcanic aerosols, you need to explain why you have volcanoes going off at precise 42,000-year intervals. This isn't to say that we fully understand how these drivers interact with the climate system yet (the 100,000-year problem is perhaps the best-known "wrinkle" in the theory), but the fact remains that if your glaciations are dancing to 23, 42, and 100-kiloyear beats, and your solar system happens to be providing beats at precisely those frequencies, there's probably a pretty strong connection there.

DeConto, R. M., & Pollard, D. (2003). Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2. Nature, 421(6920), 245-249.
Hays, J. D., Imbrie, J., & Shackleton, N. J. (1976). Variations in the Earth's orbit: Pacemaker of the ice ages (PostScript). Science, 192(4270), 1121-1132.
Kennett, J. P. (1977). Cenozoic evolution of Antarctic glaciation, the circum‐Antarctic Ocean, and their impact on global paleoceanography. Journal of Geophysical Research, 82(27), 3843-3860.


How to determine that sustained wind speed exceeded the threshold value?

You are essentially asking how to determine what the sustained wind speed is, and as pointed out in a comment, this is merely temporally averaging your 50 s instantaneous wind observations.  The specific application you are targeting likely has a standardized definition of a time period over which the averaging should occur.  This might be a 3 minute wind, a 5 minute wind or some other value.  Once you know this value, you can calculate a rolling average over your time series of instantaneous wind and this rolling average is your "sustained" wind.

If your application is aviation, you'll want to keep the sustained wind and the peak winds, as the difference between sustained and peak gust is important to landing aircraft (we call that difference the "gust factor" and is generally more important than the sustained wind alone).

METAR define wind direction and speed as 2 minute averages and define gusts as a minimum 10 kt deviation over the mean during a 10 minute period. See  this page for more information on observing wind for METAR applications.


Just to elaborate on David Hammen's correct comment:

The granite is old. The mountain is fairly young. There is no
contradiction

Mountain belts like the Rockies are built by tectonic forces. Two plate collide, and mountains rise in between. The material that makes up the mountain does not have to form during the collision (although it sometime does).
A "batholith" is just a collection of many granite intrusions, which are mostly underground. They do not have to be mountainous. In most cases they are covered by sedimentary rocks and you don't even know they're there. They only become mountains when you "fold" them. When you fold a piece of paper and it wrinkles, you have to separate the formation of the wrinkles (which happened now) from the manufacturing of the paper (which was in a paper factory, in the past).


Can one assume atmosphere (primarily nitrogen) is heavier than water (vapor)?

Yes, humid air is less dense, but temperature and pressure are much bigger factors in the density of air.   Temperature and pressure are what drive updrafts and wind speed and direction much more than watervapor.

Absolute Humidity, or, the mass of water vapor in air, is a smaller factor.  See here for more detail.

Temperature

a 5° change can vary air density by almost 2%.   That means that the Sahara desert (35° c) and the North Pole (-25°), with humidity and pressure being equal, the air in the North Pole is about 24% denser.  Locally, if we assume a 15° variation daily or 25-35° variation yearly, that's 5%-14% locally, give or take, based on temperature.

Pressure

Per Avogadro's law, a 10% increase in pressure, everything else being equal, corresponds to a 10% increase in gas density.  10% variation in air pressure is quite a bit (unless you're climbing a tall mountain).   Locally, 10% variation in air pressure is rare, unless you're looking at records.  Daily/Weekly highs and lows in barometric pressure might vary air density by 3%-7%, ballpark estimate.   See some record high and low pressure here.

Water Vapor

Again, using Avogadro's law, if you add 1 water vapor molecule to the atmosphere, and maintain temperature and pressure, you need to push one other gas molecule out of the set volume, so per cubic meter, increasing humidity does displace some of the heavier gas molecules, so there is some lightening of the air, but the effect is quite small.  Water-vapor has a molecular mass of 18.  Our Oxygen-Nitrogen atmosphere has an average mass of about 29.   But Water Vapor rarely takes up more than 1% of the atmosphere, perhaps 2% in hot climate, 3% in very hot, but that's 3% of the air with a 38% decrease in mass, resulting in a net change of less than 1% in the most extreme conditions.  You'd be unlikely to see a variation of as much as 1% density by water vapor alone, outside of a very rare event, like a thunderstorm over a desert.

There's other factors for wet air, such as the evaporation of water has a cooling effect, so as water evaporates, the local atmosphere cools, so mid day when sunlight driven or wind driven evaporation is at it's peak, it's not quite so neat and tidy as to say that evaporation makes the air lighter, cause the cooling effect of evaporation may actually make the air slightly more dense, not less dense.  It's only less dense if you keep everything equal, but the cooling effect of evaporation doesn't keep everything equal.

That said, however you look at it, water vapor is likely an order of magnitude less important for air-density than temperature and pressure.   It's relevant enough to pay attention too if you want to study air-density carefully, but temperature and pressure are the two big factors.

A possible exception to this is when there's fog.  Fog contains tiny water droplets which are small enough to be suspended in air by wind, and those individual droplets are much denser than atmospheric water-vapor.   foggy air, under the right conditions might be the most dense air, but in a sense, that shouldn't count, it's like counting sand in a sandstorm as part of the mass of air.

((Corrections welcome if I made any errors)).


Could a waterfall lashing onto a road lead to a landslide?

Potentially, a landslide could occur. Whether it would be a minor slip or a major fall depends on the geological conditions at the site, the force of the water and the duration that the site is impacted by the water.

In the video in question, the rock face above the road appears competent, but there are not guarantees. The main issue would be is the water undermining the road which could cause a slip and the road to slide.

The more loose the geological material is, the easier it is to dislodge it. Once one item moves a chain of events can occur where additional items are dislodged and a slide occurs.

In addition to high pressure water dislodging material, water acts as a lubricant, making it easier for rocks and regolith to be dislodged.

To minimise the potential for a slide to occur in such a situation, the surface of the road would need to be sealed very well and a very good drainage system installed that would move the water away from the road and the slope below the road


What is the best way to accurately measure wavelength between crests on a pier?

One simple way is to measure the period $T$ by timing the arrival of each  crest and estimate the wave speed $c$ from the depth of the water column $d$. Then one can compute a wavelength $\lambda$.

Assuming the waves are shallow-water waves ($d/\lambda < 1/11$) and linear (modeled by a sine or cosine function), the error should be no more than 10% (is that accurate enough? It gets more complicated otherwise).

Since we assumed these are shallow water waves they are nondispersive and the speed is simply $c = \sqrt{gd}$, where $g$ is the gravitational acceleration.

Thus, the wavelength is
$$\lambda = c\ T=\sqrt{gd}\ T\,.$$


Where does all the salt come from in the Dead Sea?

The composition of the Dead Sea is quite unlike most other salt lakes, and is not at all like sea-water. Compare the concentrations, in grams per litre:

The potassium, bromine and magnesium are all hugely enriched relative to seawater, so clearly, it is not just a case of evaporation of residual seawater from the time of isolation of the Dead Sea. In fact, the vast majority of the water, and almost all of the magnesium, is derived from rivers draining from the north, from around the sea of Galilee, where magnesium-rich volcanic rocks weather rapidly. Much of the sodium and chlorine is derived from evaporation of rainfall originating from the Mediterranean - rainfall being just massively diluted sea water to start with. The high calcium and potassium comes from evaporite dissolution from the surrounding and adjacent rocks, especially from the Lissan Marl and saline springs emanating therefrom.

The real problem is: Where did all that bromine come from? The Dead Sea has the highest concentration of bromine in the world, and it is far from obvious how it got there. Clearly, there has been a massive concentration process. Maybe it was concentrated in the saline base of a much larger lake during the time of formation of the crustal formation of the Aqaba - Dead Sea - Gollan Heights rift? Any 'armchair theorists' out there with a better hypothesis?


How do you use the streckeisen (QAPF) classification ternary diagram to identify igneous rocks based on chemical rock composition?

Why you should not do it

The QAPF and related diagrams are intended for classification of rocks in the field, or preliminary classification with modal proportions as seen in the optical microscope. They are not designed with the chemical composition of the rocks in the mind. Furthermore, these diagrams are merely descriptive and not genetic. They do not take into account many factors affecting the various characteristics of the rocks. While doing something like this may be interesting for homework exercise, it is not something I would expect to see in a recent research article.

If you want to do it anyway

Your solution should consist of two steps.

Finding what is the norm of the rock. A norm is an estimation of the ideal mineralogy of an igneous rock, based on the chemical composition of the rock. The most common norm calculation method is the CIPW norm, but there are other methods as well. For starters you should do fine with the norm. Instructions on how to calculate the CIPW norm are available in your favourite petrology textbook, here, or here. I've also seen some algorithms that do it for you, but their success varies on the silica undersaturated side of the rock spectrum.
Now that you have the norm, add together anorthite and albite to count how much plagioclase you have. You are also given the rest of the minerals. Now all you need to do is use the normalised relative proportions of each triplet of minerals to place them on the diagram. Here's a refresher on that.


Correlating the Caledonian and Appalachian Orogenies

The article The Caledonian Orogeny redefined (McKerrow et al. 2000) have done exactly that - correlating the stratigraphic and orogenic aspects of all of the orogenic movements (as you have listed) that they define as being orogenic phases comprising the Caledonian Orogeny.

An important distinction the McKerrow et al. make is to state that the term 'Caledonian Orogeny' is not a single event, but rather comprised of all the tectonic movements that occurred in the ~200 million year development and closing of the ancient Iapetus Ocean, through the Cambrian to Devonian.

With this framework, the authors were able to determine a continuous stratigraphy through deposits of the tectonic events of the Caledonian Orogeny in the present day North American and European continents.


Could this study "totally dismantle" Global Warming claims?

There is several credibility problems with this work.

First, they mention after the title:

  Abridged Research Report

but I cannot find any related full work from the authors on the matter. As a comparison, in this case, a short, simplified article was prepared as a companion for a full paper. The former is useful for news agencies and general public, and the latter for interested peers.

Second, references are poor. Data sources are cited, from government or agencies FTP sites, which is probably legit (I did not verify the linked data in great detail). GAST dataset are publicly available, as the freedom to publish possible misinterpretation in a proper peer reviewed journal, which remain to be done for the authors actual work.

Third, there is no real methodology. The abridged paper is presenting results and interpretations, but there is no real method.

Fourth, p17

  Clearly the historical GAST data adjustments that have been made have been dramatic and invariably have been favorable to Climate Alarmists’ views regarding Global Warming

This type of statement is having no place in a scientific paper, as this is poorly opinionated based on nothing of substance (Clearly, dramatic, Climate Alarmist) and does not prove much, except that the contribution is not scientific.

Fifth of less importance. the formatting is very poor, which is not helping with the credibility of authors - not that it is very hard to prepare nice and efficient looking reports these days. In a few words, poor communication (in this case, this paper) is not helpful to convince colleagues of alternative ideas (or any ideas).

Sixth until this work reach the stage of being published by an independent peer reviewed medium, I don't see how this could even begin to be a 'threat' to current climate science.


How to convert mol m-2 s-1 CO2 emission to Megaton day-1 (MtCO2 per day)?

Do the calculation for 1 mol of CO$_2$
1 mol of CO$_2$ weighs 49 grammes = 0.0049 kg
86400 seconds in a day, so 864000 * 0.0049 = 423.36 kg/day/m$^2$
The surface area of the globe is 5.1 x 10$^{14}$ m$^2$ - so 423.6 * 5.1 x 10$^{14}$ = 2.16 x 10$^{17}$ kg/day
Convert from kg to Megatons, 10$^9$ kg in a Megaton  - so we get 1 mol CO$_2$/m$^2$/second = 2.16 x 10$^8$ Megatons/day
This assumes, as farrenthorpe commented, that the molar emission rate represents a rate evenly distributed over the globe - if, for instance it only represented terrestrial emissions, or emissions in a particular region the calculation would need to take that into account.


Why does gold and other metals conglomerate

Some things to consider. Even if elements are formed randomly in stars that does not necessarily imply that the elements will be distributed evenly and randomly when the star explodes. Following the explosion of a star there will be a gravitational attraction between the elements created within the star which will cause clumping/agglomeration of the elements.

The other thing to consider is chemical attraction due to ionic charges and the lack or excess of electrons in the outer shells of atoms which causes atoms to chemically combine with other atoms to form molecules.

Many elements and molecules are soluble in water. When conditions change, such as temperature, pressure or chemical attraction, metals can precipitate out of solution and collect en-mass, sometimes forming nuggets.


Calculating mean time spent precipitating for a specified period/area?

Check with the Met Office to see what data is available.

My experience, from elsewhere, is that weather data: temperature, pressure and precipitation are recorded at important weather stations at half hourly intervals, with the data being in the format shown below

With data in format it is easy to determine the  "time spent raining" to a precision of half an hour.


I run an argon lab which does also K-Ar measurements.
The sample amount depends on the age because you need enough signal strength to measure the radiogenic argon component precisely. Young rocks have very low 40Ar* and to get enough volts on the detector you need more sample. Having the incorrect amount is akin to trying to measure micrometers with a yardstick.

For K measurements 30 mg in our lab is routine.
For the argon measurement we usually use about 2 mg; for very young rocks up to 200mg for rocks with ca. 2% K. We can date volcanic rocks of less than 20000 years using this technique and have dated historic eruptions successfully in our lab.

Usually customers can say if the rocks are very young, so I usually prepare the sample amount accordingly. I had a couple of completely blind samples where I had no idea of the age of the sample a priori, I ran a test with a ca 4 mg which yielded almost no gas, so I re-ran with more material.

Regarding sampling technique itself- look for minerals with more potassium, such as muscovite, biotite, amphiboles, or more felsic rocks. If the rocks are obviously weathered, they are not suitable.

I also have to say that Ar/Ar is a more accurate tool for most rocks and minerals, and then just a few mg is enough if the samples are Mesozoic or older. If they are very young, higher sample amounts are required as with the K-Ar technique.


What causes the colors seen during a sunset / sunrise?

There are many references about this on the web, such as Wikipedia and the NOAA site.

At sunrise and sunset the angle the Sun's light makes with the Earth at those locations is low compared with angle the light makes at midday. Because of the low angle, the light has to travel through more of the atmosphere before it reaches the Earth's surface and the eyes of anyone watching either the Sun rise or the Sun set.

The colour of the Sun's light is white, being composed of the colours of the light spectrum: red, orange, yellow, green, blue, indigo and violet. The wavelength of these component colours are all different. Red has the longest wavelength at 650 nm. Each of the other colours have shorter wavelengths with violet having the shortest at 400 nm.

As the Sun's light passes through the atmosphere it get scattered by the air molecules and particles in the air such as dust and aerosols.

Due to a phenomenon known as Rayleigh scattering the shorter wavelengths of light (greens, blues, violets) are scattered first, leaving the shorter wavelengths (yellows, oranges and reds) to travel further.

The greater the amount of particles in the air, dust and aerosols, the greater the degree of scattering and the more red the sunrises and sunsets will appear. This is particularly evident after large amounts of ash have been ejected by volcanoes, after large forest fires and in locations where air pollution, particularly from industrial chimney stacks and internal combustion engines from road vehicles is a major source of airborne particulate matter such as soot or ash and other very small products of combustion


What is the difference between Precipitable Water (PW or PWAT) and Quantitive Precipitation Forecast (QPF) in terms of computer weather model data?

Precipitable water is the total amount of moisture throughout the air (the total in the entire tropospheric air "column"; most moisture is found in the lowest few km, due to decreases in temperature and density and where humidity sources being at the ground).

Whereas QPF is the amount of precipitation that has fallen or is predicted to fall in a certain period of time (often 6 or 24 hours).

Generally more moisture (higher PWATs) do indicate the potential for more precipitation.  But you could definitely have a large PWAT and get no rain/snow/etc to fall from the sky.

I believe the greatest PWAT values are typically found in the warm saturated columns near tropical cyclones (hurricanes/typhoons).  From experience, in the US South, PWATs near/above 2 inches are generally considered quite large in the summer, and tend to indicate a greater chance of rain from air mass/sea breeze/frontal storms.

Whereas hourly rainfall rates can often be nearer 3-5 inches per hour, and locations can report over 20 inches of rain in a day [rainfall records].


If the top layer of a large river freezes, is the remainder's rate of flow affected?

No, the rate of flow would usually be unaffected. The same volume of water has to get to the sea, so unless the ice was so thick and so well anchored to the riverbank as to exert pressure on the flow of water beneath, which is very unlikely, the rate of flow would remain the same. If, in the unlikely event that the ice exerted pressure on the water, the rate of flow would speed up.

It's the same when you pinch the end of a garden hose. The same volume of water has to get through a narrower opening, so the jet becomes smaller but faster and more powerful because it is under pressure. For your purposes a faster flow would help your turbines to do their job but as I say, icing conditions are rarely such that ice would exert pressure on the flow. The friction between the current and the relatively thin coating of ice which usually occurs would not be enough to have any noticeable effect on the rate of flow.


Simple way to understand these narrow frequency peaks in recently published "ice shelf singing"?

The wavelengths that travel through the ice have a faster speed of travel, and the physical size of the pressure variations that cause the sound are not 100 meters. It's more like 1 meter, so it's similar to having an oversized speaker cone blasting air waves into the ice, which the ice then transmits to the microphone most clearly at a depth of 1-2 meters.

The best illustration I can find of pressure differentials and resonance modes from wind, of about 5-15 hz are from this 1960's YouTube video:

https://youtu.be/TqTSyFz6DJc?t=176

The frequencies of the speaker cones are guided by air turbulence buffeting from the angles of the snow dunes and the wind, which generate 1/2/3 frequencies, perhaps from 1/2/3 different snow dunes types in the same area, depending on the local dune shapes, and when a storm changes the dune shapes, the frequencies change correspondingly.

The compressed snow has an elastic property which absorbs higher frequencies at depth and adds higher waves together to form lower waves, so the frequency sounds lower in the ice.

It's not probable that the frequencies are generated by 100 meter wide diaphragms and pressure differentials because that would correspond to very high dunes and long valleys. the high dunes are not likely, and the wind pressure events in the valleys would not generate major pressure differentials.

If I was a bob moog, and I wanted to copy the physical resonance process of the dunes, It would be a relatively easy synthesizer to design. They have place bass audio cones at different zones of the dune at different times, and measure a 3D map of frequencies and timings from a zone near the artificial sound generator.

The unclear statements of the article say that:

They measured Perturbation Velocity, a coefficient of flow dynamics for seizmology and of aerodynamics turbulance equations for physics? which kind of perturbation velocity is implied? Where are the equations for perturbation velocity and what a the name of the equations?

Sound propagates through the firn layer, a study which may have already been measured and demonstrated by other snow and ice physicists? Sounds travel through snow, ice and water for different distances. To what distance and efficiency does firn transmit sound? there are graphs for snow acoustics and some of the research is hilarious:

one of the most complex pages of research i have ever seen

from this page: https://www.google.fr/search?q=sound+propagation+in+ice&num=100&source=lnms&tbm=isch&sa=X&ved=0ahUKEwjYptm3s5feAhVLOBoKHa2sBpEQ_AUIDigB&biw=1572&bih=808&dpr=1.5#imgrc=1z-RRNglm0UEGM:


Oldest to Newest Bedrock in the USA "road trip"

If you were hoping for a smooth succession from Archean all the way down to Quaternary, you're going to be disappointed. Geology is messier than rocks being serenely laid down continuously through time like that. A drive from the Appalachians to the East Coast would get you everything but the Archaean rocks, although the only Proterozoic rocks would be found in the Piedmont.

The tough part is finding rocks of Archaen age. Although the North American craton contains Archaen rocks, they are only at the surface in northern Wisconsin and Minnesota (That is, if we restrict ourselves to the United States as you asked), and the Upper Peninsula of Michigan. There are a few outcrops in the Black Hills of South Dakota.

Here's a link to a large detailed geological map of the three states.

But this is just the bedrock geology. The trouble with looking for Archean age rocks in northern Wisconsin and Minnesota, of course, is that these areas are mostly covered by glacial till from recent ice ages (although you might find an Archean glacial erratic that the ice sheets carried down from Canada). Archean outcrops might be small and inaccessible.

(Source: Wikimedia commons)

Minnesota has early Archaen ("Superior" craton) rocks and a whole succession of Paleozoic. It has some Cretaceous rocks but lacks other Mesozoic/Cenozoic bedrock. North Dakota has some Jurassic age rocks in its northeastern corner.

(Source: Steven Dutch, University of Wisconsin Green Bay)
https://www.uwgb.edu/dutchs/index.htm

Wisconsin has late Archaen ("Penokean" craton) rocks and the same lack of later rocks as Minnesota. Wisconsin has a field-trip planning site with an interactive outcrop map at this link.

If you could get access to the Black Hills outcrops (uplifted bits of the "Wyoming" craton), you might be able to approximate what tou want with a trip east through South Dakota, starting in the Black Hills. I haven't found an image of South Dakota geology appropriate for embedding, but
Here is a link to a large, detailed PDF of South Dakota geology, and  here is another link to an interactive site with generalized SD geology.


Is the giant impact hypothesis still alive?

The giant impact hypothesis was not formulated to address the issue of how the Earth acquired its waters. At the time the giant impact hypothesis was formulated, the dominant theory for how the Earth acquired its waters was impacts by comets and wet asteroids during the late heavy bombardment.

The giant impact hypothesis was instead formulated to address the issue of how the Earth acquired its very large moon.


Why are tropical cyclones forming earlier in the North Atlantic basin?

The shift appears to match up to a large change in the number of cyclones that peak as tropical storms in the early part of the TC season (here defined as March-July), shown by the blue (tropical storms) versus purple (hurricanes) in this graph (made using the HURDAT2 dataset from NHC):

It appears that a large part of the increase in tropical storms lines up with a coincident decrease in tropical depressions (shown in green).
It's notable that tropical depressions only start appearing in the dataset starting in 1963.  I don't know it for a fact, but because the timing lines up with the advent of satellite weather data it suggests TDs may have been added once satellite offered a better picture to find and analyze weaker systems.
Therefore, it would seem one possible theory might be that there was an initial predilection to hold less organized systems at tropical depression status, but as data has increased from hurricane hunters, satellite resolution upgrades, and additional/more rapid data reports, more of these systems were progressively graded as tropical storms.

Looking into the data at full resolution, it appears the trend may be greatest in weak and moderate tropical storms (focus on the lesser change in dark blue colors, and in most of the pink bands):

Does this pattern also match the rest of the year?

I'd suggest yes and no.  Here's the corresponding graph for the late parts of the season:

So it looks like:

Tropical storms are still on the upswing in the late season, just not nearly as much (the trend line for early season goes from 0.5 to 2.5, for late season it goes from 1 to 2).
Cyclones maxing as tropical depressions have also sharply dropped away in the late season, closely matching the early season pattern (indeed, late season TDs were less to start with, in parallel with the smaller TS increase).
Also note that the number of hurricanes themselves have increased in the late season by over 50% (while remaining fairly constant in the early season).

You can look into the trends in each storm type in the following set of graphs:

TD/TS/HUR 50 years: early, mid, late, total
TS/HUR 100 years: early, mid, late, total
By strength full history: early, mid, late, total
(Note these analyses don't include 19 unnamed TCs in 1967-69 where no intensity is given in HURDAT)

Many certainly do propose climate change as a possible mechanism to shift the intensity and numbers of TCs.  Quite a few warming modeling studies have suggested there would be an increase in tropical storms.  It appears that this paper (Kunkel et al 2009) has some interesting discussion into the topic in the hurricanes and typhoons section.  The conclusion of:

  In summary, robust detection of trends in Atlantic and western North
  Pacific TC activity is significantly constrained by data heterogeneity
  and deficient quantification of internal variability. Attribution of
  past TC changes is further challenged by a lack of consensus on the
  physical linkages between climate forcing and TC activity. As a
  result, attribution of any observed trends in TC activity in these
  basins to anthropogenic forcing remains controversial.

seems to offer a fair reflection of the overall situation as of now in tropical cyclones and possible connections to climate change.  There's certainly plenty of debate over how significantly climate change is influencing the shifts seen; some will draw more conclusions than others.

Regardless of whether it's due to changes in identification practices or other causes like human climate change, it's clear there are more named systems in the early season, and that would certainly often result in an earlier first name.

On the other hand, is it due particularly to sufficient ocean temperatures existing earlier in the season over wider areas?  It would seem odd that such a change would mostly impact only the number of tropical storms, and not change the number of hurricanes.  But further analysis should certainly be done and the other MPI factors.

I do offer one final small postulate, based both upon these graphs and upon my own perceptions... perhaps at least a small part of the upswing in tropical storms might be due to an increase in the buzz at the start of each new year.  It seems there is more and more talk and "excitement" and interviews as each year get started.  And I wonder if that may prime forecasters to make earlier designations sometimes.


How can every ton of CO2 cost 3 square meters of summer sea ice per year - quantitatively?

First lets take the question at face value and do the simple comparison. I will take the years 1979 and 2016 as arbitrary example, over a 37 year period - the longest for which accurate data are available. During that time the minimum extent of Arctic sea ice, defined as the area of Ocean with at least 15% of sea ice (as determined by satellite) decreased from 6.93 to 4.14 million square kilometers. That is, a decrease of 2.79 M Km2. The actual ice loss was much greater because of ice thinning, but that is incidental to the question. During the same period the CO2 emissions by the USA increased by about 160 M tonnes. So on the face of it, assuming a direct linear relationship, 1 tonne of emitted carbon from America results in an average of 0.029 km2 reduction in ice, or about 3 hectares (Not Km2! let's get the units correct!).

Of course, as every scientist knows, a correlation - even a good correlation, doesn't necessarily imply causation. In this case it would be correct to say that every tonne of burned coal eventually contributes towards the loss of Arctic ice, but the whole process is much more complex, with an abundance of other contributing factors, feedback processes, and non-linear relationships coming into play. Among these complicating factors are Arctic ice thinning, changing Arctic albedo, changing ocean-scale oscillations, Other country emissions, inter-annual changes in thermal inertia (land, ice, sea and atmosphere), and high-level atmospheric chemistry (volcanic gasses, aerosols, etc.). So although there is an element of truth in your article, it would be naive to imply a direct relationship.

To keep an eye on how the Arctic ice is responding to climate change I highly recommend
http://nsidc.org/arcticseaicenews/


In which state of matter exactly are the clouds?

Clouds consist of suspended (floating) liquid water droplets ("liquid clouds"), frozen (solid) ice particles ("ice clouds"), or a mixture of both ("mixed phase clouds").  In-between those droplets or ice particles (meteorologists use the phrase hydrometeor to encompass both) is air which will contain water vapour, but what you are seeing is the liquid and solid parts.  Some people believe that when they're seeing clouds, they're seeing water vapour.  They are wrong.  Don't feel bad about sharing this belief, I've known an atmospheric (!!) scientist at a national research institute have the same misconception.  Whether the humid air between the droplets or particles is part of the cloud is a matter of definition, but ice particles may contain air bubbles so I think it would be unreasonable to say there is no water vapour in a cloud.

One way to tell this by yourself is experiencing fog.  Fog is nothing else than a cloud that is connected to the ground.  If you walk through fog (preferably dense fog) and look carefully, you will notice it consists of many tiny water droplets (or ice particles, but then it should be very cold, as small cloud particles will not freeze immediately at -5°C or -10°C).

Tall clouds such as Cumulonimbus usually consist of liquid droplets near the bottom, ice particles in the anvil or incus (the top part that may spread out horizontally), and mixed in-between.  Mixed phase clouds are pretty difficult to model or even measure accurately, as the exact proportion between liquid and solid depends on many (unknown) factors.

See also Ice and Mixed Phase Clouds at the Centre for Atmospheric Science, University of Manchester (UK).


How deep was the Vredefort Crater when it happened?

Therriault et al. (1993) suggest an initial diameter of 192-300km. Turtle & Piarazzo (1998) suggest a smaller initial diameter but make no estimates of the depth; they do, however, suggest an impactor of 10-14km diameter. Dietz (1961) describes the impact crater as "40km across and 16km deep" - i.e. does not take into account the extensive erosion that has occurred in this location. Grieve et al. (2008) also give no estimate of transient depth.

Numerical modelling of the impact diameter-crater depth relationship has been carried out: see e.g. Wünneman & Ivanov (2003), which also discusses crater morphology; meanwhile Turtle et al. (2003) suggest that for an impactor of 10km diameter the maximum transient crater depth will be 24km.

It seems likely that difficulty in estimating transient depth arises due to the 2Ga history of erosion in the area; as such the best option is probably to appeal to uniformitarianism, and assume that the Vredefort-forming impact obeyed the same diameter-depth relationship as has been modelled for the population of recent craters in works cited above.


Where can I find information about monthly seasonal change in a given area?

You can try climatemps.com for easy access and plots. There they have a map you can click on or a list by countries.
More data and analysis tools are available at the KNMI Climate Explorer, a more reliable and scientifically sound source.

This is one of the outputs for Jakarta from jakarta.climatemps.com


Why is the concentration of highly siderophile elements so uniform in the mantle?

First, note that this plot is normalized to a reference, here the composition of CI chondrites (your version lacks the Y axis label, it's figure 2.1 from Walker 2016). So if the concentration of highly siderophile elements (HSE) seems uniform, it's partly because it is a relative concentration, not an absolute one. If you look at the raw data (Table 1.1), you'll see that the absolute concentrations vary by more than one order of magnitude depending on the element (from 0.35 ppb for Re to 7.6 for Pt). Also, as you noted the scale is logarithmic, which tends to flatten the differences.

Now, why do HSE have the same relative abundance in the mantle compared to chondrites? Because elements from the same family show the same behavior—actually it's why they form a family in the first place. HSE all are, well, highly siderophile, so they all went into the core during the core segregation, and now they all are highly depleted in the mantle compared to chondrites.

Note that despite this depletion, HSE are actually still too abundant in the mantle: there should be even less of them. Geochemists have long debated this issue. This nice paper (Walker 2009) reviews the different hypotheses that might explain this HSE "enrichment": incomplete core segregation, lower metal/silicate partitioning, late accretion of chondritic material after core segregation...


Why do cities at high altitude regions have high atmospheric pressures?

The reason for this is that the reported value is the relative pressure and not the absolute pressure. If meteorological stations reported the absolute pressure, dependent on elevation, it would been really confusing. So air pressure is always adjusted to sea level.

This is also why your home barometer has to be adjusted to show the correct pressure depending on the altitude where you are.

Here are a link to the weather close to where I live. It is at 150 m elevation,
https://www.yr.no/place/Norway/Buskerud/R%c3%b8yken/B%c3%b8dalen/hour_by_hour_detailed.html?spr=eng If you seek for Drammen you will see the green line showing the same pressure but the elevation there is close to sea level 10m or so.


How does radiogenic argon-40 get into the atmosphere?

Most of this 40Ar makes its way to the atmosphere in two primary ways. Firstly, since most of the K is concentrated in the continental crust, volcanic eruptions on the continents over geological time have concentrated Ar in the atmosphere. Since it is too heavy and inert to decrease in any appreciable method it has a long residence time. Secondly, volcanism at mid-oceanic ridges releases Ar into the ocean and then into the atmosphere. The current combined rate of these volcanic events is ~ 2.2×109 grams/year.


How have Farallon plates's remnants stayed as they were inside the mantle?

Rock is dense, is a good insulator, and usually has very high specific heat capacity; the crust is also kilometers thick. The combination of these qualities means that it takes a very long time, even geologically speaking, for crustal blocks to melt completely in the mantle. This is exacerbated by the fact that the mantle, especially the shallow layers close to the crust, is not actually much hotter than the melting point of most of the minerals in the rocks.

The reason that the crust is still visible in seismic wave variances while it moves in an apparently molten fashion is that even though it hasn't been completely melted it has been in the mantle long enough to reach a uniform high temperature, high enough to become plastic and flexible. So it still presents as a density anomaly because its not yet as molten as the material around it but it will flow, if slowly, because it is semi-molten, similar to the asthenosphere.


Is surface temperature relevant for the creation of high- and low pressures areas?

Your logic is wrong. Do not think of the atmosphere as a closed system. Your analogy of heating a bottle is not appropriate.
In uncomplicated terms, the Sun heats the ground, the ground radiates thermal energy heating the air just above the ground and the heated air rises. In rising, the air heated has less density than the surrounding air. By rising it exerts less pressure on the ground than the surrounding and thus has a lower pressure relative to the air surrounding it - it is a low pressure system.
The rising air reaches the tropopause, around 10 to 15 km above sea level, where it is no longer buoyant. Forced by the continually rising air it travels away from the heated zone. As it moves at such elevations  the air cools, increases in density and falls to the ground. As it falls the pressure it exerts on the ground is higher than the air surrounding it and it forms a high pressure system.
The system is best explained with Hadley Cells.
Air tends to rise around the equator and at latitudes 60° north and south, where most of the low pressure systems are located. Air tends to fall around latitude 30° north and south and the poles, where most of the high pressure systems are located.


What was the oxygen concentration in the air during the late miocene period?

R. Tappert et al (2013) used carbon isotopes in ambers as proxies for atmospheric oxygen concentrations. Their work indicates an initial Miocene O2 concentration of 16% and rising to about 20% at the end:

It's pretty remarkable how different their results look from other models. Some think that some inferred upward trend in O2 levels since the Eocene gave rise to the mammals, or at least bigger brains in mammals.
Hope this helps!


What goes into a tide power prediction for every fifteen minutes over the next twenty five years?

Tide prediction at some locale is more of an empirical art rather than an analytic science. It essentially is a reduction of decades or centuries of historical tide levels at the locale to Fourier-like coefficients. Tides at a locale are modeled as a sum of various frequency components, each with a magnitude and a phase offset from some reference. The frequency components are based on the Earth's rotation about its axis, the orbit of the Moon about the Earth, and the orbit of the Earth-Moon system about the Sun. Given a sufficiently long historical record at some locale, mathematical techniques enable teasing the magnitudes and phases for each frequency component from the record for that locale.

There are issues with this approach that limit the usefulness of these tidal coefficients for future predictions. The utility of the computed coefficients to predict future tides declines as time passes. The coefficients occasionally need to be recomputed. One issue is that there's a lot of noise in the historical records; a decent storm will temporarily make the tides behave differently than the record would suggest. This noisiness alone means that the computed tidal coefficients are not perfect. This makes the accuracy of predicted tides decline over time.

Another issue is that neither the Earth's rotation rate nor the Moon's orbital rate is constant; the tidal models assume they are. Even without the noise, a set of tidal coefficients from a hundred years ago would be worthless today because of the small changes in those rates.

Yet another issue is that the oceans themselves change over time because of sedimentation, changes in mean sea level, and changes in the shapes of the oceans due to plate tectonics. An estuary filling with sediment will drastically change the high frequency overtones that result from interactions between the driving frequencies and the coast. The oceans' responses to each of the driving frequencies is a set of amphidromic systems. Each amphidromic system comprises a central point around which water waves rotate at the driving frequency. The nature of these amphidromic systems slowly change over time as the oceans change.


What is the origin of the Laacher See caldera magma in Germany?

The East Eifel Volcanics, of which the Laacher See Caldera is a part of, is located on the Rhenish Shield and is associated with the Cenozoic Upper Rhine Graben continental rift zone (Aber, 2012).

Ukrich and Gabrielle (2013) hypothesise that as the region did have and still has active tectonics, that the magma chamber for the Laacher See Caldera could have been the result of magma accumulating in voids opened up through regional strike-slip faulting (including the 'Laacher See Strike Slip' and Ochtending Fault), block rotation and regional uplift.

According to Schmitt et al. (2010), the parental magmatic melt that formed the carbonatite-syenite suite based petrology that dominates the Laacher See caldera is derived from a mantle melt differentiated to phonolite.

It is believed that the magma resided/accumulated for around 20,000 years prior to the eruption.  Schmitt et al. hypothesise that the magma had a cooler and older outer edge, compositionally zoning to a hotter phonolitic core - the presence of younger phenocrysts could indicate a magma reorganisation just prior to the eruption.

References

Aber, 2012, Volcanism of the Eifel, Germany Region, GO 326 Plate Tectonics course notes

Schmitt et al. 2010, Magmatic Longevity of Laacher See Volcano (Eifel, Germany) Indicated by U-Th Dating of Intrusive Carbonatites, Journal of Petrology

Ulrich and Gabrielle, 2013, Why does the Size of the Laacher See Magma Chamber and its Caldera Size not go together? - New Findings with regard to Active Tectonics in the East Eifel Volcanic Field, EGU General Assembly 2013


Is the centre of Italy still at risk of earthquakes?

The Italian Civil Defense's map of earthquake risk zones shows Rieti in at best Zone 2, "Medium-high seismicity, quite strong earthquakes possible", and near or in Zone 1, "High or catastrophic seismicity, strong earthquakes possible".

The map of recent earthquakes in Rieti shows regular earthquake activity. Last year an earthquake killed hundreds in Rieti.

There was a famous long legal case in Italy over earthquake predictions and warnings.


Does a green or yellow sky actually indicate a tornado?

You know, there hasn't been too much research into this... but there has been some. For the most part, it's been proven that a green sky most likely means that a thunderstorm is coming. According to a researcher:

  Green is significant, but not proof that a tornado is on the way. A
  green cloud “will only occur if the cloud is very deep, which
  generally only occurs in thunderstorm clouds,” Bachmeier says. “Those
  are the kind of storms that may produce hail and tornadoes.” Green
  does indicate that the cloud is extremely tall, and since
  thunderclouds are the tallest clouds, green is a warning sign that
  large hail or a tornado may be present.

In addition, a Scientific American article was run on this:

  Over the past 15 years, a small group of scientists have weathered the elements working on green thunderstorms as a pet project, publishing a handful of articles in meteorological journals. All point to the existence of green skies with severe thunderstorms but no direct connection to tornadoes or hail can be made.

They then go on to state:

  Threatening green skies during a thunderstorm also proved entirely
  independent of the type of severe weather that came with it. Gallagher
  measured hailstorms where the dominant wavelength of light was green
  as well as hailstorms where it was the typical gray-blue color of
  thunderstorms. Tornado-producing storms proved similarly divorced from
  any particular sky color, other than dark.

We do know that green skies are a sign of thunderstorms, though:

  The moisture particles are so small that they can bend the light and
  alter its appearance to the observer. These water droplets absorb red
  light, making the scattered light appear blue. If this blue scattered
  light is set against an environment heavy in red light—during sunset
  for instance—and a dark gray thunderstorm cloud, the net effect can
  make the sky appear faintly green.

So to sum all of this up: we know that thunderstorms sometimes create a green sky. However, there is no evidence to prove that a green sky is a sure sign of a tornado or hail. It is however a warning sign, as it shows that a thunderstorm is most likely coming, and it could be a strong storm.


Since OP wants data in text format to plot pressure, temperature and dew point data this site University of Wyoming soundings map does provide data in a text format as shown in this example for Essen Germany.


How will climate change affect planetary waves?

As a non-climate specialist, this topic is on the edge of my understanding of meteorology, but here are some papers that I found potentially relevant to your topic.

Here is a quote from the summary of Limpasuvan and Hartmann, 1999:

  The planetary wave propagation characteristics can be used to link
  changes in the tropospheric annular mode to changes in the strength of
  the stratospheric polar vortex during winter. Planetary waves are
  strongly attracted to polar regions during the low phase of the
  annular mode when the tropospheric westerlies are displaced
  equatorward. We should expect a weaker stratospheric polar vortex
  then, since planetary waves weaken the polar vortex by generating
  irreversible mixing.

And here is a quote from Shepherd and McLandress, 2011

  In particular, the tropospheric warming that is robustly expected from
  climate change leads to a strengthening of the upper flanks of the
  subtropical jets, which causes the critical layers on the equatorward
  side of the jets to move upward, and with them the Rossby wave drag,
  allowing more Rossby wave activity to penetrate into the subtropical
  lower stratosphere (Figs. 4, 5). Because the subtropics represent the
  critical region for wave driving of the Brewer–Dobson circulation, the
  circulation is thereby strengthened.

So my conclusion from these two papers (there is obviously a lot more detail in the full text) is that polar vortex will weaken, subtropical jets and Brewer-Dobson circulation will strengthen, and Rossby waves will penetrate farther south. Of note, neither paper seemed (to me) to indicate that a cooler stratosphere was predicted.


How does Earth's thermal radiation into space vary by location and time of day?

The yearly average Top Of Atmosphere (TOA) Outgoing Longwave Radiation (OLR) is around 145–345 W/m², as measured by the AIRS instrument:

Source: Wikimedia Commons contributors, "File:AIRS OLR.png," Wikimedia Commons, the free media repository.

Now, this is an average that includes both day and night.  How much does it vary?  This depends on the location.  Based on GERB data, a 2007 paper estimates (please pay attention to the thick solid line only):

Source: Comer, Slingo, and Allan (2007)

Even in places with a very large diurnal temperature cycle such as the Sahara, the difference between maximum and minimum is only about 10%.  In oceanic areas it is closer to 2%.  That means that if you take the mean (shown in the top figure) and subtract around 1–5% depending on the region (the drier, the more difference) you get a reasonable estimate of the nighttime outgoing longwave radiation.

If you want a more precise estimate, you can always download satellite data and calculate it yourself.

Full source for second figure: Comer, Slingo, and Allan (2007), Observations of the diurnal cycle of outgoing longwave radiation from the Geostationary Earth Radiation Budget instrument, Geophysical Research Letters, Vol. 34, L02823, doi:10.1029/2006GL028229


How to check the recurrence intervall of heavy rain events

In engineering it is common practice to build intensity-duration-frequency (IDF) curves, which basically map out the frequency of a given rainfall event based on its average intensity (mm/hr) and duration of the event. This addresses the issue of needing to classify a 'heavy' rainfall event. In general, the duration and intensity are inversely related (more intense rainfall events tend to last a shorter time).

There are many examples of calculation and software packages to actually build these curves, which are used often for engineering design to help decide the storm a given piece of infrastructure is being designed to (e.g. 5 year storm, 25 year storm, etc.). Most municipalities will have developed their own IDF curves to set standards for design.

There are also examples of online tools to help generate IDF curves for a given location, such as this one in Ontario. This tool is neat as it calculates the IDFs for a given year, and uses trend analysis to predict future changes to the IDF curve, allowing you to also pick the target year for generating the IDF curve.

If you see that the intensity/duration changes for a given frequency storm event (e.g. 50 year), that would indicate a shift in the rainfall patterns due to climate change. You may need additional statistical tests to check if these changes are statistically significant (examples of this type of analysis applied here and here). You will likely not see much change in these curves over a few years as the datasets overlap quite a bit and the trends will not change rainfall patterns in that short a time frame, however, over a 25 or 50 year period you will likely see some changes in the IDF curves, depending on the location.


How to calculate the solar radiation at any place, any time

Look at the pysolar docs (http://pysolar.readthedocs.io/en/latest/) under "Estimate of clear sky radiation". The algorithm does not return zeros at night, but instead just plugs those numbers straight in, giving nonsensical values. Filter the results so that if altitude_deg < 0, the radiation is 0. An example just using pysolar, datetime, and pyplot (I don't use pandas, so I can't comment on that) and lists looks like:
import datetime
import matplotlib.pyplot as plt
import pysolar
lat, lon = 39.9075, 116.39723  # Beijing, China
timezone = datetime.timezone(datetime.timedelta(hours=8))  # 0800 UTC
start = datetime.datetime(2018,1,1,tzinfo=timezone)  # 1 Jan 2018

# Calculate radiation every hour for 90 days
nhr = 24*90
dates, altitudes_deg, radiations = list(), list(), list()
for ihr in range(nhr):
    date = start + datetime.timedelta(hours=ihr)
    altitude_deg = pysolar.solar.get_altitude(lat,lon,date)
    if altitude_deg <= 0:
        radiation = 0.
    else:
        radiation = pysolar.radiation.get_radiation_direct(date,altitude_deg)
    dates.append(date)
    altitudes_deg.append(altitude_deg)
    radiations.append(radiation)

days = [ihr/24 for ihr in range(nhr)]
fig, axs = plt.subplots(nrows=2,ncols=1,sharex=True)
axs[0].plot(days,altitudes_deg)
axs[0].set_title('Solar altitude, degrees')
axs[1].plot(days,radiations)
axs[1].set_title('Solar radiation, W/m2')
axs[1].set_xlabel('Days since ' + start.strftime('%Y/%m/%d %H:%M UTC'))
plt.show()


How can I convert the negative values of the ERA5 PET data into positive?

You can multiply all the values by -1

cdo mulc,-1 infile.nc outfile.nc

If you want also to get rid of the condensation data (and, please, note that I am not implying that that is the right thing to do), you can do something like this

cdo setrtoc,0,9999,0 ifile.nc ofile.nc

Hope this helps


Can clouds be formed without a pollen particle's role?

Pollen is one of many types of cloud condensation nuclei (CCN). So can you make clouds without pollen? Yes, but you still need other sources of CC. Don’t fall into the false dilemma that pollen is a requirement for cloud formation. The more soluble the CCN is, the easier it is to form a cloud (see Koehler theory).
Can a cloud be formed without CCN? I saw it once calculated that it would take longer than the age of the universe for something like that to occur.


Do Hydro-Carbon extraction units pollute ground water?

The types of hydrocarbon extracted from the ground ranges from gas to crude oil and bitumen. Each deposit of hydrocarbon is different; some are all gas whereas others are various types of crude oil or mixtures of oil and gas.

Extraction methods also vary depending on the style of geology containing the hydrocarbon.

Geology with relatively large spaces between the grains of the rock, such as sandstone, may have hydrocarbons that can flow easily. This type of deposit represents the classical oil deposits, such as in Saudi Arabia. Generally, with such deposits, holes are drilled into the deposit and oil is pumped out.

Geology with very tight spaces, such as shale, do not have the conditions for hydrocarbons to flow easily. In this type of geology the rock needs to be fractured to allow the hydrocarbon fluids to flow more easily. To achieve this a relatively new technique called fracking is used to fracture the rock containing the deposit.

Both classical hydrocarbon extraction and fracking require the use of drill holes to access the deposit. If the deposit of hydrocarbon occurs below a water aquifer, or other form of ground water storage, the drill holes that access the hydrocarbon deposit will pass through the underground water store.

To prevent the hydrocarbon wells (drill holes) from contaminating the water lying above them, the wells need to be cased (lined). The casing of hydrocarbon wells needs to be done by people who are committed to doing so and who are extremely competent in doing such tasks.

Nothing is ever perfect and there will always be risks of well casing failing which would result in ground water contamination. It then becomes a question how large is the risk, what will be the effect of such a risk and who is prepared to take such risks.


Would ultra-efficient carbon sequestrion produce immediate results in global temperatures?

The issue of the lag time between carbon addition to the atmosphere and maximum warming that results from it, is probably pretty divisive. I had previously heard estimates around 50 years, but the most recent work I could find (that was available for free) indicates that 10 years is about right, with Figure 1 of the linked paper being the best graphical evidence. This 10 year response is for a one-off injection of carbon, so we can't assume it would work the same for a one-off removal of carbon, but we can go with that number for now.

So, looking at Figure 1, if we started rapidly removing carbon from the atmopshere, the temperatures should reflect within a year or two, and if we removed ALL of the anthropogenic delta-CO$_2$, we could expect temperatures to go back to pre-industrial revolution plus or minus any natural changes since then in about 10 years.

A side note: supposing we could sequester as much carbon as we put into the atmosphere every year. That would be great! But how much energy would it take to sequester that carbon? And where would we get the energy to sequester the carbon. Sequestration seems like a great idea, but I don't think it would work, even if an excellent method of sequestration could be found, until the world's energy demands are met from non-fossil fuel sources.


The reported pressures are sea level pressure.  For stations not at sea level (most of them), they can be corrected to sea level through use of the hypsometric equation.  The reason the values are reported as sea level pressure is so that pressure values between stations can be interpreted in meaningful ways.  See for example a typical sea level pressure plot:

In order to produce such a plot, you need pressures on a common reference plane, which is often mean sea level or some other reference pressure level (e.g. 850mb, 500mb, 250mb).  This is why stations report sea level pressure rather than actual station pressure.  This also has applications for aviation, where aircraft operating below a specific altitude (18,000 ft in the US) have to reference their altimeters to a common value regionally and must know the local sea level pressure.


Does Earth's rotation cause sea levels to increase from east to west?

I ask as in Bill Bryson's book 'A Short History of Nearly Everything' on p.334 ch.18, he says

The Pacific is about a foot and a half [~46cm] higher along its western edge - a consequence of the centrifugal force created by the Earth's spin.

Bryson is right in the sense that in places there is a difference in height between the eastern Pacific and western Atlantic, at least in some places. He is however wrong about the magnitude of that height difference and wrong about the cause. From the Permanent Service for Mean Sea Level,

Sea level is about 20 cm higher on the Pacific side [of the Panama Canal] than the Atlantic due to the water being less dense on the Pacific side, on average, and due to the prevailing weather and ocean conditions. Such sea level differences are common across many short sections of land dividing ocean basins.
The 20 cm difference is determined by geodetic levelling from one side to the other. This levelling follows a 'level' surface which will be parallel to the geoid (see FAQ #1). The 20 cm difference at Panama is not unique. There are similar 'jumps' elsewhere e.g. Skagerrak, Indonesian straits.
If the canal was open sea and did not contain locks, i.e. if somehow a deep open cutting had been made rather than the canal system over the mountains, then there would be a current flowing from the Pacific to the Atlantic. An analogy, though imperfect because there are many other factors, is a comparison between Panama and the Drake Passage off the south tip of Chile, which has a west-east flow. (The flow in the Drake Passage is primarily wind-driven, but Pacific-Atlantic density must play some role.)


The rock you show is a conglomerate - it contains a substantial amount of clasts (your pieces) that are gravel or larger size. The pieces have been cemented together into a new rock - kind of like concrete.

There are a couple of additional things that can be seen in your pictures. First the clasts are very angular. This means they haven't been rounded be wave action or transport to the location where the rock formed. It was very likely formed close to where you found it. If you look at the clasts, the grey ones look like the rock to the lower left and the light ones seem similar to the rock to the lower right. This suggests that the conglomerate formed by eroding those rock types followed by cementation very close to the source. Then a new phase of erosion formed the pieces you see.


Is there a name for this weather phenomenon?

It is called frost smoke or steam fog (or a half dozen other names), sea smoke is the same effect just over the ocean.

It is caused by  high moisture saturation and strong temperature differences between the water and the air. http://glossary.ametsoc.org/wiki/Steam_fog


Why do greenhouse gases affect ocean temperature so much?

No, greenhouse gases do not absorb infrared radiation from the sun... the Earth is really the source of infrared.  The amount of infrared energy from the sun that reaches Earth is insignificant.  Visible light from the sun heats the Earth, NOT infrared light.  The visible light passes through the atmosphere and is absorbed by the surface of the Earth.  Then, the Earth re-radiates that energy back into the atmosphere in the form of heat (aka infrared radiation).  The infrared radiates back into space, but if there are infrared absorbers in the atmosphere, the energy is not lost to space.  That has a net warming effect.  In fact the Earth needs greenhouse gases, or we would all be frozen.  It is a delicate balance between GHG concentrations and climate effects on the hydrologic cycle.

It is important to note that ocean water expands in response to temperature increase... so even just a modest increase in ocean temperature can lead to significant sea level changes.  Human civilization is thus directly affected by oceanic temperature increase due to sea-level rise.

As a side note, the absorption of carbon into the ocean is really of more environmental concern than the actual heating of the ocean, in terms of acidic effects on the marine ecosystems.  The ocean absorbs roughly half the carbon emitted into the atmosphere and there are areas already seeing the negative effects of acidification.


Which months in Japan probability lowest of natural disaster?

There is no season for earthquakes or tsunamis. They can hit at any time of the year, and at any time of the day or night.

Typhoons happen in the warm season, but they will be forecast by the meteorological service, giving you time to move to a safe area.

If you want to go to Japan, just go. It is better to go in the season you want to go than to try and avoid earthquakes and typhoons, as they happen in random places out of anybody's control.


Define components of mineral assemblage?

Let's start by understanding what a component is. The components of a system are the minimum amount of chemical 'species' required to describe a system. What does that mean? Let's take a familiar example. Periclase, forsterite, enstatite and quartz. That's MgO, Mg2SiO4, MgSiO3 and SiO2. So we can say we have 4 components, each of those formulas I just noted. But that's not the minimum number. We can get a smaller number. So we can say, for example that our components are Mg, Si and O. We can create all of the mineral formulas from those 3 components. But wait - we can go even lower! If we choose our components to be only MgO and SiO2, we have 2 components that can still describe our entire system. We can combine 2MgO+1SiO2 to describe forsterite and 1MgO+1SiO2 to describe enstatite. Basically, the components have to be independent. If there is one component that can be described by others, then it is not actually a component.

So let's go to your problem. First of all, I would say that your assumption that the oxidation state of Cu is +1 and that of S is -2 is not entirely correct. In pyrite, S is actually -1 and Fe is +2 (Fe4+ does not exist). As an aside, the oxidation state of Cu (and others) in sulfides is a can of worms: those are not ionic compounds but rather a mixture of metallic and covalent compounds where oxidation state does not mean much, especially in the more complex cases such as bornite and chalcopyrite.

That said, if you look carefully and try to balance your reactions (try to make one mineral using the others), you can see that bn = cp + 2cc, so bn is not a component. Can you still reduce the amount of components? No. Fe3O4 must be there, and there is no way you can make CuFeS2 from Cu2S and FeS2. You might think about using the components S-Fe-Cu-O, but that would actually be incorrect because for that to happen S has to be the same valence, which obviously is not (compare Cu2S2- and FeS1-2).


How much time is there between an underwater earthquake and the moment a tsunami hits the coast?

As a general guideline, the time between the actual earthquake and the time the tsunami arrives is on the order of minutes to hours.
Tsunamis out in the deep ocean travel very fast -- around 500 mph -- which means that they cross ocean basins in about as much time as it takes a plane to fly across. So an earthquake in Japan gives Hawaii and the US West Coast many many hours of warning.
Close to shore, tsunamis are much slower, but of course the distances are also shorter. For a place where earthquakes happen close to shore because of a subduction zone, say in Japan, this only gives you a few or a few tens or minutes of advance warning. If you take the 2011 tsunami in Japan, warnings were sounded quite quickly, and that allowed a large number of people to get to higher ground and will have saved tens of thousands of lives. But at the same time, it was not enough time to actually go door to door, put people onto buses, and get them out of harm's way if either they did not hear the warning, or refused for whatever reason to immediately evacuate.


Why do buoyantly rising mantle minerals melt, yet buoyantly rising atmospheric waters condense?

There is no comparing the chemical composition of "atmosphere" with that of mantle rocks and the consequences of rising in each have almost nothing to do with one another. The cooling of rising atmosphere is a fairly simple thermodynamic process requiring neither molecular change of ingredients, chemical release of water, nor thermally impervious boundaries.

By contrast, rising mantle materials will undergo different melting processes depending on their water content and chemistry. In the simplest case, like a mid-ocean hot-spot, unpolluted by melt fluxes like water and carbonates, rising mantle rock undergoes "decompression melting" in which 2 things happen:

1) The pressure needed to keep rising mantle material solid is released and the material becomes liquid (like that crudely drawn by Michael, above). Remember, given enough pressure, you can heat up ANYTHING and keep it solid...even hydrogen, like that believed to exist in the earth's core.

2) Constituent minerals undergo phase (mineralogical) changes on their way up to the base of the upper crust. Remember that mantle materials come to the earth's surface as basalts which are mineralogically different from the olivene-rich peridotites of the mantle. Despite being chemically similar, deep mantle rocks contain minerals that are crystallographically denser than those found basalts. As they are brought up, these minerals undergo a phase change that alters their crystalline structure; they become different minerals, lighter and more buoyant, further reducing the density of the rising melt.

So, there it is (in a nutshell): reducing pressure on hot solid material allows it to become liquid and also invokes phase changes in minerals that make the overall material less dense.


How is there enough $\ce{O2}$ in the atmosphere to breathe if you are in a desert with no plants?

Look at it this way: According to the American National Center of Atmospheric research, the Earths atmosphere weighs 5.148 x 10^^18 kg., and that atmosphere is composed of about 20.8 to 20.9% oxygen (depending on moisture content of the air). So the Earths atmosphere contains about 1.07 million trillion kgs of oxygen.

The 7.5 billion (or so) humans on the planet, each converts an average of about 0.73 kg of oxygen per day, converting most of it to exhaled CO2. So the planetary consumption of oxygen by humans, as a percentage of the total available, is about 100 x 0.73 x 10^^9 / 1.07 x 10^^18 %.

That is, about half of one millionth of 1% of the Earths available oxygen, a level of oxygen deficiency that is almost instantly dispelled by turbulent mixing in the troposphere (i.e.by 'weather'). So no, there is no chance of gasping for oxygen in deserts or polar wastes.

Now gasping for air 8000 metres up a mountain, or in a crowded disco with cigarette smoke and poor ventilation - that is another question!


Calculation of river width in relation to contributing area

It's a function of flow volume rather than catchment area. The flow rate can be vary by an order of 10 to 100 for the same catchment area, https://www.google.com/search?q=average+river+width+based+on+flow+volume&tbm=isch There's so many variables like flow speed, inclination, bedrock type, flow rate.
This document includes the river width, it says there are too many variables.
https://www.nature.com/articles/s41598-019-44347-4
https://link.springer.com/article/10.1007/s11629-014-3265-0
here's a cool reference:
https://agupubs.onlinelibrary.wiley.com/doi/10.1029/2019GL082027
Did you know that a given type of rock gives mountains with all the same slope angles, i.e. there are mountains with ravines averaging 23 or 14 or 33 or 50% for the same mountain group, and screes inclines are rarely an irregular mix.


What causes these circular swirls of islands?

Near the Lake of the Woods, the island swirl or vortex is due to structures in bedrock beneath the lake.  The rocks in this area are old and have been folded by tectonic action. The area has either been folded into a dome or a basin, exposing different layers of bedrock. Glacial activity afterwards has 'flattened'the area, and differential erosion within the folded area formed valleys that flooded where the rock eroded faster.

Geologic history of The Lake of the Woods.


How Can Smog in Metropolitan Cities like Delhi & Beijing Be Reduced?

The first thing to do is to stop putting pollution in the air, particularly very small particulate matter that are produced by combustion.

For the Beijing Olympic Games of 2008, the Chinese government forced the polluting plants and factories in the vicinity of Beijing and nearby areas to stop operating for weeks prior to the games and during the games to ensure the air in Beijing was clear and had minimal pollution during the duration of the games. The measure was successful.

Burning wood, animal dung, coal, petroleum products (particularly diesel and heavy oil) produce soot and other small particulate matter which leads to poor air quality and smog.

This is an easy solution that results in clean air. The difficulty with this is that it is detrimental to the economy in the short term. For a longer term solution, energy sources need to be changed to ones that do not cause air pollution.


What is the rock I found on the Delaware river yesterday?

The boulder appears to be dark grey  fossiliferous limestone or dolostone with softer tan layers which might be: limestone or calcareous claystone/siltstone/sandstone.
From the photo, the tan layers do not appear to be shale.

I have a hand specimen which is very similar from southern New Jersey.
It is harder grey limestone inter-layered with light tan calcareous siltstone.


Why is ozone layer so important when oxygen atoms absorb UV Rays?

The cross section of ozone to UV radiation is many, many orders of magnitude higher than is the cross section of $\text O_2$ to UV radiation, so very much higher that despite the paucity of ozone molecules compared to diatomic oxygen molecules even in the stratosphere, it is the ozone molecules that tend to absorb incoming UV radiation.

When there is so much oxygen present in atmosphere how will UV Rays reach us?

Oxygen has a low cross section to UV radiation. It absorbs some, but not very much.

Are we concerned about oxygen being depleted?

Not at all. Suppose the ozone content did become rather high compared to nominal. This would increase the rate at which ozone combines with monatomic oxygen to form to diatomic oxygen molecules. Ozone is a transient component of the atmosphere. It is constantly being created but is also constantly being destroyed.


Is "Chasm One" the really the name of this feature on the Brunt Ice Shelf?

Is "Chasm One" an "official" name for the feature?
No. This is only an informal name used to designate a rift structure (fracture) in the Brunt Ice Shelf, East Antarctica. For example, another rift structure, which trends perpendicular to "Chasm 1," was informally named the "Halloween Crack" because it was first detected on October 31, 2016.

How was the term coined?
It is one of two rift structures that are arbitrarily and sequentially numbered, "Chasm 1" and "Chasm 2", starting from the seaward edge of the Brunt Ice Shelf, East Antarctica inland along the ice shelf as shown in Figures 1 and 2 0f King et a. (2017).

Will there be a new Chasm One someday, or will the name be retired after this one splits?
The name will likely be retired because having multiple "Chasm 1"s in the same ice shelf will be too confusing. Most likely as new rift structures from the sequential naming of them, e.g. "Chasm 3," "Chasm 4," and so forth would continue.

The papers are:
de Rydt, Jan, Gudmundsson, Hilmar, Nagler, Thomas, Wuite, Jan and King, Edward (2018) Recent rift formation and impact on the structural integrity of the Brunt Ice Shelf, East Antarctica. The Cryosphere, 12 (2). pp. 505-520. ISSN 1994-0424 http://dx.doi.org/10.5194/tc-12-505-2018
de Rydt, J., Gudmundsson, G. H., Nagler, T., and Wuite, J.: Calving cycle of the Brunt Ice Shelf, Antarctica, driven by changes in ice-shelf geometry, The Cryosphere Discuss., https://doi.org/10.5194/tc-2019-46, in review, 2019 https://www.the-cryosphere-discuss.net/tc-2019-46/
King, E. C., De Rydt, J., and Gudmundsson, G. H.: The internal structure of the Brunt Ice Shelf from ice-penetrating radar analysis and implications for ice shelf fracture, The Cryosphere, 12, 3361-3372, https://doi.org/10.5194/tc-12-3361-2018, 2018. https://www.the-cryosphere.net/12/3361/2018/
Hodgson, Dominic A., Jordan, Tom A., de Rydt, Jan, Fretwell, Peter T., Seddon, Samuel A., Becker, David, Hogan, Kelly A., Smith, Andrew M. and Vaughan, David G. (2019) Past and future dynamics of the Brunt Ice Shelf from seabed bathymetry and ice shelf geometry. The Cryosphere, 13. pp. 545-556. ISSN 1994-0440 http://dx.doi.org/10.5194/tc-2018-206


Need help understanding this satellite image of Larson C ice shelf

I found a natural-color image of the same area: 68.28 South, 60.47 East, North is up, resolution is 130m/px, which makes the whole image about 100 km x 100 km. Looking at the image i'd say that:

sea ice is water with pieces of ice in it,
the boundary between the two regions is clear water, probably caused by winds and currents moving the floating ice away from the edge of the ice shelf.

I got the image at Sentinel Playground using 100% cloud filter, 0.3 gain and date selection of 2016-11-21.

EDIT: Added more info about the position, scale and orientation of the image.


The context I often see the u,v,w components shown in one plot are forward and backward trajectory plots like those from the NOAA HYSPLIT Model, which provides separate panels for horizontal and vertical movement.  There is also 3-D imagery like what's available from UCAR in the cross sections examples for WRF, shown below.


Phase changes deep in planetary interiors and their implications for surface tectonics

The tiger stripes of Enceladus are thought to be a result of this moon's unusual chemical composition, as opposed to any mineral heterogeneity or thermodynamic perturbations occurring due to the phase change near the rocky core.

Ammonia has been found indirectly to exist on Enceladus and the unique ammonia-water composition of Enceladus is thought to give rise to the cracks in the tectonic plates on the surface, which we know as the "tiger stripes".  Enceladus began as a frozen shell of an ammonia and water ice mixture surrounding a rocky core.  Through interaction with other moons, heat was generated above the rocky silicate core, resulting in the ice shell separating into an ammonia-enriched liquid layer directly on top of the core, and a thin layer of ice (water) above it.

Research by Dr Dave Stegman, a Centenary Research Fellow in the School of Earth Sciences at the University of Melbourne, has found that if the water ice formed near the core, then it would give rise to the "tiger stripes" which are thought to be cracks caused by tectonic activity on the south pole of the moon's surface

  "We found that if a layer of pure water ice formed near the core, it
  would have enough buoyancy to rise upwards, and such a redistribution
  of mass can generate large tectonic stresses at the surface,"

  "However, the pure water ice rising up is also slightly warmer which
  causes the separation to occur again, this time forming an
  ammonia-enriched ocean just under the surface. The presence of
  ammonia, which acts as an anti-freeze, then helps keep the ocean in
  its liquid state."

So in this case, while one could say that the boundary may have played a role, it is certainly not analogous to the role the phase transition plays in the formation of features on Earth's surface.  The linked paper provides more details as to how the ammonia-water composition can give rise to the observed terrain.

With regards to the chaotic terrain of Europa, it is an active area of research and is very poorly understood.  No model so far has been able to explain why features such as Conamara Chaos stand above surrounding terrain and contain matrix domes.

According to one paper however,

  We conclude that Europa's ocean dynamics can modulate the exchange of
  heat and materials between the surface and interior and explain the
  observed distribution of chaos terrains.

It therefore seems unlikely given current research that the chaotic terrain of Europa is a result of a phase change boundary.


What lithologies are deemed most suitable for the storage of nuclear waste

Nuclear wastes should be stored in containers designed to contain and isolate radioactive material from the environment. One possibility for the storage of these containers would then be to place them in a repository located in a tectonically stable, dry, geological formation.

As far as lithological characteristics are concerned, it would be best to locate the container repository in rock having mechanical and chemical properties that would limit transport properties and slow or contain the spread of material in the event of a container failure.

Advantageous properties include:

1) low permeability and few joints and fractures

2) low strength, so that plastic deformation of the rock would tend to reduced stress and close fractures.

3) mineralogy-fluid chemistry that tends to bind and immobilize radionuclides.

Volcanic tuffs (zeolite-rich), salt deposits, and clay deposits would be examples of lithology having some (but not necessarily all) these characteristics. Granites and columnar jointed basalts may be examples of less advantageous lithology.

As @david valentine said, the lithology would be only one of many factors that need to be considered.


What is the difference between eluvium and alluvium?

Both are very similar, as they are based on minerals undergoing erosion and the presence of water in the erosion and deposition cycles, the difference is quite subtle, an example is defined in the Gold Prospecting in Western Australia website Alluvial Gold and Eluvial Gold as being

Alluvial deposits are mixed with other deposits and are washed downstream in rivers or transported in among other sediments with water as its medium. An example is that gold deposits this way are smoothed and are ground down the further from the source.

Eluvium deposits are in situ or very near its source, rather than been washed away by water.  For example, eluvial gold are often large nuggets nearer to its source.

A much more succinct definition is provided by the Australian Museum:

Alluvium:

  Detrital material which is transported by a river and usually deposited along the river's pathway, either in the riverbed itself or on its floodplain.

Eluvial:

  Weathered material still at or near its point of formation.


Why can Thomsen's parameter $\epsilon$ be negative in VTI media?

Negative values are physical and are expected.

Indeed, Thomsen's 1986 paper has several negative values for $\delta$, $\epsilon$, and $\gamma$ — look at the data in Table 1. He also discusses negative values, at least for $\delta$ (e.g. on page 1961) . You can quickly get a sense of how common negative values are from his Figure 4:

As for physical meaning, it depends on the parameter. I recently wrote this about the physical meaning of the Thomsen parameters (edited for brevity):

  $\delta$ or delta — the short offset effect — captures the
  relationship between the velocity required to flatten gathers (the NMO
  velocity) and the zero-offset average velocity as recorded by checkshots.
  $\epsilon$ or epsilon — the long offset effect — is,
  according to Thomsen himself:  "the fractional difference between
  vertical and horizontal P velocities; i.e., it is the parameter
  usually referred to as 'the' anisotropy of a rock".
  $\gamma$ or gamma — the shear wave effect — relates, as rock physics
  meister Colin Sayers put it on Twitter, a horizontal shear wave with
  horizontal polarization to a vertical shear wave.

Usually these parameters are, at a gross scale anyway, positive, because usually velocity is faster along bedding (roughly horizontally) than across it (roughly vertically). But it's easy to imagine scenarios where the relationship is reversed, especially if we're talking about small scales — as in log measurements.

Intuitively, we can draw these conclusions about negative parameters:

A rock with $\delta < 0$ has the zero-offset reflections 'seeing' faster velocities than the long-offset reflections.
A rock with $\epsilon < 0$ has a faster vertical velocity than horizontal velocity.
A rock with $\gamma < 0$ has a faster vertical shear velocity than horizontal shear velocity.

Reference

Thomsen, L (1986). Weak elastic anisotropy. Geophysics 51 (10), 1954–1966. DOI 10.1190/1.1442051.