How to extract lat-lon from MOD10C2 hdf data in matlab?

The latitude and longitude of each pixel is not stored in the HDF file. But using

metadata=hdfinfo('file_name.hdf');

You can get the info to generate those latitudes and longitudes. In metadata.Attibutes you will find this among other things:

    GridName="MOD_CMG_Snow_5km"
    XDim=7200
    YDim=3600
    UpperLeftPointMtrs=(-180000000.000000,90000000.000000)
    LowerRightMtrs=(180000000.000000,-90000000.000000)
    Projection=GCTP_GEO

If you rather a more human-readable format, check the product specifications for MOD10C2.

There it say:

  Projection

  MODIS CMG data sets are produced in a Geographic Lat/Lon
  projection. This simple projection treats geographical longitude and
  latitude degrees as if they were x- and y-coordinates in a plane.
  Figure 1 shows the geographical lat/lon projection known as Plate
  Carrée, which plots longitude and latitude degrees as coordinates on
  the x and y axes, respectively:

  Figure 1: Plate Carrée projection.

  Grid

  The MODIS CMG consists of 7200 columns by 3600 rows. Each cell
  has a resolution of 0.05 degrees (approximately 5 km). The upper-left
  corner of the upper-left cell is -180.00 degrees longitude, 90.00
  degrees latitude. The lower-right corner of the lower right cell is
  -180.00 degrees longitude, -90.00 degrees latitude...

With that you have more than enough information to generate the latitude and longitude vectors. Now you have to decide if you will store the center of each pixel, or one of the corners.

Assuming you will store the center of each pixel you can generate the latitude and longitude vectors like this:

gridSize=0.05 % arc degrees
lat=-90+(gridSize/2):0.05:90-(gridSize/2);
lon=-180+(gridSize/2):0.05:180-(gridSize/2);

And if you want instead matrices with the coordinates of the center of each individual pixel, you do

  [lonGrid,latGrid]=meshgrid(lon,lat);


Rate of climate change with and without humans?

The Earth should probably be cooling, at least, that's what the Milankovich cycles and historical variation and recent temperature charts all indicate.

See XKCD and related question on XKCD chart, and temperature chart over the last 800,000 years.  Source.

Now, it should be pointed out that the Milankovich cycles don't line up in perfect synchronicity, so no two warm periods and no two ice ages should be exactly alike, but there are similarities, like a steady cooling after a warm period.   Earth has been gradually cooling for roughly the last 7,000 years, and this is due to the gradual changes in the Earth's orbit per XKCD.   (scroll to 5,000 bce - see note).

If Earth cooled 1°C in 6,500 years and is due to cool 4°C in the next 10-30,000 years as the next ice age comes along, we can ballpark estimate 1 degree of cooling per 5,000 years, and if we use an estimate of 2 degrees warming by 2,100 and climate change took hold in the 1980s, that's 1 degree every 60 years current rate of warming.

So, by my estimate, man is responsible for 101% of the current warming and Earth's natural cycles are shaving about 1% off man made climate change.   To say it's all us is accurate enough for me.   There's currently no natural warming of the Earth as far as I can tell, Earth should be cooling.   Granted there's variation, like the current solar cycle is a few tenths of a degree warmer than the maunder minimum that is believed to be the cause of the little ice age and our relative lack of major volcanic activity for much of this century might have a slight warming effect, so precise numbers are hard to pin down, but I think 101% man, -1% natural is pretty close to accurate.

That part of the video begins about 2 minutes in, goes on for about 3 minutes, then it moves onto "how would the Earth be different"

If I may rant, there's several things I don't like about the interview.
Tucker Carson says 1:18  "The essence of science is extreme skepticism" - that just ain't so.   Skeptisism doesn't equal scientific discovery.   Bart Simpson is a skeptic - I don't think we should listen to his views on science.  Skeptisism is important to science but it is absolutely NOT the essence of science.   The essence of science is asking the right question and working out an answer through evidence and testing and peer review.   Peer review doesn't mean denial.  For Peer review to be meaningful, evidence or solid counter argument must be presented - not just empty skepticism.   Skepticism that ignores the evidence is about as valuable as a restaurant that doesn't serve any food.   Skeptics must respect and understand the evidence if they are going to provide intelligent skeptical arguments on why the evidence might mean something else.  If they don't do that, it's just noise.  Intelligent skepticism that respects the evidence and data is always welcome.   Uneducated skepticism is a pointless and senseless distraction.    It's like trying to form sentences without using any words.

But try explaining that to a skeptic sometime who thinks he doesn't need to be educated because skepticism is his education.

Tucker then says, about 1:50 "the climate has always changed" - again, not really.  There are periods of what might be called climate consistency and periods of climate change.   The climate isn't "always" changing, but it does change fairly frequently.   There's also some clarity on what constitutes a change - weather changes during the seasons, but that's not climate, not really.   Climate incorporates the seasons and year to year variations.  Real climate change, by my definition, happens every few thousand years - give or take, and big changes, with the current ice age cycle on a 100,000 year time-frame, big changes happen twice every 100,000 years, with the rise and fall of ice ages.   There's some room for opinion in this though, but "always changing", a common phrase by deniers - but simply not accurate, not if you're talking about real change.   Now if you're talking about irrelevant change then, sure.

Pretty much everything is always changing.   A human's height changes about 1/2 inch from when they wake up to when they go to bed,   A human in space grows a full inch, but, . . . I still say I'm 5'10 when asked and I'd say I'm 5'10 if I lived on the space station.  I don't say 5"10 1/2 cause I just woke up.   Even though my height is always changing depending on how long I've been standing up, 5'10 is close enough.   Relevant, significant change is worth identifying.   Incidental or irrelevant change based on fluctuations that go back and forth mostly doesn't need to be identified.

So, no, the CLIMATE is NOT always changing.   Weather is always changing, climate goes through periods of decades, centuries, sometimes Millennia, where it remains consistent enough that we can say it isn't changing.   "The climate is always changing" is a red herring.

Everything Bill said is true, though I wasn't crazy about his initial time scales "change used to happen over millions of years" and "now it happens over decades and years" - that's iffy, but mostly everything he said was true, but he didn't handle the interview very well.    Tucker's Gish Gallop was successful.

When Tucker moves onto "how would the Earth be different", Bill does answer him with specifics, but Tucker just pretends those aren't good answers and interrupts Bill or goes back to the first question when he doesn't like that his 2nd question is being answered.    Overall it's a terrible interview designed to sell disinformation, not inform.   Painful to watch and I hate Fox News for that reason.

OK, rant finished.

There's no right answer.    101% - by my estimate.   100% if you believe the Earth isn't getting cooler.  102% or more if you set the rate of cooling a little higher, with the next ice age due in 10,000 years not 20,000 years.    (as of now, the next ice age is on indefinite delay - but that's another story).

Or, the answer could be, 70-90% if you believe there's an un-accounted for natural warming period over the last 30-40 years.  That's one of Judith Curry's arguments that climate change has gotten a natural push to make it look bigger than it is, but, she has no good proof, which is why she's mostly alone in that argument.  It's just something she's claiming.

100% is a good answer too, and if you listen, Bill does say 100% at one point, but it's during an interruption and hard to hear.   "We aren't sure but close to 100% is also a good answer".

If Tucker had asked me what percentage.   I'd have showed him XKCD's chart and said "see this point here, the cooling began shortly after 5,000 BCE, at a rate about 100 times slower than the current warming.  101% is relatively consistent with past Milankovich cycles and past periods of cooling following a warm period between ice ages.  So, that's my answer.   101% of the current warming is man-made.


Debunking scientific paper "Has global warming already arrived?"

The comment is saying that the authors are making a fallacy as follows:

Temperature increase will be associated with an increase in tropopause height.
Using instrument/dataset X, we fail to measure a tropopause height increase.
Therefore, there is no temperature increase.

The fallacy here is that instrument/dataset X is not suitable to measure tropopause height, therefore one should not expect it can measure a tropopause height increase.
The comment is referring to the University of Alabama in Huntsville temperature dataset.  This is derived from satellite microwave temperature sounders¹.  From the Wikipedia article, this dataset provides:

UAH provide data on three broad levels of the atmosphere.

The Lower troposphere - TLT (originally called T2LT).
The mid troposphere - TMT
The lower stratosphere - TLS

The tropopause is the boundary between troposphere and stratosphere.  It can be defined in various ways, but to measure tropopause height you generally need to measure the temperature in the vicinity to the tropopause.  As this is apparently not provided by the dataset, it is impossible to use the dataset to measure tropopause height.

¹From personal experience, I can tell you that it is difficult to determine long-term temperature triends from satellite data.  Polar-orbiting satellites in sun-synchronous orbits experience a drift over time, which means that their local time ascending node changes; in lay terms, this means that when they previously always passed at 14:00 over a certain spot, 2 years later this may be at 16:00.  Even if that time wouldn't change, instruments degrade over time and get replaced by new instruments.  You need to be very careful to make sure you're detecting a trend in the temperature and not in the instrument itself!  I've worked on this in the FIDUCEO project, I was doing infrared temperature sounders and colleagues from Hamburg were doing microwave humidity sounders, but microwave temperature sounders were out of scope because none of us had the depth of expertise needed.  Even with the expertise, we underestimated the difficulty of the problem and ran out of time before we could properly declare we had delivered what had been promised to the funding agency, although we learned a lot.


Why did the carboniferous period have so much atmospheric oxygen?

The Carboniferous was when the growth of woody plants took off. Non-plant life had not yet evolved the ability to consume lignins, the key chemical components that makes woody plants "woody". Lignins are rather hard to decompose. Despite high volcanic activity, carbon dioxide levels fell by a factor of over four during the Carboniferous, from over sixteen times preindustrial levels at the start of the period to less than four times preindustrial levels at the end of the period.

The end result was a gradual increase in oxygen levels and huge deposits of then non-digestible materials that eventually became coal.


How do they know the 2016 Kaikoura (NZ) Earthquake was 'complex', involved six different faults?

You need to see the InSAR data. E.g., see this image which is based on radar data acquired by ESA's Sentinel-1A satellite. For straight faults the pattern is not this complicated.

Using such observations we can estimate which parts of the fault slipped. E.g., take a look at these images. This is done by solving an "inverse problem", i.e., you have some observations and you're trying to estimate what parameters in a (physics-based) model can reproduce the observations. In essence, it is an optimization problem like curve fitting.

Note: Besides InSAR data, we can also use data from seismometers but the former makes it rather obvious.


where to download NASA-NEX daily downscaled datasets?

Google Earth Engine's NASA NEX dataset (or this) might be of interest to you. It is an online repository, where you can do your analysis using the GEE platform without having the need to download to local machine.


If 75% of radioactive material remains, how many half-lives have elapsed?

@gerrit provided a formula, but without stating the reasoning behind it.

Radioactive decay is an exponential function.  After $n$ half-lives, the amount of the original material remaining is

$$\textrm{amount remaining after}\ n\ \textrm{half-lives} = \left(\frac{1}{2}\right)^n$$

Therefore, you want to solve

$$\begin{align*}
\left(\frac{1}{2}\right)^n &= \frac{3}{4}\\
\log_\frac{1}{2} \left(\frac{1}{2}\right)^n &= \log_\frac{1}{2} \frac{3}{4}\\
n &= \frac{\log \frac{3}{4}}{\log \frac{1}{2}} = \frac{\log \frac{3}{4}}{- \log 2}
   \approx 0.415
\end{align*}$$


Do large-scale modes of variability (like NAM/SAM/ENSO) exist in the ocean?

The large scale modes of variability present in the atmosphere are also found in the ocean. There is a strong feedback between the two systems with wind, heat flux and atmospheric pressure modifying ocean surface conditions and with parameters such as sea surface temperature altering atmospheric conditions.

A lot of studies have explored teleconnections in the ocean looking for instance at the EOFs of sea surface temperature. A good compilation of different atmospheric and oceanic time series and references can be found in Climate Indices: Monthly Atmospheric and Ocean Time Series.


How does fertile soil reach newborn volcanic islands?

This image may serve as a base to illustrate the points from the question:

La Palma, Aridane Valley and Cumbre Vieja volcano:

On the left (north) one sees the incisions of erosion at the flank of Bejenado volcano. It formed between ~500 and ~400 ky ago. Volcanic activity has ceased and it is now slowly weathering down. In the center and right one sees the Aridane Valley and the Cumbre Vieja whith its picturesque cones. The Aridane Valley is an erosional structure formed by a series of landslides slightly earlier than the Bejenado. Cumbre Vieja is an active volcano, last eruption is Teneguia 1971 in the south, just out of the right of the image.

On can distinguish several lava flows from historic and modern times by their darker colour. They are between ~70 and several hundred years old, but the whole island is built of such lavaflows, layer by layer (simplifying here). Wind, weather, insects and birds bring on pollen and seeds. Even on a fresh layer, after just a few months to years, pioneer plants like lichen will start to settle. Once exposed and solidified, the basalt starts to weather and erode. These processes form clay minerals, which release the nutrients to grow more and more plants and biocenoses, and so on. And basalt weathers quickly, releasing a lot of nutrients in relatively short time.

So, yes, your asumptions are in principle on the right track. I'm not sure about the direct role of ocean currents here, and soil is not brought in by the wind (at least not in decisive amounts, more or less dust from a nearby continent will allways be in the air), it forms through weathering of the basalt.

Weathering and erosion are very complex. Obviously, chemical and physical processes play an initial role; once plants have settled, their roots cause physical changes, bacteria from decay amplify chemical processes, and so on.

This is mostly textbook knowledge of the general process. For more specific information about the processes one can read up more on basalt weathering, chemical and physical erosion, pioneer plants, and so on.


Beta plane approximation: variation of Coriolis parameter

The Beta effect describes how the Coriolis force affects fluid motion depending on spatial changes due to the curvature of the Earth. In other words, it describes the variation of the Coriolis parameter with latitude.

One can model this change exactly or approximate it via Taylor series expansion at a given latitude. The latter option is typically used to make the theoretical analysis of geophysical phenomena possible because the equations are easier to solve. This is the Beta plane approximation, where the Coriolis parameter varies linearly in space.


Yes.  The height of the ground or ocean surface is of no consequence to the lapse rate as long as we remain above it -- in the atmosphere.  E.g. the dry adiabatic lapse rate is a conservation of entropy as a parcel of air rises or descends.  This means the temperature change is related only to the expansion of contraction of the parcel as it responds to changes in pressure.  When you move down below sea level there is nothing fundementally different than starting at 500 m height and moving down from there.  Both are moving down into higher pressure and the parcel will contract and warm as a result.


Physicalgeography.net and the Colorado State basic hydraulic page have a good explanation of Horton's Laws.

The first thing that needs to be done in analysing a drainage basin is to classify the stream segments in a basin according to Strahler's method. For each stream order tabulate:

the number of segments
the average length of the segments
the average area of drainage for the segments

According to Physicalgeography.net the bifurcation ratio is the ratio between the number of stream segments in one order and the number of stream segments in the next order.

Horton saw that the bifurcation ratio was always around 3, this he called the Law of Stream Numbers. Apparently a bifurcation ratio of 3 also applies to plant roots, branching of woody plants, veining in leaves and the human circulatory system. I get the impression that without knowing about it, Horton was laying some ground work for fractal mathematics that came to prominence in the 1980s, with the work of Benoit Mandelbrot.

With the Law of Stream Lengths, the average length of stream for each order is calculated, then cumulate lengths found before length ratios between segment orders can be calculated.

Colorado State basic hydraulic page has a more mathematical approach to explaining Horton's Laws, but it's very good. It gives a worked example of how to determine the all the coefficients.

Additional information is also on this site as well.


Radon is a naturally occurring radioactive gas. How does this work?

Radon (more specifically Radon-222) is produced in the decay chain of Uranium-238.   Radon-223 is also produced by the decay chain of Uranium-235 and Radon-220 is produced by the decay chain of Thorium-232 but both Radon-223 and Radon-220 have half-lives of less than a minute, so they almost never reach the atmosphere where they can be breathed in because they mostly form underground and they decay too quickly to reach the atmosphere.

Radon is unusual in that it's the only noble gas along the 4 primary decay chains and only the Uranium to Lead chain produces Radon-222 which has half life long enough to reach the atmosphere and get breathed in.

More on decay chains here and here.

Uranium-238 has half life of about 4.5 billion years, so about half the Uranium-238 that was present when the Earth formed is still here.  It decays very slowly, which is why it's not dangerous to be around Uranium in it's natural form.  (though if somebody hands you a block of it, you might still want to wash your hands after touching it - then call national security) . . . but I digress.

Radon-222 has a very short half life of 3.8 days, so while the Uranium that produces it decays very slowly, the Radon is highly radioactive and it decays (into other radioactive elements) quite rapidly.   If you had a sample of Radon-222 for example, in less than a month, 99% of your sample would be gone.

Because it forms slowly and decays quickly it never collects beyond a very trace concentration and it continuously needs to be regenerated.

Houses with a Radon problem need to be continuously ventilated because of that regeneration.  At least/about two or three times a day I would think (see comment directly below, once a day may be sufficient), but it's worth pointing out that the Radon in houses is so faint that it takes months, if not years, for any kind of health problems to arise.   It's kind of a weird thing.  It's not dangerous at all to walk through a house with unsafe Radon levels, similar to how it's not dangerous to visit Chernobyl.   It's just not a good idea to live there.

Radon is also likely to only be a problem in poorly ventilated houses, (basement's especially, because the heavy gas tends to settle) but a good ventilation system should make any house safe.  And it's more common in specific areas.

There's the problem of keeping the house warm in winter and maintaining ventilation, because ventilation does need to be maintained.  Houses can be also built above ground to reduce exposure.

As a general rule, it's the ingestion, either breathing or swallowing of radioactive material that's most dangerous.  That's why it's a good idea to put on a gas mask to prevent breathing in any radioactive dust or fallout (though a gas mask won't keep gas like Radon out).   And it's a good idea to leave your clothes in a separate changing room and shower thoroughly if exposed or walking through radioactive fallout - that has nothing to do with your question, just putting it out there.   Also the opposite applies if there's radiation outside from a nuclear accident or bomb- close all windows and try to keep ventilation as close to zero as possible, at least for a day or so until you get instruction on the levels, but . . . I digress.   Point is, because Radon is easily breathed in, it's quite toxic even in very small amounts.   At the same time, the Radon concentration inside houses with a radon problem is so small, that it still takes months if not years of exposure to lead to problems.

That's why Geiger-counters aren't used to test for Radon.  There's too little radiation.  You need specific Radon detectors.

  Are these rocks common?

Yes, and no.   Because the gas comes from Uranium, (and mostly from underground), Uranium isn't exactly common but it's not super-rare either.

  How do these rock’s become radioactively charged?

This was covered above, but Uranium, in small amounts, is in lots of different places.   The Rocks were always (mildly) radioactive.

  Pictures or examples?

To my knowledge, pictures or examples don't do any good because trace amounts of Uranium in rocks doesn't look any different.  Besides, most of the Uranium is underground.   You have to rely on Radon testing and look at locations where Radon is more of a problem.   If you live and work above the first floor, and not near a mine or massive dig-site, you probably have little to worry about.   If you live in a basement, you should have it checked out.

On the process

The Uranium or U-238 goes through several steps in it's decay and this chain is only the most common outcome.  Part of the problem with Radon, is if you breath it in, and don't breath it out, it becomes Polonium and goes through a few other steps.  In high enough concentration, Radon is extremely toxic.  From rocks, the concentration that's likely to form in a house is usually low enough that harmful exposure takes months or years.


Will increased level of ocean acidity lead to more frequent acid rain?

More likely, it works the other way: increased acid-forming compounds in the atmosphere are the cause of more ocean acidification.
Pio et al. [1] report measurements of sulfur and nitrogen compounds in air masses that they traced to either continental or oceanic origins.  They report that the lowest levels of these compounds were from ocean-origin air masses, indicating that the ocean is absorbing acid-rain causing pollutants such as sulfur dioxide.  Even so, levels of these compounds over the oceans has increased in recent years, likely from increased pollution on land.
In this answer it is noted that increasing acidity can alter the salt composition of the ocean, producing more acidic species (such as $\text{H}_2\text{PO}_4^-$ ions).  However, these tend to remain dissolved in the water rather than evaporate into the atmosphere.
Reference
1.
Casimiro A. Pio, Mário A.Cerqueira, Luis M.Castro, Maria L.Salgueiro, "Sulphur and nitrogen compounds in variable marine/continental air masses at the southwest European coast", Atmospheric Environment
Volume 30, Issue 18, September 1996, Pages 3115-3127.


What determines the differences in results between various weather models?

Everything.

Parametrizations
Spatial (horizontal and vertical) and temporal resolution
Initialization
Dynamical core
Handling of some complex non-linear physical processes (i.e. snow)
Topography representation
How the mathematical equations are numerically implemented
The computer used
etc...

These are some of the main differences between 2 given numerical weather model.

With that being said, the same model will give different results when run on a different computer (Hong et al. 2013).

Hong S-Y, Koo M-S, Jang J, et al. (2013) An Evaluation of the Software System Dependency of a Global Atmospheric Model. Mon Weather Rev 141:4165–4172. doi: 10.1175/MWR-D-12-00352.1


Why is potential vorticity so emphasized in technical work, but often neglected in maps on weather websites?

This one has not been answered for a long time and I am going to summarize what I wrote in the comments. If I understood OP's question correctly I believe it is asking why Potential Vorticity  is not shown in weather maps in a operational sense.

From this old(but still very useful reference) Isentropic Potential Vorticity presuming isentropic surface are available operationally(AFAIK GFS provides isobaric PV surfaces Warning: You need to register to access the GFS link) and you need to interpolate from isobaric to isentropic.

  Generally, as in constant pressure analyses, one would like to use at least two or three isentropic surfaces to analyze. However, unlike constant pressure analyses, one has to choose different isentropic levels depending upon the time of year.

| Season     |   Low Level Potential Temperature  |

| Winter     |       290-295 K

| Spring     |      295-300 K

| Summer     |      310-315 K

|Fall         |      300-305 K

As one can see the correct isentropic surface to choose for a particular day can be quite a challenge. Also each part of the world may have it's own low level potential temperature complicating the problem.

  Isentropic surfaces tend to intersect the ground at steep angles causing analyses near where they intersect the ground to be suspect. One must be careful about over-interpreting analyses made near where the isentropic surface intersects the earth. One would do best to choose isentropic levels which never reach the ground. However, to depict moist/dry tongues associated with synoptic scale systems one tries to go as low as possible without hitting the ground. So there are trade-offs; as usual, there are no quick-fixes!

In my part of the world(tropics) an all season isentropic surface that does not intersect with the earth's surface globally is the 370 K isentropic level. From a isobaric perspective this turns out to be around 200 hPa from a perspective of climatology.

As one can note this is at a very high level and corresponds to the level of the jet stream. As one analyzes lower isentropic levels one can see maps (you need 3-D to plot PV on an isentropic surface) that intersect the earth's surface and when that happens you need sophisticated extrapolation methods to calculate PV especially along orography(and these turn to be generally inaccurate). Over the tropics generally at lower isentropic levels PV surfaces tend to be perpendicular and their utility is restricted to as OP puts it to the inside of tropical cyclones and mesoscale convective systems.

An example of using PV at lower levels of the atmosphere can be seen in this youtube video Sandy PV filaments


How much land does it take to support New York City?

The average ecological footprint of a US citizen has been estimated as 8.00 global ha.

Multiplying 8.5 million by 8.00 hectare gives 680,000 km², or around 5 times the area of New York state.

Of course, this calculation contains a lot of assumptions and simplifications.  This doesn't mean you could simply allocate 680,000 km² around New York City and use this to support the lifestyle of their inhabitants.  There is a considerable uncertainly around the calculation, and the land is spread all over the world (New Yorkers want their bananas, almonds, and iPhones too, even if none of those are local).


Are we at the beginning of a Heinrich Event?

Definitely not.

A Heinrich event requires massive ice sheets to grow and then collapse in the Northern hemisphere. The large outflow of icebergs that would result form such collapse would deliver fresh water and debris to the North Atlantic, which is what constitutes a Heinrich event. These events are detected by existence of deposits of ice rafted debris and dropstones in the sea floor.

Example of a dropstone carried by an iceberg, dropped on the sea floor, and then embedded in sea floor sediments (image taken from snowballearth.com)

Current ice masses in the Northern hemisphere are tiny compared with those that generated all recorded Heinrich events.

Something similar could happen now further south if East Antarctica collapses. However the circulation pattern in the Antarctic ocean limit significantly the distance that icebergs can travel.


How does argon-argon dating work - need a simple but not-wrong explanation

As noted in the comments the wikipedia articles (at the time this question was submitted) are contradictory. There are quite a few steps to the logic of how argon-argon dating works but none are too complicated, although I won't go into all of the possible interferences. One thing to keep in mind is that high-precision isotope measurements always measure ratios between isotopes, not absolute concentrations.

To understand argon-argon dating, you need to understand potassium-argon dating.

The isotope potassium-39 makes up about 93% of natural potassium. Potassium-40 is radioactive but has such a long half-life that it is primordial - it has been around since the earth was being formed. Because of this, we can assume that the potassium-40:potassium-39 ratio in minerals at any time is a constant. Potassium-40 decays in 2 different ways. Most decays by beta decay to calcium-40. About 10.7% decays to Argon-40 by emitting a positron.

If the argon-40 stays trapped in the crystal and you can measure the ratio of potassium-40 to argon-40, then you know how long it has been since the mineral formed. This also assumes that there is no other source of argon like trapped air. A problem is that it takes two separate measurements to get the potassium concentration and the argon isotope ratios, increasing the uncertainty. Argon-argon dating gets around many of the issues by measuring only multiple isotopes of argon.

The trick is to irradiate the sample with neutrons along with samples of known age. Some of the potassium-39 forms argon-39 by an n,p reaction. By converting potassium-39 to argon-39 then measuring the argon-39:argon-40 ratio, you can calculate the sample's potassium-40:argon-40 ratio, remembering potassium-40:potassium-39 is fixed. The standards of known age are used to account for differences in the neutron flux during irradiation. Argon-36 in the sample accounts for any air contamination.

Argon-argon dating, ideally assumes that:

all argon-40 in the sample comes from either atmospheric argon or from decay of potassium-40 in the sample
all argon-39 in the sample comes from irradiation of potassium-39 in the sample and as noted above, if you know potassium-39:argon-40 ratio then you know the potassium-40:argon-40 ratio because the potassium-40:potassium-39 is constant (at this point in time)
all argon-36 is the sample is from atmospheric argon

The actual calculations are pretty simple algebra, combining all the pieces.


Is it possible to create an enclosed manmade weather system?

Real clouds are beautiful because they are huge and you observe them from far away, thereby gaining the ability to see a distinct "boundary" and, therefore, shape. But if you ever travel through a cloud in a plane, thereby seeing one close up, you'll find that they really are "just fog". You'd struggle to recreate a scale cloud in a tiny environment; water molecules have a reasonably consistent size and you can't just downscale the entire system.

Similarly, you could probably create a thunderstorm but at that scale it would be over so fast you'd barely see it. An obvious example is the movement of water droplets as steam leaves your kettle and condenses. You just see a quick whoosh of vapour particles spiralling about and, well, that's about as close to a rainstorm as you'll get.

Some phenomena, such as air vortices, can manifest at smaller scales — I've seen more than a few mini-tornados forming in my garden dragging leaves around in a funnel fashion — but I'm not sure you'd ever be able to contain enough energy to see that happen for more than a fraction of a second in a small tube.


Is the iron on Earth's crust a leftover of the Iron catastrophe, or it was brought back by volcanoes?

Not all the iron sank to the core. Have a look at my answer to a previous question:

https://earthscience.stackexchange.com/a/7076/725

Your question is similar, but coming the other way. You're asking - why is there iron in the mantle/crust?

The answer is that there was enough oxygen left in the Earth after oxidising the other lithophile elements (Si, Mg, Al, Ca, etc) to oxidise some of the iron. And when iron is oxidised - it is not a metal anymore, but instead incorporated into rock forming minerals like olivine and pyroxenes.


So let's get through some definitions. I will not discuss the derivations of this, but you can look this up, if you want to in the source I provided.

We find ourselves in a porous medium, so we will have always some volume filling factor $\Theta$ of water in rock.

 (copyright K. Roth, Heidelberg University)

Then we can start with the hydraulic conductivity, that can be defined as $$K = \frac{\Theta \left< \kappa \nabla P \right>}{\mu}$$
Here we have quite some notation to clarify:

$\Theta$ is the local filling fraction of water in an aquifer
$\mu$ is the molecular diffusivity
The brackets $\left< ... \right>$ denote the macroscopic average over the microscopic aquifer structure that is given by Permeability $\kappa$ and local pressure gradient.
The Permeability itself is a way to encapsulate how easy water can flow through a given geometry.

This is the most rigorous definition I could find in my notes. The lecture however is unavailable on the internet, so you'll have to take my word for this. I just mention this as I don't know whether you're more interested on the theoretical side, or the pragmatic.

The pragmatic approach is usually to simply state Darcy's law $$ q = - K \frac{dh}{dz} $$
relating the water mass flux $q = \rho v$ to the gradient of hydraulic head.
We see now that a flow velocity will result from a pressure gradient, but strongly modified through the microscopic properties encapsulated in K.

The hydraulic diffusivity you search for is then written as $$D = \frac{K}{S}$$ where S is the water storage fraction, with $S \sim \Theta$ (not strictly correct). So in a way this just cancels the $\Theta$ in $K$ and appears in the pressure diffusion equation:
$$ \partial_t P = D \Delta P $$
and therefore D gives the local diffusion speed of pressure disturbances (which is interestingly not the speed of sound $c_s$ in aquifers!)

We could now say, for educatory purposes that the difference between $K$ and $D$ is only $\Theta$. This makes sense when we look at the context where those two parameters appear:
$K$ gives the strength of mass-flow for the fluid, the better filled the volume is, the more mass will flow.

Pressure, however does not care for the amount of water that flows, as it exists everywhere where water is sitting at a given moment, so the coefficient for its propagation does not depend on the filling of volume.

You can look up the derivations for example here.
Tell me in the comments, if anything is unclear.


Are atmospheric halogen oxides "supposed to be" in the atmosphere? Where do they come from?

Classifying the presence of halogen oxides in the atmosphere as either natural, pollution or mixed bag, would result in mixed bag.

Natural sources of halogen oxides include the ocean and volcanoes. In 1963, Duce et al,

  showed that bromine, like chlorine, was lost from the sea salt particles

Volcanoes are another source of halogen oxides,

  Halogens are emitted from volcanoes primarily as hydrogen halides (HCl, HF, HBr, and HI). Upon mixing with the atmosphere, chlorine and bromine species are partially converted to the halogen oxides OClO and BrO.

and

  Traditionally, emissions of volcanoes were regarded to be mainly of importance for the atmospheric sulfur cycle, acid deposition, and stratospheric effects from explosive eruptions. This view changed recently, mainly because of the observation of very high concentrations of bromine oxide, BrO, in the tropospheric, nonexplosive plume of Soufrière Hills, Montserrat.

The Sun is a requirement for the ocean source of halogen oxides.

Salt lakes, such as the Great Salt Lake in Utah are also sources of halogen oxides.

Forest fires can be a source of fluorine.

Pollution sources of halogen oxides includes: steel production, phosphate fertilizer production, burning coal, the manufacture of glass and ceramics.

Bromine and chlorine are used in cleaning products which are another source. Fire fighting chemicals such as PFAS (PolyFluoroAlkyl Substances) are another source.


What do quasi-geostrophic and ageostrophic mean?

Ageostrophic winds are merely the component of the actual wind that is not geostrophic.  In other words, given the actual wind ($\mathbf v$) and the geostrophic wind ($\mathbf v_g$), the ageostrophic wind ($\mathbf v_a$) is the vector difference between them.  The ageostrophic wind represents friction and and other effects.  This, for example, is responsible for surface wind crossing isobars rather than following them.

$$\mathbf v_a =\mathbf v - \mathbf v_g$$

Quasigeostrophic refers to a modified set of equations that are make a number of assumptions, approximations and neglecting terms due to scaling.  The equations are only valid for Rossby numbers much less than 1 (Ro << 1)

Some of these include:

neglect advection by $\mathbf v_a$
neglect advection by vertical velocity
neglect the time tendency of $\mathbf v_a$
neglect advection of $\mathbf v_a$ by $\mathbf v_g$
replace $f$ with the beta plane approximation ($f = f_0 + \beta y$)
neglect friction
horizontally constant static stability ($\sigma$)

Starting with the frictionless horizontal momentum equations you end up with a number of "Q-G" equations: a thermodynamic energy equation, a vorticity equation and the omega equation.  The Q-G omega equation:

$$\left( \nabla^2_p + \dfrac{f^2_0}{\sigma}\dfrac{\partial^2}{\partial p^2} \right)\omega =  - \dfrac{f_0}{\sigma} \dfrac{\partial}{\partial p} \left[ - \mathbf v_g \cdot \mathbf \nabla_p(\zeta_g + f) \right] + \dfrac{R}{\sigma p}\left[ -\nabla^2_p(- \mathbf v_g \cdot \mathbf \nabla_p T) \right]$$

The first term on the RHS vertical change in advection of geostrophic absolute vorticity by the geostrophic wind.  Positive vorticity advection increasing with height results in upward vertical motion.  Negative vorticity advection increasing with height results in downward vertical motion. The second term on the RHS is related to temperature advection by the geostrophic wind.  Cool air advection (CAA) correlates with upward vertical motion.

This is the traditional form of the equation and other forms exist to aid in diagnosing vertical motion with specific variables (e.g. the Sutcliffe-Trenberth recasts the equation using the thermal wind and Hoskins et al. (1978) defines the equation in terms of $\vec Q$, "Q vectors").

There isn't much NWP utility to the Q-G equations with todays computers, but they are good for diagnosing vertical motion in hand map analysis.

(will add the QG chi equation here)

Further reading:

Real-time anlyses and forecasts of the QG diagnostic equations
The QG equations (Thanks @DrewP84)
An abbreviated derivation


At what altitude a ballon is no longer pushed by the wind?

In the range where a balloon can fly, there is always wind.

The NASA Echo 1A satellite was used to test the satellite triangulation. GPS works in some other way...

The GPS system used active satellites (non-pasive as Echo 1A) that constantly supplies their position, their time and additional coding information. So the satellite position should be known and corrected constantly. With a balloon constellation it will be very difficult.

Supposing that we can install all the equipment in a balloon, the top we could reach will be 53 km. The actual Navstar GPS constellation it is working at 20.200 km from our surface. So it means that we will need a lot of balloons in order to create a similar network, with a lot of ground stations to manage it.

Even if that point could be possible, there will be additional problems, as the areas with no islands or no continents when additional ground stations should be required to correct the signal and position.

The actual GPS satellite geometry was decided in order to reduce the number of satellites with the maximum cover.


Difference in sun activity between two towns (Eastern and Western hemispheres)

I believe this is biology related, not weather related

I think your story is a bit anecdotal because there is no measurable evidence that the sunlight energy deposited into your skin is actually stronger in New York as compared to Ukraine. Let me offer two lines of evidence that this change is more likely to be related to you and your skin than it is to the weather.

First, Rostov-on-Don, (the nearest large city I could find sunlight data for) has sunnier summers than New York. From NOAA via Wikipedia, Rostov has 286/314/293 hours of sunlight in June/July/August. New York has 257/268/268. This is largely because New York sees two more rainy days per month (and about twice as much rain on those rainy days) during the summer.

Sunlight intensity at a certain latitude is directly related to the angle of incidence of the sun. The declination of the sun is the relative angle from the sun to the horizon given your latitude and the time of year. The sun moves (well the Earth moves...) from the Tropic of Cancer to the Tropic of Capricorn each year, from 23.45 N to 23.45 S. During the northern hemisphere summer solstice, the sun is directly above the Tropic of Cancer. From New York, the angle of incidence of the sun is thus 41.07 N - 23.45 N =  17.62 degrees. During an equinox, when the sun is directly over the equator, the angle of incidence of the sun is 41.07 N - 0 = 41.07 degrees. The cosine of the angle of incidence is the percentage of full equatorial sunlight energy that you would receive at that latitude. Thus, in mid-summer in NY, you get cos(17.62) = 0.953 of maximum possible sunlight; at the equinox you get cos(41.07) = 0.754; at the winter solstice you get cos(64.52) = 0.430.

For any point in the Northern Hemisphere outside of the tropics, sunlight intensity will always be greater at all times of the year at lower latitude. Thus, New York always has greater sunlight intensity than Ukraine...but the difference is not very significant. At summer solstice NY gets 0.953 of the max sunlight, but Ukraine gets cos(23.3) = 0.918 of max sunlight. This is the difference between early July and mid-August in NY; not very significant. Given the close latitudes involved, you would expect to have gotten more net sun in the summer as a child than you do now due to fewer cloudy days. Since this is not what you observe, there must be some other explanation.

Secondly, I grew up near Boston, and my mom made me wear sunscreen in the summer. I used to get sunburns pretty bad. Now I'm 35 and I live in Virginia and I never wear sunscreen, even when I get to the beach. I don't remember the last time that I got a sunburn. Things change, I guess? This is a purely anecdotal observation, but then so is yours. Without any data to measure the changes (maybe I am smarter about being in shade in my older age?) all I can offer is guesses.

I think you should be looking at either your skin or your behavior as the cause of this change, not necessarily at the climate.


Does being in the air provide any protection from an asteroid?

To answer the radiation question, it is both absorbed and reflected into space. A lot of these processes are complex relations between atmosphere, magnetosphere, and solar radiation. Solar radiation does penetrate through as it drives everything we need or any creature needs to live, whether directly or indirectly. Aurora Borealis is caused by Solar radiation trapped in our atmosphere. This is why Ozone (O3) is so important as it does a massive support function of helping block those rays. Some of this radiation is reflected by the earth as thermal radiation. The magnetosphere also plays a role in capturing and diffusing such particles. A little more research may help, it is a very fascinating process. For more:

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

This was from courses in astronomy, hydrology, and my brain. Use wisely.


What impact on climate did 2011 earthquake and tsunami have?

Local effects are definitely possible, mainly from the tsunami itself - turbulence in the air from the waves and increased evaporation from flooded areas after.  However, it appears that the earthquake and tsunami has had no significant effect on the world's weather, particularly in the long term.  According to the Lamont-Doherty Earth Observatory, Columbia University web-article, Can Big Earthquakes Disrupt World Weather?, a key point is that although the earthquake released a massive amount of energy, it is not enough to disrupt the energy balance of the atmosphere.

A particular point is that one of the significant effects - the axial shift from the earthquake, is, according to the article, minimal compared to natural cyclical axial fluctuations.  The article also mentions that other major earthquake and tsunami events have the same minimal effects.

Although, some studies such as what gansub mentioned in comments, Impact of tsunami on Tamil Nadu Monsoon Rainfall, suggest that the tsunami itself can cause disruptions to local and regional climatic systems  -particularly with rainfall patterns.  This is an ongoing study by the University of Canterbury's Dr Iman Soltanzadeh research "The Atmospheric Impacts of Volcano and Large Tsunamis" where land use modifications due to a tsunami would affect local and regional climate and weather patterns.

However, the effects on the thinner upper atmosphere were a bit more pronounced according to NASA observations reported in the web-article Quake and Tsunami make waves in the Atmosphere, causing ripples in the ionosphere (~85km above the surface), as can be seen in the image below:

The quake caused acoustic and Rayleigh waves that reached the ionosphere in about 10 minutes, and the rolling motion of the tsunami caused gravity waves to propogate to the ionosphere in about 30-40 minutes, continuing westward even after the tsunami was stopped by the east coast of Japan.

The most significant aspect of NASA's findings can be interpreted that as the waves (all types) propogate through the atmosphere from the earthquake rupture and tsunami to the ionosphere, they appear to cause no significant climatic disruption to the lower near-surface and even the middle layers of the atmosphere, further emphasising the conclusions made by the Lamont-Doherty Earth Observatory that large earthquakes and associated tsunami do not cause any long term affects on weather patterns.


Princples of process (systems) based modeling

I guess the only thing the modeler should know is either the mathematical equation describing the system or the statistical relationship between a predictor and a predictand. You might have "access" to the exact equations or you might need to fit a mathematical model onto empirical observations. Then you need to code these mathematical or statistical relationship into a software (i.e. numerical model).

Fairly general. The devil will be in the details.


Why is ignimbrite associated with felsic magmas?

Felsic magmas contain much more silica (SiO2) than mafic magmas (almost by definition). The excess silica chains cause the magma to be much more viscous and therefore more prone to explosive eruptions (they trap gas and require high pressures to flow). This is why felsic magmas produce crazy explosive pyroclastic flows (forming ignimbrite) and very mafic magmas (like in Hawaii) just flow nicely downhill.

Btw, water decreases the viscosity of magmas, but the amount depends on composition as well as temperature. There is a nice transition between felsic magmas and mafic magmas showing that decrease in viscosity. Check out the source below:

Whittington et al (2009): "The viscosity of hydrous dacitic liquids: implications for the rheology of evolving silicic magmas"


Typical values of Glen flow law for glaciers?

For glaciology related doubts, the first place to look is The Physics of Glaciers by Kurt M. Cuffey, W. S. B. Paterson. Going through the section 3.4.5 Controls on Creep Parameter A, should give you a good insight on the topic. It also includes example values.

As well as recommendations for values of A as a function of temperature.

This section is included in the preview of the book on Google books.


Can anyone help me identify these rocks please?

The first two images look like banded calcite to me.  The rock appears to have distinct cleavages, no clearly conchoidal fractures, and a slightly waxy luster on the weathered surfaces.  Sometimes this type of rock goes under the term onyx but traditionally onyx is a type of chalcedony.  If it is banded calcite a typical knife will easily scratch the surface, additionally it would fizz with some muriatic acid (or dilute HCl).  If it is type of chalcedony, then knife will have a harder time scratching the surface an may not if the knife is on the soft side.  Also the acid will not react with the stone.

Jan Doggen's suggestion will help you get better results for the other stones.


What is the connection (if any) between jarosite and subsoil biological activity near Spain's Río Tinto?

From what I've read so far, it appears jarosite may not be a prerequisite for the formation of certain life forms, instead that it is produced by certain organisms.

  Río Tinto (Huelva, southwestern Spain) is an extreme environment with a remarkably constant acidic pH and a high concentration of heavy metals, conditions generated by the metabolic activity of chemolithotrophic microorganisms thriving in the rich complex sulfides of the Iberian Pyrite Belt (IPB). Fungal strains isolated from the Tinto basin were characterized morphologically and phylogenetically. The strain identified as Purpureocillium lilacinum specifically induced the formation of a yellow-ocher precipitate, identified as hydronium-jarosite, an iron sulfate mineral which appears in abundance on the banks of Río Tinto. The biomineral was characterized by X-ray diffraction (XRD) and its formation was observed with high-resolution transmission electron microscopy (TEM) and scanning electron microscopy (SEM) coupled to energy-dispersive X-ray spectroscopy (EDX) microanalysis. Jarosite began to nucleate on the fungal cell wall, associated to the EPS, due to a local increase in the Fe(3+) /Fe(2+) ratio which generated supersaturation. Its formation has been also observed in non-viable cells, although with much less efficiency. The occurrence of P. lilacinum in an ecosystem with high concentrations of ferric iron and sulfates such as Río Tinto suggests that it could participate in the process of jarosite precipitation, helping to shape and control the geochemical properties of this environment.

Another reference, states that

  But there is something else about jarosite that makes it interesting. One of the steps in its formation involves combining pyrite (ferrous sulfide) with oxygen. This oxidation reaction can be performed by certain "rock-eating" microorganisms.

  ... And yet, there remains the tantalizing possibility that martian jarosite owes its existence to the martian version of rock-eating microbes. If so, remnants of these organisms may be locked in the mineral.

  ... This is because jarosite on Earth is known to let all sorts of foreign elements incorporate into its crystal structure.

including,

  amino acids, the basic components of proteins

Fate of Lipid Biosignatures in a Mars-Analogue Sulfur Stream

Formation of Rubidium Jarosite During the Microbiological Oxidation of Ferrous Iron at Room Temperature


Possibility to influence oceanic evaporation to protect Sahel/Sahara

Changing ocean evaporation would impact weather & climate globally. While that may benefit some regions, it would be detrimental to other regions - robbing Peter to pay Paul.

One of the risks would be the effect on rainfall intensity, rainfall duration and the amount of rain falling in any location. It could have disastrous consequences for landslide prone regions or low lying areas prone to flooding.

Increased rainfall would result in accelerated soil leaching requiring soil nutrients to be replaced at a great rate to allow the continuation of farming and for forests to keep developing.

The accelerated soil leaching would also have an impact on the oceans and marine life and land based life reliant on marine life. Additional phosphates would result in increased algal booms, particularly in estuarine waters. Excessive algal blooms can make such waters toxic to life than can only live in such waters.

In addition to accelerated soil leaching there will be associated soil run-off and silting of rivers, estuarine systems and coast outflow regions. For marine wildlife parks such as the Great Barrier Reef, that would have a devastating consequence and may lead to the destruction of all biodiversity with such reefs.


How much further can weather forecasting models go before the limits of Chaos Theory set in?

There are (at least) two factors involved here, before we even get to questions of chaos theory.  First, thanks to weather satellites and other sensor improvements,  we can measure the initial conditions much more accurately.  (One can do a halfway decent 3-day forecast for the West Coast just by eyeballing the GOES West images.)

Second, we have greatly increased computing power.  Forecast models (simplisticaly) work by dividing the world, or part of it, into a 3D grid, applying a set of differential equations in the grid, propagating the changes to neighbors, and then stepping forward in time to repeat the process. The finer you can make the grid, the more accurate the forecast can be.  However, if you cut the size of a cell in half, you need to do 8 times as much computing.  And if it takes longer to do your computation than the actual weather, it's not much use as a forecast :-)


Why is there so much oil in Saudi Arabia, Venezuela and Canada, but almost none in Europe?

I wouldn't say there's 'almost none' in Europe, but the global distribution of petroleum is uneven. The reason is that petroleum systems need a convergence of conditions that is relatively rare.

For a start, the comment about the inappropriateness of a political map for this purpose is spot on. This USGS map of global petroleum systems, and non-petroleum-rich basins, is much better — apart from the fact that it perversely omits the USA's substantial endowment:

These 'petroleum systems' are essentially modern or ancient sedimentary basins with a particular combination of features. I'll refer to a previous answer about a specific region: Why would there be no hydrocarbons in the Sveconorwegian belt? Paraphrasing, and self-plagiarizing, here's what you need for a hydrocarbon (oil or gas) accumulation:

  A kerogen-rich source rock that has been 'cooked' to thermal maturity. So you need lots of organic matter, burial, and time.
  A migration pathway from the source to a trapping configuration, and time for this to have happened.
  A structural or stratigraphic trap, such as an anticline, and the geological conditions that have preserved it since filling.
  A reservoir rock — a porous and permeable rock. Usually this is a sedimentary rock (like sandstone, which there's lots of in Saudi!).

  Only 'conventional' hydrocarbon deposits, such as you might find in
  the North Sea, Saudi Arabia, or the Gulf of Mexico, need all these
  conditions. 'Shale gas' is basically just a mature source rock — we
  can extract hydrocarbons from it by fracking, for example.

So the map of global petroleum resources is a map of places where these criteria converge. Certain deltas are prolific (Mississippi, Niger), because you have rapid burial of sand and organic material. In other places, one or more of the conditions has not been met. Much of Canada, for example, is exposed basement granite: none of the components are there.

The unevenness is exacerbated by the Pareto distribution of system productivity — as with most natural things, we have a few giants, and a long tail. So the WCSB and Saudi stick out as anomalous, making the distribution even more 'lumpy'.


What kind of plot do you want?

  Lat = [25.5 26.5 33.5 34.5 35.5 36.5 41.5 42.5];

  Lon = [89.5 91.5 78.5 79.5 83.5 84.5 75.5 76.5];

  Rain = [110 120 122 135 114 116 145 120 110 110];

  figure();

  plot3(Lat,Lon,Rain,'o')

will give you a scatter plot with Lat being the x, Lon being the y, and rain being the z.

Also note that because your vectors are different legnths, you cannot plot them. You must have vectors of the same lenght to plot (each point must correspond to another point on the axis).

Other types of plots will require you to interpolate between the data points.

If you want to plot it like in the comment below: pcolor is your best choice.

Say your Lat/Lon vectors have n points. Then to make an nxn grid, you can use the command

  [X,Y] = meshgrid(Lat,Lon);

This will give you the grid you want, as long as your Lat/Lon Vectors are spaced how you want. To get the 'color" of the pcolor, you will need to have a nxn matrix of rain values: you will need to know what those are at each point. If you do not know those, then then you cannot plot it in map view unless you do some form of modeling or interpolation.

If you have an irregular shape, I would not use matlab. I would use Visit or Paraview, and there are many guides online on how to use this.

If you must use matlab, I would create "fake points" to make the grid a regular shape, and give them false rain values (such as NaN). I would then edit the plot in a postprocessor (photoshop) so that Only the irregular shape appears.

The spacing of the grid does not matter as its specified via your vectors.


Are lightning storms more common at night?

The answer is dependent on the geographical location. Over sea, there is hardly any diurnal cycle of lightning (this means that there is no time of the day when lightning is more/less often observed).
In continental regions (e.g. Siberia), however, there is a strong diurnal cycle of lightning: it is most common in the late afternoon, and least common in the early morning.
The third type of regions are regions mainly affected by mesoscale systems (as is the Great Lake region in the US): here, there is also a strong diurnal cycle, but the peak (most lightning) is shifted towards the late evening or early morning. Thus, to answer your question: in these regions, there is indeed more lightning at night.

Reference:
Blakeslee, Richard J., et al. "Seasonal variations in the lightning diurnal cycle and implications for the global electric circuit." Atmospheric research 135 (2014): 228-243.


Why do (some) silicic bodies behave effusively instead behaving explosively as in common?

Explosive volcanic events happen mostly because of saturation in gases, and increase in pressure above the strength of the top of the magma chamber. As the magma decompresses or cools, H2O (mostly), CO2 (also important), and other gases such as H2S, SO2, HCl, etc, form bubbles and increase in volume. If the magma chamber is confined, there is also an increase in pressure.

An obvious corollary is that gases have to be present. If the magma is mostly dry and volatile-free, there are no volatile species to form bubbles and the magma cannot explode.

Another factor is the viscosity of the magma. The less viscous it is, the easier it is for the magma to flow (and not build up pressure) and also the easier it is for bubbles to escape the magma. Viscosity of magma depends on temperature (hotter = less viscous), composition (more alkalis = less viscous), crystal content (less crystals = less viscous).

Taken together, a hot alkali magma without crystals and no volatile species will flow, whereas a cold partly crystallised wet sub-alkali magma will probably explode, even if they have exactly the same SiO2 contents.


Why is fluid pressure in a fractured rock reservoir only dependent on hydrostatic pressure?

Fluid (or 'pore') pressure does not depend only on hydrostatic pressure — it also depends on stratigraphy, fluid content, and the geological history of the rock.

The fluid 'stack' can be thought of as a (mostly) connected body of fluid — dominantly brine and hydrocarbons. The rock 'stack' is a similarly interconnected body. The fluid stack defines a typical soft lower limit of pore pressures; the rock stack defines the hard upper bound.

In practice, we don't experience lithostatic pressure in the pores because at some level of stress below lithostatic pressure, we find the fracture pressure. If the pore pressure reaches this level, the rock breaks and pressure equilibrates. This is the mechanism behind induced hydraulic fracturing, or fracking.

But pore pressure does not have to be hydrostatic. 'Geopressure' or 'overpressure' or underpressure can occur if a stratigraphic layer is unusually tight, for example salt, and a porous formation experiences rapid uplift or burial. We might also depart from hydrostatic pressure as the density of the pore fluid changes, with salinity or gas saturation for example.

This cartoon shows pressure measurements (green) in a gas well. The other trends can be computed from models or data (for example the bulk density log). The shallow part of the well is hydrostatic; the deeper section shows overpressure. Natural gas is low density, so the gas zone shows a different trend. Clearly there will be a potentially dangerous pressure kick as the drill penetrates the top of the reservoir. If the gas trend were to hit fracture pressure, the trap would leak and the hydrocarbons would escape — a common natural phenomenon.

You might also like to read these related questions:

Why is the lithostatic pressure gradient 1 psi/ft? How is it derived from density?
How do I derive the formula for lithostatic (overburden) pressure?
What is the reasoning behind the statement "Faulting will occur along the plane where the shear stress is the highest"?


Does US have more forest fires in Sep 2020 than average?

For now it seems to be average, at least compared to the last decade. The National Interagency Fire Center has a page with a year-to-date statistics table. You can see that so far, the values for 2020 are pretty similar (even slightly below) to the 10-year average, both in terms of number of fires and burned acres.
2020        |   Fires: 41,599   |   Acres: 5,288,247
2010-2019   |   Fires: 44,177   |   Acres: 5,761,034

Now if you go further back in time, there seems to be an upward trend. I did not compute the means, but just by looking at the numbers you can guess that there were less fires in the 80's and 90's, and about the same amount as today from the 2000's.


What causes the entrainment of atmospheric gases towards a volcanic ash/tephra plume?

This answer seeks to just answer about ambient air entrainment, as per the question (not eruptive plume height, as suggested in the comments) which is a separate question.

According to the book, Modeling Volcanic Processes: The Physics and Mathematics of Volcanism, (Fagents et al, 2012, p. 155-156), your assumption (2nd paragraph) is on the right track, particularly for energetic eruptions (e.g. Plinian).

When the plume initially erupts, it possesses significant momentum, with a greater density and are influenced by pressures considerably greater than the ambient atmosphere.  However, once in the atmosphere, the plume undergoes rapid decompression and expands, ascending as a turbulent flow in the convective ascent region (an example is shown below).

Image source: USGS page about the Mt St Helens eruption in 1980 demonstrating the turbulence in an eruptive column.

As the flow continues to ascend, the eruptive column begins to exhibit lateral gradients in temperature, momentum and density, allowing for the mixing with the ambient air at the edges of the column - over time, this mixing continues to the core of the eruptive column by shear mixing.  Effectively, 'stirred into the column by the turbulence'.(Fagents et al. 2012; Kaminski et al. 2011).

Image source: MTU.edu

As the entrained air heats, expands and rises, more cooler ambient air is mixed into the turbulent eruptive column (just as long as the eruption continues) - as per the MTU.edu diagram above, the plume rises by buoyant convection.

Entrainment of air into the eruptive column can be increased by the right wind conditions, as observed at the 2011 Kirishima-Shinmoe-dake volcano eruption in Japan (Kozono et al. 2014).

Additional resources

Kozono et al. 2014, Correlation between magma chamber deflation and eruption cloud height during the 2011 Shinmoe-dake eruptions, Earth, Planets and Space

Kaminski et al. 2011, Rise of volcanic plumes to the stratosphere aided by penetrative convection above
large lava flows, Earth and Planetary Science Letters


For (a) through (c), consider the differences between the geoid and the reference ellipsoid, in addition to the barycentre.

For (d): A slightly higher perigean spring tide than usual, meaning in some geographical locations perhaps an amplitude difference of inches rather than millimetres.


In hydrology, what's the difference between specific and total catchment area?

I will try to bring you some insights. In my opinion, SCA is poorly named.

Actually, the width is not involved in the catchment area which is given by TCA. SCA introduces a diffusive flow factor by considering flow width. It is a one dimensional value so it is not representative of an area and that's why it might be confusing. It gives us an idea of how concentrated are the incoming flow.

Besides this, I think you are also confused by the outlet concept which is often defined in GIS or in some conceptual definitions by a point. But actually, in order to compute a flow at an outlet you need flow velocity and a cross section. If this cross section area is assumed to be rectangular, it can be defined by the width and the height will vary according to the incoming flow. So when the outlet is considered as a point, it is more like a targeter of the outlet that has some dimensional characteristics.

So, for studies at the plot scale or the hillslope scale, the outlet is often defined by a line which is representative of the flow width at the downslope.

For grid based data, a pour point targets a representative area defined by the spatial resolution of your terrain data. If a point has no flow width, this area has one and the flow width is generally assumed to be the cell size as mentionned in your quote.

If you understand that, you may understand that the broader the width, the more diffuse will be the overland flow and therefore the less wet regarding the TWI or the less erosive. Of course, it remains resolution dependent.


Movement of the Prime/Greenwich Meridian

Remember it is just an imaginary line on the Earth's surface used for georeferencing purposes, so movement of the reference line has no implications so long as we can still reference to it (hence the International Reference Meridian).

In fact, the position of the Greenwich  meridian has changed throughout history, mainly due to the Airy Transit Observatory (the original location of the Greenwich meridian) being built next door to the previous one (to maintain the service to shipping). Such changes had no significant practical effect. Historically, the average error in the determination of longitude was much larger than the change in position. The adoption of WGS84 ("World Geodetic System 84") as the positioning system has moved the geodetic prime meridian 102.478 metres east of its last astronomic position (measured at Greenwich). The position of the current geodetic prime meridian is not identified at all by any kind of sign or marking (as the older astronomic position was) in Greenwich, but can be located using a GPS receiver.
Due to the movement of Earth's tectonic plates, the line of 0° longitude along the surface of the Earth has slowly moved toward the west from this shifted position by a few centimetres; that is, towards the Airy Transit Observatory  (or the Airy Transit Observatory  has moved toward the east, depending on your point of view) since 1984 (or the 1960s). With the introduction of satellite technology, it became possible to create a more accurate and detailed global map. With these advances there also arose the necessity to define a reference meridian that, whilst being derived from the Airy Transit Circle, would also take into account the effects of plate movement and variations in the way that the Earth was spinning - the International Reference Meridian.

See:

Malys, S., Seago, J.H., Pavlis, N.K. et al.  (2015) "Why the Greenwich meridian moved" Journal of Geodesy. 89 (12) pp 1263–1272

Dolan, G (2013). "WGS84 and the Greenwich Meridian". The Greenwich Meridian.


Your assertion is correct! See e.g. Stein & Wysession An Introduction to Seismology, Earthquakes, and Earth Structure (2003) p. 90 ,section 2.7.3: Love waves in a layer over a halfspace (https://books.google.ch/books?id=-z80yrwFsqoC&lpg=PP1&hl=de&pg=PA90). In particular, for any particular frequency/period, Love waves can only have certain horizontal apparent velocities/wavenumbers. Hence, different frequencies have different apparent velocities, which is what we refer to as dispersion. See for example also the figure 2.8-2 from the book, https://books.google.ch/books?id=-z80yrwFsqoC&lpg=PP1&hl=de&pg=PA96, which shows the dispersion curve for a layer over a halfspace.


Some website or institute with integrated statistics on forecasting the occurrence of rainbows

A rainbow is not a physical object that has a position.  It is an optical phenomena that depends on your location relative to the sun and rain.  If you are standing where your eyes can intercept the colored light, you are standing with your back to the sun and the sunlight is reflecting on raindrops in front of you.  Someone else standing in a different location would not necessarily see a rainbow if they looked towards the same location.
From University of Illinois:

According to Descartes' calculations using laws of optics, the three stage refraction-reflection-refraction pattern that light undergoes when passing through a raindrop produces a concentration of outgoing rays along a line that is 42 degrees above the head of an observer's shadow. This concentration of light rays is the rainbow that we see.

Also this National Geographic article has a nice description:

Viewers on the ground can only see the light reflected by raindrops above the horizon. Because each person's horizon is a little different, no one actually sees a full rainbow from the ground. In fact, no one sees the same rainbow—each person has a different antisolar point, each person has a different horizon. Someone who appears below or near the "end" of a rainbow to one viewer will see another rainbow, extending from his or her own horizon.

What this means is that a rainbow is not really a meteorological occurrence that can be measured or catalogued, because you would get a different answer depending on your reference point.  Lightning, in contrast, is a physical phenomena that has a precise location which can be determined and verified from multiple points of reference.
Rainbows are photographed and archived by enthusiasts, but it's really about artistic appreciation.
How Rainbows Happen has a nice description:


Why is Belgium (and Luxembourg, Switzerland, Austria, Norway) still above consumption CO2 levels per capita of 1990? While many others did go down

My answer will not be complete, but consider one factor: population.
Belgium population per year:
1990    9,967,000
2000    10,251,000 (+10.2%)
2009    10,796,000 (+5.3%)
2018    11,376,070 (+5.4%)
On top of that, you are considering countries with relatively small population increasing significantly (Belgium, Austria, the Netherlands). Most of the population increase is from immigration and high fertility rate of the new population (see the CO2eq impact of about 9tons per capita on the parents due to a new born), with industrial powerhouses like Germany and Italy where a lot of the production has been delocalized in the same time period (check CO2 of Romania or Spain)


Can large earthquakes happen twice/thrice at the same place within a short timeframe

Aftershocks after a major earthquake can occur for a period of weeks after the initial major earthquake, but the magnitude of the aftershocks is always less than that of the initial major quake. The paper History of Earthquakes of India & the Himalayas discusses the each of the major earthquakes in the region for the last 200 years. Information on earthquakes before 1800 is patchy. The earthquakes discussed are the ones that occurred in: 1803, 1833, 1869, 1897 & 1905.

Nothing was mentioned about a second or third major earthquake happening shortly after a major earthquake; even for the devastating 1934 earthquake.

Due to the different tectonic settings and causes for earthquakes in different parts of the world it is best not to look at the history of one part of the world and assume the same will occur elsewhere. The expectancy of earthquakes and their patterns in the Himalayas should not be compared with earthquakes in Japan, New Zealand, western USA, Turkey or elsewhere.


Yes, they can. Hawaiian Trough is a good example. The impact on thin oceanic crust is naturally larger/faster than on stiff continental crust.

Generally the lithosphere will always respond to load, even if it's sediments, ice or water. The process also works the other way, exhumation by erosion ease the load and cause uplift.


Does the US National Weather Service use Celsius or Fahrenheit?

NWS Temperature forecast or new forecast

From these URLs, it  appears that the unit is Fahrenheit.

and if you click on this URL - Max/MinT

  Is the maximum daytime or minimum overnight temperature in degrees Fahrenheit.

In the USA  NWS always used to issue forecasts and bulletins in Fahrenheit and some background can be obtained from here US Customary Units and here - Why Americans still use Fahrenheit as well here - Fahrenheit Versus Celsius: Why the US Hasn't Converted

  Degrees Fahrenheit are used in the U.S. to measure temperatures in most non-scientific contexts. The Rankine scale of absolute temperature also saw some use in thermodynamics. Scientists worldwide use the kelvin and degree Celsius. Several U.S. technical standards are expressed in Fahrenheit temperatures and American medical practitioners often use degrees Fahrenheit for body temperature.

In reality, the NWS and NCDC weather forecast model outputs for the different systems (GFS, NAM, NARR...) use temperatures in Kelvin. This satisfies the international standards (e.g., CF1.6 convention compliant) and also avoids issues with advecting fields (in this case) that are equal to zero in some locations. You can see this if you look at the model output directly (for instance, here or here). Afterward, in post-processing the temperature is transformed to either Celsius or more commonly Fahrenheit for public consumption.

Scientists and meteorological researchers are more used to Kelvin and/or degrees Celsius.


Why do we see the limestone on top of Cambrian layer?

No.  CaO will not exist in most environments for any significant time in the presence of CO2, it will react to form CaCO3.  I doubt CaO is the primary source of Ca in our world.  Silicates are likely the original source of Ca in our oceans https://en.wikipedia.org/wiki/Silicate_minerals.  CaCO3 will partially dissolve or corrode in water to form an aqueous solution of Ca +2 + 2 HCO3 -.  The dissolution of the CaCO3 in water is an equilibrium reaction based on the acidity and temperature of the water, this is why the acidification of the oceans is a concern for our marine life.  I am not a chemist or a biologist but organisms will extract the aqueous Ca +2 ions found in the water to form shells etc.  Because these organisms are not evenly distributed in the ocean their shells and skeletons will and have accumulated the CaCO3 in distinct areas.


Do divergent tectonic plates destroy mountains?

Quite the opposite. Divergent boundaries can cause mountain (well, actually volcano) building, because upwelling magma is part of the rifting process.

First and most importantly, the Mid-Ocean Ridge can be considered the longest, most massive mountain range in the world.

It's more obvious, of course,
 on continental rifts like the East African Rift. Mt. Kilimanjaro, a product of rift volcanism, is the highest mountain in Africa.

Another famous locale of volcanism at a divergent boundary is Iceland, although a hot spot may play a role there.

Source: USGS (via usu.edu)

But BUT BUT it seems you want to know what happens to existing mountains. Some others have answered that only erosion destroys mountains, and that's mostly right, but only because it's a matter of timing.

It's often difficult for us humans to comprehend just how big geological time scales are. Most of the time, a mountain range created by a continental collision is eroded away completely by the time the next rift comes along.

This was the case along the eastern seaboard of the United States. The mountains created by the collosion of Africa and North America in the Carboniferous (the Alleghenian Orogeny) were almost completely gone by the Triassic, when the Atlantic Ocean began to form from a rift along about the same line.

However, we have an example that might result in a qualified "yes" to your question, a little closer to the present. This is the way the Yellowstone Hotspot moved across what would become the northwestern United States.  One of the things that caused geologists to recognize the Yellowstone Caldera was the 80km gap it melted in a mountain range it passed under, separating the Gallatin Range in the north from the Red Range in the south.

The hotspot's track might just be the genesis of a new rift that breaks North America apart, given enough time and the right stresses.

(Source: USGS)


What would happen if we could revert $\mathrm{CO}_2$ production but took it too far?

The average global warming due to greenhouse gases corresponds to a 33 Kelvin temperature increase.  If you remove all greenhouse gases the average global temperature would then decrease 33 Kelvin (from 288K to 255K).

You might want to check out:
http://www.nasa.gov/topics/earth/features/co2-temperature.html
 which estimates the CO2 portion of global warming to be about 80%.

  "... it is the 25 percent non-condensing greenhouse gas component, which includes carbon dioxide, that is the key factor in sustaining Earth’s greenhouse effect. By this accounting, carbon dioxide is responsible for 80 percent of the radiative forcing that sustains the Earth’s greenhouse effect."

Simple math might suggest then that the average global temperature of Earth would be ~262K if CO2 were completely removed.  There are always sources of CO2 though, so you could never remove it all as it is constantly being replenished when animals breathe and things burn.


Can someone identify this 'striped' stone?

Looks like a shell from a bivalve of some kind, that has been worn presumably by wave action.

You may want to update your question with more context. Where did you find it? Also, your photos are all out of focus and some are overexposed, so you may want to re-take the photos. You might also want to try asking on a biology or zoology site.


Clouds have ceilings and bases because the atmosphere is stratified.
Atmosphere is stratified due to earth's rotation and variance of composition, humidity, density,  temperature, and pressure from surface of the earth to the edge of the orbital space.

Clouds form under specific conditions of composition, humidity, density,  temperature, and pressure.  These conditions are often persisted within specific layers in the atmosphere.  Complex fluid flow of air is also a contributing factor for layering within the atmosphere between air masses for varying density.

The answer is probably best summed up as the result of the physics of fluid dynamics.


What is likely to have happened with these newly discovered antarctic volcanos below the ice?

That's a very interesting study, but only provide very rough information on the posible volcanoes that might exist under the ice.
In the case of the volcanoes shown in the radargram I'll highlight some points that might be the source of your confusion:

The tephra layer that overlay the volcanoes in the radargram was not erupted  by those volcanoes. It was most likely erupted by a volcano from above the ice (subaerial), or a subglacial one far away. It was later buried deep in the ice by the snow falling on top. Otherwise the layers would be much messier in the area and of varying thickness.
If those cone are volcanoes, its shape suggest that they were formed before they became covered in ice. Subglacial eruptions form flat-topped volcanoes with steep sides calles Tuyas, and what is observed are broad shield-type cones, that suggest submarine or subaerial formation.
They don't know if those volcanoes are active, but if one were to start an eruption, wouldn't be of the explosive type, because are likely to have fluid basaltic lavas, like the ones observed in Hawai'i. The explosiveness will come from the steam produced. It is hard to tell if it will blow the ice on top or not. It depends on ice thickness, eruption power, etc. But it is definitely a possibility for a strong enough eruption.


Which universities are best for studying Oceanography as an undergrad?

I noticed that there is a push to close the question, and I get why. But I do think that guidance towards a university is still important, even if it does not fit the Earth Science SE guidelines. So here is my answer (as someone who does not study oceanography, rather as a meteorologist): It depends.
What I have found is that the question you should ask is not 'what is the best,' rather 'what is the best for me?' You may want to learn from the best, but you might end up miserable. What can you afford? How far are you willing to travel for your degree? What aspects of oceanography are you interested in -- chemistry, climatology, biology, geology, etc.? Presumably, different universities will emphasize different specialties. Look at what the faculty research, and you will find what
Knowledge is knowledge. With solid reading skill and good resources, you can probably teach yourself enough without needing a degree. If it is just a passion, I would recommend that route. If it is what you want as a career, go to university and get the degree.


What is the best way to mount white mica separates?

I had asked the same question on ResearchGate and got some good feedback. So anyone who is interested in this kind of methodology can follow the link below.

https://www.researchgate.net/post/What_is_the_best_way_to_mount_white_mica_separates


How is geological time divided into units?

The divisions in the geologic time scale have evolved over time.
Its origins can be traced back to Nicolaus Steno in 1669 described two basic geologic principles.

The first stated that sedimentary rocks are laid down in a horizontal manner.
The second stated that younger rock units were deposited on top of older rock units.

Work by James Hutton, Charles Lyell and William Smith helped define "principle of uniformitarianism". This work led to definitions in the Mesozoic and Paleozoic eons in Europe and Great Britain.

The Mesozoic and Paleozoic eons helped define the extinction events reflected in the fossil record. It was these correlations that led to the discovery of the extinction events and not the other way around.

Radiometric dating based on the work of Clair Patterson added absolute ages to the time scale.

Over time, the process of grouping together or splitting apart rock units  has grown more sophisticated as better dating techniques have been introduced and more data from mapped rock outcrops have been collected analysed.

References:

http://www.ucmp.berkeley.edu/exhibit/histgeoscale.html

http://www.sepmstrata.org/page.aspx?pageid=22

http://evolution.berkeley.edu/history/radiometric2.shtml


I feel bad answering this one without any research reference, but I can tell you that what you are seeing in the OP's picture is a 'man overboard drill.' In that drill, the objective is to rotate the ship's rear section away from a man who many have fallen overboard and then circle the ship around (in an exact circle) to come up alongside the fallen man.

In order to do this with a ship, you throw the rudder over hard and fire up the engines ahead full. With many warships, the engine's toque is enough to produce massive cavitation (bubble formation) for the duration of the turn. As you end the turn you will usually throw a 2/3 backing bell, which will produce even more cavitation. That is the 'trail' you see behind the ship.
Specifically, the ship you see there is HMS Echo, which has a diesel-electric azimuth drive mounted below the ship, which will provide a very high torque.

Lots of cavitation (and you can feel a 10,000 ton ship vibrate during these maneuvers) means lots of bubbles are formed up to 15m below the surface (depending on the size of the ship; only about 6m for the pictured Echo). As the bubble propagate to the surface they disrupt the passage of surface wavelets and form the calm area shown.

One more factor is that navies train to put the man on the leeward side of the ship during recovery. Thus, in this picture the stern was swung to port (as we can see from the 'trail') so the man must have been on starboard, so the man is on the 'starboard' side of the ship during this recovery. That means the wind should be on the port side, so the calm area is being protected from the wind by the mass of the ship.


Broadly speaking you are correct on both counts: magnetite is the most magnetic mineral, and it can oxidize, first to the matastable phase maghemite, and ultimately to the fully oxidized haemetite. This process can yield grains with a zoned appearance, both in hand specimen and more clearly under the microscope, with brown on the outside and residual black magnetite in the core. Maghemite, as the name suggests, is also magnetic. There are several other moderately to strongly magnetic minerals, closely related to magnetite, and with a similar molecular structure. For example ilmenite, a very common mineral that sometimes occurs with magnetite, is the double oxide of iron and titanium. Tantalite / columbite, or manganotantalite $(Fe, Mn)(Ta, Nb)_2O_6$ is not as magnetic as magnetite but may still be magnetic enough to swing a compass needle. It looks identical to magnetite, but can have a slightly purplish brown sheen. Similarly, chromite, the double oxide of chromium and iron, can be very magnetic, but I don't recall ever seeing anything other than black chromite. Franklinite, which is reddish purple, is another mineral of the magnetite group, and is a complex oxide of zinc,iron and manganese. There are several other weakly magnetic minerals of the magnetite group, most of which are quite rare. As a rough rule of thumb, the more oxidized or the more iron is replaced with some other metal, the less magnetic it is.

PS, if you ever find metallic looking sand that is magnetic, stake a claim! Platinum is also weakly magnetic.


Why does the so called "tornado alley" exist?

The kind of tornadoes "tornado alley" refers to are associated with supercell thunderstorms.  To first figure out why this region exists, we need to explore why this is a hotspot for supercells.

Thunderstorms require energy and this energy comes in the form of convective available potential energy (CAPE).  This is simply the vertically integrated buoyancy of a parcel from its level of free convection (LFC) to its equilibrium level (EL).  Thunderstorms need CAPE but CAPE is not a great predictor of what kind of storm we get, that falls to vertical windshear.  Supercells form in environments with a 0-6 km shear (this measure if just a vector difference of the winds at these levels) greater than 20 m/s.

CAPE is going to be maximized where you have warm, moist air at the surface and cold air aloft.  The Gulf of Mexico has plenty of water and it is common to find strong southerlies advecting this moisture into the US.  With a particularly strong low level jet, this moisture can be advected as far north as the Dakotas. As warm air is typically found toward the equator, this is also advecting warm air northward.  This results in a tongue of warm, moist air extending northward out of the gulf.

The cool air aloft is provided by the Rockies and high plains.  In the boundary layer, mixing drives the temperature lapse rate toward dry adiabatic, while in the free troposphere the lapse rate is typically less than dry adiabatic.  The high elevations of the mountains mean that there are boundary layers and some layer of atmosphere with a dry adiabatic temperature profile.  These cool, dry adiabatic layers get advected by the westerlies aloft and end up on top of the warm moist air provided by southerlies out of the gulf.

This setup provides CAPE and the necessary shear (southerlies at low levels and westerlies aloft) for supercell thunderstorms.  However, not all supercells form tornadoes, and why is an area of active research.  Tornadoes will be favored with low LCL heights (lifting condensation level) and large low-level shear.  The occurrence of these environments combined with empirical data result in the area termed "tornado alley".

The US isn't the only home to such a place.  There is a similar setup in Bangladesh where warm moist southerlies come off the ocean and cool adiabatic layers come from the high terrain in the region.

Because the atmosphere is giving a nice case study, here is an example of a sounding that demonstrates the above concepts.  This is from a radiosonde launched at Jackson, MS this morning at 12Z.

Key features:

Boundary layer is well mixed (dry adiabatic temperature profile and constant water vapor mixing ratio)
A cap (and a rather large one at that)
An elevated mixed layer extended up to nearly 500 mb (nearly dry adiabatic temperature profile)
Dry midlevels
Southerlies at the surface
Westerlies aloft

Of note, the hodograph has a lot of low-level shear with almost all of the 0-6 km shear contained within the lowest 1 km.  The LCL is also somewhat low.  These are both favorable for tornado formation.  The big question is whether a storm will actually fire, as this sounding has considerable convective inhibition (CIN) from the large temperature inversion capping the boundary layer.  This is a morning sounding though and so there is plenty of time for the temperature to evolve.  The cap can be broken through pure solar heating, though requiring a temperature of 94 F to do so.  Throughout the day the boundary layer will be mixing with the cap, which will reduce its strength.  Moistening the boundary layer can also help decrease the CIN.  Aside from the large cap in the morning, this is a setup favorable for supercells and severe weather.

And the result?  As of 2218Z, here is a view of the Jackson, MS radar:

This is a supercell (well, a line of them and a bit messy looking) with a possible tornado due west of Jackson and moving to the east.

For a broader picture, lets also take a look at the 18Z NAM.

Surface moisture:

This shows a tongue of moisture being advected by the southerlies out of the gulf.

Surface temperature (F):

It is also warm.

Surface based CAPE:

Put this together with midlevel lapse rates and we have lots of CAPE.  But do we have adequate shear?  Here is the 500 mb flow:

500 mb height and relative vorticity:

Flow somewhat westerly, but direction is not as important as the magnitude.

Surface to 500 mb shear:

And as this shows, we have plenty of shear.

This is a classic setup for severe weather and the frequency that this setup occurs and the resulting weather is how tornado alley earned its name.


At what sea level would beach area be maximized?

There are multiple ways one can look into this. For example, one simple way of increasing the length of coastline and, thus the beach area, would be to expose all of continental shelf.

The shelf break, where the continental shelf ends is pretty uniform globally and is in most cases at a depth of 140 m. As such, lowering water level by this amount will produce a large increase in beach areas.

Alternatively, it might be possible to increase the overall length of the coast by increasing the water level by ~100 m. While here we lose a substantial amount of coast due to flooding of low-lying areas of continents, there will be substantial gains as well.

Such an increase firstly will create a lot of new inlets resulting in minor increase of coastal areas, but most importantly this will cause the water level to reach bases of several mountain ranges - Alps, Himalayas, Caucasus to name a few. This will create an extremely rugged coastline with ridiculous amount of fjords and bring huge increase to the coastline length.

The issue with the latter option is that I'm not sure how likely you are to have a 'beach' in a fjord environment or what exactly we should consider a 'beach' for the purposes of your question.

In reality it's a pretty complicated question and it can only be solved by sitting down with modelling of coastline length at different water levels.

EDIT: Another interesting option is to reduce water level by ~3-4 km. This will maximize the land area while maintaining water in the deep oceanic basins and at the same time the longest mountain range in the world - the mid-ocean ridge - will get exposed above sea level adding on to the overall coastal length.


It might be a smoke ring, but it's not known for sure.

There have been several sightings of similar objects over the past few years.

A ring was seen in Leamington Spa in 2014. Theories about its origin included a group of insects, as well as an ordinary smokestack (perhaps the ring stayed in one piece for an inordinately long time). Eventually, it was discovered that it was the result of a fireworks test.

A similar object was seen in Kazakhstan in 2015. Video of it received quite a lot of publicity, and many people labeled it a UFO. In that instance, the object was ~100 meters in diameter and ~200 to 1000 meters in altitude. The smokestack hypothesis was once again brought forth. Another article mentions that some people attributed the ring to thermal microbursts (see also here); however, microbursts move down, and your ring rose up.

An irregular ring was observed in Birkenshaw earlier this year (2017). This case is notable because the ring in this case was distinctly non-planar; it was warped, just like yours. It may have been from an explosion from a military reenactment.

This article notes that another ring was seen in Windsor, right near where you were:

There are many more examples besides these.

Some notable features about these rings:

They are "hazy" or smeared in parts. In your case, you can see a dark section on the left; the Leamington Spa ring has a smear on the upper left and the Kazakhstan ring has a smear on the right.
The rings are pretty circular. This may be an indication that they are artificial.
Most are flat, but some (like yours) exhibit some warping, which could indeed be cause by wind.
The rings are darker than the clouds around them, as we can see in all cases but that Kazakhstan ring.
They were sighted near places where explosions were taking place on the ground (a similar ring in California was seen at Disneyland).

I'm willing to rule out microbursts in your case because the ring rose. Insects are still a possibility, and perhaps the smears are due to individual bugs flying outside the pattern, but I have yet to see any behavioral study to explain it. This leaves the theory that these rings are from smokestacks or certain detonations, which is well-supported. Not all of the rings were seen near heavy industrial areas, mind you, but that doesn't rule out that hypothesis in those cases. Smaller smoke machines or explosions could still be the culprits, possibly at a ride in Legoland itself.

The most similar type of cloud I can think of is a lenticular cloud, a common explanation for UFO sightings:

Image courtesy of Wikipedia user Omnisource5 under the Creative Commons Attribution-Share Alike 4.0 International license.

However, lenticular clouds aren't ring-shaped, but disk-shaped, and they usually aren't quite that flat. Therefore, I'd rule a lenticular cloud out here.


What geophysical instruments should I use to detect water without drilling?

Hydrosource Associates (no personal relation) claims to use the following:

  HSA’s use of geophysical instruments and methods includes seismic, electrical resistivity, ground penetrating radar, electromagnetic, magnetic, gravimetric, self-potential, and magnetotelluric.

Since you're looking for a list, you could investigate each of those technologies above.

However, the one instrument not mentioned above and the most high recommended method is simply using geological maps.