Is there any new water formed on, or brought to, Earth?

Your explanation(s) sounds correct.

Your first article says as much.

  There is a water cycle on earth that takes wet sediments deep into the
  mantle to be re heated and circulated back up as new sea floor. This
  is where the water in hydrothermal vents originates - it is NOT new
  water. However, there remains a possibility that some of the water
  emerging from the mantle has been there since the formation of the
  earth so some of it MAY be 'new'.

And your 2nd article

This is at least partly semantics calling it "new" water.  When we burn gasoline for example, the hydrocarbon structure becomes Water and CO2 - is that new water, or just re-arranging molecules by chemical reaction and fire?

  I'm also wondering if new water is coming here from
  meteors/meteorites.

Water absolutely reaches the Earth by comets and meteors.   We're hit by comets and meteors all the time and comets especially are water-rich.   That is new water, though I wouldn't want to put an estimate on how much.  Too big a margin of error.

Earth also loses water by UV rays from the sun.   Most of the atmosphere the Earth loses is Hydrogen and most of that Hydrogen comes from Water.   Losing 90 tonnes of Hydrogen per day works out to nearly 800 tons of water per day, which sounds like a lot, but compared to the vastness of our oceans, it's a proverbial drop in the bucket, even over hundreds of millions of years.

So Earth adds water by comets and Earth loses water by photo-disintigration and atmospheric escape.   I've read that it's a net loss, not a net gain, but it's pretty insignificant either way.    Some articles suggest Earth has lost a pretty good share of it's water over billions of years.   I think there's a pretty big margin of error in those estimates, personally.

In 200 or 300 million years, as the sun grows a little larger and brighter, we might need to begin to worry about Earth losing too much water (maybe).  That's if we're still around, of-course.


Waves on sandy beach separating differently-sized rocks?

There are two ways in which waves can sort particles on a beach, and both depend on surface area to weight ratio. The larger, toe-sized particles you describe have less surface area to volume (weight) ratio than the sand-sized particles, so were first to drop out of the water flow. The lighter particles had more surface area per unit of weight for the waves to act on, so were slower to drop out and were carried further up the beach. Why the lowest level sand grains were precipitated in deeper water, before the toe-sized particles, is less easy to understand, but one possible reason is that they contained some heavy mineral such as tin, which altered the surface area to weight ratio and caused them to drop out first. This principle is well seen in gold panning machines, where the heavy gold particles drop out of the flowing water first,while the lighter particles are carried further on, even when they are larger than the flecks of gold.


Why don't cold fronts and other steep-gradient weather effects just dissipate?

Good question.  It would seem without much thought, that air in a high pressure zone should move towards the air in low pressure zone, resulting in a disappearance of the pressure gradient.  The reason this does not occur is because there other forces (or pseudo-forces) at work, acting in addition to the force resulting from the pressure gradient.  I will outline such forces below:

1.  Pressure Gradient:
This is the force resulting from the pressure difference between a high and low pressure zone.  We term this a pressure gradient, because the pressure change is continuous rather than a discrete change between a high and low pressure zone.  We can model the acceleration in a particular direction resulting from a pressure gradient using the equation:

$$\alpha=\frac{-1}{\rho}\frac{dP}{dz}$$

where $\alpha$ is the acceleration at a given point, $\rho$ is the density of air at that point, and $dP/dz$ represents a small change in pressure over a small change in horizontal distance.  More generally, we can model the acceleration vector in 3-dimensions using the equation:

$$\vec{\alpha}=\frac{-1}{\rho}\vec{\nabla}P$$

Now if the pressure gradient was the only force at work, it is obvious from above that the acceleration would be directed from high pressure areas to low pressure areas, ultimately resulting in a dissipation of such gradients.

The next pseudo-force to consider however is the Coriolis effect.

2. Coriolis Effect:
The Coriolis effect influences winds away from the equator that move horizontally.  Such winds in the northern hemisphere are deflected to the right, whereas winds in the southern hemisphere are directed to the left.  This is a result of the Earth's rotation.  (More information on this effect can be in the question and answer here).  The acceleration resulting from the Coriolis psuedo-force is given by the following equation:

$$\boldsymbol{a}_C=-2\Omega\times\boldsymbol{v}$$

where $\Omega$ represents the angular velocity of the Earth and $\boldsymbol{v}$ represents the velocity of the wind.  The cross product here is of significance and indicates that the deflection of the Coriolis effect will be at right angles to the direction of the wind's velocity.  More details of deriving the specific result for the Earth at different angles of latitude can be found here.

So how does this Coriolis effect stop wind from moving from high pressure to low pressure?  Well imagine that wind begins to move North (in the northern hemisphere) from a high pressure region to a low pressure region.  Due to the Coriolis effect, this wind will be deflected to the right, and will continue to be deflected in such a manner until the pseduo-force resulting from the Coriolis effect exactly balances the force due to the pressure gradient (ignoring friction for the time being).  At this time, we say the wind is said to be in geostrophic balance.  The wind therefore is no longer moving directly from the high pressure region to the low pressure region, and it is for this reason that the pressure gradients do not dissipate straight away. (See friction force below)  This can be represented by the picture below, and I will include the formula when we have access to mathjax (note the Coriolis term is represented a bit differently in this diagram, but don't worry I'll explain how it is the same when mathjax is added - basically it just a certain direction component of my more generalized vector above):

3. Friction

As I mentioned previously, the geostrophic balance presumes the absence of friction.  In reality, friction acts to slow the flow of wind, in turn lessening the influence of the Coriolis effect. Thus ultimately the wind does tend to spirally slightly inwards towards the low pressure zone.  The effect of friction is more noticeable in the lower atmosphere, and in the upper troposphere the geostrophic motion approximation is more accurate, and therefore the pressure gradients will take longer to dissipate in the upper atmosphere than the lower atmosphere.

The force of friction is given by:

$$F = cV$$

where $c$ is a constant, and $V$ is the velocity of the wind.

4.  Gravity

Pressure gradients can also be sustained vertically, due to the influence of gravity.  When the force of gravity balances the pressure gradient, this situation is known as hydro-static wind balance, and is represented by the equation:

$$dP/dz = -{\rho}g$$

where $\rho$ is density of air, and $g$ is the acceleration due to gravity, which is approximately $9.8 m s^{-2}$.

Net Effect:

While I have already answered the question, I have decided include the equation combining all 4 forces for completeness.  Combining all these forces acting on the wind, the net acceleration of wind can be determined by the equation:

$$\frac{D\boldsymbol{U}}{Dt}=-2\Omega\times\boldsymbol{U}-\frac{1}{\rho}{\nabla}p+\boldsymbol{g}+\boldsymbol{F}_r$$

where $\boldsymbol{U}$ represents the velocity of the wind, and $t$ represents time.  The quantities in bold are vectors, and act in a specified direction.  (e.g. $\boldsymbol{g}$ acts vertically, where as $\boldsymbol{F}$ acts in the opposite direction to $\boldsymbol{U}$).  Below is in image of this:

This image shows how the forces act (excluding gravity) around high and low pressure zones.  PGF is the pressure gradient force, CF is the psuedo-Coriolis force and F is the frictional force opposing the velocity of the wind.  Note that the wind moves slightly in wards towards the low pressure region, rather than perpendicular to the gradient predicted by geostrophic motion.  This is due to the frictional force.


Why do some parts of the West Coast of North America get hot later in the year than others?

I am not an expert, but ...

the pacific ocean has seasonal patterns:

You can think of the water coming from the North being colder, the one from the South warmer.
On top of that, then you have associated rainfall etc. that will affect the climate (it can work both ways, warmer water may mean more rain, then more cloud coverage so less solar radiation so slightly colder days).


The characteristic funnel of a tornado is caused by condensed water.  A tornado is a swirling mass of air with very high vertical vorticity and a corresponding drop in pressure.  Large tornados can have pressure deficits on the order of 100 hPa, which is significant compared to synoptic horizontal pressure gradients.  The drop in pressure causes air to expand and cool and if the air is humid enough this will be accompanied by condensation and the visible appearance of the funnel.

It is also worth mentioning that the visible tornado funnel does not have be in contact with the surface to be a tornado, it is only required that the surface wind circulation is connected.  In these cases the lowest part of the tornado may remain invisible.

As a tornado persists the funnel cloud can pick up debris (dust, dirt, plants, parts of destroyed structures, etc) and some of this debris can orbit the tornado (other parts may end up lofted into the upper troposphere or centrifuged out at low levels) adding to its visual presentation.


At what rate are the polar ice caps shrinking?

It's important to identify which ice.   Polar bears are arctic, and they hunt in large part on sea ice.   Arctic sea ice is decreasing and the most common point used for the disappearing arctic ice is the arctic sea ice minimum, meaning, the yearly low point, usually late September, so by that definition, we'd have an ice free arctic, you know, for a few days, but ice will form again as winter kicks in.

That loss of arctic sea ice probably won't kill "all" the polar bears but it would likely kill a fair share of them, making their hunting more difficult.   This has already started and will probably continue to get worse.

Also, arctic sea ice has virtually nothing to do with flooding cities.    Flooding of cities has to do with melting of glaciers on land - essentially water that isn't currently in the oceans but as it melts it adds to the oceans.   Also, warming oceans expand, so warmer water increases flooding too.

As far as the timing of the ice free arctic minimum, it's very hard to predict due to natural variability year to year, but 40 years doesn't seem far off - at least, looking at the trend, but there's also no guarantee the trend will be consistent.

It's gone from the 8 million square miles plus range into the early 70s into the 4s and 5s millions recently, dipping below 4 million in 2012 but rising back above that 2013-2014.  2015 we haven't hit the minimum yet so it only goes up to 2014 for yearly minimum.

If there's a mechanism that helps retain ice, such as cold water currents near the pole or a weakening of the warm Atlantic gulf stream, that could extend the ice quite a bit longer.   It could also happen quite a bit sooner than 40 years if we have a few more years like 2012 or 2007, each year showed a significant and unexpected reduction in minimum ice cover compared to previous years.

A rather famous sea ice prediction was done by Professor Wieslaw Maslowski who in 2007 predicted we could see an ice free arctic by 2016 plus/minus 3 years - which Al Gore later quoted and said "there is a study that says we "could see" an ice free arctic by 2013 and the deniers have loved referencing and misquoting that quote ever since.   I think Maslowski's predictions moved later a few years shortly after, but nobody remembers that.  Everybody remembers 2013, though he actually said 2016 plus/minus 3 years.    Ironically, we could still see a big sea ice drop by 2019 and in that case, Maslowski wouldn't be far from wrong, but his is still one of the most made fun of predictions in all of science.

Maslowski's estimate was more aggressive than anyone else, but that doesn't mean he did bad work.   I've never looked into the specifics, but there's a ton of articles, some less friendly than others, on his 2016 plus/minus 3 years (which some people simply refer to as a failed 2013 prediction)  Here's one

Also an ice free arctic in late summer means sea ice will still form in fall and stay through the winter and spring, so Polar bears will still likely have some sea ice to hunt from long after the "ice free arctic" happens, but the warming in general makes their survival more difficult and that's likely to continue and get worse.

As far as flooding cities, sea ice doesn't raise sea level, so that's a different subject.   That has more to do with the melting of glacial ice on land, primarily Greenland and Antarctica.    The melting of entire glaciers is on a whole different timescale and the melting of all of Antarctica might never happen, even in worst case global warming models, at least, it might not happen until Antarctic drifts off the south pole into warmer waters, but that's several million years away.    Parts of the Antarctic glacier could melt and parts have already melted, but only a teeny tiny percentage so far.

The IPCC forecasts for sea level rise includes both melting glaciers and warming and expanding oceans and they predict maybe 2-3 feet by 2100 (or 1-3 feet, depending on who you ask).   Compared to that, if all the glaciers melted, we could expect a sea level rise of about 230 feet, so clearly, nobody is predicting glaciers will melt completely anytime soon - not for many hundreds if not thousands of years, but those predictions are even more difficult.

But like sea ice predictions, glacier melting predictions are hard to estimate by trend cause the ice can give way more quickly or more slowly depending on a variety of factors.   Precise predictions are enormously difficult and not guaranteed to follow trends from the past.

There's no shortage of articles to be found on sea level rise as well.

This is, of-course, one of the problems that a good climate scientist faces.   "When will that happen?" - The honest answer is, we don't know, we can predict about when it's likely to happen, so the skeptic says "so you don't know."- which misses the point entirely.    There's no question bad things will happen as a result of climate change.   It's just hard to predict exactly what will happen or exactly when.


What is the natural replenishment rate of oil?

Almost nil on human time scales.

The total estimated reserves (this number keeps changing over time) are of the order of 300E9 m^3. For convenience lets say all of this oil formed over the last 300 million years at a constant rate. Then the rate of formation is  1000 m^3 per year or ~6000 barrels of usable oil.

This obviously is a simple back of the envelope calculation and doesn't account for oil that has been lost/degraded/converted to other hydrocarbons over time. Also the rate of formation varies a lot (depends on climate, position/structure of plates and what not).


What is the time period of these chalk/clay layers?

The layers correspond to thousands of years, i.e. 23,000 years in the Danien timeline:
The page sais that there is a variation of 23,000 for precession of the equinoxes and 100,000 for variation of ellipticity. https://planet-terre.ens-lyon.fr/image-de-la-semaine/Img421-2013-04-15.xml


I believe what is being referred to here is the problem of determining where, in a continuous deposition sequence, a particular geologic time transition occurs.  If you have uniform depositional conditions you look for a transition in fossil communities that have been agreed on as marking the transition.  Life is not so simple and you could have a delta sequence overlaying a deep water deposit. Obviously the geologic aeon does not change everywhere at the contact between clay and sandstone and one must determine where in the clay the line is to be drawn and where in the sandstone.  On a larger scale a time boundary that, in the type section, starts or ends at an unconformity needs to be more precisely defined so that correlations across geologic provinces can be made.


How do scientists confirm iron core at the centre of the earth?

This is more a geophysics than an astronomy question—and thus the available methods of investigation are greatly increased. An Earth model also is not a one-person-show based on one measurement, but requires many different measurements from different fields with greatly different methods which form a unique picture which leaves only few possibile explanations which fit all observations.
One of the easiest methods to investigate the interior of the Earth is seismic sounding. Investigations of the deep interior of the Earth use teleseismic, which means we scan the seismic velocity of Earth by using the seismic waves generated by an Earthquake. The time-of-arrival of the different direct but also reflected waves at the different seismometers all over the world—or the absence of any arrival at all—allows to get a quite detailed mapping of the interior structure in terms of seismic velocities as function of depth and also whether the material is liquid or not. This already gives you the principle structure of Earth with a mantle with many of its different layers and the existence of an outer, liquid core and an inner solid core, e.g. see the 40 year old preliminary Earth reference model. See also the outstanding answer to this question about seismics and the video by the answerer or a newerver version of it.
Measuring density is much more complicated and needs a detailed analysis of Earth's rotation, deriving the moments of inertia to as many degrees as you can get. However from that you get a good indication that the center has to be much denser than the crust and mantle. There's a lot of work on that, as a random paper the one by Kennet (1998) might give some overview.
This paragraph is now extremely abridged, yet still: With knowledge about density and seismic velocity you already have a very good handle and constraint on the mineralogy or chemistry. Especially with some knowledge about equations-of-state of the materials the choice becomes very limited. In laboratory setups you can create high-pressure and high-temperature configurations and measure the properties of the materials—including their seismic velocity, be that directly or indirectly via their Young modulus and poisson number etc (some links in this answer by user20217 to a similar question). Assuming that the whole solar system formed from one primordal cloud, the chemistry should be pretty uniform—and that also means that iron is missing in the materials on the Crust and mantle—and iron incidentially fits magnetic observations (we have a magnetic field!) and the requirement for a heavy core very nicely. It also is logical as heavy elements tend to sediment towards the centre in a differentiated body.
As such to answer your question: it's not a hypothesis, it's a well-established theory backed by a multitude of greatly different observations which require the existence of a a liquid outer core and a solid inner core, which both consist of a iron with some nickel and traces of other heavy elements mixed into it.


ERA-Interim how to select only grid-points over land area?

The simplest way is to download another variable in which data is only available over the ocean, such as Sea Surface Temperature (SST). You should be able to download it in the very same way you do with precipitation (let us call it PREC hereafter).

Then, you can use any software that handles this type of data (Matlab, Python, NCL, GrADS...) to mask out the ocean cells. The logics is to assign a missing value (NaN) in PREC, where SST is not a missing value, to get the land-only PREC (PRECL). Or the other way around: keep the values of PREC where SST has missing values.

Imagine SST and PREC are 2D fields, that is, PREC=PREC(y,x) and SST=SST(y,x), where y and x are indices for latitude and longitude coordinates. In Python, the code should read something like the following, given that you have PREC, SST fields and the lat and lon arrays of coordinates as Numpy arrays.

import numpy as np

# Initialize variable with shape of PREC, filled with missing values:
PRECL = np.zeros(np.shape(PREC))
PRECL.fill(np.nan)

# Check the content of each cell in SST, to decide about PRECL:
for x in range(len(lon)):
    for y in range(len(lat)):
        if np.isnan(SST[y,x]):
            PRECL[y,x] = PREC[y,x]
        else:
            PRECL[y,x] = np.nan


I presume you mean if one were a substantial distance away from a lightning strike in the mountains, would it be heard better or worse by another observer the same distance away in the plains and foothills? It depends whereabouts in the mountains this lightning strike occurs and where the observers or listeners are.

If it occurred between two rocky ridges forming a V shape with the open end directed toward the plain, it is likely that the observer on the plain would hear it more clearly than an observer or listener the same distance away in the mountains. The very mountain walls which reflected the sound toward the plain would act as barriers to listeners placed, let's say, 10 miles away in the mountains to either side. This is called acoustics.

One can also imagine an acoustic layout in which the mountain observer would hear the strike more clearly and loudly, but on balance the plains observer would be more often in a position to hear the thunder clearly. My own observations of thunder in the mountains and coastal areas of Brunei and Sarawak would seem to bear that out


What sort of geological features would you look for to find copper?

Two types, low volume high concentrations, and vice versa. For high concentrations start with gravity mapping, and check out high Bouguer anomalies. Generally speaking basic and intermediate igneous, and metamorphic terraines are a better bet than sedimentary terrains - though circulating groundwaters and water-rock interaction can produce local copper shows almost anywhere. Regional mapping of surface water and sediment chemistry should highlight the areas worth exploring. Search for oxidized copper minerals like malachite, azurite, brochantite, etc.

In Australia one of the richest copper mining areas was famously discovered by a dog chasing a rabbit into its' hole. The dog owner found malachite in the excavated spoil of the rabbit warren.

On the big industrial scale, (high volume, low grade) look for copper porphyry of Andean type, which should be obvious from general geological mapping.

A crude but novel way of exploring is to dump bits of scrap iron in local streams, then check them out a few weeks/months later to see if iron-copper exchange has occurred.


How much does the productivity of modern agriculture depend on Glyphosate?

Chemistry is not a bad thing; life depends on it. And just because a pesticide or herbicide is natural or synthetic has practically nothing to do with its toxicity. Many so-called natural or organic pesticides are many times more potent than widely-used synthetic ones, as this article mentions.As to whether or not Glyphosate is necessary, this article explains some of the economic impacts from an outright Glyphosate ban. Some of the effects include:...French research institute Arvalis suggested a ban would cost that country’s agriculture industry 976 million euros ($1.1 billion). And in Germany, the Kleffmann Group said restrictions could hurt barley and corn output—with profit margin shrinkage between 40 and 70 percent–as farmers start planting alternative, more profitable crops.

Meanwhile, in the United Kingdom, where in 2014 2.2 million hectares of farms—a third of arable land—was treated with glyphosate, Oxford Economics estimated the impact would reduce wheat yields by 12 percent, oilseed/rape yields by 14 percent, and cereal production by 15 percent. Agricultural contributions to the nation’s GDP would shrink by about £930 million ($1.23 billion).In another article I recall reading (but can't find the citation for), Glyphosate is applied at a rate of only one pint per acre. Farms are not drenched in it as many anti-Glyphosate advocates would have us believe.As to whether or not Glyphosate is a carcinogen, this article calls much of that into question. Apparently, there were individuals involved who might have benefited substantially by having Glyphosate declared a human carcinogen.Edit:Some other interesting articles:This article  from Factcheck.org had this interesting tidbitQ: Does the herbicide glyphosate cause cancer?

A: There is evidence to suggest it may cause cancer at very high doses, but not at the low doses typically found in foods.and
The European Chemicals Agency...concluded in March 2017 that “the available scientific evidence did not meet the criteria to classify glyphosate as a carcinogen.”And this article from the-scientist.com said A new study has found no conclusive link between exposure to glyphosate—the main ingredient in a popular weedkiller—and cancer.And Reuters in this piece  said:
The World Health Organization's cancer agency says a common weedkiller is "probably carcinogenic." The scientist leading that review knew of fresh data showing no cancer link - but he never mentioned it and the agency did not take it into account.


Strangely bright morning twilight over Switzerland

If these were polar stratospheric clouds, that could explain a brighter than normal sky either before sunrise or after sunset.  The higher the clouds are, the more lead/lag time you will have to observe the phenomena before the sun comes into view.  The reason for this is simply that the clouds are in direct line-of-sight with both you and the sun, but you and the sun are not in line-of-sight.  The sun illuminates these clouds and being cold icy clouds they reflect much of this light to your eyes.  100% of the light you see is scattered giving the light a diffuse glow.

Unfortunately, I'm not aware of any stratospheric forecast products for these clouds.  The closest thing is an analysis of the 450 K $\theta$-surface showing area within the polar vortex with temperature at or below -78 C.  These depict the area within the polar vortex that are favorable for polar stratospheric clouds.  However, these do not show where the favorable area is, nor give an indication if these clouds will actually form.  You can view the northern hemisphere plots here.  The other stratospheric products deal with the size of the polar vortex, UV-B penetration and ozone analysis which do not aid in the forecast of these clouds.


The spiraling cyclone track - Cyclone Nathan

Hurricanes backtracking and looping seem to be quite common in the Atlantic (Nadine, Jeanne, Alberto, Dennis), and West Pacific (Ernie, Nari, Fung Wong, Parma, Roke) but not so much in the East Pacific (where the tracks are way more linear, with much less latitudinal change).

In general, tropical cyclones are steered by the global wind field. The environmental wind field (winds that surround a hurricane) guides a cyclone along its path. Hurricanes are steered predominantly by winds in the upper atmosphere, especially winds from about 3000 to 10000 meters above sea level. High-pressure and low-pressure systems often cause cyclones to divert from their initially east-to-west movement. When a high- or low-pressure system is located to the west and extends far enough latitudinally, storms are blocked and a change in direction may occur.

In the case of Tropical Cyclone Nathan, there seems to have been a stationary high over southwestern Australia on 12 March 2015 that connected with another high to the north and prevented the movement of the cyclone. The presence of Tropical Cyclones Olwyn and Pam probably influenced the change in path.

.

Nathan started to move north as Pam was moving south (13 March) and then went east without that much obstruction (14-15 March). As the high pressure to the south moved east, there was a clear path for Nathan to continue moving west (18-March).


How do I represent wind direction on a UTM (Universal Transverse Mercator) map projection?

Meteorological winds are referenced from North being 0$^{\circ}$ increasing in a clockwise direction.  Additionally, they are named for the direction the wind is coming from.  Your vector on the map, which is mathematically 45$^{\circ}$ is meteorologically 225$^{\circ}$ aka a southwesterly wind.

A 0$^{\circ}$ wind is a wind from the north (math vector 270$^{\circ}$).
A 180$^{\circ}$ wind is wind from the south (math vector 90$^{\circ}$).
A 50$^{\circ}$ wind is from the northeast (math vector 220$^{\circ}$).

In general if $\alpha$ is the mathematical angle and $\beta$ is the meteorological angle, then the relation between the two conventions is given by $$\alpha = 270^{\circ} - \beta$$ where angles are specified in degrees.

Image from https://www.e-education.psu.edu/meteo300/node/719 from Penn State available under CC-by-nc-sa-3.0


Does the Earth 'Flare' like the Sun does?

The medium for a solar flare is plasma, so nothing like that occurs in the Earth's core. The outer core fluid is highly conductive and has a low viscosity, so changes may occur in the core's field, but the mantle has enough electrical conductivity to filter out the more rapid changes (those with periods of roughly a year or less). See Merrill and McElhinny pp 49-51 for details. However, geomagnetic jerks have been observed. These are abrupt changes in the second time derivative of the Earth's magnetic field. Sometimes they are global, although mantle filtering can delay the jerk by different amounts at different locations on the Earth's surface.


Has a hurricane or cyclone ever reformed after passing over a large land mass?

Since you don't seem interested in Atlantic-Pacific crossovers, of which there are several good examples.....

2004's Hurricane Ivan made landfall on the Gulf Coast, degraded into a tropical depression and was eventually declassified while crossing the southeast US. After coming back into the Atlantic, Ivan tracked back south, re-formed into a tropical depression, then hit the Atlantic coast of Louisiana.

The key was the southward track in the Atlantic. Hurricanes weaken when they're that far north; they're away from the warm ocean waters that generated them in the first place.  But because Ivan tracked south into warmer waters it was able to strengthen a little. It may have been pushed by a cold front. But also, the next hurricane, Jeanne, was already approaching Florida, so Ivan may have been sucked into the circulation around it. Jeanne did its own loop-de loop out the in the Atlantic, so the jet stream may have affected both.


How is this crumbly crystal-rich rock formed?

Even rocks that have lasted for billions of years decompose when exposed to Earth's weather.

What you have is indeed granite, but a somewhat decomposed granite, which is treated by geologists differently from the intact, solid stuff.  The "crumbly bits" have their own
name: grus.

Granite is made of crystals of different minerals  (mostly feldspar and quartz) that grew into each other as the parent magma cooled. The final rock is solid because of the irregular way the crystals fit into each other.

Granite weathers in several different ways. Cracks can form from hot and cold cycles. However, chemical weathering is the principal way granite becomes crumbly.  Rain frequently picks up some acidity from the atmosphere, and infiltrates the granite. This acidic rain reacts with the feldspar and mica to produce clay minerals, primarily kaolinite.

This in turn makes it easier for water to get in the granite, and combined with heat cycles the process accelerates.
As a result, the joints between the crystals loosen up, producing rock in the same condition as your rock.


Is this what is meant by a phenological season?

The seasons used by indigenous Australians could be classified as a phenological season system.

Depending on the "home range" of each grouping, the year is divided into three to six seasons which are defined by weather and activity by flora and fauna - ecological knowledge.

The CSIRO in Australia has more extensive information about indigenous seasons.

The indigenous seasons in the State of Victoria.

A useful video giving a limited explanation of the some the complexity of the season recognized by different indigenous groups.

The six seasons of the Kakadu region and seasonal ‘calendars’ of Indigenous Australia.


Why would channelizing a river reduce any nearby wetlands?

Channelizing a river keeps it from overflowing its banks as often, which prevents flooding.  However, wetlands need a certain degree of said flooding to function as a biome.


What's the official reason why it became so hot in the Kola borehole?

Unfortunately, you intuition about subterranean ground temperatures is incorrect.
Basements and cellars do provide cooler conditions to store perishable items because the near surface rock insulates against surface heat.
Go deeper however and temperature increases. Near the Earth's surface, within the crust, and away from tectonic boundaries, the rate of temperature increase, due to the geothermal gradient is  25–30 °C/km. The geothermal gradient increases with depth.

Most of the heat is due to the decay of naturally radioactive elements,mostly within the mantle.

Heat flows constantly from its sources within Earth to the surface. Total heat loss from Earth is estimated at 44.2 TW.


Which particles are classified as PM2.5? How exactly is this defined?

I think answering your questions in reverse will make more sense. The "size" of PM is typically the aerodynamic/inertial impaction size, as you guessed. My standard reference for this is this paper. Their figure 8 is a rough schematic of where particles of different size deposit in the lungs. Things with very large or very small inertial impaction size get filtered out by the nose and upper respiratory system. (The "very small" inertial impaction I would consider as the fuzzy boundary between particles and gases, and gases adsorb onto mucous.) It's the particles with an aerodynamic size smaller than 2.5 microns that follow the airflow all the way from the nose and mouth into the lungs. So from a health perspective, aerodynamic size is what matters most.

Similarly, most measurements of particulate matter filter them by size first, and those filters are based on how much they deflect when the airflow has to curve around a bend. So when measurements focus on PM2.5, that's also anything with aerodynamic radius less than 2.5 microns. They might later do optical scattering or other analysis, but AFAIK the aerodynamic filtering always comes first.

I would say that PM2.5 is everything 2.5 microns and smaller, and PM10 includes all of PM2.5. When scientists want to differentiate the two, we usually use the terms for the different "modes": coarse mode for ~1-10 micron, accumulation mode for ~.05-1 micron, and nucleation or Aitken mode for anything smaller. (Fine particulates are nucleation+accumulation.) The reason for PM2.5 including everything is that PM2.5 standards are focused on the mass concentrations, usually in micrograms/cubic meter. The total mass in the nucleation mode is typically negligible compared to the other two. (The number concentrations particles in the nucleation and accumulation modes might be similar, but the masses are way different.)

Edit: I don't think I made this clear, but the reported air quality value for PM10 would include PM2.5, but if something is reported as "coarse particulates" it would be (PM10-PM2.5). You may also see a quantity TSP - total suspended particulates - which may include things even larger than PM10 that are being kicked up by particularly strong winds, or smoke and ash from nearby wildfires.


How much do tides affect earth's rotational velocity?

This question is handeled pretty throughly in Physics site;
https://physics.stackexchange.com/questions/214042/earths-kinetic-energy-change

Your question; "How big is the difference?"

Body Tides Summarize
0.3 ms for a 14 day period.
0.16 ms for a 28 day period
0.14 ms for 1/2 year period
0.02 ms for a year period.
0.126 ms for Lunar node period; (18.6 years)

Ocean Tides
Max 0.05 ms for a 14 days period
0.026 ms for a Years period
0.024 ms for lunar node period


The freezing point of carbon dioxide is -78.5C.

The temperature at which carbon dioxide sublimates is not a fixed value. It instead is a function of the partial pressure of carbon dioxide. That value of -78.5° C is the temperature at which CO2 sublimates given a partial CO2 pressure of one atmosphere. The temperature needed to have CO2 sublimate given a partial pressure of 40 pascals is much lower than that.

The Clausius-Clayperon relation can be used to estimate the temperature at which a substance will sublimate for a given partial pressure. Using the parameter values for CO2 from James et al., I get a temperature of 131 kelvins (-142° C) for the sublimation point of CO2 at a partial pressure of 40 pascals or 0.4 millibar. Using a slightly different parameterization, Agee et al. calculate that a temperature of 133 kelvins (-140° C) is needed to make CO2 sublimate from our atmosphere.

  Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica?

Carbon dioxide levels are very low during glaciations (colloquially, ice ages, but we're in an ice age right now). Using the parameterization from James et al. yields a temperature of 127 K (-146° C) as the sublimation temperature for a partial pressure of 18 Pa (0.18 millibar), or 180 ppm CO2. The Earth cannot get that cold, so no, ice ages are not affected by the freezing out of CO2 in Antarctica.

References:

Agee, Ernest, Andrea Orton, and John Rogers. "CO2 snow deposition in Antarctica to curtail anthropogenic global warming." Journal of Applied Meteorology and Climatology 52.2 (2013): 281-288.

James, Philip B., Hugh H. Kieffer, and David A. Paige. "The seasonal cycle of carbon dioxide on Mars." Mars (1992): 934-968.


What natural phenomena increase stratospheric ozone?

Like BarocliniCplusplus said, ozone is generated when you have a single free oxygen atom. This can come from photolysis of O2 in the upper stratosphere, or photolysis of ozone itself, or photolysis of NO2 in the troposphere. The stratosphere gets its NO2 from the breakdown of N2O by other radical species. But NO and NO2 both react with ozone, typically destroying it.

So if you want a natural process that would enhance ozone, I would look for a process that reduces the amount of N2O (or other ozone-depleting species) reaching the stratosphere. N2O is produced by bacteria in soils, so anything that suppresses that production -- especially in the tropics -- would enhance stratospheric ozone. Carbonyl sulfide (OCS) is another species that only photolyzes in the stratosphere and depletes ozone; its concentrations would similarly decrease if there were a decrease in transfer of it from ocean to atmosphere (it's a product of plankton). You could also have a meteorological effect that suppresses deep convection in the tropics, though I can't offhand think of what this would be.

If you're interested in understanding the specifics a bit more (I'm not great at summarizing all of the cycles involved), I recommend checking out http://acmg.seas.harvard.edu/people/faculty/djj/book/bookchap10.html. Daniel Jacob is a pretty influential atmospheric chemist, and he put his whole book online.

NB: NO2 destroys ozone in the stratosphere, but typically enhances ozone in the troposphere. This is because the troposphere has much, much higher concentrations of organic species and the hydroxyl (OH) radical. Instead of depleting O3, the NO produced when NO2 photolyzes can react with HO2 to re-form NO2 and OH, so the ozone-depleting nature of NO is reduced. Since that process re-forms OH, OH can attack organic species and leave the H radical, which then pulls in O2 to form HO2, which will later end up producing an odd oxygen and thus form ozone. (Sorry if this is a bit rambly. I haven't tried to summarize all of this before, so let me know what things are confusing.)


Are high velocity winds, or the lack of wind, the most common cause for low visibility?

Light or calm winds do not cause reductions in visibility, but stronger winds will generally be associated with better visibilities. Poor visibility is more likely in a humid, polluted air-mass than a clean dry air-mass.

Reductions in ‘visibility’ or visual range are caused by the scattering and absorption of radiation by atmospheric particulates or aerosols. This attenuation of radiation will depend on the type, size and concentration of these particulates or aerosols. In a humid airmass water droplets can form on certain types of aerosols and these droplets can increase in size as humidity increases.

Strong winds will tend to mix the polluted air near the surface with cleaner air aloft. This mixing will also create a more uniform profile of temperature and humidity in the lowest portion of the atmosphere. If there are light winds overnight, the air near the surface becomes cooler and more humid than the air aloft. The pollutants become concentrated in this cool stable layer of air near the surface.

There are exceptions, namely advection or coastal fog. In far north-east of the U.K it’s not that uncommon to see fog with 20-30 mph winds during late spring and early summer.

https://www.metoffice.gov.uk/learning/fog


What is caesium-137 used for in fracking?

Caesium-137 is not used in the fracking process.

Caesium-137 is used as a source of gamma-rays in some logging tools, most notably the density tool (one example), and some other instruments such as flowmeters. This is what the story you linked to is about. Logging tools are used after drilling to measure the properties of the rocks in the borehole, and thereby calibrate geological models of the subsurface. These sources are valuable, and should be secured and only handled by trained engineers. The caesium is completely enclosed in the tool, and none is left in the subsurface, unless something goes badly wrong with the logging process and a tool is lost.

Caesium-133, the naturally-occurring non-radioactive isotope of caesium, is sometimes used in drilling and fracking fluids in the form of caesium formate brine. Its high density (ca. 2300 kg/m³) improves drilling efficiency and rig safety, and assists with pressure build-up for induced fracturing. It's still pretty valuable stuff, so companies often rent it, retrieving as much as possible (5–15% losses are common, however) and paying only for what they use. Cabot is one vendor of such brines.


Reference units for CO2 concentration in the atmosphere and meaning of a slight downward tendancy during the 1600

The file you provided do not have metadata nor context, which make it pretty much useless as it is.

But, by reading the title and as you suggested, we can assume that the unit used in the sheet is mole fraction of $CO_2$ in air.

Also the value of the data is fitting the range of the $CO_2$ historic measurements on Earth.

By definition, a mole fraction is the ratio of mole of a given component (solute) over the total mole count in a target solution. In our case, this mean:

$mole\:fraction\:of\:CO_2= \frac{measured\:CO_2}{total\:mole\:in\:the\:sample\:solution}$

This is well expressed and explained here in the section titled: Parts per Million by Volume (or mole) in Air

  In air pollution literature ppm applied to a gas, always means parts per million by volume or by mole. These are identical for an ideal gas, and practically identical for most gases of air pollution interest at 1 atm. Another way of expressing this value is ppmv. One part per million (by volume) is equal to a volume of a given gas mixed in a million volumes of air:
  $1\:ppm = \frac{1\:gas\:volume}{1\:million\:air\:volume}$ at 1 atmosphere pressure.

Thus a simple conversion can be applied and the equation solved, knowing the weight of a mole of $CO_2$ and the typical weight of air. To answer your question, mole and volume are interchangeable in this context.

This would be my honest take, considering the limited available information.

About the downward tendency during the 1600: This was around the time when the Little Ice Age began; There was the Maunder minimum (first low) due to a solar spot low and then a small peak and then the Dalton minimum (second low) before the present peak. Here is an example of how low the sunspot activity was at that time (especially Maunder) from Britannica.com

Consequences of those two events, detectable already during Maunder was a trend of global cooling and a diminution of the atmospheric $CO_2$.


Why are there more intense earthquakes in Iran than in Iraq?

These two images probably explain it best:

This is a map from the US Geological Survey Earthquake Hazards Program, which shows all recorded large earthquakes in the region from 1900 to March 2012.

The black lines are tectonic plate boundaries. The plate in the middle is the Arabian Plate. The current movement of that plate is show in this image from mediawiki:

So the Arabian plate is currently pushing north against the Eurasian plate, and sliding under it, causing uplift in Iran, and probably causing various slip and thrust fault lines. The pressure on those fault lines is released as earthquakes.

Iraq is not so affected, because it is on the plate. Maybe it will be in a few hundred thousand years :)


Why does the earliest sunset time not coincide with the shortest day of the year?

If you follow the sunset timing for the equator you will notice that although the day remains pretty much the same all year round, the sunset moves up and down twice a year. The biggest difference is about a half hour.

This is due to the changing speed of the orbit of Earth. Earth's orbits is slightly oblong. Therefore on the longer parts the planet picks up speed. Which means that although Earth made a full rotation, since it is further in its orbit it is still seeing the sun.

This happens twice, on both longer stretches of the orbit. However the effect on one is more pronounced than the other. This is because in one leg Earth is speeding away from the sun, which slows it a bit, and in the other it is coming toward the sun.

The longest and shortest days are on both points of the oblong circle but the later sunset is before that point.


Is cloudfraction a proper measure of gaseous data expanse?

No, cloud fraction is not a good measure of $\ce{SO_2}$. Clouds are functions of moisture, temperature, and cloud condensation nuclei. Som of the other variables, such as (but not limited to) ColumnAmountSO2 or ColumnAmountSO2_TRLare better indicators.


OilPrice

Petrochemicals are used to make numerous products.

Source


Why does the intensity of sunlight depend on your latitude?

As noted in the comments, this answer applies to things like sun-bathing and solar panels, but it does not apply so much to a specific point-receptor like an eyeball. If all objects in question are pointing directly at the sun, then the angle of incidence is equal for all of them and this answer does not apply.

For an optic facing its target, the amount of atmosphere that the light passes through is a very large influencer. At higher latitudes, the sun is not directly overhead, and so the light is not coming straight down through the path of least atmosphere. Instead, it comes in at an angle, passing through more of the atmosphere before it gets to you.

For sun-bathers, solar panels, and the ground in general, the sunlight absorbed and reflected does depend very much on what is described in this answer. For that reason, more expensive solar panels are mounted on devices which alter their angle to face the sun for increased light exposure. And a sun-bather could likewise increase their exposure by mounting their platform at an angle. This is the direction the rest of the answer will take.

The answer is similar to the answer to some other questions, such as "Why does the solar power intensity change with the season?" and "Why does the solar intensity change with the height of the sun in the sky (ie: with the time of day)?"

The very short, non-technical version (tl;dr)

Each unit (think "beam of sunlight") is spread over a larger area.

That might not seem intuitive at first, but that is the answer in a nutshell. To see why, continue to the long version.

The mechanics of the situation

The sun is huge, but at great distances it can be thought of as a point-source of light. The sun emits light in every direction, so its energy, the electromagnetic radiation, can be thought of as beams of sunlight coming out from it in every direction. However, the farther away you get, the fewer of those sunlight beams cross your path, and if you get far away you can see, from the below illustration, that the lines which cross your path are becoming ever more parallel and directional.

However, the sun is very, very, very far away - many millions of miles (and kilometers) away. At this distance, the electromagnetic radiation is all arriving at roughly parallel trajectories. That is, the light reaching us can be viewed as coming from a directional light source; it's all going in the same direction. You will see my crude illustration of that coming up after the next picture, but first...

When this happens, the angle at which the light arrives relative to the surface of the earth that it is arriving at, known as the angle of incidence, is what makes all the difference here. In the image below, we have light arriving from the left, perhaps from a flashlight(s), and two objects we want to see. The surface of the object below will be illuminated more, but the surface of the object above will be illuminated less.

Notice the object above gets 2 units of light to illuminate its entire surface, whereas the object below gets 5 units of light for its surface.

Looked at another way, the object above has to spread 2 units of light across its entire surface, where the object below gets that same amount of light concentrated on only a smaller part of it.

Now back to Earth

We see the same thing happen. Notice in the below picture that I have labeled the diameter of the area covered by my arbitrary unit of light. The distance is literally measured in image pixels. Near the equator, 1 unit of light illuminates 27 pixels, but closer to the pole the same amount of light needs to be spread out over 61 pixels of Earth's surface, so it's illuminated less.

And that is the answer to the question, and the related questions mentioned in my introduction.

Some specific calculations

The specific ratio of illumination difference for the two areas in the above image would be (approximately) simply the division of the two numbers.

The area closer to the pole is getting 27/61 as much light per longitudinal unit cross-section (a north/south strip of land) as the area closer to the equator, or 0.4426 times as much light.

Or, in the other direction, the area at the equator is getting 61/27 as much light, or 2.26 times as much light. So the equator area is getting more than twice as much light.

We can easily see from this why the sun might appear very much brighter or dimmer depending on the angle, and therefore depending on the latitude. This also explains the temperature difference: the equator is receiving a lot more energy, so it gets hotter.

Answer applied to seasons

I said earlier that this also answers the question about the illumination change for the seasons. The only extra bit of information that we need to understand that is this: Earth's pole around which it revolves is not perfectly perpendicular to the direction that the light is arriving from. Because of this, the specific angle changes as Earth orbits around the sun. The orbit around the sun takes a year (That's what a year is, by definition), so this change of angle over time has a yearly cycle during which the angle of incidence (the fancy term from above again, which just means "the difference of angle of the light to the object it is hitting") changes. This change is large enough to further change the sunlight that we receive, in the exact same way as discussed above.

Further notes about temperature

Just like before, this also affects temperature. The temperature, however, cannot be calculated by a simple ratio of area coverage. The temperature is affected by multiple other complicated systems. One of the major temperature influencers is the weather. Another of which is the difference between energy absorbed and energy lost (a physics thing: Earth is not a "black body" radiator).

Weather affect on temperature is very complicated and would require its own post much longer than this one, but to sum it up super succinctly: stuff like the wind and rain and such change the temperature and also move it around.

The physics black-body thing likewise would require its own long post, but again, super succinctly: Earth is also putting out its own energy into space at the same time it is receiving energy from the sun, and the affect this has on temperature is a fine balancing act. Once that balancing act tips to one side, the temperature swings way over in that direction: during the spring when temps are rising the energy absorption is enough higher than the energy radiation that the temperature rises, and the opposite is true for autumn when temps are falling.

The above descriptions for both weather and block-body radiation are way oversimplified.

That's it

And now the answer applies fully to seasonal changes as well, and it applies not only to illumination but also to temperature. I will leave it as an exercise for the reader to think about the daily affect (Why is it so much easier to look at the sun when it is low on the horizon just before it sets?)

And, as stated before, there are other influencers for these things; this just happens to be the biggest one.


Where can I get hourly ambient temperature for each county in United States?

You can get this from the Integrated Surface Dataset (ISD).

First get a list of all weather stations from ftp://ftp.ncdc.noaa.gov/pub/data/noaa/isd-history.txt:

stations = pandas.read_fwf("ftp://ftp.ncdc.noaa.gov/pub/data/noaa/isd-history.txt",
                           skiprows=20, parse_dates=["BEGIN", "END"],
                           skip_blank_lines=True,
                           dtype={"WBAN": "O"})

Then select the ones in the USA:

stations_us = stations[stations["CTRY"]=="US"]

That give us 7326 stations.  Although the state of each station is described, the county is not.  To get the county you will need to combine the lat/lon for each station with a county database.  That is a bit beyond the scope of Earth Science SE, but maybe you can get help at GIS SE.  The station ID is a combination of two fields:

ids = stations_us["USAF"] + stations_us["WBAN"]

We can then download the measurements for a particular year from AWS S3:

meas = pandas.read_csv(f"s3://noaa-global-hourly-pds/2020/{ids.iloc[200]:s}.csv", parse_dates=["DATE"])

And extract temperatures:

temps = meas.TMP.str.extract(r"([+-]\d{4}),([012345679ACIMPRU])")[0].astype("f4")/10

Let's get the valid ones (there's a 9999 fill value) and plot:

valid = temps<999
meas[valid].set_index(meas.DATE[valid])["temps"].plot()

Enjoy!

For a description of the fields, see the ISD Format Document at https://www.ncei.noaa.gov/data/global-hourly/doc/isd-format-document.pdf .


Atmospheric Carbon: Whence the discrepancy?

There's no discrepancy here.  The first graph (total emissions from fossil fuels and industry; Fig. 4a of Le Quéré et al, 2016) is an input to the system, and the second graph is a proxy for the amount stored in one part of the system (the atmosphere).  For the latter, it probably makes more sense to look at the total atmospheric growth rate (Fig. 4c of Le Quéré et al), which has remained positive for decades.

Note that when you add in emissions from land-use it's likely that the total emissions have continued to increase.  But that doesn't detract from the main point here: if you keep putting stuff in the bucket, the amount in the bucket will continue to increase.  You don't need to invoke any feedbacks for that to happen.


Is there a way to tell whether land is cleared from forest, or naturally bare?

Just by looking at a treeless region it would be difficult to know whether it was naturally treeless or whether the lack of trees was due to human actions. The history of the region would need to be known.

In Scotland, due to the extent of glaciation during the last ice age some of the ground was scoured, leaving bare rock when the ice finally melted.

With soil removed there is little opportunity for trees to develop deep roots and establish forests.

Loss of soil can result from natural causes and human actions. The area around Queenstown, Tasmania, in Australia is now denuded of trees due to a combination of logging and sulfuric acid rain from smelter fumes that killed the then existing trees followed by heavy rainfall washing away the soil from the steep terrain.

One of the best ways to tell if an area is naturally bare is to leave it allow for at least several decades so that no humans can do anything to it. If trees naturally return to the area, that area once was capable of having a forest. If trees do not grow, the area either never had a  forest  or it has been so badly degraded that  trees can no longer grow there.

Despite the environment carnage experienced by Queenstown, Tasmania during the 19th and 20th centuries and the subsequent lack  of soil, if left alone, trees will try to grow in the area.


Why more matters appear in hot equator, when they should flow to the cold poles?

This is very simple to explain when we consider that the 'model' you have been presented with is a gross oversimplification - a one dimensional mechanism. But the Earth is a multi-phase (air water ice), three dimensional system in which convective currents circulate. Hence there is a counterflow of both air and ocean currents in addition to the basic entropy model. The entire thermal circulation is also massively influenced by considerations of conservation of mass, conservation of energy, and conservation of angular momentum. Its a pretty complex system, as climate modellers are only too aware, and cannot be reduced to any simple model.


Is this possible?

Definitely.

  I know you can get sparks from some rocks and minerals - but granite boulders [?]

Yep. Quartz is one of those minerals that "sparks". It is piezoelectric, and triboluminescent.

Here's a wonderful video of this phenomenon: https://commons.wikimedia.org/w/index.php?title=File%3ATribo.ogv

Granite is a rock which has plenty of quartz in it. By definition, granite has more than 20% quartz.

  underwater!!?

Why not? Those are properties of the quartz itself, not the surroundings. The light does not come from electric arcing of the air, it comes from electronic processes occurring within the crystal. The fact that there's water around it probably does not matter.


The specific humidity q is a quotient - mass of water vapor in mass of moist air. The mass is expressed per volume, i.e. the density of water vapor $\rho_v$ and the density of dry air $\rho_d$ are used for the definition of the quotient $q$ known as specific humidity:

$$ q = \dfrac{\rho_v}{\rho_v+\rho_d} $$


Why don't green house gases escape into space?

The reason the atmosphere (including GHGs) stays attached to the earth is gravity. This is called the Hydrostatic Equilibrium. There is one GHG that this does not fully apply to: water vapor. While water vapor can be considered to be in hydrostatic balance, the fact that it undergoes a phase change (and becomes dissociated if it reaches too far up) prevents it from being more evenly distributed vertically like $\ce{CO_2}$ or $\ce{CH_4}$.


Venice has plans for a new hydraulic flow controlled by levees and a dam during runoff & tidal events as sealevel continues to rise.

This has a brief summary of progress: https://www.citylab.com/life/2016/09/venices-vast-new-flood-barrier-is-almost-here/498935/

[edit]
The context of Venice has 3 parts, the freshwater seasonal and episodic flow including groundwater in a relic delta, this with enough fetch to sea  allowing winds to pile water for days, and, there are seasonal tides with that.

The almost complete solution deals with sediment compaction separately from defense against high water, those solutions have injection strategies, they're dealing with pore-pressure, flow and having clean water in the canals or they stink.

My view, it's analogous to the high water dam against the North Sea that's closed for storms.

Long-term a dam at Gibraltar Strait, 1200-ft deep has been proposed to save history, otherwise we hit 3mm in a year in 2016 of rise, at 600-ppm Antarctica's land ice begins an unstoppable melt as is going on with submerged valley glaciers.

To the question of littoral habitat that's ok unless there's an oil spill, pollutants in runoff are poisoning it pretty fast being an enclosed sea vs oceanic facing littorals from my reading.


Can impact events cause widespread volcanic activity on the other side of the planet?

Note: this is a part answer, based on recent research and modelling

There has been considerable research recently in what is known as antipodal disruption, in particular, a group from Princeton University have produced a model that overcomes the main deficiencies of commonly used models that have the Earth as a 'featureless sphere' (1)(2).  Simulations using a symmetric spherical Earth produce a deceptively large peak at the antipode (2) - this is often cited as being some form of proof for the P-T example that you provided in the question and an antipodal relationship between the Deccan Traps and the Chicxulub crater (1).

However, the Princeton team's simulation (1), (2) show that there ought to be an antipodal effect, but when the elliptical shape and the heterogeneity of the surface is taken into account - where the waves end up and their displacement when they get there are quite different to the spherical models (1), to the order of 4 times less displacement and the antipode effects are not on a point source (2).

This results in a disagreement with the Deccan Traps-Chixculub relationship, as shown in the late Cretaceous model below, from (1):

This has implications for not only seismicity, but for volcanism and hot spot activity, due to the modelled impact seismic waves (across the surface and through the Earth) showing to be unfocused and scattered, this results in less severe ground displacement, tsunamis, and seismic and volcanic activity than previously theorized. Their models showed that the antipodal region had 'chimneys' of peak stress, strain and velocity.

Meschede et al. 2011 (2) conclude from their model that there would be greater seismicity in the region around the antipodal 'chimneys', this increase in seismicity can trigger volcanism, and even though the impact energy has been modelled to be insufficient (by several orders of magnitude) to induce melting to form an antipodal hotspot.

Some ongoing research by Hagstrum, 2005 (3) has suggested that oceanic impacts may result in hotspot/large igneous province antipodal pairs, this is due to, according to Hagstrum, oceanic crust having a greater seismic efficiency that continental crust. The mechanism is, according to Hagstrum,

  an
  inherently antipodal mechanism of hotspot formation
  is proposed in which one hotspot forms at an oceanic
  large-body impact site and a second hotspot and
  possible LIP are formed from seismic energy focused
  in the lithosphere and upper asthenosphere at the
  impact’s antipode.

However, it is not clear if the non-spherical heterogenous nature of the Earth's lithosphere was taken into account, given that, as stated, the impact energy is insufficient to cause melting, Ivanov and Melosh (4) state that the seismic mechanism may contribute as a trigger for a "pregnant" hotspot to activate, not through melting, but through increased seismicity (fracturing rocks etc).

(Note, the use of "pregnant" is their words, not mine)

Conclusion

The models created by Meschede et al. (2) have found that it is theoretically possible for localised antipodal volcanism to occur, but this volcanism would not necessarily be the direct result of the impact itself, but due to the contribution of an increase in antipodal seismicity (increased earthquakes fracturing rocks in the lithosphere etc).

Meschede et al. (2) contend that their model indicates that the impact energy is very much insufficient to result in a sustained mantle plumes and hotspot volcanic regimes as in the previous models.  However, there is still ongoing research about the impact energy contribution to the formation of hotspots and 'traps', particularly for oceanic impacts (3), but this is very much uncertain (2) and unlikely to be the direct cause (4).

References

(1) Kelly, 2011, Impact study: Princeton model shows fallout of a giant meteorite strike, News at Princeton, Princeton University

(2) Meschede et al. 2011, Antipodal focusing of seismic waves due to large meteorite impacts on Earth, Geophysical Journal International

(3) Hagstrum, 2005, Antipodal hotspots and bipolar catastrophes: Were oceanic
large-body impacts the cause?, Earth and Planetary Science Letters

(4) Ivanov and Melosh, 2003, Large Scale Impacts and Triggered Volcanism, in Large Meteorite Impacts


Since it is not known at this stage what measures were implemented for each building in regard with eventual flood situations, it does not make sense to purposely exclude the buildings from the flood zone until some kind of general database with that info is built and put into context in your system. Even-more, a lot could happen in a potential flood zone when an extreme event occurs, regardless of the prevention plan by various owners and city management. A risk management model with proper risk probabilities, potential damages and monetary values would eventually be required to better represent the up-to-date context of the site.


How do long, thin, island chains such as North Carolina's outer banks, form?

The outer banks are, literally, a textbook example of what are known as Barrier Islands. They are thought to be formed through interactions between sediment undergoing longshore drift, coastal currents and seabed irregularities, but to spite a number of theories being put forward since the 19th Century we really don't understand their formation.
We do know that their ongoing behaviour makes them analogous to underwater sand dune systems in that:

the material in them is constantly on the move.
their form is controlled by the prevailing conditions.
they offer a degree of protection to the landscape on their inland side.
and
they are vulnerable to drastic alteration during extreme events such as storms or tsunamis.


Can there be ice in the core because of pressure?

what happens if you manage to add some water in the inner core or near it.

It will probably react with the solid iron to form iron (oxy)hydride:

Our observations indicate that H2O is likely introduced into the deep Earth through reaction between iron and water during the accretion and separation of the metallic core. Additionally, reaction between Fe and H2O would occur at the core‐mantle boundary, given water released from hydrous subducting slabs that intersect with the metallic core. Accumulation of volatile‐bearing iron compounds may provide new insights into the enigmatic seismic structures observed at the base of the lower mantle.

(source: https://doi.org/10.1002/2017GL075720)
In other words, the question of whether the water would be ice, liquid, or vapour is a non-question because water as molecules of H2O would cease to exist.
You don't need the core for this. Take water, put it on a piece of iron, and the water would be absorbed into the iron in the form of rust:
$\ce{Fe + 0.5H2O + 0.5O2 = FeOOH}$
Regarding the question of what would happen to just water if you would put it in core-like pressures and temperatures, the answer is simple: we don't know. I don't think anyone attempted that experimentally. It will probably not be a gas - pressures are way too high for that. Since the melting point of H2O is much lower than that of iron, I suspect it will be a liquid.
Something from the comments:

On quora, they said that high pressure would lower the melting point of ice, not as expected, probably making it vapor

This is only relevant at relatively low temperatures because of the anomalous crystal structure of ice. For most compounds, you need greater temperature to melt something which is at pressure. It's actually opposite for water, and closely related to the fact that ice floats on water (which is very counter-intuitive - usually solids are denser than liquids). But at high temperatures, of hundreds and thousands of degrees, water starts to behave normally under high pressure.


Rivers - How to calculate maximum velocity from average velocity in a cross section

The velocity profile that is shown is parabolic. It is characteristic of laminar flow in tubes or channels. A development of the equation is shown in this link. An exposition about flow in open channels is at this link.

The maximum velocity over the entire profile is at the surface (see Equation 4.7 and statement 17 in the first reference). The maximum velocity at an other range of positions as measured vertically from the bottom of the stream is always found at the top of the range (i.e. at the point closest to the surface of the stream).

Let's propose a velocity profile from the bottom to top of the channel as this.

$$ v(z) = Cz^2 $$

This satisfies the boundary condition that $v(0) = 0$ at the bottom of the channel. The parameter $C$ is found by taking one additional measurement anywhere in the stream. With this function, we find the average velocity over a range of positions $zo$ to $zt$ is an integral over the parabolic profile ...

$$ <v> = \frac{\int_{zo}^{zt} v(z) dz}{zt - zo} = \frac{C}{(zt - zo)} \int_{zo}^{zt} z^2 dz = \frac{C\left(zt^3 - zo^3\right)}{3\left(zt - zo\right)} $$

An alternative way then to find $C$ when given an average velocity over a range of distances is to use this expression.

A distinction is required to understand the average velocity expressed above. An alternative view of average velocity is from measuring at a set of points over a range $zo$ to $zt$ and then averaging the measured values. This measured average has the expression

$$ <v>_m = \frac{1}{N} \sum {v_j} $$

With $H$ as the height of the channel, in the limit that $zt - zo << H$, we can assume $<v> \approx <v>_m$. Otherwise, the better approach is to use a one-point method with $v$ at $z$ and the source equation for the profile.

Finally, consider when you have multiple measurements at different positions where the positions are not differentiated but the velocities are differentiated. One approach here is to average the velocities and use any one value to the profile for $C$. The better method however will use non-linear regression method to fit data. By example, consider this hypothetical "measured" data set generated using $v = 4 z^2$ as its base.

z=1, v = 3, 4, 5, 6

z=2, v = 14, 15, 16, 17

z=3, v = 32, 33, 35, 45

A plot of the data and a non-linearized regression fit to $v = Cz^2$ is shown below. The result is $C = 4.0 \pm 0.2$.


Does the extension of the absorption line of $\text{CO}_2$ with temperature play a role in the climate change?

No. Not in a significant way.

The full width at half maximum (FWHM) of a spectral line widened by thermal Doppler broadening is

$\Delta f_{\text{FWHM}}={\sqrt{\frac{8kT\ln(2)}{mc^{2}}}}f_{0}$

where $m$ is the mass of the emitting particle, $T$ is the temperature, $f_{0}$ is the frequency of the spectral line, and $k$ is the Boltzmann constant.

Let's look at the CO$_2$ absorption lines:

(Image from Wikipedia commons, source)

Let's take for example the band roughly between 12 and 20 $\mu m$. That corresponds to frequencies from 15 to 25 THz, with a mean of 20 THz.

If we solve the above equation for the mass of a CO$_2$ molecule ($44.01/6.02\times 10^{23}$ g), a frequency of 20 THz and an Earth's mean temperature of let's say 15°C (288.15 K) we get 1158 kHz broadening, and for an scenario 2°C warmer it would be 1162 kHz.

Therefore, the width of the absorption band would grow 8 kHz (4 kHz on either side). Which considering the original width of 10 THz corresponds to a 0.00008% increase. This could be roughly equated to an analogous increase in absorbed energy, which is absolutely negligible for all practical effects.


How much water will flow into the Caspian Sea if it is connected to the World Ocean?

Welcome to earth science stack exchange !

People living along the banks and flat hinterlands in the flooding areas will not be amused of such an enterprise. I would also say that sacrificing all that potentially fertile land might trigger protests. And as the Caspian water table reaches global sea level, power production will go down.

The mentioned canal would need locks to keep the water from flowing from the Black Sea to the Caspian because the Black Sea only has a ~50m layer of fresh water over a huge basin of anoxic salty waters that contain gases from the decay of organisms. The "interface layer" is unstable, raising it via an outflow of fresh water could eventually cause a release of gasses like hydogen sulfide in a larger scale. Also, the anoxic water below the boundary layer is highly corrosive to machinery.

Power generation with water in such a large scale is cheaper and more sustainable along fresh water currents or in tidal power stations.

Now that was not a real answer, that would have had some math like flooded area  * height difference(28m) * fudge factor for topography and a division by the cross section of the inflow to get a feeling for the time it would take to fill the pan, but it has some background on the setting we're talking about.

Hope that helps, if not, let me know :-)

Edit: i just realized that much of my answer is somewhat nonsensical because there is a water divide between the two water bodies from where it goes downhill to both sides. While a closed pipe could be imagined for a constant flow and to drive turbines, it doesn not seem very practical. But that's engineering, not my strength ...


Do seismic travel times from one location to another differ based on factors other than distance?

Yes

The biggest controlling factors are:

Distance
Velocity Model
Composition (though velocity model and composition are related)

I believe you understand the first factor, so I will focus on the other two. The most common GLOBAL velocity model is PREM, which is depicted below(Image Source):

Velocity models basically assume the internal P and S velocity structure of Earth. If the crust is thinner than average in the area where the source is, the arrival times will be faster than if the crust is thicker than average, though depending on the distance this could be negligible. This is because seismic waves travel faster in than they do in the crust, so the least time tends to involve travel through the mantle.

The other controlling factor is composition, or in other words, heterogeneities within the earth. Depending on the composition the wave travels through, arrival times could be slower or faster. For example, imagine an interplate earthquake traveling through a subducting slab and into a seismometer: the arrival times are slower because the wave speed of lithosphere is slower than the wave speed of mantle. In fact, its these deviations from our velocity model predictions that help us find heterogeneity in the earth to begin with! This is essentially how we find our natural resources, though instead of using earthquakes as the source we use man made active seismic waves.


Is 2015's record average temperature evidence that we are now experiencing runaway climate change?

Runaway climate change is, given our current state of knowledge, only something that could be confirmed in historic context - in the rear-view mirror. Inconveniently, there's likely to be a much-diminished version of human civilisation around to observe it, if and when it does happen.

In other words, it's too early to tell if we've passed a catastrophic tipping point.

We don't know what the equilibrium state of the Earth's atmosphere is. It will take 30 years for our current stock of GHG emissions to fully show its effects: and we'll be continuing to release GHGs for a while, so the equilibrium will continue to change.

But it's worth bearing in mind what we can do, when we really have to; World War II saw massive realignments both in industrial production and in expectations within a very short space of time: after decades of delay, it now seems likely that decarbonisation will require at least a similarly fast and large industrial realignment; and it is possible.


Why are January and February the coldest months although 21 December is the shortest day?

Short answer: air, land and water take a while to cool down (or rise in temperature; we see the same thing happening with July and August being the warmest months on average – not June, while June 21st is the longest day). In December, the fall just ended, and everything is relatively warm.
Also, depending on how far North you go, the difference between day length in December, January and February isn't that much. See this graph from Wikipedia:


How do Kelvin waves determine surface temperature variations?

Coastal trapped Kelvin waves are important processes contributing to variability in the sea surface height and temperature near the coast. Field studies have measured large temperature fluctuations mainly made up of low-frequency internal Kelvin waves mostly of semi-diurnal tidal period at the continental shelf on the great barrier reef (Wolanski, 1983). Because they are balanced by Coriolis, in the Northern Hemisphere they remain fairly stable if they are propagating towards the North if the coast is on the right, or to the South if the coast is to the left.

  My question is this: are Kelvin waves important in determining the surface temperature variations of regions that are, for example, on the west side of mountain slopes like the Andes or Rockies?

It is pretty clear that Kelvin waves and associated upwelling play a crucial role in introducing nutrients, larvae and other components into the ocean's coastal regions (relatively cold water). However, the connection between surface temperature variation in the coastal waters and the temperature in the regions west of mountain ranges you mention is not so clear.

One thing that could happen is that, because upwelling is associated with relatively cool water being introduced to the near shore from the deep abyss, the coastal marine layer will have a lot of moisture. As the moisture laden air traverses a coastal mountain range, it will rise due to orographic lift and cool adiabatically, thereby raising relative humidity all the way to 100% resulting in rain. So the coastal side is cool and wet, whereas on the other side of the coastal range it will be much warmer and drier.

Wolanski, E., and G. L. Pickard. "Upwelling by internal tides and Kelvin waves at the continental shelf break on the Great Barrier Reef." Marine and Freshwater Research 34.1 (1983): 65-80.


In the United States, mining minerals is similar to mining for precious metals (for the most part). You can establish a mining claim on a likely spot of Federal/State land and go to town. There are rules and regulations that guide the appropriate ways to establish, work and maintain a claim. You can also negotiate with a private land-owner for rights to mine on their land.

One step up is wholesale markets that sell mineral specimens (and all the items that go with them). There is a huge one in Tucson AZ in Jan/Feb with an amazing spectrum of stuff.

These markets are where most small retailers go to get their product.


Does Earth's magnetic field arise from a fission reactor in its core?

The conventional explanation for the Earth's magnetic field is that some combination of differential rotation and/or convection occurs in the Earth's outer core, primarily in molten iron-nickel (+ sulphur, hydrogen etc.), which acts as a kind of dynamo. Whilst we can't prove it by direct observation, this seems an eminently plausible mechanism. If this is true, then the heat of the core will eventually dissipate, resulting in freezing of the core and cessation of the Earth's magnetic field. The existing heat is partly primordial and partly radiogenic from the decay of U, Th and K, and will take many billions of years to dissipate.

The georeactor hypothesis requires a critical mass of uranium at the centre of the Earth to start up and maintain a nuclear reaction. There are two reasons why this hypothesis is seldom taken seriously except by Herndon himself. Firstly, in order for uranium to reach criticality it has to be a very high concentration of uranium. There is no known concentration mechanism which could achieve this in the Earth's core, whereas there are many reasons to believe that the uranium would be dispersed or 'poisoned' by lead and other heavy metals. Whilst the pressure at the Earth's core would be immense, gravitational separation, i.e. density fractionation, would be almost non-existent. Secondly, if this hypothesis was correct we would expect to see a huge flux of anti-neutrinos in such detectors as the super Kamiokande. We don't. So I'm not losing any sleep at the prospect of the Earth losing it's magnetism within the next billion years.


Will dust storms be more frequent in the future?

Most dust storms occur down-wind from areas with a lack of moisture, little vegetation, and high soil content.  Vegetative roots help to keep the soil intact when there is a lack of moisture. So any shift in the future that leads to a net decrease in vegetation, net decrease in precipitation, or an increase in exposed soil content will increase dust storm occurrence.  Thus, the most plausible reasons for increased dust storms in the future that have related scientific research are:

land-surface changes due to human influence: forests/vegetation being replaced by land management practices for agriculture or mining that do not sustain roots in the soil or expose more soil
decreases in precipitation (e.g. due to climate change) that potentially lead to desertification of the region.
diversion of rivers for human use, thereby removing water from any ecosystems that were previously downstream
extreme cataclysmic events (e.g. comet impact or nuclear war) that causes removal of most vegetation

So, in my opinion, it is a very real possibility that if humans continue to cause a net decrease in vegetation... there will be increases in dust storms.  However, there are good land management practices that can curtail dust entrainment into the atmosphere, such as those adopted after the historic 1930s "Dust Bowl" in America.

Finally, from IRO-bot's comment link to Wikipedia dust storms:

  It has been argued that recently, poor management of the Earth's drylands, such as neglecting the fallow system, are increasing dust storms size and frequency from desert margins and changing both the local and global climate, and also impacting local economies.


Why does exhaust smells linger some days?

You can see this post for a more detailed discussion, but the typical answer to your question is air stagnation.  When the atmosphere is stable, there is little mixing, and the air can stagnate.  Typically this coincides with low wind speeds and a low boundary layer.  The boundary layer holds air near the surface like a blanket. The boundary layer collapses overnight, becoming shallow, and grows when the sun heats the surface of the Earth.  So, in the morning, the shallow boundary layer allows less vertical mixing to occur.

You might be noticing that on cloudy days, when clouds are low, there is little wind and no solar heating.  Air pollution has no place to go, so it sticks around.

Another aspect is that vehicles emit more emissions under cold-start conditions.  This is because vehicles get cold overnight and take a while to get up to normal temperature when they startup in the morning.  The cold vehicle will have a low combustion efficiency and catalytic converters won't work as well.


If I can drill a hole to mantle, does it form a volcano?

As Bon says, the mantle is solid, albeit somewhat viscous / plastic under the prevailing pressure and temperature conditions, so your hypothetical borehole isn't going to puncture any liquid magma chamber. Could it liquify if suddenly depressurized in a borehole? I doubt it, although it might do so if there was a local concentration of volatiles to depress the melting temperature.

But the question is forever going to be hypothetical because there is no drill string capable of cutting into the lower crust, let alone the upper mantle. The heat would soften the drilling bit to the point where it was like putty. Also, the lateral rock pressure would be so high that the borehole walls would implode.


Where can I find a data set containing wetland loss by decade

Start with US Fish and wildlife services National Wetlands Inventory site.
Site has links to :

Wetlands Mapper.
National Wetlands Inventory home page
Status and Trends web page
Download Seamless Wetlands Data


What was the lowest temperature ever recorded on the surface of Earth?

The wikipedia article List of weather records explicitly states

  This list does not include remotely sensed observations such as satellite measurements, since those values are not considered official records.[1]

Reference 1 in that article, a web archive link to a page on World Meteorological Organization Global Weather & Climate Extremes, adds that (emphasis mine)

  Although claims of a "world-record coldest temperature" have been made for a remote-sensed location in Antarctica, the WMO official coldest temperature remains -89.2°C (-128.5°F) recorded on 21/7/1983 at Vostok, Antarctica. Official weather measurements are made at using standard equipment at a fixed height of between 1.25 m (4 ft 1 in) and 2 m (6 ft 7 in) above the ground for a fixed location over a specific length-of-record. Remoted-sensed values of temperature are not at this time regarded as official weather measurements.

There are many reasons why remote sensed temperature values (especially extreme ones) should not be considered as official with regard to record temperatures. First and foremost, those remotely sensed values are not measuring temperature. They instead measure proxies for temperature in the form of intensities of electromagnetic radiation in various frequency bands in the thermal infrared. The surface temperature is derived from these observations by a complex set of algorithms that make various assumptions regarding the nature of the sensed data.

These algorithms need to be calibrated against ground truth. These is no ground truth data for temperatures that low. The interpreted data were well outside the sensors calibrated rate. Moreover, the "ground truth" data is actually the recorded temperature at 1.25 meters to 2 meters above the ground. Official weather stations are supposed to be slightly elevated to avoid boundary layer effects. The sensed data on the other hand are primarily  a result of surface temperatures, confounded by the fact that snow is a lousy thermal infrared emitter ("a good reflector is a lousy emitter") and confounded by contributions from the atmosphere between the surface and the satellite.

That said, those satellite readings almost certainly do indicate temperatures well below the reading at Vostok that officially counts as the lowest temperature recorded on the Earth.


How accurately can explosions be triangulated from the IRIS seismogram data?

David Salzberg and Margret Marshall suggest that using green receiver functions (which might make more sense given how we determine the difference between explosions and earthquakes) can locate a detonation in North Korea with up to 0.5 km accuracy. I am assuming that IRIS data sets carry enough information to make receiver functions, as I think triangulation may require a much larger event than a single nuclear warhead (not sure about this point) to be very accurate.

For a little background on how we determine if an event is a explosion or an earthquake (I know this isn't part of the question, but still useful for others) we look at "beachball" diagrams(from csegrecorder.com):

As you can see, the "beachball" diagrams are visual representations of the three linearly independent stress vectors or moment tensors. I may be getting these colors reversed (so someone check on it) but "white" means dilation and "black" means compression. A fault rupture will have some compression and some dilation, meaning some "white" and some "black", but an explosion will appear to be fully compressed because an explosion pushes on every direction. Think about a slinky: when you push on it, there is compression, and when you pull on it dilates. So an Implosion, that pulls everything towards one point, would be extensional, and thus be fully "white".


How do you calculate the depth of penetration in a Schlumberger array?

Short answer: 0.2 times the total length of your cable(s).

100m rollout --> ~20m depth

Bear in mind that the deeper you get, the more you have to be careful with your data interpretation. Also if you do a roll-along your depth doesn't get deeper.

Long answer see Bernard J (2003): Short note on the depth of investigation of electrical methods. Heritage Geophysics.


Is wave spectrum always positive and why?

Yes, wave variance or energy spectrum, direcional or non-directional is positive-definite as @aretxabaleta said in the comment.

In linear water-wave theory, the surface elevation is described as a linear superposition of sinusoids:

$$
\eta(t) = \sum_{i-1}^{N}a_i \sin(f_i t + \phi_i)
$$

where $a_i$, $f_i$ and $\phi_i$ are the amplitude, frequency and phase, respectively, of each wave component $i$.

The most commonly used wave spectrum is the wave variance spectrum. Wave variance is:

$$
\langle\eta^2\rangle = \dfrac{1}{2N}\sum_{i=1}^{N}a_i^2 = \sigma^2
$$

and wave variance spectrum $F(f)$ is defined such that:

$$
F(f)\Delta{f}=\dfrac{a_i^2}{2}
$$

In the limit of $N \rightarrow \infty$ (continuous spectrum), the following holds:

$$
\int_{0}^{\infty}F(f)df = \sigma^2
$$

Being quadratic, both wave variance (spectrum integral) and individual discrete spectrum components are positive-definite.

Note that so far we implied non-directional frequency spectrum, i.e. spectrum defined in frequency space. It can be also defined in wavenumber $k$ space, and the following holds:

$$
\int_{0}^{\infty}F(k)dk = \int_{0}^{\infty}F(f)df = \sigma^2
$$

$$
F(k)\Delta{k} = F(f)\Delta{f}
$$

$$
F(k) = F(f)c_g
$$

where $c_g$ is group velocity of an individual component.

The non-directional spectrum is simply an integral of directional spectrum over all directions:

$$
\int_{0}^{\infty}F(k)dk = \int_{0}^{2\pi}\int_{0}^{\infty}F(k,\theta)dkd\theta
$$

Be careful about units here. All spectrum integrals must come up at $m^2$. Thus, $F(k)$ has units of $m^3$ and $F(k,\theta)$ has units of $m^3$ $rad^{-1}$.

If you are considering polar (spectral bins scaling with $k\theta$ instead of $\theta$) directional wavenumber spectrum such that:

$$
\int_{0}^{2\pi}\int_{0}^{\infty}F(k,\theta)k\ dk\ d\theta = \sigma^2
$$

then $F(k,\theta)$ has units of $m^4$ $rad^{-1}$.


What does slat and elat (slon, elon) in latitude and longitude values mean?

This might be product specific, but if it's anything like my MODIS experience this refers to start and end latitude and longitude. Are you looking at a small region on the Mississippi/Louisiana border?


Are we entering a new Ice Age according to Milankovitch cycles?

It thus seems reasonable to say we are entering another Ice Age according to Milankovitch cycles.

Some of the Milankovitch conditions would appear to make the Earth ripe for a new glacial epoch starting now, or perhaps a few hundred years ago. In particular, aphelion occurs in early July, and obliquity is low. Both of these make for mild northern hemisphere summers, a key condition needed for snowfall from the previous seasons to linger into fall.
But one other key Milankovitch condition needed to make snowfall linger, orbital eccentricity, argues against a new glacial epoch starting now. The low (and decreasing) eccentricity makes the current dip in summertime insolation at high northern latitudes too small of a dip to trigger the onset of an glacial epoch. Look at the graph you posted in your question. Glacial epochs start when summertime insolation at high northern latitudes drops to very low values. The current local minimum is not low enough to enable widespread accumulation of snow and ice over the summer.

Some of you may cite the current anthropogenic climate change as a rebuttal, but for the question's sake, just ignore it.

Even without anthropogenic help, the current interglacial is likely to last for 50,000 years [Berger and Loutre]. With anthropogenic help, the current interglacial may even last indefinitely [Steffen].

Throughout geological history, Earth has seen far lengthier and more widespread glacials than interglacials. Indeed, interglacials are just short blips in the geological history.

That is true only for last 2.58 million years, possibly the last 34 million years. The Earth has been ice-free for most of the last 550 million years. Ice ages (periods during which ice can form, intermittently, are just short blips.

References:
Berger, André, and Marie-France Loutre. "An exceptionally long interglacial ahead?." Science 297.5585 (2002): 1287-1288.

Steffen, Will, et al. "Trajectories of the Earth System in the Anthropocene." Proceedings of the National Academy of Sciences 115.33 (2018): 8252-8259.


The apparent anomaly, known as the Lunar Terminator or Moon Tilt Illusion, is indeed a matter of perspective. A brief explanation can be found here: http://chrisjones.id.au/MoonIllusion/

The essence: 'The illusion occurs when the moon and sun are separated by a wide angle, so that they are perceived relative to the horizon, as if in a panorama. A panoramic photograph is a cylindrical projection. In this projection, most straight lines project as sinusoidal curves. The moon-sun line is curved, unless the moon and sun are on the horizon or directly above one another.'

A long, technical explananation is in the PDF The moon tilt illusion. Quoting from page 21:

  Modern cameras use lenses whose properties are designed to deliver a rectilinear
  or curvilinear image.  Rectilinear lenses reduce barrel or pincushion distortion from
  the image but such lenses are difficult to manufacture for the wide angles (90°
  and above)  needed  to  record  both  the  sun  and  the  moon  on  a  single  photograph.   A
  photograph [3]  of  the  moon  and  sun  at  an  azimuth  difference  of  80°
  containing  a
  leaning  tower  and  unnaturally  leaning  trees  illustrates  the  difficulty  of  eliminating
  distortion in a wide-angle photograph

That reference [3] is to A Different Moon Illusion on Jerry Lodriguss astrophotography site Catching the light where he shows and explains the exact same situation (picture taken from there):


Why is Massanutten mountain so dramatically different than surrounding mountains?

If you look a wider view from above and a bit to the west, you will notice Massanutten is not that straight nor is it unique most of the surrounding mountains are the same, especially to west. Basically you camera is pointed in exactly the wrong direction to see the other mountains.

on a geologic map it becomes even more obvious.

A false color which hides the difference in plant life makes it even easier.

You can picture the appalachians as a flat section of rock that has been compressed like an accordion east to west, that's why they are more or less parallel, but not perfectly parallel becasue the rock is not completely uniform in strength or hardness. Plus the compression has a bit of a curve to it making it even less uniform.