In what geological situations can I find gold?

I think Azzie's answer describes the situations where gold is formed and found as Lode deposits. But native gold in lode can then be subject to weathering when it is exposed, which releases the gold into the environment as flakes, grains and nuggets. This gold is then subject to erosive and sedimentary processes.

As gold is denser than most minerals it can often be concentrated by sedimentary processes as Placer Deposits, where the gold is concentrated by gravity. Dense gold quickly settles out of a water column, and lighter minerals are winnowed away. These accumulations of gold can then be economically mined using Placer Mining techniques such as Gold Panning. The Witwatersrand Basin in South Africa is an important palaeo-placer deposit from which nearly 50% of all of the gold ever mined has been obtained.

Alluvial placers are formed by the deposition of dense particles at a site where water velocity remains below that required to transport them further.Typical locations for gold placer deposits are on the inside bends of rivers and creeks, in hollows, at the break of slope on a stream or the base of an escarpment, waterfall or other barrier.

The vast majority of the Earth's gold and other heavy metals are locked up in the Earth’s core, being a dense material most of the gold is thought have sunk to the centre of the Earth as the core formed. Though there is 1000 times more gold in the Earth's silicate mantle than would be expected. Evidence from tungsten isotope studies indicates that most of the gold in the mantle and crust (which we can access) is derived from gold which arrived during the Late Heavy Bombardment some 3.9 billion years ago.(BBC Article 1) Which has been called the Late Veneer Hypothesis.(BBC Article 2)

Future mining of asteroids for gold and other metals has been proposed,(Reuters Article) with estimates that there are up to 20,000 million tonnes of gold in the near-Earth asteroid Eros, with an estimated value of $1,000 billion (1999).(BBC Article 3)


Did global warming cause the extreme cold 2013-14 winter in North America?

I bet you live on the eastern half of North America, which had a cold winter of 2013-2014, Europe and Alaska had a very warm winter, and China had its second warmest January.

Jennifer Francis of Rutgers has been advocating the Arctic or Polar Amplification theory (Wikipedia). In which she hypothesises that warming of the Arctic has been greater than lower latitudes, and this lowers the temperature contrast between the poles and the equator. This in turn weakens the jet stream which becomes slow and meandering. This weakened and meandering jet stream then is less able to hold back cold polar air, the so called "polar vortex" which can then bring outbreaks of cold air from the poles to the mid latitudes.(BBC Article outlining the theory)

However, the theory is not without some problems...

  One problem is that the changes in atmospheric thickness and wind
  speed observed have become apparent only since the mid-1990s, which
  gives fewer than 20 years of data to work with. Another difficulty
  concerns the blocking patterns. Dr Francis’s theory suggests there
  will be more of them in future, as the world warms. But climate models
  unanimously disagree, saying that global warming will produce fewer of
  them...(The Economist)

and...

Tim Woollings, an atmospheric dynamics researcher at Oxford University pointed out in an email exchange that over the Atlantic the jet stream was stuck, but was not meandering or slowed, however he did concede that the jet stream over the Pacific did match the hypothesis.(Yale Environment 360) The jet stream over the Atlantic reached sustained speeds over 230 miles per hour (370 km/h) during the winter,(Liam Dutton) reaching  275 miles per hour (443 km/h) on 22 December 2013. 30% stronger than the normal jet stream.

So yes, there is a theory which describes how warming can bring locally colder winters, but also, the science isn't exactly settled yet.

Addendum: here's a link to a good blog post on the matter Polar Amplification, Vortex Disruption to Set off Extreme Weather Events For US, UK Yet Again

An overview of the debate as of 2016:Wapo 2016


The factor of 1000 may be related to the expected units. The mass 'units' can be found in the derivation.
The full derivation of mixing ratio goes like this
$$w=\epsilon\frac{e}{P}$$
since, by the ideal gas law,
$$e=\rho_vR_vT$$
and
$$P_d=\rho_dR_dT$$
then the mixing ratio is expressed as
$$w=\epsilon\frac{\rho_vR_vT}{\rho_dR_dT}=\epsilon\frac{\rho_vR_v}{\rho_dR_d}$$
Since $\epsilon=\frac{R_d}{R_v}=0.622$ (see above hyperlink),
$$w=\frac{\rho_v}{\rho_d}$$
To return back to the question 'what is the difference between your two equations?' The units reported are $g/g$ and $g/kg$ for the first and second equations, respectively.


Why do crystals, like quartz and diamonds, form in different colors?

The reason minerals like quarts and diamonds vary in color is generally caused by the chemical elements involved while the crystal is being formed.

Chemicals
Different colors can be created by different chemicals. Amethyst for example has traces of iron built into its crystalline structure giving it a purple hue. Iron can also give crystals a yellow hue.

[edit: See Gimelist's answer for a much more detailed and colorful explanation]

Growth Imperfections
Some colors, like in smoky quartz, are from growth imperfections. These imperfections change the way the crystal reflects light, which changes the appearance of coloration.

Light
Part of the color seen when looking at a crystal is light. When light enters a crystal its spectrum is broken apart, and part of it is absorbed while other parts are reflected. This changes the apparent color of the crystal.


When there is snow on the ground, can a hurricane still form?

First off, hurricanes form in tropical seas over warm water. In general, they form in places where it never snows at all. Also, they form over the ocean, and it is hard to have snow on the ground in the ocean. So in that sense, the answer is: No, hurricanes cannot form in a place where there is snow on the ground.

However, you may mean to ask can a hurricane show up to a place where there is snow on the ground. This is a little more difficult.

Wikipedia's off-season Atlantic hurricane page lists 21 hurricanes that formed in Dec-Feb. Of special interest is the 1952 Groundhog day tropical storm which hit Cape Cod on Feb 4th and Maine Feb 5th of that year. Hyannis, MA had 2 inches of snow on Jan 28th of that year, which melted by Feb 1st (temp data found here). It dropped to 30 degrees F the night of the 3rd before the hurricane hit.
The airport in Bangor, ME had snowfall the 28th and 29th of January which persisted on the ground until the 3rd of February. The night of the 4th dropped to 21 degrees F before the hurricane hit on the 5th.

In both cases, temperatures got into the 40s and heavy precipitation while the storm was passing assuredly melted the snow on the ground. But in that sense of your question: Yes, hurricanes can strike somewhere with snow on the ground, although the warm air and rainfall of the hurricane will probably melt that snow.


Is there a reliable way to identify regions with negatively-correlated winds?

My suggestion would be to do a Principal Component Analysis (PCA) or Empirical Orthogonal Functions (EOF) analysis on the wind data. The result of the analysis would be a set of modes of variability. You would be looking for modes that show areas that are large in magnitude but out of phase. As for the time scale, you need to check the eigenvectors and eigenvalues of the analysis to determine the scale of temporal variability.

You can find appropriate code in many places, for instance here.


How is the total area of the world's oceans 361 million sq km?

Commenter Universal Learner points out "Currently NOAA says there is only one ocean"

https://oceanservice.noaa.gov/facts/howmanyoceans.html

and "At the comments of the question I linked you can read a great: "I once heard a lovely description of the world's seas (by a polar scientist) as "One ocean with three big estuaries" ;-) "

  While there is only one global ocean, the vast body of water that
  covers 71 percent of the Earth is geographically divided into distinct
  named regions. The boundaries between these regions have evolved over
  time for a variety of historical, cultural, geographical, and
  scientific reasons.

  Historically, there are four named oceans: the Atlantic, Pacific,
  Indian, and Arctic. However, most countries - including the United
  States - now recognize the Southern (Antarctic) as the fifth ocean.
  The Pacific, Atlantic, and Indian are known as the three major oceans.

  The Southern Ocean is the 'newest' named ocean. It is recognized by
  the U.S. Board on Geographic Names as the body of water extending from
  the coast of Antarctica to the line of latitude at 60 degrees South.
  The boundaries of this ocean were proposed to the International
  Hydrographic Organization in 2000. However, not all countries agree on
  the proposed boundaries, so this has yet to be ratified by members of
  the IHO. The U.S. is a member of the IHO, represented by the NOS
  Office of Coast Survey.

And they have a graphic saying 1 world ocean.  Historically 4 basins.  Now 5 basins. And that the boundaries aren't agreed upon by all countries. Though that text refers to a basin as an ocean, so their terminology doesn't quite match their graphic.


The easiest global sea surface height database is from Aviso: http://www.aviso.oceanobs.com/en/data/products/sea-surface-height-products/global.html
Aviso has been distributing Topex/Poseidon and ERS altimetric data worldwide since 1992.


Saying that warm air "holds" more moisture is technically incorrect, but is a common colloquialism. Let's break it down to the technicalities.

Let's consider a glass of water with a vacuum (no air) above it. What will happen? The molecules that are at the top most layer of the water will evaporate. At what rate will the water evaporate? Better yet, what is evaporation?

Evaporation is when the water molecules gain enough kinetic energy (how fast they vibrate) to break the bonds that hold them to one another. Kinetic energy is dependent on temperature. So the molecules vibrate faster, break their bonds, and enter the vacuum as a vapor. Some molecules will stay as a vapor in the vacuum, but others will reenter the liquid. When the molecules enter the liquid as fast as they are leaving, then it is saturated.

If the air is cooled down, then the rate at which molecules leave the liquid slows down. The molecules entering the liquid do not slow down at the same rate, causing the liquid to grow toward it's initial state.

Note that I specifically said it is a vacuum. Instead of a glass of water, picture the water as little drops. The atmosphere can act to warm or cool these drops, and vice-versa.

In the more nitty-gritty aspect of this, the equation that describes the vapor pressure as a function of temperature is called the Clausius-Clapeyeron equation/relation. The American Meteorological Society has one approximate solution, but I prefer this equation: $$e_{sat}(T)=611 Pa \exp[\frac{L_v}{R_v}(273.15^{-1}-T^{-1})]$$, where $L_v$ is the latent heat of vaporization, $R_v$ is the specific gas constant for water vapor, and $T$ is the absolute temperature in Kelvin. Combined with the ideal gas law for water vapor (assuming saturation) $$e_{sat}(T)V=m_vR_vT$$, and given the volume ($V$) we can write an expression for the mass of water vapor $m_v$. The equation comes out to $$m_v=611 Pa \exp[\frac{L_v}{R_v}(273.15^{-1}-T^{-1})]V R_v^{-1}T^{-1}$$

To answer your final question, the molecules are approximated as being infintessimally small, per the ideal gas law. To be more specific, one molecule of water is about 7.08$\times$ 10$^{-19}$ cubic feet (after some math), so the added volume is considered negligible. In short, the molecules are treated as point masses.


Is the association of fluorescent minerals calcite, fluorite, and apatite with fluorescent rare-Earth minerals a coincidence?

The answer to your question is probably the second:

  Or do REEs only modify the color of their fluorescence, but not necessarily cause it?

I will give an example of apatite. Here's a cathodoluminescence (luminescence excited by electrons) energy spectrum of a natural apatite. Source.

You can see several different rare earths triggering the luminescence, but there's also manganese. Apatites from granites usually have lots of manganese, and very little rare earths. So their luminescence would be dominated by the 2.1 eV range, which would be yellow. In contrast, apatite from REE deposits would be dominated by Ce, giving a blue-violet colour. They will also have lots of Nd, but that does not help us because it's in the infra-red range.


How and where do double-terminated crystals form?

Double-terminated crystals can from by crystallizing from a melt. The crystallization nucleus has to float freely in the magma chamber. As long as no other crystals obstruct the growth the crystal will grow in its own characteristic form (euhedral). This happens for example with feldspar crystals. (Example: http://www.erdwissen.ch/wp-content/uploads/2010/12/granit-feldspat.jpg)

If the crystal forms in a fluid cavity it can form double-terminations when it doesn't grow with the c-Axis normal to the wall. Sometimes crystals also grow with their c-Axis parallel to the wall (Example: http://wannenkopfe.strahlen.org/titanite.html). Probably super cooled pegmatitic melts also form free floating double-terminated crystals like tourmaline.

On the smaller scale (microscope and electron microprobe) double terminated crystals are pretty common in metamorphic rocks. Sections cut parallel to the stretching lineation (or the lineation which elongated crystals aligned themselves to) will show many porphyroblastic crystals with double-terminations.


Does the Composition of Rock Near the Epicenter Affect the Effects of an Earthquake?

The soil and rock type are one factor that determines the amplification of the shaking.  In general, the softer the underlying material is the greater the shaking.  This table, from the USGS, presents the velocities of 5 soil types in the San Francisco Bay area and their shear velocities.

  Soil type A   Vs > 1500 m/sec Includes unweathered intrusive igneous
  rock. Occurs infrequently in the bay area. We consider it with type B
  (both A and B are represented by the color blue on the map). Soil
  types A and B do not contribute greatly to shaking amplification.

  Soil type B   1500 m/sec > Vs > 750 m/sec Includes volcanics, most
  Mesozoic bedrock, and some Franciscan bedrock. (Mesozoic rocks are
  between 245 and 64 million years old. The Franciscan Complex is a
  Mesozoic unit that is common in the Bay Area.)

  Soil Type C   750 m/sec > Vs > 350 m/sec  Includes some Quaternary (less
  than 1.8 million years old) sands, sandstones and mudstones, some
  Upper Tertiary (1.8 to 24 million years old) sandstones, mudstones and
  limestone, some Lower Tertiary (24 to 64 million years old) mudstones
  and sandstones, and Franciscan melange and serpentinite.

  Soil Type D   350 m/sec > Vs > 200 m/sec  Includes some Quaternary muds,
  sands, gravels, silts and mud. Significant amplification of shaking by
  these soils is generally expected.

  Soil Type E   200 m/sec > Vs  Includes water-saturated mud and artificial
  fill. The strongest amplification of shaking due is expected for this
  soil type.

The slower the shear wave velocity, the greater the shaking.

Source: https://earthquake.usgs.gov/hazards/urban/sfbay/soiltype/

Additionally, the composition of the rock that the seismic waves are travelling through is a major factor in determining the speed of the waves.  Two rock properties that determine the speed of the waves are reflection and refraction:

Reflection

  When a wave encounters a change in material properties (seismic
  velocities and or density) its energy is split into reflected and
  refracted waves.

Refraction

Source: http://eqseis.geosc.psu.edu/~cammon/HTML/Classes/IntroQuakes/Notes/waves_and_interior.html

There are many factors involved in determining the magnitude of an earthquake with underlying sediments and rock being one of the major factors.  This is not an exhaustive list of all those factors but hopefully it points you in the right direction for an answer to your question.


Looking at ocean depth/latitude profiles of dissolved oxygen and nitrate. Why is dissolved oxygen low when nitrate is high?

In general the relationship between dissolved oxygen and nitrate is complex. While in areas of water mass formation, especially in the Arctic and Antarctic Oceans, nutrient concentration and dissolved oxygen can be high, water mass evolution and biological activity can rapidly modified these concentration. The relationship is affected by several factors including: 1) the age of the water mass: the "older" the water mass (longer time since in equilibrium with atmospheric oxygen), the lower the dissolved oxygen concentration; and 2) the proximity to primary productive areas like the surface: the higher the primary production, the lower the nitrate concentration.

In some parts of the interior of the Atlantic Ocean, the water masses present (North Atlantic Deep Water, Antarctic Bottom Water) are pretty old and haven't been in contact with the surface layers for a while, so their oxygen concentration is high while they remain nutrient rich. The water masses in the surface layers have recently been in contact with the atmosphere and thus have a high oxygen concentration. Meanwhile, by being near the surface they are subject to primary production that tends to rapidly consume the nutrients (like nitrate). The relationship is highly variable spatially specially near the coastal regions, where processes like upwelling/downwelling can rapidly modified nutrient and oxygen concentrations.


What percentage of cumulonimbus clouds create lightning?

I've done some research studies about the flash rate in various storms. My paper is now in review, but here is some info from this paper:

We have computed measurements for supercell and moderate thunderstorms, counting CG+ discharges. There are 24 times more discharges in supercells than in moderate thunderstorms. Supercells on average had better thermodynamic conditions to develop into a huge storm cluster.

The only help to answering your question is that Cb clouds are not similar to each other. But what I can tell you is that Cb lightning in my studies for CG+ discharges occurred once a minute, whereas for a supercell this number is equal to 24 per minute.

I studied thunderstorms from 19th of July 2015 and 17th of April 2016 over Poland.


Identifying serpentinite reworked during high-T metamorphism

Of course, any ultramafic rock will ultimately melt at about 2000 deg C, but long before that there will be some interesting phase transitions, possibly involving serpentine > talc > olivine + orthopyroxene.
Various subtle changes occur in the rock during its original hydration from peridotite to serpentinite. There is high- and low-temperature serpentinite. Isotopic studies have shown that most exposed serpentinite exposed in outcrop has hydrated at ambient groundwater temperature. Consider what happens. The Ca from the clinopyroxene in the original peridotite ends up as Ca- or Ca-Mg- carbonates, of which much is lost or precipitated elsewhere. The Fe in the original orthopyroxene, clinopyroxene and olivine is either lost from the system or re-precipitates as a mesh-texture of goethite. Cr from the silicate phases is excluded from the serpentine crystal lattice and from the surface of chromite crystals leaving a zoned Magnetite-Chromite structure in previously homogeneous chromite crystals. Since these are inert and refractory, they should survive any subsequent dehydration process. Any Ni will probably survive within the serpentine lattice. Summing up, when the serpentine is metamorphosed and turns back into peridotite, look for zoned chromite, reduced Ca (as clinopyroxene), and either reduced Fe, or Fe as a relict ghost sieve structure. Depending upon local circumstances there may, or may not, be a slight loss of silica during the hydration-dehydration cycle.


Significant difference between averaged wind speeds and averaged wind power density, for wind generation modelling?

In ECMWF data, wind direction and wind speed are collected from observation separately. Then based on a well known transformation the wind vectors, u and v are calculated.

Their documentation: http://www.ecmwf.int/sites/default/files/elibrary/2015/9208-part-i-observation-processing.pdf

You can focus on this part in their documentation:

" **Wind.**There are four wind variables: wind direction(DDD), wind force(FFF),u and v components. For each of these variables the first thing which is done is to get a local copy of it together with its related parameters from an ODB supplied array (GETSETE).Once a variable is made available locally a check is made to ensure that the vertical coordinate is pressure; if instead of pressure a flight level is supplied it is converted into pressure by assuming a standard ICAO atmosphere(Z2PICAO). If the variable in question is either u or v, then DDD and FFF are converted into u and v wind components. Furthermore, for each of the four variables appropriate observation error statistics are assigned (ERRSTAT, FINOERR). Also, if any flags are set at this stage an appropriate word in the local copy is updated (PPVAFL). Finally, an updated local copy of an observed quantity and its related parameters are returned back into the ODB (AIREPBE)."*

Once wind speed and direction are obtained calculations are made to get the two components of wind u and v.
e.g.
    $$u = -FFF sin(DDD \frac{\pi}{180})$$
    $$v = -FFF cos(DDD \frac{\pi}{180})$$

In calculating wind power, we need wind speed and not wind direction. If we are given u,v components of wind, we can calculate wind speed as
$$ U = \sqrt{u^{2} + v^{2}}$$.
Then, the power density,
   $$ P = \frac{1}{2}\rho A U^{3}$$
To sum up when we calculate wind power, what we need is the speed and not the direction.

This may not answer your question but I hope it may give some hint about it!


In the northern hemisphere only, what percentage of the surface is land?

I get 40.44%
With a workflow using a tiny bit of Python.

After Polygorial‘s comment I am adding (Feb 17, 2021 update) point zero to state more explicitly that this method requires a map like the one I used (Gall-Peters projection) with equal area projection, as regions of same area on the Earth’s surface will have the same area on the map, and therefore same number of pixels.

Invert and import B/W image of equal area projection for the Northern hemisphere (land = white pixels). Source of original image (full globe): Wikimedia Commons.

Store as Numpy array.

Calculate total number of pixels in image array (black + white).

Calculate total number of white pixels (1s) by summing the entire array (black pixels (0s) will amount to zero).

Calculate percentage of white pixels.

UPDATE September 20, 2018
As suggested by @JeopardyTempest in a comment, as a validation test I run the script for the full image with both hemispheres, and got the expected 30%


I typed in the commands as shown using your data in SAC. I've uploaded my result.  The plot window shows the result of the commands run in the highlighted red area. Is this what you are trying to do? The plot xlim is set from 1750 s to 2700 s.


Why does wind blow offshore in the morning?

The phenomenon you describe is denoted as a land breeze. It is caused by a difference between the sea surface temperature and the land surface temperature.

Surface Temperature

During day time the surface temperature at land rises faster than the sea surface temperature, whereas during night time the land surface cools faster than the sea surfaces. As a result, the sea surface temperature is higher than the land surface temperature in the morning.

Formation of the Breeze

The sea surface heats the air above the sea stronger than the land surface does with the air above land. The warmer air masses above the sea rise to higher altitudes yielding a low pressure region. As a result, the colder air masses from above the land 'travel' to the low pressure region above the sea. This 'traveling' of air masses is wind: wind, which blows from the land to the sea.

Here is a nice Figure from Wikimedia Commons describing the sea breeze (A, evening/afternoon) and the land breeze (B, morning). The Figure was provided by Jesús Gómez Fernández.

Shower Curtain Example

If you shower in a shower with a shower curtain, you might experience that the lower end of the curtain moves towards your legs. The physical processes are similar: The warm shower water heats the air within the shower. The warm air rises which causes a low pressure region at the bottom of the shower. The air is colder at the bottom of the room outside the shower which leads to a high pressure system. The air from the high pressure system (bottom outside the shower) 'tries' to flow towards the low pressure system (bottom inside the shower) which moves the bottom end of the curtain towards you.

This example works only if the room temperature in the bathroom outside the shower is not too warm/hot.


Does this really mean that on the Equator, where day and night are of the same length all year long, winter is the hottest season?

By "winter", I assume you mean December, January, and February. The answer is "No!"

Insolation varies on an annual basis outside of the tropics, one maximum and one minimum every year. This is not the case in tropical regions, where available insolation has two local maxima and two local minima every year. This effect is greatest at the equator. The graph below depicts available insolation at increments of 30 degrees latitude, from the equator to the north pole.

Note that at the equator, available insolation achieves local maxima at the two equinoxes and local minima at the two solstices. The reason is that the Sun is directly overhead at local noon on the equinoxes but is 23.5 degrees from vertical at local noon on the solstices. Sunlight has to travel through more air at the solstices than at the equinoxes.

The slight variations in insolation at the equator are easily overcome by climate. Equatorial regions tend to have wet seasons and dry seasons. When these occur depends much more on wind patterns than it does on aphelion / perihelion.

  Does this also mean that Winters in the Southern hemisphere are colder than our Summers and their Winters are hotter than or Summers?

The answer is once again "No". The slight variation in insolation due to the Earth's eccentric orbit is once again easily overcome by other phenomena. The driving characteristic for this part of the question is that the northern hemisphere has much more land mass than does the southern hemisphere. This means that except for polar regions, southern hemisphere seasons tend to be more moderate than do northern hemisphere seasons.


Could we control the weather with a disk in space?

Maybe this question belongs also into the space department here.

The only Lagrange point that makes sense is Earth - Sun - L1, and it is unstable (needs continuous correction). Satellites have already been put there, e.g. SOHO. But what we really need to do is cut down greenhouse gas emissions, anything else is not sustainable, or not practicable (a 300km sail in L1 belongs to the latter). Looking at the problems NASA has with the heat shield of the James Webb telescope i am tempted to say that it is not makeable with current technology.

Geostationary orbit is not an option. The spacing between satellites is much too small and the shield would only cover the equator. Even in geosynchronuous orbits the satellite spacing is down to 73km (https://en.wikipedia.org/wiki/List_of_satellites_in_geosynchronous_orbit) i read, so that's also occupied for such a frond. It'll collide in the ascending/descending nodes with other stuff.

The risks of geo- and climate engineering, e.g. lack of knowledge about possible side effects and the potentially drastical acceleration of global warming when engineering efforts cease (out of money error ;-)) and the time when they were in effect has not been used to cut down greenhouse gas emissions, are huge.


Why are impact craters radially symmetric?

The main reason why impact craters are close to symmetrically round is because it's the explosion of the impactor, not its collision, that creates the impact crater. The impactor is travelling so fast that, rather than simply exploding on impact, it burrows deep into the collision site, heats up from compression and friction, and explodes deep underground, thus creating a more-or-less perfectly round crater.


How does total pressure affect relative humidity and how do I correct my hygrometer for pressure?

The maximum vapor pressure in air is a function of the temperature and not of the total pressure. So when you humidify air at 12°C you get a maximum vapor pressure of approximately 1.4 kPa. However, when the air is humidified at 140 kPa the vapor pressure is still only 1.4 kPa. Therefore, you have a water/air ratio of 1.4/140= 1%.

Therefore, for every mol of water, you will have 100 mol of air. So when the total pressure drops to 100 kPa, the mol/volume fractions will not change. This is also valid for the vapor pressure ratio. Therefore, in this case the vapor pressure will still be 1% of the total pressure. Thus, the vapor pressure will only be 1.0 kPa at a total pressure of 100 kPa.

Therefore, to "correct" an "under-pressure" reading you will need to multiply your "under pressure" reading by (101.3 kPa)/(P_actual), where P_actual is your actual total pressure in kPa.


Seasonal ponds are ponds that only exist for part of the year. Jamesqf covered it well in his comment. There is just a wide variety of terms explaining the same thing. The terms were originally used more for streams (Perennial water), but it has slid into broader usage.


What is an isolated land area of one type of rock surrounded by land of a differing rock type called?

You might want to look at these topics, depends on the size of features that you want to look at:

Batholith -- s a large mass of intrusive igneous rock (also called plutonic rock), larger than 100 square kilometres (40 sq mi) in area,[1] that forms from cooled magma deep in the Earth's crust. Batholiths are almost always made mostly of felsic or intermediate rock types, such as granite, quartz monzonite, or diorite -- https://en.wikipedia.org/wiki/Batholith
Stock (geology) ==  is an igneous intrusion that has a surface exposure of less than 100 square kilometres (40 sq mi),[differing from batholiths only in being smaller. A stock has a discordant relationship with the rocks that it intrudes. The term stock usually refers to individual, relatively small plutons, less than 20 km (12 mi) diameter, usually in relative isolation.Many stocks are cupolas of hidden batholiths. Circular or elliptical stocks may have been vents feeding former volcanoes -- https://en.wikipedia.org/wiki/Stock_(geology)
Dike (geology) --  is a sheet of rock that is formed in a fracture in a pre-existing rock body. Dikes can be either magmatic or sedimentary in origin. Magmatic dikes form when magma flows into a crack then solidifies as a sheet intrusion, either cutting across layers of rock or through a contiguous mass of rock. Clastic dikes are formed when sediment fills a pre-existing cracks -- https://en.wikipedia.org/wiki/Dike_(geology)


Are fossil fuels really formed from fossils?

Let's look at this. A very large number of points for one question.

First, the solar system. We do not see any hydrocarbons in the inner solar system (Mercury to Mars). This is because in this region of the solar system, dissociation by solar UV rapidly destroys primordial hydrocarbons.  This effect is much weaker further out.

Oil well 'replenishment' will happen to some degree over several decades, just from internal migration of oil. Typically only a certain percentage of oil in place is recovered, with the rest left in isolated pockets by the water flood. Give it a few decades and these oil pockets will tend to remigrate and link up, giving the appearance of replenishment.

I'm not sure what you comment of The source of methane way too deep to come from fossils. No fossils involved.. That's an unreferenced assertion.

Helium is present in Natural Gas as a result of accumulation of alpha-decay particles from radioactive isotopes; we can see this from the massive enrichment of Helium-4 over Helium-3. It's not a paradox; geological structures that can trap methane will also trap helium.

The current theory behind petroleum geology is that source rocks with a high organic content (often containing biological hydrocarbons from algae and leaf waxes) are buried in sedimentary basins; at temperatures around 100-150 degrees C this kerogen breaks down to form crude oils (this is verified in the lab). Oil then migrates out of this source rock; if it encounters a trapping geological structure, which need not be sedimentary, then it accumulates as an oil deposit. Gas is similar, with a wider range of source rocks.

The physics of how this happens are well known and established.

I would also note that we don't see hydrocarbons coming out of mantle-derived volcanoes such as at Hawaii. This is a major problem for any theory of primordial hydrocarbons.

Additional Points

First, it would be nice if you provided references rather than a link to a book to buy.

If hydrocarbons were primordial, then we would expect to find them mostly in areas where the mantle or mantle taps reach the surface - mid ocean ridges, and ocean island volcanoes. We don't. The major oil fields are located in continental extensional basin settings.
There is plenty of evidence for mantle outgassing - including all volatile species such as hydrocarbons - in the first few hundred million years. Furthermore, on geological timescales the mantle is still undergoing vigorous convection and can be considered liquid.
Is irrelevant.
This is simply wrong, if referring to pores that can offer any support against pressure. The crust becomes ductile at about 10-15km, and the mantle at 60+km, meaning that conventional porosity cannot exist.
See (1). For the Earth, outgassing was essentially completed billions of years ago, as we can see from isotopic evidence (and I suspect that the moon-forming impact didn't help).


How does salting roads help prevent ice?

Sodium chloride rock salt, NaCl, is usually used for de-icing roads. As mentioned in another answer, the dissolved ions lower the freezing point of water.

Other kinds of salt are also used. Calcium chloride, CaCl2, is more efficient at melting ice. NaCl can not melt ice at temperatures lower than -18C (0 F). A saturated calcium chloride solution won't freeze until ~ -46 C. Calcium chloride is often applied as a solution because the solid becomes sticky as it absorbs water from the air.

Edit: per the link to the Colorado road dept from a comment on another answer, magnesium chloride is used in the liquid deicers. Here is a link to information on different deicers


How does El Niño affect thunderstorm/tornado/CAPE activity in the central United States?

According to the NOAA document A Comparison of Rawinsonde Data from the Southeastern United States during El Niño, La Niña, and Neutral Winters (Sankovich et al.) report that

  Schaefer and Tatom (1998) considered
  the number of tornadoes per year in the United
  States and sea surface temperatures (SST) in
  various portions of the Pacific Ocean to try to
  discern an impact of ENSO on the occurrence of
  tornadoes. Their statistical inquiries showed no
  major influence, but their data does show a signal
  that more tornadoes tend to occur in the mideastern
  states during the La Niña phase.

However, another study cited by Agee
and Zurn-Birkhimer (1998) state

  that tornado
  occurrences do not favor one ENSO phase but
  rather exhibit a shift in geographic location. For
  example, their results suggest that more
  tornadoes occur in the lower Midwest, Ohio Valley,
  Tennessee Valley, and mid-Atlantic region during
  the La Niña phase than in any other phase.

This is further concluded by Bove (1998) concluded that

  increased tornado activity over
  the Ohio and Tennessee River Valleys during the
  cold La Niña phase.

Sankovich et al. conclude that

  Like all climatological signals, they [ENSO]
  represent long-term trends. They do not provide a
  tool for making seasonal or other extended
  forecasts; rather, they show that other things being
  equal, the atmospheric stratification over the
  Southeastern United States is typically less
  compatible for the occurrence of severe
  thunderstorms (3/4” or larger hail, thunderstorm
  gusts of 58 mph or faster, tornados) during a La
  Niña winter than during Neutral or El Niño winters.

In the paper A seasonal-scale climatological analysis correlating spring tornadic activity with antecedent
fall–winter drought in the southeastern United States (Shepherd et al. 2009), state that to

  remove the uncertainty
  associated with the ENSO debate, we consider a new approach
  by focusing on antecedent drought conditions for a region.

Whereby, they conclude that the relationship between drought and incidences of tornadic and severe thunderstorm behaviour to possess a

  statistically significant tendency for
  fall–winter drought conditions to be correlated with below-normal tornado days the following
  spring in north Georgia (i.e. 93% of the years) and other regions of the Southeast. Non-drought
  years had nearly twice as many tornado days in the study area as drought years and were also
  five to six times more likely to have multiple tornado days

References:

Schaefer, J. T., and F. B. Tatom, 1998: The
relationship between El Niño, La Niña, and
United States tornadoes, Preprints, 19th Conf.
on Severe Local Storms, Minneapolis, MN,
Amer. Meteor. Soc., 416-419.
Agee, E., and S. Zurn-Birkhimer, 1998: Variations
in USA tornado occurrences during El Niño
and La Niña, Preprints, 19th Conf. on Severe
Local Storms, Minneapolis, MN, Amer.
Meteor. Soc., 287-290.
Bove, M.C., 1998: Impacts of ENSO on United
States tornadic activity, Preprints, 19th Conf.
on Severe Local Storms, Minneapolis, MN,
Amer. Meteor. Soc., 313-316.


Why is the average 1 Bar temperature on planets with a thick atmosphere proportional to the distance of the sun?

I will throw out 2 hypothesises to answer the why of the question. Not saying it is true, just saying that it may be valid hypothesises. And both hypothesises don't discount the internal properties of greenhouse gasses.

Somehow positive and negative feedback forces level each other out in the 1 bar thick atmosphere sytems on all 3 planets

There is another overruling equilibrium mechanism, as proposed by Dr. Ronan Connolly & Dr. Michael Connolly, who studied all the weather balloon data.

https://youtu.be/XfRBr7PEawY?t=2506


Did we succeed, is this indeed cinnabarit?

Probably yes. Cinnabar has a very distinct brick-red colour, and some of your samples definitely have it. I'm not certain how much of this is actually cinnabar and how much is other stuff, but there is enough cinnabar in there to make it obvious just from the picture.

IMPORTANT

Cinnabar is toxic. It will release mercury metal on oxidation (that is, exposure to air), on exposure to water (so don't throw it in the river), and on exposure to strong light (that is, sunlight). On heating it will release mercury vapour. People die because of this.

Go to the mine, and put it back in there, never taking it back. In case you do want to keep one of them, make sure it is clearly labelled as TOXIC and DANGEROUS and POISON in both English and Hungarian, and keep it away from children and pets.


What is the tectonic setting for the formation of the Great Dividing Range in Australia?

The tectonic history of Australia's Great Dividing Range is very complex, extending back into the Neoproterozoic era (1), and is far more complex than the Wikipedia quote. Additionally, evidence (shown in this answer) demonstrated that the eastern third of the Australian landmass is comprised of accreted arc systems that developed along the continental-oceanic Eastern Gondwana boundary following the initiation of subduction in the late Neoproterozoic (1) forming in a series orogenies (as shown on the map below (2) - not due to a single continental collision. These orogenies are incorporated in the 'Terra Australis' Orogen that ceased approximately 230 million years ago (3).

As can be seen by the diagram below (2), the youngest accreted orogen occurs in the eastern most margins of the Australian landmass, where the Great Dividing Range is.

Also, the cessation of arc accretion, did not end the tectonic story affecting the Great Dividing Range.  Large Igneous Province volcanics occurred in north Queensland in the early Cretaceous, then epeirogenic uplift, exhumation and continental rupturing culminating in the opening of the Tasman Basin occurred in the mid Cretaceous, leading to the separation of Zealandia (New Zealand + submerged continental shelf) and giving shape to the eastern Australian coastline (and eastern boundary of much of the Great Dividing Range) (4).  The rifting process is illustrated below

Image source: Formation of The Australian Alps

References

(1) Cawood et al. 2009 Accretionary orogens through Earth history, The Geological Society

(2) Foster and Goscombe, 2013 Continental Growth and Recycling in Convergent Orogens with Large Turbidite Fans on Oceanic Crust, Geosciences

(3) Cawood, 2005, Terra Australis Orogen: Rodinia breakup and development of the Pacific and Iapetus margins of Gondwana during the Neoproterozoic and Paleozoic, Earth-Science Reviews

(4) Bryan et al. 2012, Early-mid Cretaceous tectonic evolution of eastern
Gondwana: From silicic LIP magmatism to continental rupture, Episodes


What are the major contributors to the amount of infra-red emitted by the earth?

It depends on the wavelength.

The figure shows the most absorbing species between 6 and 16 µm for a U.S. standard tropical atmosphere (Note: this figure does NOT include the Earth's surface!).  Absorption data is taken from Anderson et. al (1986) and simulations are performed with the open-source Atmospheric Radiative Transfer Simulator (ARTS; Eriksson et al., 2011).  The plotting was carried out with LaTeX and pgfplots.  ARTS is open-source and includes the Anderson et al. data, so you can try different wavelengths for yourself.

Depending on wavelength, we have dominant absorption from H₂O, O₃, CO₂, N₂O, CH₄, and others.

I have also uploaded a PDF version (PDF, 117.68 mm × 228.21 mm, 5.1 MiB) for higher-resolution viewing.


What would the precursors to a repeated Lake Toba super eruption?

Massive, caldera-forming eruptions like the one at Toba usually happen at large silicic systems. At such systems, we expect a surface uplift as the pressure builds in the magma reservoir. This can be measured by radar interferometry (InSAR). It is the case at Laguna del Maule volcano (Chile), were uplit up to 28 cm per year has been measured by InSAR (Feigl et al. 2014). A similar pattern would be observed at Toba if a magma reservoir was being replenish. However:

We don't know the timescale needed for overpressure, thus eruption, of the reservoir. It depends on many parameters, such as reservoir size and depth, strength of host rock, rate of fresh magma supply...
We don't even know if such uplift will lead to an eruption. The magma could very well be intruded into the crust (in the form of dikes and sills), releasing the pressure in the reservoir. The uplift would then cease without an eruptive crisis.


Tornadoes meeting with an Immovable, Unbreakable, Large Cube

It depends.

Take a look at this recorded presentation from the 27th Conference on Severe Local Storms by David C. Lewellen and the accompanying pre-print.  This talk focuses on the effect of buildings on tornadoes though the buildings are examined as fixed blocks they are not modified or damaged, but remain a fixed obstacle to the tornado (he toward the end does show that he models forces of the tornado on the building but does not allow that to change the building).

The effect of the block depends on whether the tornado is high or low swirl, the relative position of the block to the tornado and the size of the tornado.  The block weakened some tornadoes and strengthened others.


Geology: What's make a group of bedrock a formation?

Basically a formation is just a layer or group of layers of rock that is both distinct enough to be identifiable in the field and large enough to show up on a geological map. Usually it is many nearly identical layers grouped together or just one large layer. Its not a hugely precise definition but it is a lot like the term "species" in biology, it's a working definition, created more for usability than precision.


The volume of a sphere is $\small\sf{\frac4 3\pi R^3}$, where $\small\sf{R}$ is the radius.

The volume of Earth with the 4 cm deep iridium rich layer is,

$\small\sf{V_{Ei} = \frac 4 3\pi (6.378\cdot10^6)^3}$ $\small\sf{m^3}$ = $\small\sf{1.086 \ 781 \cdot 10^{21}}$ $\small\sf{m^3}$

The volume of the 4 cm deep iridium rich layer is,

$\small\sf{V_i = \frac 4 3\pi (6.378\cdot10^6)^3} -\frac 4 3\pi (6.378\cdot10^6 - 0.04)^3 $ $\small\sf{m^3}$ = $\small\sf{2.044 \cdot 10^{13}}$ $\small\sf{m^3}$

Now, density is mass divided by volume, $\small\sf{\rho = m/v}$, thus the mass of the iridium rich layer is,

$\small\sf{m_i = 2.5 \cdot 2.044 \cdot 10^{13} = 5.110 \cdot 10^{13}}$ tonnes

The proportion of iridium in the layer is 10 ppb, therefore the mass of iridium within the layer is,

$\small\sf{5.110 \cdot 10^{13} \cdot 10 \cdot 10^{-9}} = 511 \ 000$ tonnes

Now, the proportion of iridium in the meteor was 0.5 ppm, therefore the mass of the meteor was,

$\small\sf{511 \ 000 / (0.5 \cdot 10^{-6}) = 1.0220 \cdot 10^{12}}$ tonnes

The density of the meteor was  $\small\sf{6.0 \ g/cm^3}$, which is the same as $\small\sf{6.0 \ t/m^3}$, therefore, the volume of the meteor was,
$\small\sf{1.0220 \cdot 10^{12}/6.0} = 1.703 \ 333 \cdot 10^{11} m^3$

Using this and the equation for the volume of a sphere, the radius of the meteor was,

$\small\sf{\sqrt[3](\frac 3{4\pi} \cdot 1.703 \ 333 \cdot 10^{11})} = 3438.774 \ m$

and the diameter of the meteor was 6877.5 m or 6.878 km

Not the 10 km you wanted.

To get the thickness you want for a 10 km diameter meteor, do the calculation in reverse.

For diameter of 10 000 m, the volume of a spherical meteor would have been,

$\small\sf{\frac 4 3 \cdot \pi \cdot 5000^3} = 523.598 \ 776 \cdot 10^9 \ m^3$

With a density of $\small\sf{6 \ t/m^3}$, the mass of meteor would have been,

$\small\sf{6(523.598 \ 776 \cdot 10^9)} = 3.141 \ 592 \ 6 \cdot 10^{12} t$

with a metal grade of 0.5 ppm of iridium, the mass of iridium in the meteor would have been,

$\small\sf{3.141 \ 592 \ 6 \cdot 10^{12} \cdot 0.5 \cdot 10^{-6} = 1 \ 570 \ 796 \ t}$

The metal grade of iridium in the layer on the Earth is 10 ppb, therefore the mass of the iridium layer is,

$\small\sf{(1 \ 570 \ 796)/ (10 \cdot 10^{-9}) = 1.570 \ 796\ 327 \cdot 10 ^{14} \ t}$

With a density of $\small\sf{2.5\  t/m^3}$, the volume of the layer is,
$\small\sf{(1.570 \ 796\ 327 \cdot 10 ^{14})/2.5 = 6.283 \ 185 \cdot 10^{13} \ m^3}$

From the previous calculation, the volume of layer is,

$\small\sf{6.283 \ 185 \cdot 10^{13} = \frac 4 3\pi (6.378\cdot10^6)^3} -\frac 4 3\pi (6.378\cdot10^6 - x)^3 $ $\small\sf{m^3}$ = $\small\sf{2.044 \cdot 10^{13}}$ $\small\sf{m^3}$

Solving for $\small\sf{x}$, which is the thickness of the layer, gives $\small\sf{x} = 0.123\ m\ or\ 12.3\ cm$


What might cause these "wave clouds" near the horizon? Could it be gravity waves?

Identification of the phenomenon based solely on the photograph is unfortunately inconclusive, although several reasonable possibilities exist. While a wavelike structure is apparent, exact identification of the phenomenon is difficult due to the lack of cloud condensate (which would better illustrate the local vertical air motions ultimately driving cloud development) and of corresponding local weather observations (which could suggest which phenomenon is most likely to occur). Three possibilities seem most likely:

Horizontal Convective Rolls - a mode of convection in which clouds (and corresponding upward vertical air motion) preferentially organize in approximately linear lines, with downward vertical motion between (image from linked source). These clouds are observed over both land and water surfaces, although formation over water is more likely in cold weather when the water is relatively warm compared to land. This mode is possible, though perhaps least likely, given that weak clouds are visible across the horizontal length of the photograph - well-organized horizontal rolls commonly have clear air between the lines of cloud.  (image source)

Gravity wave clouds - clouds that form in the upward motion regions of large-scale "waves" of vertical motion propagating through the atmosphere. Gravity waves are a common phenomenon occurring in many different atmospheric environments, with the resulting clouds varying greatly in appearance depending on the strength of the vertical motion and the amount of atmospheric moisture available for condensation. Given this, gravity wave clouds are a reasonable possibility based on the photograph. (image source)

Kelvin-Helmholtz wave clouds - An overturning motion that may develop at the interface between two atmospheric layers with substantially differing horizontal winds, with cloud condensation (assuming sufficient moisture) taking on an appearance similar to rolling ocean waves (image from linked source). This explanation also seems reasonable, given that air masses with distinct characteristics commonly occur in the lower atmospheric boundary layer and between ocean and land masses. Anecdotally, the clouds in the photograph look most visually similar to near-surface Kelvin-Helmholtz wave clouds I've seen, although again, the lack of actual cloud condensate makes this difficult to assess with any certainty.  (image source)


Here's an idea:

You can use dark chocolate and white chocolate. Use a grater to create "sediments": layers of alternating grated dark and white chocolate.

Now heat them up just before melting so you can stick them together with pressure, preserving the layered structure. Now fold them. There's your "metamorphic" rock.

Then, just melt the entire thing to create some chocolate-lava flows. Grate them again and eat!


Check out the USGS seismic data maps for each area of interest. For example,
http://walrus.wr.usgs.gov/tsunami/samoa09/
gives you the relative speed and direction of the Pacific Plate relative to the Fiji-Tonga-Australian plate. The directional arrow on Figure 2 gives the mean relative motion in mm/year.


A turbidity current can easily account for what you've observed. It could be part of a repetitive sequence of shallow angle sloughs caused by accumulating overburden, much like the Bouma Sequences that make up a Turbidite Deposit, or it could be a one-time gravity flow caused by an earthquake.


Hydrocarbon potential in Ganges Brahmaputra delta

There have been a few discoveries in the Bay of Bengal.

Santos made a gas discovery in 2012, and depending on what you'd call part of the delta complex (all of the Bengal Fan?), there are others. One field, Sangu, saw several years of production, but seems to be shut-in today. Another, Kutubdia, is awaiting development.

It's true though that there have not been many at all, if you compare with some other big deltas, like Niger or the Gulf of Mexico. Blakely (2010) suggested there are border disputes, which definitely slows exploration. I'm just guessing, but there may be other factors, such as regulatory issues, slow government licensing, or political pressures. Reading around, it does seem fair to say that the region has not been fully explored, and clearly there is a working hydrocarbon system.

References

Blakeley, I (2010). Bay of Bengal. GEO Expro 7 (6). Available online


What is the difference between roughness length and zero plane displacement?

First some definitions:

$z_0$: Roughness length is defined as the height at which the mean velocity is zero due to substrate roughness. Real walls/ground are not smooth and often have varying degrees of roughness, this parameter (which is determined empirically) accounts for that effect.

$d$: Zero Plane displacement is defined as the height at which the mean velocity is zero due to large obstacles such as buildings/canopy.

The two parameters are not the same because they describe the effects of two fundamentally different processes. $d$ can be anywhere from $6$ to $20$ times larger than $z_0$.

The basis for most turbulence modeling is the eddy viscosity model:

$$-\overline{u'w'} = \nu_t \frac{\partial U}{\partial z}$$

where $\nu_t$ is the eddy viscosity. Employing some scaling arguments with basis on the Prandtl mixing length model and integrating one arrives at the logarithmic law of the wall:

$${U} = \frac{u^*}{\kappa} \ln\, \frac{z}{z_0}$$

Your equation is

$${U} = \frac{u^*}{\kappa} \ln\, \frac{z-d}{z_0}$$
which is the law of the wall with $d = 0$ because it applies to flat plates. It is easy to see then, that by subtracting $d$ from $z$ the effect is to reduce $U$ at that height, which makes sense because large obstacles remove energy from the mean flow and slow it down.

Note that if there are no large obstacles then $d \approx 0$, but $z_0$ is still larger than zero.


What's up with the "jelly sandwich" analogy of the lithosphere, asthenosphere and mesosphere?

The introduction to Morgan et al., 2013 has a good summary of the features you are asking about, as well as proposing a mechanism for why it happens.

From the intro:

  The Earth’s mantle underneath the tectonic plates, commonly referred
  to as asthenosphere, is known to be the lowest viscosity region of the
  upper mantle. Several potential mechanisms have been suggested to be
  responsible for this low viscosity zone. These mechanisms...include:
  (1) the temperature and pressure dependence of the mantle rheology may
  lead to a viscosity minimum between 70 and 200 km depth; (2) a small
  and immobile fraction of partial melts may weaken the mantle; (3) wet
  mantle below its dry solidus (deeper than about 70 km) would be
  expected to be weaker than shallower mantle that dehydrated during
  partial melting at mid-ocean ridges (MOR)—but this mechanism does not
  explain the physical origin for the base of the asthenosphere; (4) a
  reduction in mantle grain size within the asthenosphere.

The paper's proposed cause for this is that:

  the sub-oceanic asthenosphere forms because it is the ‘graveyard’ for
  rising (i.e. hotter-than-average mantle) plumes. In this view, below
  the plate-age-dependent 60–100 km-thick oceanic lithosphere there
  exists a pool of hot plume material that has risen as far as the
  overlying thermal and/or compositional lithosphere  will allow.

Whether that mechanism is correct or not, only time will tell. In conclusion, due to the temperature and pressure characteristics of the asthenosphere, it is less viscous than the chemically identical mesosphere. This may be because of its place on temperature and pressure curves, because it contains pockets of partially molten rock, because rising mantle plumes make the asthenosphere actually hotter than the mesosphere, or otherwise.


What influences tide-height the most? Can I guess the height by looking on a globe?

I don't know about the size of land masses, but their distribution and the shape of ocean basins definitely play a big role.
When considering the ideal case of an all-ocean globe, i.e. one with no land masses (equilibrium tidal theory), the combined effect of sun and moon give a theoretical tidal range of less than 1 m(1). As tidal ranges can be much larger than this,  there are other effects that has a greater influence.

The Bay of Fundy for example, is one of the places with the largest difference between low tide and high tide, at about 16 m. The large difference in this location has to do with the shape of the bay. The bay has a natural frequency for waves that is about the same as the frequency of the tide itself, giving an amplification of the tidal amplitude. In addition there is a funnelling effect in the inner part of the bay, giving an additional contribution.(2)

Another example of large tidal differences is the English channel, particularly the French side. In this case the tides are large at least partly because the tide moves as a coastal trapped Kelvin wave. These are waves that propagate along land, with the land to the right when looking in the direction of propagation (on the Northern hemisphere, land to the right on SH). The amplitude of the wave is highest near the coast, decaying exponentially away from the coast. As the tide in the English channel moves northward, the largest tidal range is on the French side.

With regard to guessing the tidal range, this is not entirely straight forward.
First, when discussing tides, we generally split the tidal potential into a series of oscillations having different frequencies, mainly either diurnal (period of ~24 h) or semi-diurnal (period of ~12 h).
These given frequencies are obtained through trigonometric considerations, and depend on the latitude of the point, the declination of the moon or sun relative to the equator, and the hour angle.
(The hour angle is basically the longitudinal difference between the sub-lunar point and the point we consider.)
Each of these components can vary in time and space.

Further, the pattern of the amplitudes of each component is not necessarily simple. In addition to the differences in potential, the topography modifies it.
See for example:

from wikipedia

which shows the amplitude of the M2 tidal component.
This is the strongest semi-diurnal tidal component caused by the moon. You'll notice that there are places where the amplitude is zero, i.e. this component causes no tides here.
These are known as amphidromic points.

Also, depending on which components dominate at a given location, you can have either a mainly semi-diurnal tide, a mainly diurnal tide, or a mixed tide where there are two high tides in a day, but one has lower amplitude than the other.  A sketch of which can be seen here:

from wikipedia

(1) Pugh, David T. (1987) Tides, surges and mean sea level, chapter 3.

(2) http://www.bayoffundy.com/about/highest-tides/ (for lack of better sources)


You are pretty much spot on in terms of the date.  According to the article Shoreline reconstructions for the Persian Gulf since the last
glacial maximum (Lambeck, 1996) based on models of glacio-hydro-isostatic effects of the end of the last ice age and the article Early State Formation
in Southern Mesopotamia:
Sea Levels, Shorelines,
and Climate Change (Kennett and Kennett, 2006) indicate from archaeological observations that at around 6000 years before present (~4000 BCE) that the present shorelines were approximately shaped.  Both articles record an initial inundation of the Tigris-Euphrates delta.

The process is summarised in the image below:

Image source: University of California - Santa Barabara


As you say in your question, ball lightening and and St Elmo's Fire are related to thunderstorm activity (e.g., Griwr'ev et al, 1991). Grigor’ev et al (1999) worked out a formula for the charge on small drops of water (which is a bit complicated for a simple answer), but suffice to say the total voltage involved  is high when you scale from one drop to millions. For example ~30kV per cubic centimetre is in the literature for initiating Ball Lightening, and lower for St Elmo's Fire because the coronal discharge nucleates on pointed or sharp objects.

If you troll physics forums about demonstrating St Elmo's fire in a laboratory setting, you'll see that it is actually quite dangerous, due to the high voltage. Most suggestions by physics teachers are to demonstrate the effect in neon gas, rather than air, and within glass bulbs. So one answer to your question is that the effect can be dangerous, e.g., when creating conditions of coronal discharge in an experimental setting.

What about in a natural setting? You can read in Griwr'ev et. al (1991) about several hundred reports of St Elmo's Fire sightings, but it isn't mentioned whether anyone has been 'within' the effect. However, St Elmo's Fire was observed on the Hindenburg shortly before it exploded (Robinson, 1964); not that this was the likely 'spark' that caused the explosion, but part of the prelude.

I can't find any verified reports of people immersed in St Elmo's Fire during my quick review of published literature, or non-peer reviewed sources like Scientific American and Wikipedia. There is an interesting reference in Wikipedia to Tesla managing to light up some butterflies with one of his coils, though!

Griwr'ev, A. I., I. D. Griwr'eva, and S. Shiryaeva. "Ball lightning and St. Elmo's fire as forms of thunderstorm activity." (1991)

Grigor’ev, A. I., and S. O. Shiryaeva. "Critical conditions for instability of a highly charged oblate spheroidal drop." Technical Physics 44.7 (1999): 745-749.

Robinson, Douglas. LZ-129 Hindenburg. New York: Arco Publishing Co, 1964.


If we burn all carbon in the Earth's crust, by how much would the atmospheric concentration of $CO_2$ increase?

Short answer: $\rm CO_2$ levels would increase by $209,460$ $\rm ppm$ by using all the available oxygen.

Long answer: The mass of carbon in Earth's crust is $9(10)^{22}$ $\rm gC$ (grams of Carbon). The mass of the atmosphere is $5.15(10)^{21}$ $\rm g$. If all the carbon was burned, or otherwise moved to the atmosphere, then the limiting factor would be the $\rm O_2$ (molecular oxygen) available for carbon to bond with to make $\rm CO_2$. Oxygen makes up $209,460$ $\rm ppm$ of the atmosphere. So, assuming the carbon bonded with all available $\rm O_2$ and the remaining carbon did not enter the atmosphere, then there would be an additional $209,460$ $\rm ppm$ of carbon dioxide in the atmosphere.


Is volume of air increasing as CO2 levels increase?

[Major edits below]

In short the answer is NO.

Before we get into volume changes, I have to say that volume is a tricky measure to apply to the atmosphere as a whole, because there is no clear limit between the atmosphere and outer space.
Also, the thickness of the atmosphere is quite insensitive to changes in atmospheric mass. For example, the atmosphere of Venus is much more massive than Earth's (93 times more massive). Leading to surface pressures 92 times those of Earth. However, the thickness of the atmosphere is quite similar, with the mesosphere extending to 120 km, only 41% higher than on the Earth, despite having 9300% the mass.

This planetary comparison suggests that more CO$_2$ will lead to a more massive atmosphere and higher atmospheric pressures, but little change in its actual volume (if you somehow manage to define how to measure the volume of the atmosphere).

As an analogy, imagine you have one meter of snow cover, and there is one meter of snowfall. You won't end up with two meters of snow cover. Thise is because the new snow will compact the snow below, leading to something like 1.7 meters of snow cover.

Therefore, more gases in the atmosphere will lead to a denser atmosphere, but have little impact on its thickness.

Now we have to make a very important distinction: It is not the same to add CO$_2$ from a CO$_2$ source (like a volcanic eruption) than add it due to combustion of fossil fuels. This is because the latter do not add molecules to the atmosphere, just turn O$_2$ molecules into CO$_2$. Now, if you look into what this transformation means in terms of volume, you will get a surprise (at least it was a surprise to me):

Given standard conditions (20°C and 1 atm). One cubic meter of O$_2$ weights 1.331 kg. When you use that oxygen to burn fossil fuels all the molecules in it will go from a molecular weight of 32 (O$_2$) to 44.01 (CO$_2$), meaning you end up with 1.831 kg of CO$_2$. Now comes the interesting part: under the same conditions, one cubic meter of CO$_2$ weights 1.842 kg, consequently, our initial cubic meter of O$_2$ turned into 0.994 m$^3$ of CO$_2$, equivalent to a volume reduction of 0.6%. Therefore, burning fossil fuels reduces the volume of the atmosphere.

I was surprised at first by this result, but it nicely explain the classic experiment where a boiled egg get sucked into a bottle:

This is an screenshot of this video where you can see the trick in action (skip to minute 1:10)

Now, despite that burning stuff decrease the volume of the atmosphere. It is important to note that if you add greenhouse gases like CO$_2$ or methane, you are not only increasing the amount of those gases in the atmosphere, because the increase in temperature will lead to an increase in water vapor too. So the atmospheric mass increase will be larger than the mass of CO$_2$ or methane added. And that extra mass is related to additional molecules, so it will lead to extra volume (contrary to the combustion case where the amount of molecules is constant).

Thus, as we burn fossil fuels the mass of the atmosphere increases (as well as the atmospheric pressure), but the volume decreases, and due to the fact that CO$_2$ is the product of combustion, that increase will be at the expense of reducing the amount of molecular oxygen (O$_2$).

Although, this decrease is very small: the atmosphere have ~21% of Oxygen and 0.04% of CO$_2$, so an increase in CO$_2$ of a 30% (similar to going from 300 to 400 ppm), means a reduction of O$_2$ of 0.01%, a relatively small change (using Wikipedia numbers it would go from 20.946% Oxygen to 20.934%). Also, that's strictly true only if you make an instantaneous combustion. Because over time there could be negative feedback working against this imbalance. For instance, plants will increase the rate of photosynthesis (CO$_2$ fertilization effect)

That said, the mass increase (and volume decrease) associated to the CO$_2$ jumping from 300 ppm (pre-industrial levels) to 400 ppm is negligible, and probably dwarfed by day to day changes in particulate material or water vapor.

As a side note, the book "Red Mars", makes a fairly scientifically sound description of how to "terraform" Mars, and how adding CO$_2$, or water vapor increase the atmospheric pressure and surface temperature.


Why does El Niño only exist in the Pacific Ocean and not the Atlantic/Indian Oceans?

First, to describe El Niño as a Pacific Ocean event seems overly simplistic. The effects of El Niño are felt worldwide as can be seemed by a principal component (EOF) analysis (e.g., Alexander et al., 2002). Also, using the term "El Niño" to describe the entire oscillation (ENSO, El Niño Southern oscillation) can lead to confusions as the term "El Niño" corresponds to one of the phases of the oscillation.

The size of the Pacific Ocean and the lack of equatorial constraints makes it a prime candidate for large oceanic fluctuations such as ENSO. The large distance between the western and eastern sides of the basin allows for a more dynamic equilibrium with the presence of large scale waves (Kelvin and Rossby; e.g., Kirtman, 1997). This equilibrium can be altered by external (atmospheric) forcing resulting in the different modes of oscillation of ENSO.

Apart from that, there are a number of significant modes of oscillations (see http://www.esrl.noaa.gov/psd/data/climateindices/list/ for a very good list) that occur in basins outside the Pacific ocean. A good example is the North Atlantic Oscillation (NAO; Hurrel [1985, Science]; http://www.cpc.ncep.noaa.gov/products/precip/CWlink/pna/nao.shtml) that affects not only the North Atlantic but also the climate of Europe and North America.

Other examples of modes of climate variability include the Pacific Decadal Oscillation (PDO; Zhang et al., 1997), the Atlantic Multidecadal Oscillation (AMO; Schlesinger & Ramankutty, 1994), or the Arctic Oscillation (AO; Thompson & Wallace, 1998).


Is there a map that displays every country at its correct relative size?

Yes.
Every equal-area map displays all countries (and other areas) in their correct relative size. Inevitably, they don't show the correct shape (unless you're looking at a globe). Personally, my favourite projections are pseudocylidrical equal-area projections, such as:
Equal Earth projection

Mollweide projection

Eckert IV projection

Tobler hyperelliptical projection

There are others; see this list on Wikipedia.
The pseudocylindrical part means that lines of latitude are horizontal lines. I think that for any non-polar projection in the Earth sciences, this is a highly desirable property. A truly cylindrical projection means a projection onto a rectangle, but that just makes distortions even worse than they need to be.  There are other practical considerations, such as whether the poles are points or lines and whether the outer lines of longitude are ellipsoids or sinusoids, which differ between the various examples I've listed above.


Convert OMI NO2 Vertical Column Density (molecules/cm^2) into Mixing Ratio (ppm)

No, you shouldn't really do that.  A vertical column density (VCD) retrieval provides the user with a representation of the total number of molecules over some vertical slice (e.g. the entire troposphere).  A mixing ratio, often defined in parts per million, is meant to express the average number of molecules in a parcel of air.  The problem with converting VCD to ppm is that the troposphere is a whole lot more than "a parcel of air".  The density of air and mixing ratio of NO2 changes as you move vertically through the atmosphere. So, saying that NO2 has any one mixing ratio through the troposphere is really not appropriate.

There are methods you could use to estimate ppm NO2 from VCD (such as inferring mixing ratio from the shape of the a priori profile), but they would be inherently uncertain for many reasons:

The retrieval of tropospheric NO2 from OMI is not representative of the surface, but rather a well-mixed free troposphere.
The NO2 product is dependent on a global model to subtract the stratospheric contribution.
There are many quality control steps needed for quality assurance, such as accounting for clouds, terrain, surface albedo, detector issues (e.g. striping or row anomalies), etc.

In my experience with OMI tropospheric NO2 data, any expected temporal correlation to daily surface measurements is futile.  You will sometimes find temporal correlation at the seasonal or coarser scale, for what that is worth.

Spatial correlation with models and surface monitor networks should be expected, but your results will be highly dependent on your 3D spatial comparison methodology. When comparing to a model, you will want to apply the "averaging kernels" which help to remove the dependence on the a priori profile of the satellite retrieval.

In general, OMI tropospheric NO2 data is useful for identifying large emissions sources that are missing from air quality models.   It is also useful for identifying inconsistencies across political borders that appear in air quality models due to old emission inventories (e.g. mixing circa 2006 Canadian emissions with circa 2011 USA emissions).


1 in 100,000 is an estimate of frequency based on past eruptions which should not be confused with possbility or probability.  It is an oversimplification to state the probability of an eruption as 0.001% chance per year.


Why is Sacramento so warm for its latitude?

The main reason for Sacramento's warmth compared to some other cities at the same latitude is, like in many cases, due to the city's surrounding topography, as can be seen in the topographic map below:

Source: Wikipedia: Geography of California

In regards to the climate of Sacramento, it is probably better to consider why it is seasonally warmer than cities on the same latitude.

Sacramento is located in a regionally low elevation Great Valley (also Central Valley) (1), in between two roughly parallel mountains ranges that converge in the north of the Valley in the Klamath Ranges. The Coastal Range on the west and the Sierra Nevada to the east (2).

The Köppen climate classification for Sacramento is Csa, which is defined as a Mediterranean environment with hot summers (1). The Coastal Range largely shields the city (and the Valley) from the climate (especially much of the humidity) of the Maritime climate to the west, and the Continental climate to the east (2).  Essentially, according to the WRCC, the climate of the Valley (including Sacramento) is intermediate between the climates either side of the bordering ranges (2).

The very cold winters that can occur in the Continental climate are blocked by the Sierra Nevada.  Even if cold air does get over the mountain, the air warms as it compresses as descends into the Valley, and hence is milder when it reaches the Valley (2).

In regards to the Urban Heat Island, The US EPA (3) performed measurements and observations of Sacramento between 1998-2002, revealing that there is an urban heat island of the order of an average increase in temperature in the city of 0.5-1°C (0.9-1.8°F) compared to the surrounding non-urban areas.

References

(1) Kauffman, E. Climate and Topography California Department of Fish and Wildlife

(2) Western Regional Climate Centre (WRCC), Climate of California

(3) U.S. EPA Urban Heat Island Pilot Project: Profile of Sacramento


What is the difference between chalcophile and siderophile elements?

First, a small correction: Fe, Co and Ni and considered chalcophile. Mg, Sr and Ba are lithophile. Ar is atmophile.

Here's the classification, just in case you need to have it in front of your eyes: source: the Wikipedia article on Goldschmidt classification

  What is the exact difference between them? It just seems to be the
  same thing as sulfide liquid must contain metals as well.

This is a bit confusing because most siderophile metals are also chalcophile. Let's begin by defining what are metal and sulfide liquids in the Earth.

Metal liquid: Siderophile elements are concentrated in molten Fe. Not just any metal, but specifically molten Fe. This is truly molten metal, where most of the atoms are neutral, the bonding is metallic, and there are no ionic bonds. The only place that a liquid like this exists to any significant proportion today is Earth's outer core.
Sulfide liquid: Chalcophile elements are concentrated in molten sulfide. In the Earth this will mostly be Fe-rich sulfide, the liquid analogue of pyrrhotite and pentlandite (known as mss in high temperature). This liquid is dominated by the presence of sulfide as S2-. This is no longer a metallic liquid with neutral atoms. This is a liquid where the bonding character is a combination of ionic (because you got Fe2+, Ni2+ and S2-), metallic and covalent. Sulfide liquids can exist in the core (we do not know), but they exist in the mantle and the crust where they are how you move the chalcophile (and siderophile) elements around. Ore deposits of these elements almost always form from sulfide liquids, or their alteration products.

Because of the contrasting bonding properties of the metallic and sulfide liquids, trace elements partition differently to them. For example, Te and Cu will "feel more comfortable" in sulfide liquid, whereas Ir and Au will prefer the liquid Fe metal.

How does this fit in the bigger picture? The main importance of the siderophile-element category is that there are not enough of them. When you look at how much siderophile elements there are in the solar system, and then compare to how much we have in the crust and mantle, there are not enough. This is especially true for the highly siderophile elements (HSE: Au, Re, Ru, Rh, Pd, Os, Ir, Pt). This is unfortunate, because these are very useful metals. We could all use some more Au, Pt and Ir. The accepted explanation is that when the Earth formed, the liquid Fe metal that sunk to the core scavenged the siderophile elements from the surrounding silicate (lithophile-nearing) magma ocean and locked them in the core, far away from us.

But this occurred a very long time ago, and has little relevance for moving the siderophile elements around in more recent times, and in places closer to us. In the absence of liquid metal, siderophile elements actually behave as chalcophiles. Ore deposits of HSE and particularly the platinum group elements (Ru, Rh, Pd, Os, Ir, Pt) occur in sulfides.


What is the impact of climate change on tropospheric ozone production and vice versa?

Since ozone is a greenhouse gas, I would say it would enhance warming.

This article explains how regional climate may be impacted by ozone

This article says that while global ozone should decrease as a result of warming, ozone over populated areas should increase.

Water vapor plays a minute role in the production of tropospheric ozone- it increases the amount of hydroxyl radical to be used in hydroperoxyl formation.


The process of forming continental crust is indeed thought to have started in the early Archean (i. e. between ca. 4 Ga and ca. 3.5 Ga). But it did continue later: Hawkesworth & Kemp showed in their 2006 review that while much of the continental crust had formed by 2 Ga, i. e. until the middle of the Paleoproterozoic, some of it still continued forming later.

As far as the Fennoscandian shield is concerned, it seems that though it started forming in the Meso-Archean, and that much of the eastern and northern part of it are Archean (see Slabunov et al. 2006), the southern and western part is indeed mostly Paleo- and Mesoproterozoic (see e. g. Lahtinen et al. 2008). In Figure 1 of Lahtinen et al. 2008, it seems that the southern part of Finland, just north of the Gulf of Finland (the Uusimaa Belt) is Paleoproterozoic.

Sources:
Hawkesworth & Kemp, 2006. Evolution of the continental crust. Nature, 443: 811-817.
Lahtinen et al., 2008. Paleoproterozoic evolution of Fennoscandia and
Greenland.Episodes, 31: 20-28.
Slabunov et al., 2006. The Archaean nucleus of the Fennoscandian (Baltic) Shield. In Gee & Stephenson (eds): European Lithosphere Dynamics, Geological Society of London, Memoirs, 32: 627-644.


How to calculate humidity using outside temperature and outside relative humidity?

You can easily achieve that assuming that there is no sources of water vapour inside, so the absolute humidity (mass of water per volume of air), remains constant. This excerpt from my undergrad tesis will explain the formula for absolute humidity

Once you know the absolute humidity, you can adapt the same formula to calculate the relative humidity of a parcel of outside air (of now known content of water), that is taken from outside to inside a building where its temperature risen to a new value. If we add subscripts "e" to exterior temperature and relative humidity and "i" for interior ones. Most of the constants can be dropped and the interior relative humidity would be given by


Yes, in terms of appearances (as in your question), the Earth's ocean basins have more than likely have been carved with features of some kind or another throughout Earth's history; however, the Martian surface is not featureless - not even close.

The reason being that the geological evidence suggests that plate tectonics has been going on for much of the Earth's history, a mechanism that seems not to be present on Mars - many observations and subsequent models show that the plates have been in motion for much of the history of the planet - resulting in trenches and underwater (and above water) volcanoes (subduction ones), ridges (sea floor spreading). Additionally, hot spot activity has given rise to numerous sea mounts, such as the Emperor-Hawaii seamount chain.  These features often taken millions of years to fully develop.

Even though oceanic crust is recycled through plate tectonics, it could be assumed that these processes have formed similar ocean-floor-scapes on occasions over a long period of the Earth's history.

One of the main differences is that the processes that form these features on Earth have been, overall, semi-continuous on Earth - whereas on Mars, these processes, if started, died out a considerable time ago.


Has a scientific consensus been reached concerning the formation of the Grand Canyon?

I'm studying Earth Science right now, and I found conflicting reporting re: the formation of the Grand Canyon; whether it was formed singularly by the Colorado River over millions of years, or if it was formed by other processes with the river only filling into it relatively recently.

Yes, it was formed by other processes with the river only excavating into it relatively recently.
The Grand Canyon National Park Service describe the events involved in the formation of the Grand Canyon widely. The sequence of events was as follows:

Emplacement of an igneous and metamorphic body.
Sedimentation over the igneous and metamorphic body.
Uptlift of the complex by tectonic forces forming Colorado Plateau.
Excavation of the Plateau by Colorado River.

Read full explanation at Grand Canyon National Park website.


The Cascade Mountain Range in the US Pacific Northwest is a good example to use to explain this. The predominant wind direction is from the West - over the Pacific Ocean. The air over the ocean picks up moisture from evaporation. After it passes the coast, the mountains cause the air to rise. As it does so it cools. Colder air can hold less water vapour than warm air so that the air becomes saturated with water and it condenses out into clouds. With enough condensation you get rain - a lot of it on the western side of the mountains. So you had it backwards, the rain doesn't allow the air to rise - the rising allows it to rain. Clouds mainly approach from the lush side because that is the prevailing wind direction but it is better say that it is the lush side because clouds mainly approach that way. When wind comes from the other direction is travelling across land so it contains less water and the cooling generally isn't enough to cause rain.

Once the air crosses to the other side of the mountain range it warms and becomes undersaturated with water. Clouds often disappear and even if they remain you aren't getting further condensation to produce a lot of rain. So those areas are much drier.


"Major Lunar Standstill" causing high tides?

Can a "Major Lunar Standstill" cause one-day high tides as described in the Jakarta article?

Possibly "fake news", but very possibly yes.
The possibly "fake news" part first: The next major lunar standstill will be in late 2024 / early 2025. The most recent minor lunar standstill was in 2015. There is no lunar standstill, major or minor, in 2020.

Now for the possibly yes part. The Moon and the Sun excite tides in the Earth's oceans at a variety of frequencies. The dominant frequency in most places is the M2 tidal component with a frequency of 12 hours and 25.2 minutes. This is due to the Moon, whose tidal influence is over twice that of the Sun. There are many other components to the tides. The longest modeled term, the lunar nodal tidal cycle, has a period of 18.61 years.
Each of those exciting frequencies results in a set of amphidromic systems. (Note: The linked site discusses the response to the M2 tidal component. Every tidal component results in its own set of amphidromic systems.) The 18.61 year period lunar nodal tidal cycle results in rather weak tides in general, typically less than a centimeter.
That said, the very long frequency means that this generally small tide can add insult to injury when shorter frequency tides line up to create very high spring tides. Moreover, the shape of continents and the depths of the oceans can make what are normally small tidal influences have locally magnified significance. Miami, for example, experiences annual king tides that flood low-lying parts of the city.
More to the point, many places along the UK coastline experienced the highest tide for 18.6 years between the 19th and 30th of September. Even more to the point, tide gauge records have shown that the 18.61 year period lunar nodal tidal cycle can change high water levels by up to 30 cm.
What about the fact that there is no lunar standstill in 2020? There are a few places experience the M2 appears to be exactly in sync with the Moon in that high tide happens when the Moon is at zenith / underfoot, low tide when the Moon is at the horizon. But it's the other way around in other places: High tide happens when the Moon is at the horizon. In yet other places, high tide happens when the Moon is halfway up in the sky.
The amphidromic systems that result from tidal forcings result in rotating waves about amphidromic points. Places do not in general experience high tide when the Moon is at zenith. Every place instead experiences a phase shift from when one would naively expect high tide to occur. With the 18.613 year lunar nodal tidal cycle, that phase shift could be as much as ±9.31 years. A peak lunar nodal tidal four years before a major lunar standstill is well within the realm of the possible.


At what latitude/longitude was Cornwall, England 75 million years ago?

The rocks that make up Britain have been slowly drifting north over geologic time.  About 700 million  years ago it was near the South Pole!

I paused this Youtube video at 75 mya, held the end of a toothpick over Cornwall, then played it to the end keeping the toothpick steady over that point, under which the approximate location of Bilbao, Spain eventually slid itself. Bilbao is at 43°15′25″N according to Wikipedia.

So now, think of how longitude is defined: Relative to the meridian through Greenwich. A cursory glance at the video I linked to shows the rocks that make up Great Britain have moved as a unit and haven't rotated appreciably over the last 75 million years. So the longitudes associated with Cornwall haven't changed much in that time.


Gravity anomalies surveys are used to understand the nature of the crustal material. Positive anomalies, or higher gravity than surroundings suggests higher density (heavier) material, (iron, metallic composition) where lower some lighter alternatives.

A good example of this is the Chicxulub impact. The map of gravity anomalies show the crater quite clearly, even if it is buried under thick layers of sea sediments or surface (Yucatan, MX).

On the other hand, Nastapoka arc is harder to define using similar methods. This recent paper (PDF) (now published here) discusses that it may have more to do with crustal dynamics than an impact. Nevertheless they present an  interesting gravity map of the site (See figure), where any links to an impact in this area would not be obvious.

It is true that major glacial activity occurred repeatedly during the Pleistocene east of the Hudson Bay (eg: Laurentidian Ice Sheet sweeping again and again), but yet the Chicxulub impact was subject to many factors of erosion as well since its formation near the K-T boundary.

Still these kind of surveys indicate the nature of the material in the crust - so even if several glaciations impacted the Nastapoka arc area, there would be some kind of patterns still present indicating heavy metals (Chondrite or anything typical of an impact, iron or circular metamorphism).

To conclude, unless other surveys suggests an alternative interpretation path in the future, few evidences strongly support the theory of an ancient impact at Nastapoka.


On what authority are carbon credits issued?

Carbon credit accreditation is a process done by independent accrediting agencies. It is comparable to the way that universities are accredited by various agencies saying that their degrees are legit. You sign up to do a project to reduce carbon output, and then the accrediting agency confirms that you did just that.

Carbon offsetting isn't a future's market, it is a (financial) commitment to a project right now that is dedicated to lowering greenhouse gasses. Here is a list of potential projects, and here is a map showing projects in progress with a certain company.

I'm actually really glad you asked this question, because I just assumed that carbon offsets were effective proven means, like planting trees. But looking at some of these projects is bringing up some doubt in my mind. I don't see how burning methane into CO$_2$ is doing anything except turning a larger short-term problem into a smaller long-term problem. Or how to measure the exact number of tons of carbon you are saving by changing domestic behavior.


Is there a name for subduction boundaries at the North of Australia?

I do not think there is one name for the area. Rather it is a region with multiple plates, namely the Timor Plate, the eastern portion of the Banda Sea Plate, the Maoke Plate and the Woodlark Plate, all of which lie on the Arafura shelf which lies upon the Australian Plate. The Timor trough, Tanimbar Trough and Aru Trough would cover the western portion of the area you are questioning.

The Papuan Thrust and Fold Belt (PTFB) and the Aure Trough make up the northern and eastern portion of the area in question. Hope this helps.


Will another big earthquake hit Kathmandu?

The partial release of strain energy makes another major earthquake in the same area less likely - in the near future.

That said, there is not just a single slip plane between the converging Indian and Tibetan tectonic plates. Rather, the nappes (slabs of rock) are stacked about 12 layers deep, with Tibet over-thrusting India at a low angle.

The main Himalayan thrust fault slipped at an average depth of about 8 kilometers. There is still unreleased strain energy accumulating in thrust faults above this level. Geographically, an area 120 kilometers long by 60 kilometers wide slipped three metres southwards and one meter upwards in just over 20 seconds.

The adjacent Himalayan regions, east and west, will eventually rupture in more or less similar manner. Bear in mind that the mean rate of tectonic convergence across the Nepalese Himalayas in the vicinity of Kathmandu is 17.5 +/- 2 mm per year, whereas the overall rate of convergence of the Indian and Tibetan (Eurasian) tectonic plates is between 26 and 36 mm per year.

The Kathmandu earthquake locally released 86 years' worth of strain energy, equivalent to 35 mm per year, so is very unlikely to slip that much again for decades to come. But if I was living in north India, west Nepal or Bhutan, I'd be worried. The recent earthquake was magnitude 7.8 according to seismometers on the Indian side, and magnitude 8.1 according to Chinese seismometers (counter-intuitively both could be right). For those parts of the Himalayas that haven't experienced a major quake for centuries the accumulating strain could be phenomenal. For these areas a magnitude 8.5 is plausible.


What do the little flags on these martian wind speed data points mean?

They indicate wind direction (given by the long line or "barb") and speed (given by the shorter flags extending from each barb). In the same linked page you can read:

  The barbs extending from each wind speed data point indicate the
  compass direction of the wind (e.g., a wind blowing from the north
  will have a barb straight up above the point; a wind blowing from the
  west will have a barb off to the left). Full and half flags extending
  from the barbs indicate the wind speed, with each half flag
  representing approximately 2.5 meters per second. A circle in place of
  a barb indicates a wind speed less than 2.5 meters per second.


I'm guessing this has been answered before, but in a nutshell, the primary mechanism over the last 3 million years or so is nothing more than colder summers in the Northern Hemisphere.  Now, one cold summer won't do it, you need hundreds, which usually requires an orbital variation or perhaps, ocean current change or perhaps an extended solar minimum, but the effect needs to last for at least for a few to several centuries, or something radical like a dinosaur killing meteor or a once in a million years volcano, but that's more of an extreme event and not relevant to your question.

There's places in the far north that are snow covered year round.  Some of the time it gets warm enough for snow and ice to melt, but where it doesn't stay warm enough for all the ice to melt, you get ice cover 365 days a year.

When you get an extended period of colder summers, then the ice cover can move south, covering more land in the Northern Hemisphere.   (The South pole isn't as important because the land near the south pole is already ice covered and that pretty much never changes).   As the ice moves south and covers more land, a few things happen, often referred to as feedback mechanisms.

1) more sunlight reflects off ice, less heat stays on the Earth to warm the atmosphere, this has a global cooling effect.

2) Oceans begin to fall as ice builds up on land.  Oceans absorb the most heat from the sun per square meter out of any surface on earth.  Ocean heat absorption also evaporates water vapor into the atmosphere, and water vapor acts as a greenhouse gas.  As oceans fall, they also cover less area and while the size change is a relatively small percentage, that also works to cool the earth.

3) as the ice grows higher, this has a cooling effect on high altitude air, which blows off the ice and cools surrounding areas and tends to keep the ice frozen longer.

4) as the oceans grow cooler, they absorb CO2 from the air, this lowers the amount of greenhouse gas in the air which has a cooling effect.

The cooler northern summers are thought to be driven by orbital changes such as low orbital eccentricity.

Interestingly, the effects such as orbital variations, milder summers and even CO2 are by themselves, quite small, but when taken together with the feedback mechanisms in place, the temperature change of the planet between ice age and inter-glacial period is quite large.  As much as 10 degrees c globally, corresponding with mile high glaciers covering most of Canada, half the United States, half of Russia and Europe, as well as 300 foot sea level drops and ecosystem changes around the globe.   Not all bad.  Some deserts will arguably get improved ecosystems, but the change is felt globally.

The inter-ice age period is the same thing just in reverse.  Orbital changes can lead to warmer summers which melts ice, and beings to reverse the 4 feedback mechanisms mentioned above.   Melting ice isn't all harmless though.  You get enormous lake sized pockets of water trapped in ice, waiting to give way, and floods like we've never seen.


What is the shortest path between two points on Earth's surface?

If you don't want to do the calculation yourself, you can use an online calculator like the one provided by NOAA.

Alternatively, if you do want to do the calculation yourself you can use the haversine formula.

  This uses the ‘haversine’ formula to calculate the great-circle distance between two points – that is, the shortest distance over the earth’s surface – giving an ‘as-the-crow-flies’ distance between the points (ignoring any hills they fly over, of course!).

  $$a = \sin^2\left(\frac{\Delta\phi}{2}\right) + \cos \phi_1 ⋅ \cos \phi_2 ⋅ \sin^2\left(\frac{\Delta\lambda}{2}\right)$$

  $$c = 2 ⋅ \text{atan2}( \sqrt a, \sqrt {1−a} )$$

  $$d = R ⋅ c$$

  where $\phi$ is latitude, $\lambda$ is longitude, $R$ is earth’s radius (mean radius = 6,371km)


What is the collective name for the seas of Indonesia?

I've always known it as the Maritime Continent, as in,

Neale and Slingo (2003) The Maritime Continent and Its Role in the Global Climate: A GCM Study, J. Clim, doi:10.1175/1520-0442(2003)016%3C0834:TMCAIR%3E2.0.CO;2

But that has an atmospheric perspective; it refers to the ocean and the land, because they're both important for the meteorology of the region.  There may be another name for just the watery bits in between the land.


How Could Sheep Graze these Steep Hillsides Without Leaving any Marks?

Those lines have nothing to do with animals.

Those lines are generated by solifluction and frost heave. It is sometimes referred to as cryoplanation or soil creep. Basically as the thin hillside soil freezes and thaws it expands and contracts and because there is a slop it moves downslope. In addition rain combined with how the surface thaws before the deeped ground causes a plane of weakness and movement. It can form a variety of patterns but on strong slopes it tends to form stripes or ripples.

That area of England is well known for such landform. Below is a picture from Dorset and another from the isle of wight. They don't only occur on grazed ground, but if ground has trees they act as anchors for the soil and you don't get the more noticeable lines and nobody is going to graze animals on ground with nothing but trees or hills with no soil which also will not have them.

1. Sugden, David E. (1971). "The significance of periglacial activity on some Scottish mountains"

2. frost creep and gelifluction features a review


How likely is Earth to naturally reverse climate change in the next 2 decades?

Very unlikely, especially as the major industrial nations will come nowhere near to meeting their greenhouse gases emission targets. Major volcanic eruptions, like major earthquakes, are random and unpredictable. The last really big volcanic eruption we had was Tambora, on the Indonesian island of Sumbawa in 1815. That caused climate cooling for a few years, but it didn't cause a mini ice age. It may have helped the Little Ice Age which was already in progress, to last until the middle of the century, but that's all.

Tambora was the biggest eruption in recorded history, dwarfing Pinatubo, Krakatoa and Thera (Thera erupted in the Med near Crete 3.5 thousand years ago and destroyed the Minoan civilisation), so an eruption big enough to cause another Little Ice Age would probably need to be as large as the Toba eruption of about 75,000 years ago on the Indonesian island of Sumatra. The chances of such an eruption within the next 20 years are virtually nil. The Little Ice Age, which lasted about 400 years and ended about 1850, is not believed to have been caused by volcanic eruptions, though such eruptions may have from time to time intensified it and prolonged it.

There is no way of inducing major eruptions short of detonating 50 megaton hydrogen bombs in sites known to be volcanically unstable, but that would not only violate international treaties about nuclear explosions in the atmosphere but would in any case be unacceptable. Fifty megatons is the world record for thermonuclear explosions, by the way, held by the Russians.