From where do weather radar maps get their data?

Images showing clouds mostly come from geostationary satellites. Geostationary satellites are at an altitude of about 36000 km, which allows them to monitor the same area of the Earth continuously. They stay in place relative to the Earth's surface above the equator thanks to balance between gravitational and centrifugal force. There are a few such satellites designated to operational weather forecasting, notably:

GOES-East & GOES-West operated by NOAA
Meteosat-7,-8,-9,-10 operated by EUMETSAT
MTSAT operated by JMA (Japan)

These satellites contain passive remote sensing instruments measuring incoming radiation in a number of channels, mostly visible and infrared. Visible is only available during the day, while infrared is available all the time. Radiation is captured on lines of sensors by scanning the view, which generally takes a few minutes to complete. Geostationary satellites are unable to capture polar regions above a certain latitude, because of the angle.

In addition to geostationary satellites, there are polar orbiting weather satellites:

NOAA-18,-19
MetOp-A,-B (EUMETSAT)

Polar satellites fly much lower (~800 km) and cannot provide continuous global coverage, only swathes along their orbits.

All of this data can be used in the assimilation (initialization) process of weather forecasting models. In turn, one can produce images of cloud cover from the output of the models, see e.g. wettercentrale.de.

NASA operates mostly research satellites, not so much operational weather satellites, although they do cooperate with NOAA on some of the missions. In Europe, the counterpart is ESA, who run some satellites on their own (e.g. Sentinel and in the past Envisat and ERS-1,-2) and cooperate with EUMETSAT.

The data from satellites is downlinked to communication centers (sometimes routed via other communication satellites), where it is processed by various algorithms into products (data files). Product files can be downloaded over the Internet by national weather services or are made available publicly to anyone (all data from NASA satellites is public - see e.g. NASA Global Change Master Directory).

Weather radars are generally located on the ground. They operate by sending short pulses of microwave radiation and measuring the reflected (backscattered) radiation from water/ice droplets. As the microwave radiation has relatively large wavelength (on the order of one millimeter), it is not very sensitive to cloud droplets, and you can see mostly bands of precipitation. Weather radars are operated locally by national weather services. You need roughly one per 250 km to get a good coverage. As with data from weather satellites, they are very important in assimilation of numerical weather prediction models. There are also spaceborne radars, e.g. DPR on GPM Core Observatory, TRMM, or CloudSat.


Effect on poles when Earth is not tilted

If we ignore the giant impact (which would have enormous effects), and just look at the effect of the Earth having a 0 degree axial tilt, the most immediately apparent effect is that the seasons would be reduced almost to nothing and the very small seasons that remain would be planet wide, not alternating between the 2 hemispheres.

The Earth is currently closest to the sun in the first week of January and furthest in the first week of July.  Source, so it's pretty obvious that being closer to the sun doesn't create summer.  The axial tilt is what causes the seasons, but the change in distance to the sun still has some effect.

There's a little  over 3% variation in distance, see source, yielding a bit over 9% variation in energy received between the Earth's perihelion and aphelion, but that doesn't mean a 9% change in temperature.  It's much smaller than that due to the Earth's oceans, atmosphere and to a lesser extent, surface are all heat sinks that take a long time to warm up or cool down.   The seasonal difference in temperature would be much less than that.   Maybe a few degrees, perhaps 5-10 degree difference between summer and winter, probably less than the change between night and day.

No tilt also means, you lose the 6 months of sunlight, 6 months of darkness that we currently get near the poles and the sun wouldn't be higher in the sky in summer than in winter.    At the poles, you'd effectively get sunset, 24 hours a day, 365 days a year but over most of the Earth you'd have 12 hours (and a few minutes) of sunlight and nearly 12 hours of, not darkness, cause you'd still have twilight and dawn, but over the most of the planet, it would be 12 hour days pretty much.

The poles would receive less solar energy and could be colder and there wouldn't be a spring thaw or summer growth.  Plant Growth would be pretty consistent all year around.

The equator would have more peak sun and could be hotter.  With our current tilt, the pole to equator solar energy ratio is 0.4 to 1.  Source.  With no tilt, it would be 0 to 1.  The poles could see an increase in permanent ice.

But, despite that increase in ice, you'd get a decrease in solar-ice-reflection, so that could mean a warmer earth, even with more ice on both poles.   The equatorial region could be hotter.

Circulation is hugely complex, so that's a great big wild-card.   Seasonal driven ocean and air currents would be greatly reduced but temperature driven currents should increase, though the reduction of temperature variation is difficult to predict.  You still get night to day temperature variation, but the overall effect on wind and ocean currents is too hard for me to predict.

Hyper-physics says the tilt is essential to life (linked above).  I'm not sure that's true, but no seasons and potentially reduced circulation due to more consistent temperatures could have a pretty big effect.   The potentially worst outcome could be a significant still water in the oceans which could create large dead zones.  That's by no means a certainty, but it's possible.

Article on the effects of the ocean conveyor belt stopping, if interested.

If I missed anything, comments are welcome.


Are there datasets like the global land-ocean temperature index for land surface temperature only?

Yes, NASA GISS has it here . If you go to the main page and search for 'Global Mean Estimates Based on Land-Surface Air Temperature Anomalies Only (Meteorological Station Data, dTs)' within that page you will find the links to the above, plus northern and southern hemispheres.


Why is the troposphere 8km higher at the equator than the poles?

To start with a definition, the tropopause is the boundary between troposphere and stratosphere; within the troposphere temperature decreases with increase in altitude (the temperature profile is dominated by radiative heat from the Earth's surface), whereas in the stratosphere temperature increases with altitude (the temperature profile is dominated by solar radiation).

Increases in troposphere temperature are associated with increase in tropopause height. Factors in play include the amount of water vapour being evaporated from equatorial seas; interannual variations in tropopause height can result from both local and large-scale driving forces. The tropopause responds to the average temperature of the entire underlying layer: this is higher at the equator and lower at the poles.


Can you measure BOD/COD real time using any sensor?

Realtech.com has a runtime monitoring senser solution for BOD/COD Sensor.
My understanding is that COD is straight-ward to measure in real-time but BOD monitoring cannot be done in real-time.   The sensor listed uses a BOD equivalent monitoring technique.

The governing environmental regulatory agencies for a specific waste water facility should have public statement of acceptable BOD monitoring methods.


Do dams reduce the flow of river downstream?

Once a dam has been constructed in a river, the natural flow of water will be disrupted.

You correctly state that initially there will be a period required for the dam to fill. Until then, little of no water will flow beyond the dam.

Dams are created for one or more of three reasons:

To supply potable water to a population of humans for domestic or
industrial purposes.
For agricultural purposes.
To generate hydro-electricity.

Water released from a dam prior to it being full may be to restore some flow for environmental reasons, because hydro electricity may need to be generated or it may be needed for agricultural reasons.

To protect dams from overfilling and damaging the dam wall spillways are generally constructed to allow the excess water to flow beyond the dam. For dams without a spillway, the dam gates will be opened to reduce the amount of water in the dam to protect the dam from failure.

One of the issues with dams is they prevent sediment carried by the river to travel the full length of the river. This can be detrimental to the natural replenishment of some farmlands of nutrient rich sediment and it is detrimental to the replenishment of nutrients to fish breeding regions near the mouths of rivers. This happened when the Egyptians built the Asswan Dam.

The other issue with dams is that people downstream of the dam cannot rely of the natural flow of the river, in terms of timing of flows and quantities of flow. This is the main concern for Egypt. It relies heavy on the Nile River as its main source of fresh water for hydro-electricity generation, agriculture and water for people to drink.


Electricity in clouds and induced magnetism

The short answer to your question is yes all charge particles (positive or negative), independent (like electron, proton) or attached to other materials like cloud droplets, molecules, atoms, etc. when in motion produce magnetic field.

If two charged particles of same charge are moving in opposite direction then they cancel out each other's magnetic field. Hence, the random motion of droplets in cloud cause net zero magnetic field away from the cloud. One can understand this by analogy to a pair of electric wires used in powering homes which does not produce appreciable magnetic field at distance when the two wires of pair are close to each other because electrons are moving in opposite directions in the two wires.
In organized motion of charged particles that is when there is net movement of charge in a preferential direction, for example a cloud with charged droplets moving under influence of wind one can have net magnetic field. However, here too, if the cloud as whole contains both positive and negative charges in equal numbers will not produce appreciable magnetic field at a long distance because magnetic field produced by negative charges will be opposite in direction with respect to magnetic field produced by positive charge moving in same direction. If there is net positive or negative charge on cloud then the magnitude of magnetic field will depend on wind speed, which for atmospheric range of wind speeds will produce very small magnetic field.
The appreciable magnitude of magnetic field is produced during lighting since large amount of charge moves along a particular path with high velocity but such movements are momentary and as soon as the lighting strike is over, the magnetic field produced starts dying. If a compass needle is having significant inertia then before the needle can move under influence of newly produced magnetic field, the magnetic field will vanish and hence ordinary compasses are unlikely to show effect of lightning strikes.

Further Reading:

Fundamentals of Lightning by Vladimir A. Rakov, Cambridge Univesity Press, ISBN 978-1-107-07223-7, 2016


What processes produced the basalt columns of the Giant's Causeway?

These are basalts with columnar joints. Basalt is an igneous rock that forms when magma (liquid + crystals) erupts onto the surface as a lava flow or gets injected into cooler shallow crust and forms an intrusive dike or sill.  Because basalt cools quickly, basalt commonly contains glass as well as crystals. The physical properties of magma changes rapidly as it cools through the liquid-glass transition temperature. When a magma cools through the liquid-glass transition temperature, its specific volume decreases and its viscosity increases rapidly. The volume of the lava flow decreases (it shrinks) and it become more viscous and brittle. This creates stresses in the lava flow that eventually causes it to fracture. Columnar joints are fractures that have formed because the stress has exceeded the brittle strength of the rock.


It is a question of radiation emission - the temperature of the Sun's 'surface' is about 5500°C (according to NASA Earth Observatory), at that temperature, it emits radiation in the UV, visible and near infra red region - due to the fact that the hotter an object is, the smaller the wavelength radiation is emitted, as can be seen in the generalised image below (from NASA):

Note: the temperature of the Earth shown is an approximattion of its blackbody temperature, explained in the answer to the question What would be the temperature of earth if there was no atmosphere?.

Realistically,

Source: Wikipedia

Not all of this radiation reaches the top of Earth's atmosphere reaches the surface, a proportion is reflected off the atmosphere and some is absorbed by the atmosphere (as shown as the difference between the yellow and red in the diagram above) - but a good proportion reaches the Earth's surface.

But that is not the entire picture, we receive this 'shortwave' radiation from the Sun:

Which is also balanced by an equal amount of energy radiating into space as 'longwave' thermal infrared radiation:

(Both images from NASA Earth Observatory)

Which leads to a major point - we have an atmosphere and a natural 'greenhouse effect' due to the water vapour and carbon dioxide (and other components) that are seen in the above solar radiation spectrum diagram.

Some of the thermal infrared is absorbed by the atmosphere and re-radiated back to the surface. This radiation budget is shown below:

Source: NASA

Something to consider, looking at the value the NASA has for the incoming radiation reaching the Earth's surface - 168 Wm-2 - imagine that being a 168 watt light globes for every square metre - that value increases markedly when the re-radiated thermal infrared is taken into account.

Also, please view the YouTube clip How the Sun Heats the Earth which is a handy verbal and diagrammatic explanation of the content of this answer.


Can weather radar be used to track swarms other than mayflies?

Bird migration has been studied by Weather radar Bird migration study using weather radars  and the monitoring can be visualized here - Bird migration density profiles. A github site Time Integrated Multi altitude Migration Patterns  has been developing algorithms to estimate the density, speed and direction of migration movement at different altitudes around a radar.


Do solar panels reduce the amount of suns rays reflected back into the atmosphere ? Therefore reducing global warming

Whether solar panels reduce the amount of suns rays reflected back into space depends on their albedo and the albedo of the surface that they cover.  Desert sand, for example, is fairly reflective and solar panels might reflect less sunlight back into space than deserts, but it's not just the reflection that matters.  You also have to account for energy production.

If enough solar panels are built that fossil fuel generated electricity (usually coal or natural gas), can be reduced, by 5% or 10%, that works out to a pretty useful drop in CO2 footprint.   Less CO2 from burning fossil fuels means less warming.   The ratio of surface temperature by absorbed sunlight vs reflected sunlight is on average, less significant than the heat trapping of CO2.   Explaining that gets kind of long and mathy and it's full of approximations, but as a ballpark estimate, 1 joule of energy produced by fossil fuels and the CO2 that's released by that process, that CO2 warms the atmosphere by several joules.   We can see this by estimating the added heat to the air and oceans as a result of climate change and comparing that to the energy use of all mankind.  I might add a crude calculation of my own later, but here's an article that says the ratio of heat captured by man made climate change to waste heat has a ratio of 100 to 1.

However you calculated it, the added heat by increases in CO2 exceeds any albedo variation by at least an order of magnitude, possibly two.   So even if Solar panels did absorb and retain more heat from sunlight than the surface area they cover, they still should lead to cooling by reducing the CO2 footprint.   The more important question is whether energy from solar panels can effectively reduce CO2 output from power-plants, because power-plants need to cover demand and solar energy can be intermittent.   Still, if there is any measurable reduction in fossil fuel generated electricity, there should be a net cooling due to how effective CO2 is in trapping heat even if the solar panels aren't efficient reflectors of sunlight.

Also,

  The way I understand the basics of global warming is we are putting to
  much Co2 into the atmosphere which increases the size / density of
  atmosphere shell.

This is incorrect.  It's not the size or density of the atmosphere but it's opacity to the long-wavelength infrared light radiating from  the Earth that drives climate change.  (feedback mechanisms like melting ice and rising albedo play a role too), but changes in the Atmosphere's density or mass are largely irrelevant.

Burning fossil fuels doesn't change the density or mass of the Atmosphere much anyway and they might even make the atmosphere a little lighter, though the overall calculation gets pretty complex with plant growth and oceanic absorption.

When fossil fuels are burned, O2 is taken from the air, combined with hydrocarbons in the fuel which becomes CO2 and H20.  The net mass change of O2 lost and CO2 gained depends on the Carbon to Hydrogen ratio of the fuel burned, but the effect is pretty small either way.   High hydrogen fuels like Methane, the primary ingredient in natural gas, takes more O2 from the air by mass than it returns in CO2.   More Carbon rich hydrocarbons like coal, the mass ratio is closer to even.   But in either case, the 30 plus billion tons of CO2 that's produced every year is negligible compared to the 5.1 million billion tons of the atmosphere.   That's less than 1 part in 100,000 by mass per year.

What drives climate change is what happens to the long-wavelength infra-red light that leaves the Earth.   The longer wavelength photons that leave the Earth sometimes hit a molecule of CO2 that temporarily wiggles, before reflecting that light-energy back.   That's the basis of the Greenhouse effect.   The reflection back to the Earth of long wavelength infrared light.   and more CO2 means more IR light gets reflected, which adds heat to the atmosphere.

In a nutshell it's the color of the sky, that is, color in wavelengths we can't see, so calling it color isn't quite right either, but that's the gist of the greenhouse effect.  Opacity not Density, though if you were to make Earth's atmosphere a lot more massive, say 10%-20%, that could have an effect, but we don't have the means to do that.

  sun rays enter the atmosphere then there is some reflection off the
  earth and then the reflected rays get trapped within the atmosphere

This is generally true.  Reflectivity is an important aspect of Earth's energy budget and Albedo of a solar panel is one aspect of solarpanel design.   That said, Solar panels cover such a small percentage of the Earth's surface, that their effect on reflection is negligible.   Also, reflected rays are less likely to get trapped in the atmosphere than infrared rays.   The Atmosphere is largely transparent to visible light and reflected rays of light are mostly in the visible spectrum.

An interesting and related question to ask is, instead of installing solar panels, what if we paint things white (well, you might not want a white roof in winter, so that might not be a perfect solution) but in someplace where it's always warm/hot all year round and white roofs are common.  White paint would reflect more sunlight back into space than a typical solarpanel would.   The math gets tricky where you have to weigh the fossil fuel use reduced against the increase in light reflected.  Here's an article that touches on that in some detail.

I also want to add that the dark color of solar panels is designed to absorb sunlight and turn it into electricity.  A reflective solar-panel kind of defeats the purpose, unless you're talking concentrated solar power which works based on reflection, but those aren't typical solar panels, though they are solar energy.


correct way to calculate transport through a section in an ocean numerical model

I have been using the routines in nctoolbox (also check here) that do all the slicing (vertical, horizontal, following a track).
The repository is in GitHub.

The one you should looking at is vsliceg.m.

You can follow the logic there or develop your own.


What is the northernmost/southernmost city that receives no snow?

On the North American west coast, Coos Bay, Oregon is the northernmost place I can find, of any significance, that gets no snow.  Astoria, Oregon gets 2.5 cm of snow per year.  Coos Bay is at 43.4 degrees north latitude.

On the east coast, Boston is of similar latitude and gets significant snow, so that coast is out.

In western Europe, A Coruna seems to be the best candidate, at 43.4 degrees north in Spain.  I had originally thought Guernsey would be a good candidate but it gets a little too much snow, and cities in France seem to get regular snow too, even on the coast.  Venice looks like a tempting alternative, but it seems to get snow consistently, if uncommonly.

So, so far, 43.4 N seems to be the answer on both the North American and European continents.

In the southern hemisphere, Comodoro Ravadavia, Argentina at 45.8 S gets snow, but Trelew, Argentina at 43.3 S does not, so the snow band in eastern South America seems to be quite close to the same latitude as we see in western North America.  There are few significant communities on the western Chilean coast, but Puerto Montt, Chile is snow-free at 41.4 S.  Southern New Zealand is at similar latitudes, but seems prone to heavy snowfalls at times, probably because of its proximity to Antarctic currents and the presence of tall mountains.

There are quite a few southern islands that are candidates, but most seem to get snow, and none have any significant settlements, short of the Falklands, which definitely do get snow.

If you get rid of the people requirement, the McMurdo Dry Valleys at 77.3 S are probably the answer.  They are very cold, but so arid that they are largely snow-free all year long.  Snow that does try to fall often sublimates directly into the atmosphere.


How do I convert a latitude/longitude coordinate to a NOAA GFS grid cell location?

** All of the links given with times will need to be adjusted to current dates if reading this at later times or else will appear dead **

Once upon a time I dealt with such files, but not in quite a few years... and Google wasn't the best help at first in finding documentation on what the .ascii is exactly... but thanks to Kevin Goebbert's code here, I was able to find the description page for the model in question is located by removing the .ascii and inputs (and thus here):

And so right now it lists:

Longitude:
0.00000000000°E to 359.50000000000°E
     (720 points, avg. res. 0.5°)
Latitude:
-90.00000000000°N to 90.00000000000°N
     (361 points, avg. res. 0.5°)
Altitude:
1000.00000000000 to 1.00000000000
     (47 points, avg. res. 21.717)
Time:
12Z07JUL2017 to 12Z17JUL2017
     (81 points, avg. res. 0.125 days)

The p50 indicates a grid space of only half a degree in that file, so you couldn't actually use your point in this moel.

However, use the 0.25 resolution instead (description):

So first is time first is time, the second is longitude points starting at the Prime Meridian and going east, and the third is latitude starting at the South Pole and going north.  (GFS time steps have always been a mire... but based on this full list of data files and the info page previously given, it indeed appears the data provided here is just every 3 hours for the first 10 days.)

So to pick your value for the second input, it'd be something like

  ifpositive: (longitude)*4 - 1
  ifnegative: (180+longitude)*4 + 719

And for latitude:

  360+(latitude)*4

And so if I didn't make a mistake, that'd be this point (lat gridpoint 505, lon gridpoint 1124).


The Navier-Stokes equations are just a couple of the equations used in Climate Models, but they are the most complex set of equations used, and describes the movement of wind. Unfortunately there is no known solution to them yet (though if you come up with one, there is a million dollar prize waiting for you). Another equation used by complex models is the conservation of energy (which in layman's terms can be describes as):

How the temperature changes at a certain point = How fast wind is blowing warm/cold air to the point + How fast the air is cooling by expanding or warming by compression + Net heating/cooling (from the sun, clouds, greenhouse gases, etc.)

With more math, sophisticated techniques, and use of previous research, a prediction is made by the climate model, for just a couple seconds or minutes into the future. Then that prediction is used for the next start of the climate model. This is also how weather models work, but climate models repeat this process for years, decades, and centuries. Climate models also consider different factors from weather models, like what is in the air. Different models have different preferences and consider different scenarios.

You can find some of the results in the IPCC report.

But if you want a simple mathematical model, the simplest out there is the zero-dimensional energy balance model. It won't really predict the temperature to any sort of accurate degree, but it is a useful balance to know.


Is the temperature (even a bit) warmer in a forest?

It will depend on the time of year and the time of day. As you noted, you often see more frost in an open field than in a forest. A comment indicated the forest insulated the surface but I believe it will also reduce radiant heat loss at night, compared to the open field. During the day, the ground surface is more shaded and the trees reduce the advective movement of warmer air into the forest floor so the forest will often be cooler than the open field.

Another factor is evapotranspiration. Forests will tend to be cooler in drier summer conditions because, in general, you get more evapotranspiration from trees than from shallow-rooted vegetation and annual grasses die off in summer. The evapotranspiration cools the area.


What is the difference between a flood and a mudslide?

A flood occurs when land that is normally dry is covered by water. The source of the flood water is generally from bodies of water, such as: rivers, lakes, dams and even the ocean.

Rivers can flood, when:

  the flow rate exceeds the capacity of the river channel

Similarly, excess water run-off during heavy rain can cause floods when the water cannot drain away quickly enough.

Flooding is the act of flood water accumulating in a area that is being flooded.

To understand mudslides you need to know what a landslide is.

A landslide is when a quantity of rock slides down a slope.

A mudslide is similar to a landslide. The only difference being the type of material that is moving. With landslides, the material moving is generally composed of rock and maybe some soil. In mudslides, the material being moved is loose, finer grained material such as mud and clay.


Newton's & Kepler's age of the earth calculations - References?

Your question may be better suited to either SE History or SE History of Science and Mathematics. The date of the so called creation of the Earth has nothing to do with Earth Science.

For Kepler I found he wrote the book KANONES PUERILES, in it he calculates the creation date to be 27 April 4997 BC.

The published works of Newton reveal little. Some authors on Newton mention an unpublished document he wrote in either 1704 or 1705. Any calculations he may have done regarding the so called date of creation may be in his unpublished writings.

You may need to review the bibliographies of authors who wrote biographies on Newton, such the 1855 book by Sir David Brewster, Memoirs of the Life, Writings, and discoveries of Sir Isaac Newton, volume 2.


Locating Missing Airplanes using Remote-Sensing Satellites

Civilian earth observing SAR satellites do not always operate over empty swaths of oceans (specially in the middle of Indian Ocean) in order to save power. They are not designed to track a fast moving target and have repeat cycle of at least a few days. Then there is the issue of resolution. High res acquisitions modes (with satellites like TerraSAR-X) are pre-programmed in advance.

So in theory it is possible that a flying aircraft might show up in the amplitude image (a pixel or two wide) if a satellite was indeed flying over the Indian ocean and acquiring data over the area where the plane was flying. But then all you have is a single image. And once the plane is under water you wont see anything.


Why is ferret giving me error that the region is not 2D while plotting

You need to use the following syntax

yes? fill 't'[k=1,l=1]

This is because ferret treats t variable name as time and to distinguish your variable name (if it is the same in the file), you have to provide it in double quotes.


Plate Tectonics: Is it possible to have an ocean-continent divergent boundary

The oceanic plates are themselves formed from the divergent boundary, so probably not. Even if a new rifting occurred exactly at the boundary, the result would eventually be that the ocean floor surrounds the divergent boundary.

A very simplified model of an ocean would have a divergent boundary in the middle. This oceanic spreading center might have basaltic volcanic islands along it, and two mirrored plates on each sides, pushing towards neighboring continental or oceanic plates.

I'm trying to think about any oddity that would fit your description, but can't really come up with a good example. Locally you might have the conditions in triple junctions eg. at Afar Triangle. Somehow, it could also describe parts of New Zealand and eastern Mediterranean, but it's very complex areas with more parameters controlling the rifting.

Earth is not controlled by any simple equation, its formed by 4.56 billion years of interaction between rocks, magma, life, atmosphere and even astronomic influence, so I'm not sure that divergent boundary never occurred between existing continental and oceanic plates, but at least it's very uncommon and couldn't last long.

A way to understand plate tectonics better, and maybe even a good inspiration for world building games, is to have a look at the (free) program Gplates that is used by students and scientists to simulate tectonic history. Don't worry about your ignorance, interest is more important than knowledge. The game might be a good inspiration for someone to learn more about something really awesome.


Gravity is a weird force.

All mass has, and is affected by, gravity. That means you, me, your cat, black holes, the sun and the earth.

It also means each little bit of the earth is attracted to every other little bit. So every bit tries to get as close to every other bit as it can.

The shape that these bits form is a sphere - because every bit is as close as it can get to all the other bits.

Now you are right - an earth which is matter all the way through would attract in the same way as one which had all the mass concentrated around the edge. But we know that the centre isn't hollow for two reasons:

Volcanoes and Earthquakes. Volcanoes erupt liquid rock from the ground, which shows that there is something down there. And we know that there is something because we feel the shaking from earthquakes on the other side on the earth - and we can map the layers of solid and liquid from these.

  If gravitation decreases as we approach the core and if density is a function of gravity we should expect a void core.

No, because every bit wants to be close to every other bit. It doesn't just want to be near the bits on it's side, it wants to be near the ones on the other side, and so the "void" would close.

  Why is the density of Earth higher at the core?

The denser stuff sinks. This is how it works everywhere that gravity applies. We can explain why.

The denser objects have more gravity than the less dense objects. This means all the objects are attracted to the more dense objects more than they are the less dense objects. Here, red is more dense.

But the ones over the other side, are also attracted to that dense object, so this happens:

Eventually, you end up with all the less dense objects surrounding the more dense object, as they try to be as close as they can to it. But the more dense objects are attracted more to the other dense objects (as they both have more mass). This means all the dense objects clump together, surrounded by the less dense ones.


What is the history of atmospheric O₂ concentration?

Refer to the stratigraphic chart for timeline and stratigraphic units. And i tried to be as up to date as possible in the limited time. Which is also the reason why i omitted some details in favour of an overview.

It is assumed that during the early and middle Archaen only very sporadic oxygen production took place. This changes towards the end of the Archean, when a flow of oxygen from shallow ocean parts to the atmosphere began.

This article suggests that the following "great oxygenation event" (goe), at the early Proterozoic 2.33Gy just took up to 10 million years. During the goe, atmopsheric oxygen increased to 1 or 2 percent, the exact percentage seems unclear. But it seems that in some places, a fully oxygenated ocean existed slightly before the goe at the end of the Archean, at ~2.5Gy. These waters would have been able to produce excess oxygen for the atmosphere in a small or regional scale slightly earlier.

Atmospheric O2 stays low during the Proterozoic, probably because it is used up in weathering processes.

At the beginning of the Cambrian, O2 was still low (~5%). This article describes the development thorugh the Phanerozoic by combining data from modelling and proxies. See Figure 3 (there's your plot;-). It shows that not before the end of the Ordovician atmospheric O2 rises to above 10%, topping off at the end of the Permian at ~32%.

These days, oceanic as well as atmopsheric O2 levels are falling and will continue to do so because of fossil fuel combustion.


How can flood inundation vary at the same river stage?

Hydrology major here, for whatever that's worth :) Some possibilities from my readings/internships:

First I'd check the gage you're using for stage--if it's moved in the last 8 years, the stage may need to be correlated to what it would be at the former site. If it hasn't, it's more likely something changed in your stretch of channel.

If the channel has deepened at your location and not at wherever the gage is located, then you'll see less flooding. If the gage is upstream of your stretch of stream, I'd be suspicious of any new wetland areas that could accommodate water; if it's downstream, of any dam removal or other loss of channel restriction that could be allowing water to get past your site more quickly. Downstream changes in the channel could also affect your site! And if it's fairly urban, maybe the city has figured out ways to divert runoff farther downstream?


How did Great-Britain separate from France?

"Is it possible that the oceans eroded land between them so they became separated"? Yes, sort of, but it isn't a simple story. There are several factors: (1) Rivers eroded much of the English channel, mostly during the last ice age when sea level was up to 120 metres below the present level. The Rhine actually flowed (and eroded) much further out into what is now the English channel. (2) Some have argued - though I'm not sure that I agree with them - that at least part of the English Channel was cut by glaciers. However, the main British ice sheet was further north than the channel. (3) There is sound evidence that an ice dam collapsed, resulting in a huge glacial lake outburst, which would certainly have resulted in major erosion. (4) The Alpine orogeny of late Mesozoic / early Cenozoic age, created a compressive zone across much of northern Europe, thereby flexing low-angle folding. One of the major folds was the Wealden anticline, most of which is exposed in southern England, but to a lesser extent also in northern France. Tension fractures in this anticline created an area of weakness and enhanced erosion across what is now the eastern English Channel.

Could microplate tectonics have contributed? Good question. Certainly it is possible for the jostling of major plates to splinter off microplates, or even mesoplates - examples being the Aegean region, and the rotation of Iberia, respectively. I don't have any information on the deep geology of the Western English channel, but I suspect that tectonic thinning of the crust in that area may have contributed to subsidence and subsequent flooding.


What are the conditions for an ionosphere to form?

Most of the visible matter in the universe consists of ionized matter (I'm citing thise from the publicly available lectures from R. Fitzpatrick and the monograph from J.A. Bittencourt - Introduction to plasma physics). This is true independent whether you measure it by mass or by number of atoms and molecules.

Why is this important?
As I see it the ionosphere is the part of the atmosphere that connects the electrically neutral atmosphere at high pressures and the low-pressure ionized regions of the universe.
Thus, any planet will have firstly an ionisphere and secondly maybe an electrically neutral region that we call "atmosphere". There is a caveat here, as the ionosphere doesn't have to be fully ionized, just have enough electrons and ions floating around to act as a plasma.

Why is gas ionized at low pressures?
The amount of ions that fly around in a certain volume is not only a function of the amount of freed electrons, but also of the amount of electrons that recombine.
The strength of ionization will be a function of the process under consideration. However recombination will be independent of this and be governed by a $\sim n^2$-dependency on the density $n$.
This will generally result in a disproportionally weak recombination as pressure / density decreases high up in the atmosphere. Or in other terms: At low pressures, you can get ionized thermally, by UV-photons, [...] but you don't find a partner anymore to recombine.

Concluding
I've presented a case why every planet must have an ionosphere. Details like the solar wind, distance from the star, it's class and atmospheric variables then control the shape of the entailing magnetosphere and exact height-profiles of ionized species.


Are there standards for tropospheric NO2 levels considered low or high?

The OMI tropospheric NO2 retrieval algorithm does not provide surface concentrations of NO2, but rather a column density.  So, it isn't appropriate to directly correspond those OMI retrievals to health standards that are based on ambient concentrations at the surface.  There have been many attempts to correlate surface concentrations of NO2 to tropospheric NO2, but the correlation is fair at best.  Furthermore, the tropospheric column inherently changes depending on elevation, since the amount of atmosphere in the tropospheric column decreases as the surface elevation increases.   There are also several assumptions that go into the retrieval that create a large amount of error (e.g. stratospheric column subtraction, a priori profiles, surface albedo, etc.).

As I discuss in this post, it is possible to distinguish clean, polluted, and highly polluted tropospheric NO2 columns.  However, the exact thresholds are specific to location and sometimes season as well, since the retrieval algorithm responds differently depending on parameter assumptions.  In general, if you are seeing values over ~5x10^15 molec/cm^2, you can be sure there is real NO2 pollution.  Anything over 1x10^16 molec/cm^2 is highly polluted.   The higher the values are, the more confidence there is in the retrieval.

You can see the responses from the creators of OMI for similar questions here:

  Does the red colour signal smog at the surface?

  No, since OMI does not measure the concentration at the surface directly. Instead, OMI measures the total amount of nitrogen dioxide (NO2) in a column up to about 10 km.

  However, research has shown that high NO2 column amounts in OMI measurements (red colours) usually coincide with high concentration levels at the surface. This concentration is usually not as high that you can it moderate or heavy smog, but it does still indicates an elevated level of air pollution. The OMI measurements clearly show that The Netherlands suffers from a significantly higher level of air pollution by NO2. See also the answers to the next questions.  Note that smog does not exist only of NO2. Other important ingredients are aerosols, ozone, sulphur dioxide and hydro carbons.

  The OMI map shows a red colour over The Netherlands but according to surface measurements of the Dutch National Institute of Public Health and the Environment (RIVM) it just minor smog. What causes the difference?

  The surface measurements from RIVM are related to the European norms for smog. Those norms are related to a peak level surface concentration. The threshold level is an average concentration of 200 microgram/m3 NO2 during one hour. The peak levels should not exceed this threshold more than 18 hours per year. Peak levels concentrations are most of the time well below the threshold values and therefore one speaks of minor smog.
  OMI does not measure the concentration at the surface directly. Instead, OMI measures the total amount of nitrogen dioxide (NO2) in a column up to about 10 km. For this column amount there are no direct European norms. The relation between column amounts as measured by satellites and surface concentrations is complicated. Therefore, a red coloured area in the OMI map cannot be related directly to European norms and no conclusion with respect to exceeding some norm can be drawn from the OMI maps.
  The colours in the OMI maps are chosen in such a way that you can clearly see the difference between different areas. Column amounts of 20 x 10 power 15 molecules per cm2 and higher all have same red-purple colour.

  Can OMI measurements be related to ground level concentrations, like those being measured by the Dutch National Institute of Public Health and the Environment (RIVM)?

  The largest contribution to the measured NO2 column amount is located in the boundary layer. This is the bottom layer of the atmosphere in which air is mixed quite rapidly and in which the NO2 concentrations are relatively constant. The height of boundary layer varies between a few hundred meters till a few kilometres. The height varies during the day and depends on the weather and season of the year. A rough estimate of the NO2 surface concentration can be calculated by dividing the column amount with the height of the boundary layer.
  A study, using a chemical model of the atmosphere, showed that NO2 measurements by satellites are consistent with surface measurements and that the red-purple coloureds area roughly have surface concentration of 40 microgram/m3 NO2. This value is similar to the European threshold norm for the year-average concentration.


What do the derivative or the integral of amplitude of a seismogram mean?

This is a very simple answer, and it depends on the what the seismometer is measuring. I'm assuming you mean the time derviative/intdegral  $\frac\partial{\partial{}t}$ or  $\int{dt}$

Most seismometers measure displacement over time or velocity over time (series). So taking the time derivative will give you the spectral velocity or the spectral acceleration respectively when you take their derivatives.

When you take the integral of displacement, you calculate the total area displaced over time, and when you take the integral of velocity, you calculated the displacement.

It's all physics 101 really!


What are those arrowlike underwater structures for?

Those are Yap Traditional Fish Weirs, according to islandculture.info

  In 2008, Yap State Historic Preservation Office (YSHPO) commenced a
  project to survey the fish weirs (aech) around the main island of Yap.
  The aech is a stone/rock structure, usually in the shape of an arrow
  (many have a shaft, some do not), that catch fish after they move
  inside a catchment area at high tide and are trapped when the tide
  goes out. It is thought 700-800 aech may be located around Yap's main
  island which has a coastline of about 100 km in circumference.


Importance of meteorite impact craters in geology?

Impact diamonds

Yes, diamonds can form in meteorite impacts. For this several things need to happen:

A meteorite of the correct size and velocity,
The stuff it hits needs to contain carbon.

If you have a meteorite hitting granite or ocean you're not going to get any diamonds. It usually has to hit something that has biogenic carbon (let's say peat, coal, graphite). Even then, the diamonds will form only in a very specific distance from ground zero, because there is a specific relation between pressure and temperature that has to hold. Pressure has to be high enough to stabilise diamonds, it has to be hot enough to break the graphite carbon bonds, but not too hot to destabilise diamond. This is why it also depends on the size and velocity of the meteorite - only some will make these unique conditions happen. A notable case is the Popigai crater in Russia (that has some weird stuff in it). Another case is the stuff found in the peat around the Tunguska event.

However, calling the material that forms "diamond" does not say much about what it's actually like. In some cases, it's not even proper diamond, but rather a carbon polymorph called lonsdaleite, which is some kind of "hexagonal diamond" which has lower hardness than real diamond. Impact diamonds are also usually not pretty, so they're not suitable as gemstones in jewelry. If anything, they're useful as industrial diamonds. The thing is, that making industrial diamonds synthetically is much easier than digging them up from these locations. So, the answer is no. The economical significance of meteorite impact craters in relation to diamond formation is negligible.

Pretty diamonds usually form in Earth's mantle and are brought up to the surface in volcanic eruptions. They are mined from volcanic pipes such as kimberlites, and even though some of them are named like they're impact craters (like the Crater of Diamonds State Park) they are not actually impact craters.

Other stuff

There is one notable occurrence of an impact crater that did cause economic mineralisation of something: the Sudbury Igneous Complex, or the Sudbury Basic, in Canada. In here, a meteorite impact caused melting of the crust and the formation of a nickel deposit. Currently, nickel, copper and some noble metals are mined from there. Even though it has been known for more than 100 years, only in the past 30 years or so the impact origin of it has been fully accepted.


What Earth Science research will be done from the International Space Station?

NASA Space Station Research Explorer allows to filter experiments by expedition and category. A query for expedition 63 and the "Earth and space science" category yields the following 17 results (as of 27 February 2021):

AMS-02 (Alpha Magnetic Spectrometer - 02)
ASIM (Atmosphere-Space Interactions Monitor)
ISS-CREAM (Cosmic Ray Energetics and Mass for the International Space Station)
CEO (Crew Earth Observations)
iSIM (Demonstration of integrated Standard Imager for Microsatellites)
ECOSTRESS (ECOsystem Spaceborne Thermal Radiometer Experiment on Space Station)
Tanpopo-2 (ExHAM-Astrobiology Japan-2)
GEDI (Global Ecosystem Dynamics Investigation)
HISUI (Hyper-Spectral Imager Suite)
NICER (Neutron Star Interior Composition Explorer)
OCO-3 (Orbiting Carbon Observatory-3)
STP-H6-NIRAC (Space Test Program-Houston 6-Near InfraRed Airglow Camera)
STP-H5 FPS (STP-H5-Fabry Perot Spectrometer for Methane)
STP-H5 LIS (STP-H5-Lightning Imaging Sensor)
SAGE III-ISS (Stratospheric Aerosol and Gas Experiment III-ISS)
SPOC (The Spectral Ocean Color (SPOC) Satellite)
Total & Spectral Solar Irradiance Sensor (TSIS) (Total and Spectral Solar Irradiance Sensor)


How does the tornado chaser locate the spot?

It starts by identifying days with good overlay of shear and surface-based instability.  In the US we have the Storm Prediction Center that helps indicate such days looking at models.  Generally the very earliest signs that get chaser's attention are a reasonable trough moving into regions with adequate moisture and warmth (sometimes a cut-off upper-level low works too).

Then the day before and the morning of the event, final target regions get narrowed down further by looking at visible and water vapor imagery, upper level air maps, and surface weather data.  Basically the focus is generally on surface features... fronts, low pressure centers, drylines, and outflow boundaries.  Chasers will usually get into that region by early afternoon, as supercells and tornadoes are most common during the late afternoon and evening.

Once in the target zone, chasers keep an eye on any available satellite imagery, surface weather data, and also to the skies, looking for initial storm developments and any adjustments that may need to be made to the target area.  In many situations, clouds will start building up and perhaps pulsate in development, giving indication of favored areas long before the cap is broken and they develop into supercells.

Once the storms get going, the interest become identifying the stronger and more isolated storms as they develop rotation, becoming supercells.  In the northern hemisphere, the "business area" of a supercell is usually near the southern end, where a supercell will typically start to develop some sort of hooked shape, as all shown in this supercell image:

(Source: What is a Supercell Thunderstorm, by Dennis Mersereau, on Vane)

Most (though not all) supercells move approximately northeast.  So knowing that, as the day evolves, a typical chaser will make choices to help end up on the south half of the storm so their visibility and path are not blocked by the stronger rain and hail.  Then it comes down to road options, and paying attention to the storm and environment around you to watch whether the rotation is tightening up in the cloud base, as well as being aware of the temperature and wind for indications of how the storm may evolve.

When it comes to models, you're right that they absolutely can't identify the tornado.  However, convective models (like the HRRR) do often indicate the approximate areas where storms will develop a few hours ahead of time.  But it doesn't appear models will be forecasting where tornadoes will form with any great reliability for quite a while still.

But in terms of hunting down tornadic storms, convective models, and for that matter any large deal of real-time data, certainly aren't a necessity.  People have been chasing storms quite successfully long before all that was available.  It's more reasonable than most realize.  You choose the climatologically favorable tornado seasons to start, then seek out favorable areas within the large-scale pattern, and then refine your target by interpreting the conditions until you find yourself magically on the southern end of a hook, even without radar help.

For more input, I also suggest Mike Hollingshead's amazing high quality graphic tutorial, with a very useful snippet available on his StormAndSky website.

It looks like tornadoes are quite regular occurrences around China.  I know of chasers around Europe, Australia, and South America, but am surprised there aren't more in China.  Maybe that is soon to change?


Why are storms relatively short on Earth?

The main driving force for storms to form at all are the equator-pole temperature gradients. The main reason  for them to stop is friction between the lower atmosphere and earth's surface. This friction counteracts geostrophic balance (the balance between the pressure gradient and the coriolis force). Longer storms can only sustain themself through latent heat release, which can act as a secondary driver (and is the reason that Hurricanes/Typhoons can last rather long). However, at the latest at landfall this mechanism stops and the storm will decay. On gas-planets, however, there is no surface, therefore friction is much less (only the friction between different layers of the atmosphere, which is much less). Once a storm develops, with a low pressure centre, there is no (or hardly) any friction which counteracts geostrophic balance. This allows the storms to exist much longer.

As to other non-gas planets:
Mars and Mercury have a very thin atmosphere, therefore, as far as I know, there is no weather as on earth anyway. As for Venus, which has an atmosphere, I do not know.

Note that also on Earth, some weather circulations last much longer than the couple of days that storms last, for example the polar vortex, which lasts the whole winter (and is far away from the earths surface). Especially if you compare the gas-planets, you might also see them as "storms" in the wider sense.

references:

(lack) of atmospheres on Mars and Mercury: https://en.wikipedia.org/wiki/Atmosphere_of_Mars, https://en.wikipedia.org/wiki/Atmosphere_of_Mercury

no surface on Jupiter: https://en.wikipedia.org/wiki/Atmosphere_of_Jupiter

disturbance of geostrophic flow due to friction: https://en.wikipedia.org/wiki/Ageostrophy

formation of storms in general: "An Introduction to Dynamic Meteorology - James R. Holton", Chapter 9, and 11


Derive Reference Potential Evapotranspiration from Potential Evapotranspiration

I agree that terminology about evapotranspiration is confusing especially when using the expression "potential evapotranspiration", as stated in the FAO-56 paper:

  The use of other denominations such as potential ET is strongly discouraged due to ambiguities in their definitions

Definition

So let's refer to the FAO terminology:

Reference evapotranspiration ($ET_0$) refers to the evapotranspiration observed on well watered grass  for given meteorological conditions (radiation, temperature, humidity, and wind speed).
Crop evapotranspiration under standard conditions ($ET_c$) refers to the evapotranspiration observed on well watered specific crop for given meteorological conditions. The relationship between $ET_c$ and $ET_0$ is given by:

$$
ET_c = K_C\times ET_0 \tag{1}
$$

Crop evapotranspiration under non-standard conditions ($ET_{c,adj}$) refers to the evapotranspiration observed on a specific crop under water and environmental stress for given meteorological conditions. The relationship to $ET_0$ is either defined using a stress coefficient $K_s$:
$$
ET_{c,adj} = K_s \times K_c \times ET_0 \tag{2}
$$
Or using an adjusted crop coefficient $K_{c,adj}$:
$$
ET_{c,adj} = K_{c,adj} \times ET_0 \tag{3}
$$

Confusions

Now, you may find different common usage for the terms potential or actual evapotranspiration that leads to your confusion.

Potential evapotranspiration is sometimes referred to $ET_0$ or $ET_c$ or even less strict definition such as atmospheric demand for water.

Actual evapotranspiration  is referred either to $ET_c$, $ET_{c,adj}$ or less strict definition such as the amount of water evaporated.

Pragmatism

Regarding your issue, pick one:

Read to find out what are the definitions involved in WEAP and HAR
Look at the data and find out if potential evapotranspiration refers to grass (definition 1) or to specific crop with a given coefficient (definition 2, eq.1)
Use the other HAR data (everything is available) to compute $ET_0$ using FAO-56 method.
Last but not least, do not bother that much as evapotranspiration is full of uncertainties and you could not proove which of $ET_0$, $ET_c$ or $ET_{c,adj}$ best represent your actual evapotranspiration. You are interested in the relative dynamics of $ET$, choose realistic ranges of landcover coefficient and calibration will do the mass balance.


How much energy does Earth surface radiate at night per square meter?

I'm not sure how accurate you need, but beginning NASA's global 398.2 watts per square meter estimate from their energy budget a rounding down based on temperature variation should give a pretty good estimate.    A lot of people have a problem with that number because it's more energy than we get from the sun, but that's because our atmosphere is a kind of blanket that traps heat, which warms the Earth above it's planetary eqilibrium temperature.

It's also (but less so), higher because Earth is warmed from below as well as above.

Diurnal temperature variation is between highest day temperature and coldest night temperature and you're looking for average.  Using that number won't give a correct answer, but using, perhaps 1/2 that number might be in the range and that's over land.   The diurnal temperature variation over water is much lower.

So, 288 Kelvin Earth, say 12 degree variation day to night, so 294 / 282.  Ratio of 1.0425, to the 4th power means 18% more heat is radiated from land during the day than at night.   Adjust the temperature if you think mine is off.    That's 18% x 29% of the surface area.

For oceans, 71% of the surface area the temperature variation is smaller, say 2.5 degrees.   289.25 / 286.75, ratio of 1.0087.   4th power, means the oceans radiate about 3.5% more energy during the day than at night.

(18% x 29%) + (3.5% x 79%) = about 7.7%

So if Earth's surface radiation global average is about 398.2 w/m^2, then the day/night numbers work out to about 7.7% variation between them, or +/- 15.5 degrees, about 413.7 watts/m^2 during the day and about 382.7 at night.    That's a pretty good estimate I think.   I'm open to a better estimate if someone can think of a way to do it.


How to model bed load transport in channels of non-rectangular cross sections

There are several approaches to answer this question. One is simple, but not that accurate. This approach would be to to discretize points along the perimeter and calculate a per point boundary shear stress. The equation would be the same as the depth averaged, except you would solve for each individual depth h1, ..., hn.

One thing to note is that the bed load will mostly be concentrated at the lowest point in the channel.

The easiest accurate method to implement is the WTA method, which uses the law of the wall to calculate boundary shear stress. The papers outlining the method are Wobus et al. (2006, 2008) titled "Self-formed bedrock channels"[1], and "Modeling the evolution of channel shape: Balancing computational efficiency with hydraulic fidelity" [2]. I have a python code that implements this, but in closed conduit conditions. It can be modified to work in the open channel case.

References:

Wobus et al., 2006: Self-formed bedrock channels. doi: 10.1029/2006GL027182
Wobus et al., 2008: Modeling the evolution of channel shape: Balancing computational efficiency with hydraulic fidelity. doi: 10.1029/2007JF000914


Reason for rotting smell after first rain of the season?

When rain displaces pore gasses in the soil, bubbles of soil gas are released into the atmosphere. It's impossible to be precise about the composition because it is so variable from place to place. It varies according to soil type, organic content, degree of rotting, temperature, and the microbiological cross section (itself hugely variable). Most soil gas is odourless, such as nitrogen, carbon dioxide, methane, etc. Others, like geosmin, are very smelly. In addition  to 'petrichor' there are terpenes, aldehydes, alcohols and esters, to name but a few of the natural volatile organic compounds.
Of course, one cannot rule out the foul smell or rotting animals in some places.


Why is ocean surface velocity around 3% of wind velocity?

A very good analysis looking at the 3% relationship is an article by Weber (1983). His main result is that:

  We assume a fully developed sea, and take the eddy viscosity to be proportional to the friction velocity times a characteristic depth. Hence the total current (Ekman current plus wave-induced current) can be expressed as functions of the wind speed. The results show that the magnitude of the total surface current lies between 3.1 and 3.4% of the wind speed at 10 m height for winds between 5 and 30 m s−1.

The idea is that by including both the Ekman current (induced by the mean wind stress at the surface) and the wave-induced current (Stokes drift), the resulting total surface velocity can be easily represented as a function of wind velocity at 10 meters. Both Ekman and wave-induced currents are about the same size and add up to be around 3% of the wind speed. The assumptions include the full range for Ekman dynamics (homogeneous, not affected by boundaries), plus some about waves (non-decaying, small amplitude). In the real ocean, eddy viscosity is vertically variable, but, as it is the case with Ekman dynamics, the approximation is quite close to what is observed in the ocean. The approximations that Weber used are valid for a large range of wind values (5-30 m s−1) and they break down in weak wind (not fully developed waves) and strong wind conditions (whitecapping, wave breaking).

Weber, J. E., 1983: Steady Wind- and Wave-Induced Currents in the Open Ocean. J. Phys. Oceanogr., 13, 524–530.


Where can I find information about the basic concepts of sedimentary basins?

In general, a good answer to "where can I learn the basic concepts of X" is "a textbook on X". For sedimentary concepts, you might try Nichols (2009), for instance. Academic papers are a publication vehicle for new research, so you'll seldom find much introductory material in them.

For terms like "intracratonic" and "intramontane", you might also find it useful to learn some common Greek and Latin prefixes and suffixes. If you look for "intra" in a list like this one, you'll find that it's Latin for "within", and you might be able to guess that "intracratonic" refers to something occurring within a craton.

If you just want to look up terms as you go, and you're happy with brief definitions, a specialist dictionary might also be helpful. For Earth Sciences, Allaby (2008) is a good concise dictionary, though it might be a little too concise if you're a beginner.

References

Allaby, M. ed., 2008. A Dictionary of Earth Sciences 3rd ed., Oxford: Oxford University Press.

Nichols, G., 2009. Sedimentology and Stratigraphy 2nd ed., Chichester: Wiley-Blackwell.


Why did people draw so many continuous squares in the sand on the beach at Cape Juby?

They are not perfectly straight. Making them with modern GPS equipment should not be too difficult, you just keep a fixed distance to the previous line. They are only 5-6 meters wide.

Googling for cape juby tarfaya sand beach experiment I found this 16 Jan 2013 entry from the blog An overland adventure mentioning:
"Between the road and the sea is another experiment to save Tarfaya from being swallowed up by the Ergs (=sand dunes), mangrove. These trees have been introduced here from the tropics as one of the few salt loving, sand rooting toughs. They seem quite young from the window of the truck so I am guessing it is too early to tell if the project has been a success."

Maybe this is what you are seeing. I have contacted the blog writer to ask for confirmation. Update: The author confirmed that this is indeed what you're seeing: "Yes. Shame there is no picture."

Subsequent Googling for tarfaya mangrove turns up more info (often in French, where palétuvier is indeed mangrove), e.g. this Les mangoves du Sahara chapter from the Book Maroc 8 - Sud du Maroc et Sahara Occidental. This Lonely Planet E-Book PDF Marokko Reiseführer which is almost a literal translation, mentions a 900 meter long strip, but the artifact in the picture is approx 3.2 km.

The planting project was named The Manzanar project


Are there measurement techniques that can help determine the exact geometry of a volcanic vent?

Interferometric synthetic aperture radar (or InSAR) is a remote sensing (airplane or, more commonly, satellite) radar techinque used to measure surface deformation. Repeated measurements of radar amplitudes over a common area are used to estimate changes to surface topography. InSAR measurements of surface changes have been used with numerical models of dyke propagation to model magma chambers in the East African Rift System.

Other geophysical methods that can be used to image/model active magma chambers include seismic interferometry, magnetic and gravity methods. Here is a recently published example from Japan which used seismic interferometry to image an active magma chamber. Magnetic and gravity measurements can be taken from airplanes, which may be a bit safer than being on the ground. If  the magma chamber has magnetic/density properties different from the surrounding country rock, then mag/grav forward/inverse modelling could be used to create a model of the magma chamber geometry.


What statistical methods are best for analyzing long-term rainfall data?

It depends on your data, if the rainfall data is in a grid with temporal and spatial dimension, you can use a NetCDF format to analyse the data via R, matlab, IDL or Python. NetCDF is Network Common Data Form, which is a very common format of grided and temporal data. In Python, you can simply do several 10-year average map to see the long term decadal trend. Or you could plot a transient period of a smaller region with average rainfall to see monthly or seasonally change. To find out the intensity of distribution you could plot a map with a logarithmic scale of colour. Use a threshold to identify extreme rainfall event that is above the threshold. I use a Python package called iris which can easily plot graphs using NetCDF data. You can look at some examples here http://scitools.org.uk/iris/docs/latest/gallery.html

For getting the rainfall data, you can download the rainfall data from the CRU-NCEP database https://crudata.uea.ac.uk/cru/data/hrg/ CRU stand for Climate Research Unit and it has the most accurate historical data available to the public. They are reanalyzed data from meteorological stations and ships. The highest resolution available is 0.5 latitude * 0.5 longitude degree grid. And for temporal resolution they have 6-hourly and daily. The data is in NetCDF format which is a format most map processing data use. If you don't know how to handle ncdf you could use Google Earth as well https://crudata.uea.ac.uk/cru/data/hrg/cru_ts_3.23/ge/ .

To know more how the data is derived you can read this paper. Hope it helps. http://onlinelibrary.wiley.com/doi/10.1002/joc.3711/abstract


Which ocean evaporates the most water per surface area?

When push comes to shove, the highest evaporation rate per unut area corresponds to the highest average temperature.
As this pair of illustrations from NASA shows, that would be the Indian Ocean.

Simply put, the Indian Ocean misses both polar regions and hits the tropical and subtropical latitudes squarely, so it is warmer overall.  Ergo more evaporation.


Simple Climate Models that Predict Climate Change

It sounds like you are asking for a simple climate model that treats the globe as a homogeneous system.  A Zero-dimensional energy balance model may be of interest (see this Penn State site ) which uses a starting point that is also basically described in this post: Temperature as a function of luminosity and greenhouse gas concentrations

If you solve for the temperature of the Earth using a blackbody approximation and thermal equilibrium (with an albedo of about 0.3), you are only taking into account the temperature of the Earth without a greenhouse effect (about 33 °C cooler than actual temperature).  It is very difficult to calculate the influence of infrared radiative forcing components (e.g. oxygen and carbon dioxide) to an empty atmosphere, since there are many biogeochemical/physical feedbacks in the climate system which are nonlinear.

However, if you start with current temperature/concentrations, you can add terms that represent particular increases to the GHG concentrations.  Those terms are constantly being refined by the scientific community and are summarized in this Wikipedia article about Radiative Forcing (see the link to climate sensitivity at the bottom of the page).  This is a kind of "back of the envelope" modeling approach that most climate scientists use to discuss past and future influence of climate forcers, which can be very helpful when discussing the expected climate effects of various emissions/mitigation scenarios.

The Radiative Forcing article in Wikipedia says:

  Radiative forcing can be used to estimate a subsequent change in equilibrium surface temperature (ΔTs) arising from that radiative forcing via the equation:

$$\Delta T_s =~ \lambda~\Delta F$$

  where λ is the climate sensitivity, usually with units in K/(W/m2), and ΔF is the radiative forcing. A typical value of λ for CO2 is 0.8 K/(W/m2), which gives a warming of 3K for a doubling of CO2 [from pre-industrial times, assuming RF of CO2 is ~ 3.7)].

It's important to note that most climate sensitivity parameters and radiative forcing values are derived with respect to some time period (e.g. 1750 - 2011) and GHG feedbacks are set for a particular climate regime.  Revised radiative forcing and climate sensitivity parameters are needed to make calculations for other climate regimes.

The IPCC AR5 figure of Radiative Forcing components attributes 1.65 W/m2 to the actual increase in CO2 concentrations from 1750 to 2011 (or ~1.3K in temperature rise, if lambda is 0.8).

The values of Radiative Forcing that IPCC provides are likely close enough for doing realistic scenario testing.  However, something in an entirely different feedback regime would need very different parameters.  For instance, halving the CO2 in the atmosphere would have a much greater absolute effect on temperature than doubling it; temperature increases logarithmically as CO2 concentrations increase. This is because strong CO2 absorption bands are nearly saturated under present conditions, and increasing CO2 from present conditions mainly affects the flanks of the absorption bands.  However, water precipitates out of the system easily under low-temperature conditions, so CO2 has a much greater forcing value in those types of climate regimes.

The most difficult problems with testing simple climate scenarios are related to the oceans and the biosphere, which could have countless effects on the average climate and GHG regime.


In Schmidt & Dilcher 2007, the authors were interested specifically on how amber can trap aquatic organism, so this is a specific, out-of-the-norm case study but it might give you at least on order of magnitude. Here is an extract:

  Within the first day or two after initial contact with water, all
  three resin fractions were traps for limnetic organisms. The resinous
  film at the surface then dried out and broke into small
  centimeter-sized fragments, so no long-term preservation can be
  expected for this exudate. The pieces of resin hanging at the water
  surface became more and more solid within a few days because of air
  contact at their upper surface. After 1 week, these pieces were nearly
  solidified (Fig. 1 D).

And later:

  In contrast, the large resin bodies on the ground did not solidify as
  long as they were covered with water. But this resin was also
  initially a trap for microorganisms before a thin hardened skin
  developed at the resin surface after 1 or 2 days in the water, which
  prevented tiny organisms from getting stuck. Nonetheless, the resin
  remained liquid inside, and therefore large arthropods that were able
  to break through this skin could become entrapped over a couple of
  weeks. [...] The resin solidified when exposed to the air in the
  laboratory or by decreasing water level in the swamp during the
  summer.

So the polymerization process to go from resin to solidified resin (copal) takes weeks. At that point, the system is already closed meaning the contained organisms correspond to that time interval.

The next step (amberification) consists of further polymerization as well as oxydation and can take several million years (Poinar 1992). However the minimum time needed for this process is unknown.

Reference:
Poinar Jr, 1992. Life in amber. Stanford University Press.
Schmidt A. R. & Dilcher D. L., 2007. Aquatic organisms as amber inclusions and examples from a modern swamp forest. PNAS, 104(42): 16581-16585.


Could this cloud be artificially formed?

There's not much context, but my guess is that this was a cavum cloud (a.k.a. punch hole or fallstreak), that was caused by an aircraft.  The UK Met Office describe how these form:

They form in clouds of supercooled water droplets, water below 0 °C but not yet frozen. These water droplets need a tiny particle, a nucleus, to freeze or to be cooled below -40 °C.
Aircraft punching through this cloud layer can cause air to expand and cool as it passes over the aircraft wings or propeller. This change in temperature can be enough to encourage the supercooled droplets to freeze and fall from the cloud layer in this distinctive pattern.

The Cloud Appreciation Society have a gallery with loads of examples.  The NASA Earth Observatory blog also has a nice satellite image from over the Southern US with multiple occurrences at the same time, which also features in Heymsfield et al (2011) Formation and Spread of Aircraft-Induced Holes in Clouds, Science:

(NASA image by Jeff Schmaltz, using MODIS data from LANCE/EOSDIS Rapid Response.)


Could a firestorm create a hurricane-like cyclone?

I don't think so. A large fire could generate a circulation with strong low-level convergence and upper level divergence that would cause subsidence as the air radiatively cooled. If the fire were stationary and huge, the Coriolis effect could make it's upper level outflow turn, but I don't think an intense hurricane-like cyclone could form unless the fire were actually relatively small (like the eyewall of a hurricane), but in that case I'm not sure that the necessary pressure gradient could be maintained (even if the fire could somehow continue to be fueled).


What are some near term effects of Global Warming?

The IPCC AR5 chapter 11 covers near-term climate change. I recommend reading the executive summary (it's only 6 pages). My summary of the summary is that near-term climate change is like long-term climate change, but scaled down and with less certainty. Surface air temperatures and upper-ocean temperatures are likely to increase, with an associated increase in atmospheric water vapor. Precipitation is likely to increase where it's already high and likely to decrease where it's already low. Summer Arctic sea ice extent is likely to decrease as well. But there is something there that I want to highlight.

The end of the executive summary talks about near-term air quality, and the beginning talks about predictability. Specifically, it mentions that emissions of chemicals that produce aerosols -- atmospheric particles that interact with solar radiation -- have a wide range of uncertainty, even in the near term. Unlike CO2, aerosols can induce a significant climate response (or at least a change in radiation) over the span of weeks and months. A change in energy use or technology, like India and China adopting sulfur control policies, can thus affect climate quickly and dramatically. This is a source of a lot of the uncertainty in near-term projections; over the long-term, CO2 dominates.


Is this scientific explanation of The Bible flood accurate?

Fishing through the links mentioned over at Christianity SE, I netted this scientific paper about freshwater and marine fish: Why are there so few fish in the sea?. Apparently the bulk (96%) of marine species have a single freshwater ancestor species extant 300 Mya (300 million years ago). Descendants of this species did not enter the ocean until about 180 Mya, with the greatest diversification and subsequent dominance of the oceans starting 110 Mya. Another fact: only 4% of current fish species can thrive in both saltwater and freshwater (e.g., salmon, trout, ...).

To get anywhere near a hypothetical event equivalent to Noah's flood would require accepting dozens of counterfactual assumptions, and a total misunderstanding of geology, evolution, paleontology, not to mention conservation of mass (where did all the water come from?).

But to address the narrow issue of survival of fish, one could imagine that the flood happened so rapidly as to create a very thick layer of freshwater on top of the saltwater. Freshwater is considerably lighter than saltwater, and would "float" on the saltwater. Marine mammals would be okay in freshwater for a few days. Then the waters could recede (where did all the water go to?), and maybe enough freshwater species would end up in the new freshwater lakes and streams.

As far as the Ocean being less salty, there is no evidence for that. A lower salinity is postulated to fit into the theories of the Young Earth proponents. Paleosalinity is a complex study. You can browse through these references here and here.

A flood such as this would have enormous, I would say overwhelming, geological, geographical, and paleontological evidence left behind, which in fact does not exist. But everything is possible with miracles.

You may be interested in this paper: An Abrupt Drowning of the Black Sea Shelf which led to this book NOAH'S FLOOD: The New Scientific Discoveries About the Event That Changed History


What kind of minerals have no cleavage plane?

I'm pretty sure a more rigorous answer deserves to come along, but I can give a simple overview of some of the important factors.

Cleavage planes have to do with bond strength and bond geometry.  If there isn't a plane of bonds that can be cut through, then you won't get cleavage.  When a mineral is fractured, the fracture "wants" to take the path where the total energy required to break all of the bonds along that path is at a minimum.

In Halite, you can "cleave" a perfect plane through weaker ionic bonds (the geometry works, and the bonds are weak).  In quartz, all of the bonds are of the same strength (strong silicate bonds), and the geometry of the mineral is such that you can not find a plane that will cut through all of the bonds, therefore the fractures must "wander" creating the conchoidal structures.  In mica, the cleavage planes form between the silicate sheets.  The silica bonds are strong, the the sheets are held together by weaker ionic bonds.


Where to find reliable snowfall rate data?

Unfortunately, what you want may not be actually available. It is standard to make measurements of snow every 24 hours. This is because it is well known that frequent observations of snowfall will exceed the total accumulated snowfall.
The total accumulation of snow is not equal to the sum of the accumulated rate of the integral. That is, $$\Delta S \ne\int_{t_0}^{t_1}Rdt$$ where $\Delta S$ is the change in snow depth and $R$ is the snowfall rate. This is because compaction and melting both occur, changing snow depth.
That being said, you can make an approximation using daily snowfall depth observations. In the U.S., there are two systems that spring to mind. The first is the U.S. Cooperative Observation Program, which uses the standard in-situ observations of snow depth. The second is the NOHRSC, which has an analysis product (use this link for archived numerical data or this link for a graphical product).


What negative side effects would occur if silicate mining were used to artificially lower atmospheric CO2 concentrations?

A review article on the subject in the AGU journal Reviews of Geophysics Enhanced chemical weathering as a geoengineering strategy to reduce atmospheric carbon dioxide, supply nutrients, and mitigate ocean acidification by Hartmann, et.al. (2013) notes many uncertainties that would need to be researched and quantified to evaluate both the potential effectiveness as well as the drawbacks of the process, known as Enhanced Weathering:

  "The potential negative environmental impact of Enhanced Weathering is
  also important to consider and investigate further. Application of
  rock powder to the land surface might increase the concentration of
  airborne dust in the local environment. The potential risk to human
  and animal health may limit the appropriate application sites (away
  from human centres or sensitive ecosystems) or the severity of
  comminution, depending on the techniques applied. This in turn will
  limit the efficacy and effectiveness of Enhanced Weathering. The
  mobilization of potentially toxic elements contained in some silicate
  rocks may detrimentally effect primary production and/or accumulate in
  the food chain, both of which could be harmful to human populations.
  Therefore an assessment of usable rocks and their locations is
  needed."

Also:

  To sequester a significant amount of carbon dioxide from the
  atmosphere, an Enhanced Weathering program would need to process 1Gt
  to 10 s of Gt of rock per year. This would make it one of the largest
  global industries.

That alone would create economic and social impacts, as well as additional carbon emissions that would need to be offset.


What is the meaning of the subscript in the abbreviations of some minerals?

Olivine is a solid solution between forsterite and fayalite, so it is generally expressed as molar percentages of these end-members, for instance Fo80Fa20. Often only one end-member is mentioned, as it is sufficient to infer the other (their sum is always 100 %).

It is the same with plagioclase, which is a solid solution between albite and anorthite and is often expressed as "Abxx" or "Anxx", where xx is the molar percentage of considered end-member.

Edit: As for the range, e.g. 95-90, I'd say they analyzed several olivine grains in the same sample, and the range represents the variability of compositions they found. It could also be the analytical error on a single composition, but I doubt it would be that large, although it could be in some old papers when the precision of chemical analyses was not as good as today.


Has the present rise of CO2 ppm been proved to be caused by human activity?

US EPA

Some of the carbon goes into the oceans and soil:

Wikipedia

The cumulative contribution to the atmosphere is  the area of the light blue region of this chart.

CarbonBrief,  Le Quéré, C. et al. (2016)


map projections that minimises differences

I am sorry, but this type of linear map can't exist. You said that you want to minimize differences, so you want to make small countries bigger. But unfortunately, big countries become bigger too (because of linear transformation), so that's not the solution.
I can only think of scaling individual portions of some standard projection. For example, you could scale Europe a little bit because of many small countries. You could also just scale the islands in the Oceania, but not the distances between them. Oops, it seems like we got too far into cheating, but as long as scaling countries to minimize differences is the only thing you want to do, there is no problem. Of course, your decision is the last.
As @KeithMcClary pointed out in his comment, this type of map is called cartogram. Thank you for this useful piece of information!


Is there a widely accepted reason for the formation of tafoni?

I had a good geomorphology teacher. He was so good that I bought his book, published on Prentince Hall at 2008. He is an aged an experimented geomorphologist, so I totaly trust there is not an agreement about the physical origin of tafonies (or at least there wasn't an agreement at 2008 when his book was published).

  "Its origin [tafonis] is controversial (Twidale and Vidal Romaní, 2005). Some authors differentiate between wall tafonis and basal tafonis, linked to the processes of basal undermining (Smith, 1978, Bradley et al., 1978). It is agreed that the dominant processes are those related to the movement of water with salts close to the surface, which correspond to haloclastism and wetting and drying. Thermoclastism, cryoclasty, dissolution of carbonated cements and wind erosion are also mentioned (Evans, 1969-70, Mustoe, 1983, Young, 1987, Robinson and Williams, 1992). In addition to these subaerial processes, some taphonis can be generated by weathering under the soil surface and subsequent exhumation by erosion (Dragovich, 1969)."

  Source: Geomorfología, Prentince Hall (2008), page 152.
  Translated from spanish by Google.

-Gutiérrez Elorza, M. (2008) "Geomorfología". Ed Prentince Hall.

-Twidale, C. R.; Bourne, J.A., y Vidal Romaní, J.R. (2005): "Beach etching and shore platforms" Geomorphology 67, 47-61.

-Smith (1978) "The origin and geomorphic implications of cliff foot recesses and tafoni on limestone hamadas in the northwest Sahara" Zeitscrift für Geomorphologie, 22, 21-43.

-Bradley, W.C.; hutton, J.T., y Twidale, C.R.(1978). "Role of salts in development of granitic tafoni, South Australia". Journal of Geology 86, 647-654.

-Evans, I.S. (1969-70) "Salt crystallization and rock weathering: a review" Revue de Géomorphologié Dynamique, 19,153-177.

-Mustoe, G.E.(1983)"Cavernous weathering in the Capitol Reef Desert, Utah" Earth Surface Processes and Landforms 8, 517-526

-Young, R.M. (1987) "Salt as an agent in the development of cavernous weathering" Geology 15, 962-966.

-Robinson, D.A. Williams, R.B.G.(1992) "Sandstone weathering in the High Atlas, morocco" Zeitscrift für Geomorphologie 4,413-429.

-Dragovich, D. (1969): "The origin of cavernous surfaces (tafoni) in granitic rocks of Southern Australia". Zeitscrift für Geomorphologie 13, 163-181.


Why would magma have high amounts of nickel and chromium?

The current thinking according to modelling and previous observations is that the high amounts of $\ce{MgO}$, $\ce{Cr}$ and $\ce{Ni}$ is due to the magma feeding the Mt. Lamington volcano being contaminated by the nearby Papuan Ultramafic Belt (Smith, 2014; Arculus et al. 1983).  The Papuan Ultramafic Belt is, according to Lus et al. (2001), a early Neogene (Tertiary) ophiolite.  The region itself is not associated with an active Wadati-Benioff Zone (Smith, 2004).

Smith describes that the composition of the magma that fed the Mt. Lamington eruption represents part of an unusual tectonic environment, as described in part in the answer to the earlier question What are the geological mechanisms for sea floor spreading in the Bismarck Sea?.  Smith describes that the magmatic geochemistry is influenced by the variables of crustal thickness, tectonic setting and the geochemistry of the lithosphere.

Finally, the relationship between the tectonics of the region and magmatism of the Papuan arc environment has been described as a 'delayed melting' as a partial melting of a source that was

  metasomatised in an earlier convergent event.

The complicated geology is shown in the image below:

Tectonic and geological map from Syracuse University Department of Earth Sciences, the ophiolite (PUB) outcrops are in purple.

References

Arculus et al. 1983, 'Ophiolote contaminated andesites, trachybasalts and cognate inclusions of Mt. Lamington, Papua New Guinea: anhydrite-amphibole bearing lavas and the 1951 cumulodome', Bulletin of Volcanology and Geothermal Research

Lus, W. et al. 2001, 'Papuan Ultramafic Belt (PUB) Ophiolite: Field Mapping, Petrology, Mineral chemistry, Geochemistry, Geochronology, And Experimental Studies Of The Metamorphic Sole', American Geophysical Union, Fall Meeting 2001, abstract #T52D-09

Smith, I. 'High magnesium andesites: the example of the Papuan Volcanic Arc' in Gomez-Tuena et al. (eds) 2014, 'Orogenic Andesites and Crustal Growth', Geological Society Special Publication 385 page 128


Will photosynthesis based carbon sequestration always be more efficient than other chemical means - in terms of rate?

Rate.. no.

Brute Force

We can treat this as an industrial chemistry question. The brute-force method for carbon sequesteration is simply:

Extract CO2 from the air (using the acid/base chemistry, Sodium Hydroxide will scrub it as fast as you can supply air)
Reduce CO2 to elemental carbon and oxygen. The exact details are not actually important - that's one for the industrial chemists - just the concept that it would take a LOT of energy. Basically as much energy as we currently get from fossil fuels, and then some, to extract and reduce at the same rate.
Store the carbon somewhere safe, where it isn't going to catch fire. As long as it doesn't, it's stable on geological timescales.

The rate of this process is dependent on how much energy you are prepared to throw at it. A fleet of several thousand nuclear reactors running 24/7 on this problem would do it.

Burial

Well, brute force sounds a bit expensive.. so we can try the approach mentioned by Jack R Woods. In this case, we capture CO2 (this still takes energy, although not much in theory), and pump it into thick basalt formations such as the ones in Iceland. Many flood-basalt igneous provinces have the combination of low-silica rocks and high porosity that are ideal for this kind of sequestration. The rate is limited by how fast you can capture CO2 out of the air.  You could imagine using a Solar Updraft Tower - this would give an air flow that you could extract CO2 from, and provide power for the process. If the reaction goes as planned, it's safe on geological timescales.

The problem is, as ever, getting enough resources to build these things on the scale required.


Can an Atlantic hurricane enter Mediterranean sea?

Apart from the fact that only a few tropical cyclones follow a more southerly route (a list bellow) after going around the North Atlantic, I think the main problem is that tropical cyclones would weaken significantly after landfall in the Iberian Peninsula. An example of this is Hurricane Raphael in 2012.
 Source Weather.unisys.com.

There is no "easy" path from the Atlantic into the Mediterranean for a system the size of a tropical cyclone. Other examples that followed a similar path but never made it the Mediterranean: Gordon (2006), Jeanne (1998), Ivan (1998), Frances (1992), Bob (1991), Arlene (1987), Chloe (1967), Carol (1965), Dolly (1953).

While the cyclones at the point of approaching the Iberian Peninsula are still tracked as tropical depressions, their characteristics are often similar to other extra-tropical storms.


As one could imagine, there is a considerable amount of conjecture as to precisely Earth got its salt content.  Ultimately, it came from the primordial planetary nebula and concentrations of the ions involved would have come from the various ingredients of the accretionary process.  This answer focuses on how salt may have first formed, hence accumulated.

Ocean salinity is almost a chicken and egg situation - was their salt before the first waters or vice versa?  According to current research, the latter appears to be true, especially in the case of the dominant $\ce{NaCl}$ species.

Knauth (2005) (2) contends that $\ce{Cl-}$ ions were outgassed through volcanic eruptions in the form of $\ce{HCl}$ and $\ce{Na+}$ were theorised to have been leached out of rocks (1).  The exact amount of these ions and salt content are not entirely known (3), but the process may have started even as far back as the Hadean, and certainly in the Archean (3) and the early water bodies were believed to have been up to twice as saline as today (2).

In terms of halite deposits, this requires evaporation of a brine, which according to Knauth (2005) (2) and Sleep (2010) (3) required large enough continental masses to be able to enclose water bodies - the amount of this occurring in conjectural for Earth, as the halite produced would be unlikely to be preserved (3).

Knauth (2005) (2) expanded on the implications of this for other worlds with:

  Inasmuch as chlorine is a common element throughout the galaxy and follows the water during atmospheric outgassing, it is likely that early oceans on other worlds are also probably so saline that evolution beyond the microbial stage is inhibited unless long-lived continental cratons develop.

Partly suggesting that the formation of salt is possible on any world - such as the salt found in Martian sediments, as per the article Magnesium sulphate salts and the history of water on Mars (Vaniman et al. 2004).

References

(1) Einsele, G. 1992 Sedimentary Basins: Evolution, Facies, and Sediment Budget (Book)

(2) Knauth, L.P. 2005 Temperature and salinity history of the Precambrian ocean: implications for the course of microbial evolution Palaeogeography, Palaeoclimatology, Palaeoecology

(3) Sleep, N. 2010, The Hadean-Archaean Environment Cold Spring Harbor Perspectives in Biology


Why does the pressure increase only by 0,3-0,4bar per km in stone but 1bar per 10m in water while stone has the higher density?

Because it doesn't!

Plots in this Physics SE answer and here and here show about 0.4 or 0.5 $\times 10^6$ bar at 1000 km depth, which is 0.4 or 0.5 bar per meter compared to your 0.1 bar per meter for water. If rock is 4 to 5 times denser than water, then all is well.


Does the Sun's oscillation affect Earth's climate?

I'll get you started at least, this is a bit too broad otherwise; I guess what you're describing are called Milanković (Milankovitch) cycles. Are climatologists aware of these? Yes, for a long time. Milanković published his first paper on the subject, Theorie Mathematique des Phenomenes Thermiques produits par la Radiation Solaire, in 1920. As for Solar oscillations in general, even much longer periodicity of ~ 26 million years of the Sun's oscillation about the galactic plane has been considered before (in 1984). As we're aware of the 11 year solar cycles, and have been integrated into climate models that climatologists work with, including collective effects of all of these manifesting in grand minima and maxima of solar activity (PDF).


Why the Indian Monsoon doesn't start in the north?

Summarizing what I wrote in the comments

1) The monsoon does not start off in the Arabian Sea. There is actually a cross equatorial gradient that drives winds from the Southern Indian Ocean into the Northern Indian Ocean and then into the Arabian Sea.

2) There is also a second branch of the Indian monsoonal winds and that is the Bay of Bengal branch. This branch also receives winds from the Southern Indian Ocean. This branch ends up contributing easterlies and south easterlies to the Indian monsoon.

3) The crucial aspect that you left out in the question is the role of the Monsoon trough. The monsoon is not just made of winds alone converging rather it is the north to south movement and sometimes south to north movement of the monsoon trough along the Indian subcontinent that researchers and forecasters track. Why is that ? It is because systems form within the monsoon trough. What governs the movement of the monsoon trough up and down the Indian subcontinent ? Well that is a topic beyond the scope of this question.

4) So the monsoon trough includes westerly winds in the equatorward section and in the poleward section you have trade winds. The Himalayan branch from that definition contains easterly winds and not westerly winds from the Arabian Sea.Actually Arabian Sea winds  only have a secondary role in providing moisture for systems to form in the Himalayan side.

5) Finally the Indian Himalayas only receive rainfall when the monsoon trough is located along those latitudes. This condition is known as a "break monsoon" condition and it happens when sub tropical westerlies are present aloft. This usually happens after the monsoon has provided rain to the southern parts of the country including the western ghats.

I would recommend going through this free e-book - sw monsoon e-book for a thorough description of what I have mentioned above.


How does 10mm/yr of plate subduction provide enough material to create eruptions?

Yes, the situation is much more complex than you make out - the generation of melt is typically caused by partial melting of the mantle wedge located beneath the volcanic arc. This process is mainly affected by the trench geometry (flat or steeply dipping slab), the local geotherm, and volatile content (water, gases etc.) of the slab or subducted material.
You're neglecting the total volume of the plate being subducted, as there is an along-trench length of the plate, as well as the thickness of the slab.

When it comes to amount of melt generated, the localisation and upwelling of melt from the mantle wedge isn't fully understood - so it is hard to determine how many volcanic centres will be fed from the material.


There was an interesting paper on this for the United States a couple of years ago:

Balch et al (2017) Human-started wildfires expand the fire niche across
the United States, PNAS, doi: 10.1073/pnas.1617394114

They estimate that in the coterminous U.S. human-started events account "for 84% of all wildfires and 44% of total area burned".  There is a marked spatial variation, with lightning-started wildfires occurring mainly in the more sparsely populated western forests.  If you have access, the paper's worth a read, it has lots of interesting figures picking apart the details.

It's worth noting that there are a number of reasons for human-started wildfires, which are could be classed as accidental, deliberate or careless:

  Human-started wildfires were caused by a variety of sources, including the US Forest Service-designated categories of equipment use, smoking, campfire, railroad, arson, debris burning, children, fireworks, power line, structure, and miscellaneous fires.

They also note that their data contains this, perhaps not unsurprising, feature:

  There was also a notable mark of American culture on the distribution of wildfires, with the peak day of wildfires occurring on July 4th, concurrent with Independence Day fireworks displays (Fig. 2). Indeed, Americans start over twice as many wildfires on July 4th as any other summer day.