Temperate Rainforests I have heard that the Appalachian Mountains is qualified as a temperate rainforest. What qualifies a temperate rainforest and what makes the Appalachian Mountains a temperate rainforest?

Yes, the Appalachian Region would be considered a Temperate Rainforest based on a combination of rainfall numbers, humidity and temperatures. Its latitude runs from in the 30's and up to high 50's in latitude location north of the equator. Feeding the forest region are a combination of two damp air masses which rotate in a cyclonic rotation inward from the marine locations, namely the Maritime Tropical air mass bringing very humid air from the Gulf of Mexico and the cooler air but also damp Martime Polar air mass. The mountains, while lower in elevation than the Western Rocky Mountains, offer much of this damp air from either air mass to move over toward the mountains when the jetstream is positioned in a way to not influence these air masses in a way that pushes them eastward. Orographic type precipitation can occur as a result, but much of it in that region is frontal as the colder Contintental Polar and Arctic air masses tend to interact with the damp air masses mentioned previously dumping significant amounts of rainfall suddenly as I can attest in my many journeys through these mountains on my way to Georgia or Florida from Ontario. Given the rainfall alone and the fact there is a diverse complexity of vegetation and animal specie, I would surely believe that the Appalachian Region qualifies easily as a Temperate Rainforest. Climate graph > location in Appalachian Region https://en.climate-data.org/north-america/united-states-of-america/virginia/appalachia-135846/#climate-table  and, location map of North American air masses paths running along and to this region https://wordpress.accuweather.com/wp-content/uploads/2018/01/static-winter-air-masses-11-am-1.jpg?w=632


Why is the eastern Pacific full of stratocumulus clouds, and why do they have so much variation in net radiation? They can be seen in the diagram below (of the CERES radiation dataset - supposedly they contribute a lot to the total variance in net radiation, which is the sum of SW and LW) - just west of Peru and Mexico (my supervisor, Dargan Frierson, said these are stratocumulus regions). I'm just wondering - why are stratocumulus clouds so abundant there?

(the diagram is taken after taking the 12-month running mean of the dataset, which smoothes out a lot of features).

On the east side of the Pacific Ocean, there are cold currents coming the poles going towards the equator. The cold currents makes it so there is almost a permanent cold air mass above the eastern portion of the ocean. As warmer air is blown over this colder air, it must go above the colder air. The warmer air expands, temperature decreases, becomes saturated and the stratus clouds form!

The cold currents are there because of the semi-permanent high pressure system in the mid-latitudes of the ocean. The winds are equator-ward on the east side of high pressure systems. This drives the ocean currents to be equator-ward on the east side of the ocean.


Calculate flow rate of wetland for gray water treatment I'm currently attempting to design a water recycling solution for a carwash in a tropical country that currently uses up to 30m$^3$ (8,000 gallons US) of water in 12 hours.

Based on my research in the subject the best way of filtering this water is by using wetlands after having passed the water through an initial filtering stage to get rid of any plastics in it, however although I have been looking around the web I haven't found any equation I could use to calculate the flowrate of water through a wetland.

You can find an image of the wetland filter I'm thinking of using here: Schematic of the Horizontal Subsurface Flow Constructed Wetland (Wikipedia).

Just in case it's not clear, I am not attempting to make the water drinkable I just want to make the water clean enough so it can be used to wash cars again. The water will be stored at most 12 hours during the night so it can be used again in the morning.

Any advice in the matter would be greatly appreciated.

What you're really looking at is a fairly basic groundwater flow problem. What you need are hydraulic conductivity values for the "gravel" sediment in question. Given the fixed 1% grade, what you want to find is the "tank" length that maximizes pollutant residence time, and is relatively easy to calculate.

I believe that this is the basic design around which your illustration comes from:

Horizontal Subsurface Flow CW

I don't know how you're going to solve the problem of finding and keeping enough water in your system during the dry season. You're system depends on growing plants!


What is the origin of the ocean's salt? We know we cannot live without salt, but an investigation into the origins of ocean's salt leads one to believe that this issue is not fully resolved yet.

What geological phenomenon caused the earth to contain so much of salt? I see questions on SE that ask about the origin of earth's water. In a similar vein did an extraterrestrial body "dump" salt on earth or is salt native to Earth?

It appears from these links that Jupiter's Moon Europa does contain a salty ocean -
http://www.space.com/20078-jupiter-moon-europa-ocean-surface.html and http://www.planetary.brown.edu/pdfs/2440.pdf.

From a geochronology perspective what causes a planet to "develop" salt concentrations ?

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


How to determine ocean bottom depth for a data set consisting of longitude and latitude? Given a data set which consists of pairs of longitudes and latitudes, is it possible to determine an estimate of the ocean bottom depth at that point?

I can find maps of estimated sea depths online (e.g. https://maps.ngdc.noaa.gov/viewers/bathymetry/), but I am not sure how to go about it extracting the data.

I could look at every single point, and look at the map and find the depth level, but I have > 1000 points so ....

The easiest products that provides ocean bathymetry (bottom depth) is the one you mentioned: https://maps.ngdc.noaa.gov/viewers/bathymetry/. It provides bathymetry data from a plethora of surveys. If you click in the map at any location, you will get a decent estimate of the depth at that point. You can also extract the surveys and data that are available for any given location. You also get DEMs and Lidar data. You can define a bounding box or a polygon (Identify tab) and it will provide the links to the original data. The original data in areas where no recent surveys are available is usually either from ETOPO or GEBCO.

If you are interested in a specific area you can also use a region selector directly from  GEBCO (pick a box around all your points and extract the data that way).

You can also try NOAA electronic navigational charts.


Data source of the planetary boundary layer (PBL) PBL is one key physical quantities aimed at analysing the condition of air pollution in an area of interest.
From WRF simulation, I can get the variable PBLH whixh represents the PBL height.
But, is there any free data source offering the observing PBL height all over the World?

For now, I can get the weather data from the NOAA weather center. The data based on observations at airports doesn't conclude the quantitative information of PBL.

Any recommendation would be appreciate!

Not exactly. The PBL is a quantity more or less derived. you may be able to derive it from upper air observations, but a direct observation of it is not yet available. Here are some methods: https://e-reports-ext.llnl.gov/pdf/235179.pdf

The question you are asking is the equivalent of "Can we observe the Jet stream?" We cannot observe the jet stream, but we can observe the winds, from which we infer the jet stream.


Volcano magma chamber If I use a really big drill and drill all the way down to a magma chamber what exactly would happen?

From what I understand we cant drill to a Magma Chamber because it is really hot, but I have a slight feeling something like shaking a soda and opening it may happen in a magma chamber due to the large amount of pressure that it is under.

You might get a lava seepage, but I doubt it. The cross-sectional area of a borehole is small compared to the total cross sectional area of fractures that are there already. Note that volcanoes bulge quite markedly due to lava up-welling and deformation due to magma pressure, so the volcano is invariably well fractured. A small hole is likely to fill up with magma rapidly, which would cool and solidify against the country rock, thereby plugging the hole - unless the borehole was very close to a gassy magma chamber. However, there might be exceptions in that very small fraction of volcanoes that are of the 'Plinian' type, in which exceptionally high gas pressures can occur. But then, nobody in their right mind would drill into a potentially Plinian type of volcano!


Is there a massive drop in quality of Cretaceous vs. Triassic dinosaur fossils? One thing that still blows my mind about dinosaurs is the massive timeline.  Relevant to this question are the time periods:

Triassic Period (252.17 to 201.3 million years ago)
Cretaceous Period (145 – 66 million years ago)

Triassic-period dinosaur fossils are 50+ million years older than Cretaceous-period dinosaur fossils.  I would thus predict a massive difference in fossil quality.  However, I'm unsure because perhaps any fossil that's able to last say 1 million years can just as easily last say 100 million years.

Question: Is there a massive drop in quality of Cretaceous vs. Triassic dinosaur fossils?

No, there is no massive difference in fossil quality due to the extra 200 million years or so that the oldest dinosaur fossils have spent in the ground compared to the most recent ones at the end of the Cretaceous. Once fossils are properly fossilised, they remain unchanged unless something happens to the rocks. This could be weathering, which damages or destroys many valuable fossils, including recent ones like hominids, or it could be metamorphism, which damages or destroys them with heat.

I have seen a photo of a one-billion-year-old fossil from the late Precambrian of a marine algae reliably dated by the new Rhenium 187 - Osmium 187 method, and it was in an excellent state of preservation. Likewise with fossils preserved in amber, some of which are tens of millions of years old but look as fresh as if they had only died yesterday.


Is the Amazon rainforest resistant to fires? Comparing the picture from Wikipedia that delimits the Amazon rainforest and the picture of the recent dramatic fires in the area that NASA published, what I can gather is that the burned zone is the periphery of the forest and not the forest itself.

Source: Wikipedia

Recent fires on South America, NASA

As much of South America is on fire, I wonder if the absence of fires in the Amazon is related to its resistance to fires due to its being too wet, as suggested in this question, or due to other reasons as absence of human activity on the truly wild parts of the Amazon.

Most fires are probably in the periphery because they are started by humans.

They encroach on the jungle from the outside, where they already live, and there are roads instead of impenetrable jungle.


What causes the beautiful Auroras on the north and south magnetic poles? What is the scientific reason for the majestic sights of the northern and southern lights, otherwise known as Auroras near the magnetic poles, and why do the northern lights differ from the southern lights?

Straight from wikipedia:

  Auroras are associated with the solar wind, a flow of ions
  continuously flowing outward from the Sun. The Earth's magnetic field
  traps these particles, many of which travel toward the poles where
  they are accelerated toward Earth. Collisions between these ions and
  atmospheric atoms and molecules cause energy releases in the form of
  auroras appearing in large circles around the poles. Auroras are more
  frequent and brighter during the intense phase of the solar cycle when
  coronal mass ejections increase the intensity of the solar wind.

  Auroras result from emissions of photons in the Earth's upper
  atmosphere, above 80 km (50 mi), from ionized nitrogen molecules
  regaining an electron, and oxygen atoms and nitrogen molecules
  returning from an excited state to ground state. They are ionized
  or excited by the collision of solar wind and magnetospheric particles
  being funneled down and accelerated along the Earth's magnetic field
  lines; excitation energy is lost by the emission of a photon, or by
  collision with another atom or molecule:

  oxygen emissions: green or brownish-red, depending on the amount of energy absorbed.
  nitrogen emissions: blue or red; blue if the atom regains an electron after it has been ionized, red if returning to ground state from an excited state.

  Oxygen is unusual in terms of its return to ground state: it can take
  three quarters of a second to emit green light and up to two minutes
  to emit red. Collisions with other atoms or molecules absorb the
  excitation energy and prevent emission. Because the very top of the
  atmosphere has a higher percentage of oxygen and is sparsely
  distributed such collisions are rare enough to allow time for oxygen
  to emit red. Collisions become more frequent progressing down into the
  atmosphere, so that red emissions do not have time to happen, and
  eventually even green light emissions are prevented.

  This is why there is a color differential with altitude; at high
  altitude oxygen red dominates, then oxygen green and nitrogen
  blue/red, then finally nitrogen blue/red when collisions prevent
  oxygen from emitting anything. Green is the most common of all
  auroras. Behind it is pink, a mixture of light green and red, followed
  by pure red, yellow (a mixture of red and green), and finally, pure
  blue.


Does El Niño increase the amount of heat that escapes into space, or does it increase the amount of heat trapped on Earth? So we know that surface air temperatures are warmer during El Niño events (which implies that there is more heat in the atmosphere, although maybe it's possible that it also means there's less heat in the oceans?).

I'm wondering... though.. Could this simply mean that the land surface emits more longwave radiation out into space during periods of El Niño.

During El Niño heat is transferred from ocean to atmosphere. If atmosphere gets warmer, yes, it generates more radiation and more heat escapes into space. The same about land surface - if it's warmer, it radiates more heat.

Of course that's all with assumption that there are no other factors influencing it - like e.g. greenhouse gases.


Manmade ditches in lowlands of New England Recently in travelling back to New England I discovered ditches in the lowlands/wetlands of the shoreline on Google Maps satellite view.  They are clearly man-made, but even with all the agriculture and fishing in the area, I cannot figure out the purpose of these.  I have discovered that they seem to be all over New England, but sometimes it's not a.
What is the purpose of the man-made lines that appear in all these satellite images?
An example image is below, but it is not very high resolution.  Here are some links that show the phenomenon:
Great Island near Old Lyme, CT
Near Stonington, CT
Marsh near Narraganset, RI
Goose Island near Old Saybrook, CT (maps view, not satellite, helps make the lines clear)
Near Marion, MA

they are drainage ditches intended to drain salt marshes.
They may be old and no longer maintained, it is impossible to tell for certain from satellite but it seems likely.
https://qsr.waddensea-worldheritage.org/reports/salt-marshes


Calculating magnetic declination for a non-axial dipole field I'm trying to answer the following question:

  Compute the inclination and declination of the magnetic field that would be observed in Boulder, Colorado (40°N, 105°W) if the Earth’s field corresponded to a perfect geocentric dipole whose axis penetrates the Earth’s surface at 80°N, 72°W.

Source: question 4, exercise set 5.10, on p. 360 of Lowrie (2007).

I found the inclination using $\arctan(2\tan(40))$, but am unsure of how to get the declination.

Reference:

Lowrie, W. (2007). Fundamentals of Geophysics, 2nd ed. Cambridge University Press.

Inclination is given by

$$I=\arctan(2\cot\theta)$$
where theta is equal to 90° minus the observer's latitude (in the Northern Hemisphere), therefore

$$I=\arctan(2\cot(90-40))=59,21^\circ$$

To get declination the following figure helps:

Declination is the angle between geographic north and magnetic north. (I suppose 80°N, 72°W are the coordinates of the North Geomagnetic Pole.) Let's do the math!

$$D=\arctan\left({{{33}\over{40}}}\right)=39,52^\circ $$


Do forests affect local rainfall and climate significantly? I know that forests can change the local temperature, but what about rainfall?.  Do forests affect rainfall in their region? I have read that if a forest is very big, it can cause minor changes to local rainfall and temperature.  How does that work?

For rain to fall, water vapour must exist in sufficient quantities in the atmosphere. The main source of atmospheric water vapour is evaporation from oceans. However, evaporation from large bodies of water such as lakes and dams also contributes. Another significant contributor, on a local level, is transpiration from forests.

  the Amazon alone creates 50-80 percent of its own rainfall through transpiration

Removing forests has

  the biggest impact on cross-continental transport of water vapour

Removal of trees from an area of forest immediately stops transpiration in the that area. This causes less rain to fall in that area. It changes the way light is reflected from the Earth's surface, which changes the heating characteristics of the ground, which changes air movements. It will also have an influence on ground water levels and depending on local geology can bring salt to the surface causing salt scars and eventually desertification.


How far above sea level can you get on the equator? Quite simply what is the highest point above sea level that is right on the equator, I figured it would be a mountain in the Ecuadorian Andes but the Kenyan highlands look to be a likely candidate as well. I've tried to find it but I simply can't find a map that has the equator and the altitude in a highly accurate format and resolution anywhere.

I would assume that's the highest point on the equator you talking about, so The highest point on the Equator is at the elevation of 4,690 metres (15,387 ft), at 0°0′0″N 77°59′31″W, found on the southern slopes of Volcán Cayambe [summit 5,790 metres (18,996 ft)] in Ecuador. This is slightly above the snow line and is the only place on the Equator where snow lies on the ground.


Does the US National Weather Service use Celsius or Fahrenheit? This tweet from the National Weather Service in LaCrosse, Wisconsin, USA says:

  We have officially hit -30 here at the NWS La Crosse office as of 520 a.m. The wind chill is -54. Be sure to dress appropriately if you're heading out for the day.

The photo shown below shows a digital readout of an electronic thermometer, showing -30.1 but has no units. The -30's are getting close to where the Celsius and Fahrenheit scales tend to have similar numerical values, so there's no way to use context in this case to choose the most likely answer. No units are shown on the front panel, and these instructions offer no help either.

NWS Temperature forecast or new forecast

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

and if you click on this URL - Max/MinT

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

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

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

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

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


Why is "at least a small tilt" between rotation and magnetic axis required by models of magnetic field formation? I saw something I don't understand in the Gizmodo article Cassini's First Grand Finale Images Are Stunning—But What Are We Really Looking At?. In a quote of Caltech Professor of Planetary Science Andrew P. Ingersoll, it is suggested that a it necessary for there to be at least a small tilt between a planet's rotation axis and magnetic axis.

Ingersoll mentioned the final Grand Finale observation he was looking forward to most at the very end of our conversation, which could solve an ongoing mystery of the planet’s formation. Saturn’s magnetic field has a very unusual property in that it’s “axisymmetric”—it has no tilt. That’s weird, because the math behind planetary magnetic fields requires a bit of tilt.
“How does a planet generate a magnetic field? The off-axis tilt is sort of part of that whole theory and if there’s no tilt at all, well, it will be interesting,” he said with a chuckle.

Is there a way to understand why a tilt is required in current theories of planetary magnetic fields?

"Tilt" is a consequence of a convecting metal inner core....not a "necessity". In the earth's case, that tilt has, over time, wandered from 0 to 180 degrees, sometimes with some temporal regularity, other times completely randomly. The science writer likely poorly paraphrased Professor Ingersoll's curiosity regarding the existence of a molten metal core deep within Saturn.


Does Earth's magnetic field arise from a fission reactor in its core? I heard about the georeactor hypothesis (Herndon, 1993), which claims that there is a natural atomic fission reactor in the Earth's core giving rise to the geomagnetic field. Further, Herndon claims that this reactor will shut down, causing Earth's magnetic field to disappear at some time between a hundred years to a billion years from now. Is this possible?

References

Herndon, J. M. (1993). Feasibility of a nuclear fission reactor at the center of the Earth as the energy source for the geomagnetic field. Journal of geomagnetism and geoelectricity, 45(5), 423-437. Link

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

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


Why can't the meteorologists predict for sure if the day would be rainy even on the beginning of the day sometimes? Why do the meteorologists still cannot predict if a day would be rainy or cloudy or blizzardy even on the beginning of the day sometimes?

My life circles around weather and an avid weather watcher.

And I noticed the computers still are not advanced enough to get all the variables to predict the weather accurately. The weathermen and women still read the probabilities. For example, there is a 70% chance of rain. I take the umbrella outside and there is no rain. Then the prediction is the day would be cloudy. But then there is rain. I am not saying it happens most of the time. But it happens sometimes.

Do we need a quantum computer then with qubits? Because it can hold a myriad of variables and consider them in the calculation of the weather.

The probability of precipitation (POP) has to take into account the areal coverage of some region, e.g. the broadcast market of your local TV station, but perhaps the size of your local county or region.

Because of this the POP is calculated as

$\mathrm{POP} = C \times A$

where $C$ is the confidence it will rain somewhere within the forecast region and $A$ how much of the area will experience the precipitation.

So a 100% chance of rain means it is going to rain in the entire forecast region and they are confident that it will rain.  That is a high bar, as spatial coverage of storms is often localized.

For example, if one storm is going to track through your city and its path is only going to cover 15% of the area, even if we are 100% sure it is going to happen, that still only yields a "15% chance of rain".  This is because people living in that area where the storm goes though will get rained on, but the other people will not.  This also helps average out temporal and spatial errors in the forecast.


Why should this be a thrust fault? Why should this figure represent a thrust fault?

I know this might be a stupid question, but I really want to understand. Since thrust faults are reverse faults why in the figure above if we turned the photo 90 degrees clockwise like this

we don't get the same shape as this

I think that in faults in general the fault plane is inclined to the horizontal, and the hanging wall is the mass of rocks above the fault plane, i.e., the side at which the angle between the fault plane and the horizontal is larger, and the foot wall is the mass of rocks below the fault plane, i.e., the side at which the angle between the fault plane and the horizontal is smaller.
In the second figure, we have a hanging wall on the left side and we have a foot wall on the right side, and it seems that the hanging wall is moving down relative to the foot wall, and that's what happens in normal faults not reverse ones, right? So why we consider the thrust fault in figure one as a reverse fault?

First don't rotate the whole thing, you are just confusing yourself by rotating the bedding plane. You can't rotate the bedding planes and expect faults to match up like that. Your eye is treating the bedding plane as horizontal which makes it a completely different from of fault.
A thrust fault is just a reverse fault with a shallow fault angle.

Pay attention to how the bedding planes move relative to each other notice how they begin to double up in both forms of reverse fault, while in a normal fault sections begin to disappear in the middle, being lost from hypothetical drill core entirely. In the reverse faults if you drilled down through the blocks there are areas where you would drill through the dark central bed twice while in the normal there are places where you would never hit it at all.


Which type of convergent boundary creates the tallest mountains? Which type of convergent boundary creates the tallest mountains?

Continental-Continental
Ocean-Ocean
Ocean-Continental

The type of convergent boundaries is not the only factor. From the current configuration of the world one could be tempted to say that Continental-Continental collisions would form the tallest mountains. And they are indeed the most dramatic tectonic collisions and they formed the Himalayas, that are almost 2,000 m taller than any other mountain on Earth. However, the india-Asia collision wasn't any collision it was the most dramatic collision in a long time with convergence rates of 16 cm/year, way more than any current convergence rate.

From USGS

Therefore, the convergence rate is also a very important factor. The tallest mountain outside the Himalayas is mount Aconcagua in an oceanic-continental boundary. With a convergence rate of about 6 cm/year, and that have been below 16 cm/year at least for the last 22 million years.
So it is difficult to say how tall would be Mount Aconcagua if you speed up the convergence rate between Nazca and South America plates by 260%.

I don't think there is a definite answer to your question, unless you constrain other factors, like convergence rate, plates thicknesses, etc.


What keeps water from sinking into earth? I remember reading somewhere that there's evidence of water on Mars but it all sank into the Martian soil. So what prevents that happening on earth?

Some people say it's because the crust is not permeable to water, but that must be nonsense because of volcanic actions and earthquakes, there certainly will be cracks that allow water to flow through. So the only thing that prevents the water from sinking in is the temperature, right?

So what prevents that happening on earth?

Not much. Quite a lot of water is recycled into the Earth's crust and mantle.

So the only thing that prevents the water from sinking in is the temperature, right?

That's part of the story. For our discussion, water can exist in two forms:

Molecular water as H2O, being in one of several phases (liquid water, solid ice, supercritical fluid, water vapour),
Structural water in solid minerals. For example, in clay minerals aka mud. Kaolinite is one of the minerals that make up mud (or dust) and has the formula Al2Si2O5(OH)4. See that (OH)4 in there? That's basically water. Even if you take a pile of mud, dry it at 110 °C in an oven until it's completely dry, the water is still going to be in there.

Molecular water can react with rocks and minerals to form hydrous minerals and get trapped as structural water (similar to adding water to Portland cement in the making of concrete), and hydrous minerals can be heated enough to release this water (usually requiring hundreds of degrees).
Let's look at some examples of how this thing might work.
Oceans have mid ocean ridges, where the oceanic lithosphere is being formed. This area has very shallow magma chambers so the rock is extremely hot. Water that percolates down through cracks gets heated to a large degree, lowering the density and increasing the buoyancy of the water. This water then goes back up through hydrothermal vents on the seafloor. Here's a spectacular video of some of those things:
https://www.youtube.com/watch?v=rTR6gGDWcJk
When the water goes down, not all of it goes back up. It also reacts with the rock, forming hydrous minerals. For example, anorthite (CaAl2Si2O8), a common mineral in basalts, is hydrated to epidote-clinozoisite: Ca2Al3Si3O12(OH). In some occasions, oceanic crust can be uplifted and is then exposed. One example is Cyprus, where you can see features like this:

What you're looking at is basically anhydrous rocks (the white stuff) replaced by hydrous minerals (the brown stuff) due to upwelling hot water in the oceanic crust. Above it, now gone, was a hydrothermal vent like the ones in the video.
On land, water does sink deep down as well. As Gordon mentioned in his answer, water is common in oil reservoirs, but it's just about anywhere else. It is particularly rich in sedimentary rocks, that still have some amount of the liquid water that existed during sediment deposition (river, lagoon, lake, etc).
A good property of water in subsurface conditions, is that at higher temperature and pressure it can dissolve and leach metals from rock. This provides a way to move metals around, eventually depositing these metals in localised locations so we can exploit them. Lead, zinc and gold are examples of metals that can be concentrated by circulating water.
Water can also go deep down into the mantle in subduction zones. Water trapped in pore spaces and hydrous minerals can sink hundreds of kilometres down into the Earth. Eventually, the temperature becomes too hot to sustain the water in there and the rock devolatilise: they lose the water (which is a supercritical fluid at this stage). This water is then incorporated into magmas, and erupted in volcanoes. In many volcanoes, especially in arc volcanoes (such as the ones around the Pacific ocean), a major component of "volcanic gas" is actually water vapour.
To sum it up, water goes down, water goes up. It's all one huge happy cycle.


What causes aurorae? I know that aurorae are caused by solar activity interacting with the Earth's magnetic field as charged particles are funneled down into the polar magnetic mirrors.

On one hand, I know that as charged particles accelerate, they will produce radiation. They will happen in at least two ways in the context of aurorae:

Charged particles will gyrate around magnetic field lines with a characteristic frequency, which presumably varies with pitch angle and position in Earth's magnetic field.
As the charged particles are slowed down by the magnetic mirror effect, they will release some radiation.

I've also heard that the visible radiation is caused by re-radiation from oxygen or nitrogen atoms which have been excited by collisions with these charged particles.

Which effects cause radiation at which wavelengths/frequencies, and what actually causes the visible aurorae?

When the solar wind is funneled into the Earth's magnetic poles, those particles excite the electrons of molecules in the atmosphere which then bumps those electrons up into another orbital. When the electrons fall back down into their native orbital, they produce a photon of a particular wavelength whose energy is equal to the difference between the energy states of the two orbitals.There is a good pdf from NASA here and another good article here.


Why would Earth have stable weather patterns if it stopped spinning and vigorous weather if it had a much faster rotation? According to https://www.youtube.com/watch?v=nH3bmG-KjvU, Earth would have stable weather patterns after it stopped spinning and according to https://www.youtube.com/watch?v=QHwLopLUrB8, Earth would have vigorous winds if it had an 8 hour rotation period. Would the Coriolis force responsible for vigorous winds?

Weather modeling is crazy complicated so I don't want to make this sound absolute, but Venus virtually doesn't rotate and it has much faster trade winds than Earth.   Venus has low surface wind speed but that has to do with the consistent temperature all around it's surface and a very dense almost viscus atmosphere.

You might not get hurricanes with a slow rotation and virtually no Coreolis, but you'd still get weather.  The heavy cold air from the night side of the planet would sink and the hot day side of the planet would rise, and you'd get a constant re-balancing of density and a steady wind and likely a lot of rain as the air cooled on the night side, perhaps continuous rain at a certain time during the night (the same process that creates dew but much bigger).

Some good answers on a related question here.


How to interpolate scattered data to a regular grid in Python? I have three txt files for longitude, latitude and temperature (or let's say three lists lon, lat, temp) from scattered weather station in the UK. I would like firstly to interpolate these data in order to get a nice colourful map of temperatures. Then, I would like to plot this interpolated temperature layer only over the land mask (thus over the british isles and not over the sea). Is that possible with Python and how?

It is straightforward to do so with numpy, scipy.interpolate.griddata, and matplotlib. Here is an example:

import matplotlib.pyplot as plt
import numpy as np
from scipy.interpolate import griddata

# data coordinates and values
x = np.random.random(100)
y = np.random.random(100)
z = np.random.random(100)

# target grid to interpolate to
xi = yi = np.arange(0,1.01,0.01)
xi,yi = np.meshgrid(xi,yi)

# set mask
mask = (xi > 0.5) & (xi < 0.6) & (yi > 0.5) & (yi < 0.6)

# interpolate
zi = griddata((x,y),z,(xi,yi),method='linear')

# mask out the field
zi[mask] = np.nan

# plot
fig = plt.figure()
ax = fig.add_subplot(111)
plt.contourf(xi,yi,zi,np.arange(0,1.01,0.01))
plt.plot(x,y,'k.')
plt.xlabel('xi',fontsize=16)
plt.ylabel('yi',fontsize=16)
plt.savefig('interpolated.png',dpi=100)
plt.close(fig)

Result:

How to use this:

x and y are locations of points - these correspond to lon and lat values of your stations;
z are the values of points - this corresponds to your temperature observations from stations;
xi and yi are target grid axes - these will be your target longitude and latitude coordinates, which must match your landmask field;
zi is the result;
This example includes a simple way to mask the field. You should replace this mask with the landmask on your grid.

Notice also the method argument to griddata. Besides linear, this can also be cubic or nearest. I suggest you play with each to see what yields the best result for your dataset.


Subrelluric forces in a volcanic eruption I am listening to a song about volcanoes. It is called "Pyroclastic Annihilation" performed by a brutal deth/thrash metal band called "Demolition Hammer". It is from their album "Epidemic of Violence" released in 1992. The song is:
https://www.youtube.com/watch?v=S_7qqsVioxo
the full lyrics can be found here:
https://genius.com/Demolition-hammer-pyroclastic-annihilation-lyrics

I have come across a term I do not understand.

  Molten debris
  Volcanic ash
  Seas of boiling mud
  Subrelluric forces exploding violently
  Pyroclastic matter intense velocity

Is the word "Subrelluric" a geological term? If yes what does it mean exactly? What are Subrelluric forces? What do they do amidst a volcanic eruption? I couldn't find anything on the web. Perhaps this is an extremely advance term not usually used in the public world?

This term does not exist in volcanology. I can’t even think of a similar sounding term that can be misheard in the song, or misheard by the authors and then put in the song.

It’s possible it exists in a different language but I am not familiar with any options.

Sounds like your best bet would be to ask the band.


formula to convert precipitation in mm/h to runoff in m³/s I have precipitation data in mm/h but to use them for my model I need them in m³/s. Is there a formula to convert them?

When we say there was 1 mm (or 0.001 m) of rain, it is assumed that it is on a 1 square meter area, so it is equivalent to a volume of water of 0.001 $\small\mathsf{m^3}$ (or one liter). So first you have to divide your data by 1000.

Then you have time, which is easy: there are 3600 seconds in one hour. So to convert L/h in m$\small\mathsf{^3}$/s, you have to divide your data by 3,600,000:
1 L/h = 2.7778 x 10$\small\mathsf{^{-7}}$ m$\small\mathsf{^3}$/s.

You can ask this sort of things in WolframAlpha; the trick here is to "convert" mm/h, assumed by the engine to be a speed, in L/h, the volume flow rate hidden by the mm/h unit.


Is the Cameroon Line still an active rift zone? The Cameroon Line is described by the Oregon State University's Volcano World webpage What is known about the volcanoes of Cameroon? as a

  a chain of volcanoes extending from Annobon Island in the Atlantic Ocean northeastward through Cameroon. The oldest rocks have been dated at 70 million years old.

As in this map from the Global Volcanism Program's Oku Volcanic Field webpage:

A notable active volcano in the area is Lake Nyos which killed 1700 people in an eruption that spewed noxious gases (mainly $\ce{CO2}$) in 1986.

The explanation for the active volcanism is given by Oregon State as being due to

  About 80 million years ago, during a reorganization of plate boundaries, the African plate rotated counter-clockwise. Then a new rift formed that failed to split Africa but apparently did form conduits that allowed magma to ultimately reach the surface and form the volcanoes of the Cameroon line.

Is there any evidence to suggest that the Cameroon Line is still a tectonically active rift system?

The actual cause of the Cameroon Line is described by many authors (including the 2 included in this answer as being source of controversy and uncertainty - but it seems that it is not an active rift system, certainly not like the east Africa Rift.  According to the article A lithospheric instability origin for the Cameroon Volcanic Line (Milelli et al. 2012) describe the Cameroon Volcanic Line (CVL) as being

  an enigmatic structure that defies common dynamic models of
  melt generation and volcanic activity on Earth.

The enigma is due to the CVL having no spatial age progression in the rift system, despite having continual magma intrusion over 70 million years along the 1600 onshore-offshore line.

The authors also suggest that

  The chain is nearly perpendicular to the coastline and
  terminates in a Y-shaped structure that has not been affected by absolute plate motions, implying that
  the mantle upwelling that feeds magmatic activity is attached to the continent.

The authors model that rather than a developing rift system, the CVL is likely to be an example of where the lithosphere becomes unstable due to cooling from the crust above.

It should be noted that the CVL lies in between 2 cratons, shown as white in the seismic tomography image below from Macquarie Universty - what also should be noted, is the colour of the active East African Rift.

Further, according to the article Formation of the Cameroon Volcanic Line by lithospheric basal erosion:
Insight from mantle seismic anisotropy (Elsheikh et al. 2014), modelled the sub-crust dynamics that

  involves a channel flow at the bottom of the lithosphere originated from the
  NE-ward movement of the asthenosphere relative to the African plate.

from this, the authors hypothesise that

  progressive
  thinning of the lithosphere through basal erosion by the flow leads to decompression melting and is
  responsible for the formation of the CVL. The model is consistent with the lack of age progression of
  the volcanoes in the CVL, can explain the formation of both the continental and oceanic sections of the
  CVL, and is supported by previous geophysical observations and geodynamic modeling results.

A key conclusion the authors made regarding the flood basalts and volcanism in the CVL is that observations do not support mantle convection or mantle plume causes, rather, they assert that basal lithospheric erosion due to

  concentration of mantle flow associated with the
  sharp change in the orientation of the continental margin of western
  Africa.


Can someone identify this 'striped' stone? The stone has a raised texture on the top where the stripes are.
I'm not sure exactly where it was found.
It is not magnetic.

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

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


Does global warming affect tsunamis? I have been doing some research into global warming, and I was curious as to whether or not increasing the temperature of the oceans would affect tsunamis to any significant degree.

My gut tells me that adding more energy into the water would make the tsunami worse, but tsunamis are caused by earthquakes, not by heating like a hurricane. On the other hand, increasing heat would reduce the density of the water, which might make them less severe.

Would these forces actually affect the tsunami? Which one would win, or would they cancel out? Or am I completely missing something obvious?

Pretty confident to answer No here.

Tsunamis are caused by water displacement due to earthquakes; this has nothing to do with global warming.  Any changes in density would be trivial, and although the water would have more thermal energy, this would not affect or be influenced by the kinetic energy of the Tsunami.

The only way in which a tsunami would be made more severe would be that any sea level rise due to global warming would be added to the Tsunami height.


Please identify- no origin known but given to me by a geologist A very dear man who love his job as a geologist gave this to me. He’s been all over the country so I have no idea where he may have picked it up

The block is quartz. The green staining could be anything, from copper-bearing minerals, to clays, to silicates like epidote, actinolite, serpentine, etc.


Is the giant impact hypothesis still alive? It used to be thought that the unusual amount of water on our planet was the result of a giant collision between proto-Earth and a dwarf planet or planetoid called Theia. I recently heard of some oxygen isotope research which indicates that the giant impact hypothesis wasn't necessary to explain the oceans. So is the giant impact hypothesis still alive, modified or dead?

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

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


What type of mineral is this? My grandfather found this thing.

The green material indicates the potential presence of copper & the shiny bits on the lower left & mid right of the specimen look metallic, but that could be just glint in the picture.

Also, there are two groves on the lower right which may indicate a soft metal like copper.

If it is metallic it could be native copper or it could be lump of copper from a foundry.


Why are lenticular clouds circular? I recently visited Japan, where I observed a lenticular cloud above Mount Fuji:

Curious by the cloud, I looked it up and found it it's a lenticular cloud, that forms because of rising moist air coming into contact with cooler air. However, why is it circular? If I would look at it from above would it still be circular? Since air moves in a certain direction, I would expect the cloud to be laminar and elongate towards one direction rather than circular.

What makes it circular?

Lenticular clouds don't form because "rising air comes in contact with cooler air" but rather from moist air cooling to its dew point as it is forced to rise over the terrain.  Unlike most clouds that move with the wind, clouds like these are "anchored" to the terrain and the air moves through them.  If you observe them closely you can see new cloud forming as air flows upward and into the cloud on the windward side of the slope and evaporating as it exits descending on the lee side.

As air rises, pressure decreases and the air expands (volume increases).  This results in a temperature decrease in the parcel.  When the rising air cools to its dew point the cloud will form.  In this case air is only rising because it is forced over the mountain.  Once past the peak, the air descends the lee slope and is compressed and warmed.  Once it warms up and relative humidity is below 100% the cloud evaporates.  If the streamlines parallel the contours of the peak, this results in a roughly circular region where the air is suitable for the cloud to form.

If the terrain was a long ridge instead of an isolated peak, the lenticular cloud will elongated as a line over the ridge tops.

You generally won't see the cloud elongated downwind, as the air is forced down the lee slope.  What you might instead see are clouds at regular intervals downstream of the mountain if the mountain (and atmospheric stability) has caused a standing wave to form. In this case you might see clouds in the peaks of the wave depending the humidity of the air and the amplitude of the wave.


Regarding forest fire season and using robotic devices for proactive efforts before any fires For many years there are terrible forest fires in the U.S. (for example); I was wondering about pro-active measures ( I'm sure there are many). One possibility is using a small army of robots that are designed to 'go anywhere' and act like 'artificial goats' eating any dry brush or grass. Of course another army of robots could ,using local water from a lake or streams, fill up with say 100 gallons each ( if designed for this) and spray water everywhere even without a fire emergency.  This might sound silly but you have a lot of robotic derigibles carrying 1000 gallons of water or more slowly floating over a forest sprinkling water everywhere like a mild shower. So could certain 'robot armies' be used to fight the dry conditions in a forest?

This is counterproductive, both ecologically and economically, and is also well beyond the capabilities of current robots.

Ecologically counterproductive
Forests have evolved to live with, and in many cases, to depend on forest fires. Aggressive fire prevention by the US Forest Service and other agencies throughout much of the 20th century resulted in unintended consequences. Many native species need fire to reproduce. For example, the pinecones of lodgepole pines remain sealed shut for years and only open when exposed to the high heat of a forest fire. Decades of active fire suppression led to the replacement of some of those native species by invasive ones.

Another unintended consequence was making large fires even larger. Some of the most intense fires happened in areas where small fires had been successfully suppressed for a number of years. The resultant buildup of dead wood, brush, and smaller trees gave fires a way to spread to the canopy level, something that didn't happen so often when small fires regularly burned away that lower level of fuel.

Economically counterproductive
One of the biggest fire threats to people is those people who insist on living in forested areas and then let the trees grow right next to their houses. The simplest solution: Don't do that then! The Forest Service and others offer education to homeowners on how to make their homes more fire resistant, and in some cases, polices areas to ensure homeowners are following some minimum standard.

Another solution, one not yet adopted by the Forest Service, is an approach taken by the Federal Emergency Management Agency with regard those who live in the most flood-prone areas. After flooding one too many times, FEMA essentially forces homeowners to sell their houses at market value to FEMA. FEMA then promptly tears them down and marks the area as uninsurable. This might appear to be a waste of money, but in the long run it saves FEMA money, and potentially saves lives. Texas and some other states take even more drastic measures with coastal properties. A house is condemned once the coast line has eroded to the point that it is closer than some minimal distance of the house.

We can't build such robots, yet
The terrain where forests grow is not exactly suitable to robots. Much of the forested land in the contiguous US is mountainous. What isn't mountainous is dotted with bogs, swamps, and lakes. The weather is often rather nasty. An autonomous robot that could navigate and survive through such terrain is far in the future. Adding the ability to clean up terrain is even further in the future.

Aggressive fire suppression requires clearing out shrubs such as chaparral, which is rather tough stuff, dead and down trees that can be several meters in diameter, and small to medium sized non-canopy trees whose trunk can be up to a meter or so in diameter. This is not the job for little goat-sized robots. This is a job for an industrial-sized robot, and ED-209 won't cut it.


Is there a formula to compute the destructiveness of an earthquake? I am trying to find out if there is a way to compute if an earthquake is destructive. I am looking for a threshold formula which depends on magnitude and depth

for example

X = (some constant) * magnitude * depth

if X > (some constant) the earth quake is destructive or secondary effects (landslides, fires, floods or tsunamis) are destructive.

This can help in finding out if there is a fixed pattern for the locations of earthquake.

The 'destructiveness' is a function of local geology and hydrogeology, type of earthquake, depth of earthquake, local population density, and whether the local builders paid attention to the appropriate building codes. So no, there isn't an equation for destructiveness. However, you can estimate the local intensity (at the surface) from the magnitude. The mathematical approach is given in the APPLICATIONS OF EXPONENTIAL AND LOGARITHMIC FUNCTIONS for earthquakes.


How to calculate the specific humidity based on the saturated specific humidity? I am using ERA5 data to drive the land surface model. One of the forcing required by LSM is specific humidity. We want to use the 2-m specific humidity. So how can I calculate the specific humidity based on dew point at 2 meters, surface pressure at 2 meters and temperature at 2 meters? I saw in ERA5 documentation we can calculate the 'saturated specific humidity' by some equations (https://confluence.ecmwf.int/display/CKB/ERA5%3A+data+documentation#ERA5:datadocumentation-Computationofnear-surfacehumidityandsnowcover).

But how can I get the specific humidity?
Thanks and hope for your early reply!

The answer is easy. Replace $T$ with $T_d$, where $T_d$ is the dewpoint temperature.
I will say I am not all that familiar with those equations, but that is besides the point.


Why does air pollution comes with cold weather in tropical areas? I reside in Bangkok where the local press have reported several times these two last months November-December about high levels of smog. A similar phenomenon occurred last year in this period (end of the tropical cold season); both this year and last year, when this smog was very evident I felt colder than in other days of the year.
Why does air pollution comes with cold weather in tropical areas?

Crop burning is a major cause.  Crops are burnt Lal across Thailand between December and march and air movements bring large concentrations south to Bangkok.  Even today islands as remote as Koh Phangan are 135 on AQI.  Can't imagine tourism can work with crop burning.


Regarding various types of atmospheric pollution Does all the car pollution (from about 150 million cars at least in the U.S. and a lot more in all of North America and the rest of the world) all the smoke-stack pollution of various factories and all the Airline pollution running day after day have a deleterious and damaging effect on the general atmosphere and, over time, the climate?

Given all the observed pollution that China has caused itself and some of the resulting weird weather events there this certainly seems to be evidence of the damaging effects of car and factory pollution. Has anyone calculated how much exhaust from cars is produced in one day on average in a 'moderate' sized city?

Of course it seems with all the increased oil production in the U.S. and elsewhere we, human beings are going to keep are love-affair with gas-powered cars for the next 200 or 300 years. That is if we don't use up all the oil and gas in the ground before then.

As a USA resident, the EPA is the best place to start when wondering about the emissions inventory of atmospheric pollutants or pollutant precursors that affect the National Ambient Air Quality Standards (e.g. Particulate Matter, Carbon Monoxide, Sulfur Dioxide, Lead, Nitrogen Oxides, Volatile Organic Compounds).  The EPA compiles a comprehensive emissions inventory of all criteria pollutants at the county level which is available in the National Emissions Inventory (compiled once every 3 years).  You can see the summary of your county at http://www.epa.gov/air/emissions/where.htm.  As for the effects of atmospheric pollution, it is important to consider the lifetime of said pollutants in the atmosphere in order to put their environmental impacts into perspective.  For instance, the air pollutants covered by the National Ambient Air Quality Standards have immediate health effects when high concentrations are breathed in regularly.  Both animals and plants are adversely affected by these irritating and sometimes toxic chemicals, but these pollutants are also reactive and do not last long in the atmosphere unless they are constantly being replenished (e.g. daily traffic).  Air quality also impacts critical nitrogen loads on ecosystems and possible production of acid rain.
If you are interested in Greenhouse Gases (e.g. methane, carbon dioxide, CFCs, nitrous oxide), the EPA has a separate site for those emissions since they are not part of the same regulatory framework  http://www.epa.gov/climatechange/ghgemissions/ .  Greenhouse gases typically do not cause adverse health effects for plants or animals on land.  However, they have long-term radiative effects (e.g. the greenhouse effect) because they stay in the atmosphere for many years and trap infrared light.  These long-term radiative effects are what can change climate and consequently land cover.  Furthermore, most of the excess carbon is absorbed by the ocean, which creates carbonic acid. Increased acidity of the ocean causes severe problems for marine ecosystems.
The EPA states that in 2012 the CO2 equivalent GHG emissions for the USA by sector was:

Electricity production (32% of 2012 greenhouse gas emissions) - Electricity production generates the largest share of greenhouse gas emissions. Over 70% of our electricity comes from burning fossil fuels, mostly coal and natural gas.
Transportation (28% of 2012 greenhouse gas emissions) - Greenhouse gas emissions from transportation primarily come from burning fossil fuel for our cars, trucks, ships, trains, and planes. Over 90% of the fuel used for transportation is petroleum based, which includes gasoline and diesel.
Industry (20% of 2012 greenhouse gas emissions) - Greenhouse gas emissions from industry primarily come from burning fossil fuels for energy as well as greenhouse gas emissions from certain chemical reactions necessary to produce goods from raw materials.
Commercial and Residential (10% of 2012 greenhouse gas emissions) - Greenhouse gas emissions from businesses and homes arise primarily from fossil fuels burned for heat, the use of certain products that contain greenhouse gases, and the handling of waste.
Agriculture (10% of 2012 greenhouse gas emissions) - Greenhouse gas emissions from agriculture come from livestock such as cows, agricultural soils, and rice production.
Land Use and Forestry (offset of 15% of 2012 greenhouse gas emissions) - Land areas can act as a sink (absorbing CO2 from the atmosphere) or a source of greenhouse gas emissions. In the United States, since 1990, managed forests and other lands have absorbed more CO2 from the atmosphere than they emit.

If we consider GHGs on a global level (see Global Carbon Project http://www.globalcarbonproject.org/carbonbudget/index.htm ) we can see how each sector has impacted the atmospheric concentration of CO2 over the past 143 yrs.


ECMWF vs NOAA forecast data accuracy I'm a novice software developer who's about to write some Python scripts for getting weather data from several U.S. stations, as well as a few in the Pacific (for checking Southern Oscillation Index & the like).

I've been oriented toward NOAA's site mostly, but having seen some mentions about 'European models' of weather forecasting in various articles over the past year, I wonder if it would be better to look toward mining the ECMWF.

Basically, I'm looking at current surface temperature and wind speeds, then trying to get a daily forecast out to 15-20 days forward. Haven't dug into ECMWF yet, but on NOAA's site, they do provide probabilistic outlooks, albeit on a monthly frequency (example). I could always check weather.com's 10-Day or Monthly, but again, I'm wondering about the accuracy.

Anyone with experience comparing forecasted vs actual results on a thorough basis, and can share some perspective?

You can compare verification scores using this application from ECMWF made from guidelines by the WMO. The example below fits nicely with what is widely known, namely that IFS (the ECMFWF global model) scores generally best. In recent year the UK Met Office global model have also scored better than GFS. The figure shows the root mean square error of MSLP.
The example below of course only covers verification for one month, so you should examine longer periods and focus on the fields you are most interested in.


How does a meandering river form? I read this explanation about rivers:
"As the river erodes laterally, to the right side then the left side, it forms large bends, and then horseshoe-like loops called meanders"

Why does the river erode laterally to the right side then the left side? Surely it would erode both sides at the same time and therefore the river would go in a straight line.

Could someone please explain more clearly how these meanders in rivers form?

Meanders amplify themselves--the stream tends to erode on the outside of the meander (forming a cut bank) and deposit sediment on the inside (forming a point bar).  Eventually, the meander will propagate so far from the stream's mean path that the stream cuts across it.  Eventually, the old meander will turn into an oxbow lake and fill in.

As to why it erodes on the outside and deposits on the inside, the simple answer is that the water has to travel farther on the outside, so it flows faster and erodes more, while the water on the inside moves slower and deposits its sediment.  A more complete answer involves vortices crossing the river bed carrying sediment from the outside to the inside.


What is the methodology to analyze future climatic extremes using the results of climate models? What is the accepted methodology to predict future climatic extremes using the results of climate models?

I have recently read a report about climatic extremes considering climate change (MICE, 2002). The report says that researchers fitted extreme value distributions (generalized extreme value, generalized Pareto) to the intensity of predicted, future climatic actions, e.g. rain, snow, wind. Applying these models, events with a large return period are used to assess the impact of climate change. Additionally, there is a recent Nature article by O’Gorman which also deals with future extreme events, particularly snow.

Considering that the predictions (projections per scenarios) can be made only in probabilistic terms. I would like to know how these predictions are made, what methodology are they using? I mean the actual climatic data, not the extreme value (statistical) analysis of them. For extreme value analysis, annual or more frequent maxima can/could be used. It is quite dubious that climate models would predict monthly or annual maxima of rain/snow for a certain region, up to the end of this century (or are climate models so sophisticated?).
Someone told me that on this site (Earth System Grid Federation) there is an example of daily predicted snow data (this can be downloaded).

So, my main question is how this data, these predictions, are produced. What are the underlying assumptions of the models? Can these 100-year long simulations be used to predict extreme events within a 100 to 1000 year return period (these are common in engineering practice).

As far as I know, the climate models contain 'accurate' models (where the phenomenon is described by differential equations) and 'approximate' models (where empirical models are used). I guess the actual amount of precipitation for a given region belongs to the latter; in this case how uncertain are these models? (Surely the 'accurate' models have large uncertainty as well, but perhaps less).

I have an engineering background and I am interested in the effect of extreme climatic events on the reliability of structures; especially considering climate change. In order to study this, it would be great to know how reliable are the climate predictions regarding extreme events. If the probability distribution (or more complex probabilistic model of the actions) is given, the reliability of a structure (system) can be directly calculated. However, I am quite suspicious about the extremes predicted by the climate models.

It is quite hard to navigate through the thousand pages reports and find the probably one page long section which would answer my question. I would highly appreciate if someone could explain the main aspects of methodology, basic assumptions or point me to specific references, any help regarding the original question is welcomed.

MICE (2002). Modelling the Impact of Climate Extremes. Description of Work

Paul A. O’Gorman. (2014). Contrasting responses of mean and extreme snowfall to climate change. Nature. Volume 512. 7515.  p. 416-418.

Extension of the question:

Can climate models reliably predict meteorological extremes?

Your question is fairly broad, and slightly vague so I don't know if I will be able to answer it in one go. If you would like any clarification, let me know.

How are predictions made?

The basic process generally used for probabilistic forecasting of the global climate is something like:

Take one or more general circulation models (GCMs), and run multiple simulations over the projection period.

GCMs are models that attempt to replicate the physics of the climate system, including land and ocean processes. They can not replicate the physics exactly, because:

they operate on scales of a few hundred meters at minimum, and so physical processes (which usually operate on much smaller scales) are scaled up and parameterised to work on the larger scale; and
because for some of the physical processes (especially those that have to be parametrised to larger scales), there is not enough data to adequately fit them. When this happens, those model parameters are usually calibrated - a large number of runs are made, with different values for those parameters, and then the best parameter values are chosen.

Usually, you run the model for some period prior to the projection period, so that you can compare that to observations (spin-up period).
You need to provide input data to the model. Mostly, this just consists of solar forcing (changes in the sun's output), as well as expected greenhouse gas (GHG) emissions, and aerosol emissions (both human and volcanic).
Simulation output is in the same format as your observational data, and generally includes all of the important variables - temperature, precipitation, etc.

Put all of those simulations in an ensemble.

Often, simulations are "bias corrected", which usually means they are changed so that the model average matches the observation average over some period prior to the projection period - this might be the last 30-40 years. This is to allow for model drift (which is mostly chaotic, and can happen in any direction).
The distribution of the simulations in the ensemble is used to create probabilistic projections. For example, each simulation has a mean global annual temperature. You could make the assumption that the errors in the simulations are normally distributed (over the ensemble), and so make an estimate of that distribution, and use that to make probabilistic estimates. This is basically saying that if ~50% of the models are over a certain temperature, you expect that (assuming the models, the input data, and assumptions they are based on are reliable*) there's a 50% chance that the global annual temperature of the earth would be over that temperature. A similar process can be used for the maximum temperature, or any other variable, and any statistics, including extremes indices. None of these predictions is a single value - they are always probabilistic, although it's probably quite common for only the mean of that distribution to be reported.
How you combine the information from the simulations in the ensemble is somewhat up to you. The basic method is as described above, and uses minimal assumptions about the data. It's also common for researchers to use a weighting methodology to estimate the ensemble mean, for example performance-based weighting, where models that perform better over the period before the projection are weighted more highly, with the assumption that they will perform better over the projection period too. Or you could weight based on model independence (if you're using multiple models), by weighting models that are less like other models more highly, in order to minimise bias from particular types of models (e.g. Bishop and Abramowitz 2013). [I have a paper in review at the moment that investigates the efficacy of some of these methods, I'll link to it when it comes out]
Can this process predict changes in 1000-year events? Yes, potentially, even when the projection period is usually more like 100 years. This is because 1 in 1000-year events are actually defined inversely - that is, they are thought to have a 0.1% chance of occurring in any given year. If your ensemble projects over 100 years, but has 100 simulations, then there are 10,000 years in which that a 1 in 1000 might occur. If you see it occurring 20 times, or 4 times, then you might get suspicious that things are changing. You probably need more than that to get a statistically significant result, but there are ensembles out there that are really big (e.g. Stainforth et al, 2005, which had 2,578 simulations totalling over 100,000 simulated
years, and  I think some of the ClimatePrediction.net have tens of thousands of simulations). Even without those large ensembles, if you assume particular distributions of extreme events where probability is a simple function of extremeness (e.g. Log-normal distribution or similar), then you can probably say something about large extremes based on the change in behaviour of less extreme events. Unfortunately, I am not aware of any experiments that look at the likely changes to very extreme events.

* Model reliability is obviously a fairly active field of debate and research. Suckling and Smith (2012) indicates that GCM-based ensembles are better than basic statistical models, but probably not currently much better than some more advanced statistical models. However, that still means that they're at least on-par with the best options we have for forecasting, unless you're in to reading chicken entrails.

References

Bishop, C.H. & Abramowitz, G., 2013. Climate model dependence and the replicate Earth paradigm. Climate Dynamics, 41(3-4), pp.885–900. Available at: http://link.springer.com/article/10.1007/s00382-012-1610-y [Accessed September 17, 2013].
Stainforth, D.A. et al., 2005. Uncertainty in predictions of the climate response to rising levels of greenhouse gases. Nature, 433(7024), pp.403–406. Available at: http://www.nature.com/nature/journal/v433/n7024/abs/nature03301.html.
Suckling, E.B. & Smith, L.A., 2013. An Evaluation of Decadal Probability Forecasts from State-of-the-Art Climate Models*. Journal of Climate, 26(23), pp.9334–9347. Available at: http://journals.ametsoc.org/doi/abs/10.1175/JCLI-D-12-00485.1 [Accessed January 8, 2015].


Why is phase rotation needed to produce the colored inversion operator? In seismic analysis, why is a –90 degree phase rotation required on the amplitude spectrum to produce the colored inversion operator?

When performing "imaging" we are generally attempting to recover the reflectivity of the earth.  At zero offset the reflectivity is the difference in Acoustic Impedance (AI) normalized by the sum. When performing colored inversion we are seeking to recover a layered representation of the band limited AI and not the reflectivity.  As we go from an AI log to a reflectivity log by differentiating we need to integrate to go the other way.  In the frequency domain integration is a -90 degree phase term and an amplitude weight term.  The amplitude term (1/freq) is taken care of when matching the spectra to that of the well log in the amplitude term.


Age of fossils found in rocks I have heard the claim by creationists that geologists date rocks by the fossils they contain and date fossils by the rocks in which they are found. This supposedly invalidates radiometric ages because they are a result of circular reasoning. Is this statement purely wrong, or is there some truth to it?

Yes, there is some amount of circular reasoning in the statement: "geologist date rocks by the fossils they contain and date fossils by the rocks in which they are found".

However, that statement does not fully describe how geologists date rocks or fossils. Dating rocks by fossils is a branch of geology called "biostratigraphy". This is a non-absolute and a relative method of dating. You know that one fossils is younger than another, so you can be sure that one rock is younger than another rock given that they have those fossils, respectively. How old are they exactly? Based on biostratigraphy alone, this is an unknown.

The problem is solved using geochronology. Using radioactive decay to accurately and precisely date rocks. This is independent of fossils, but requires that the rock have to be dateable. This means that you need some kind of volcanic material (among other things) interbedded with the fossil bearing rocks. When you do that - you can be sure that a certain fossil formed at some exact point in time. Let's say 100 million years ago. Then you can use that knowledge to assign an age to rocks containing similar fossils where you do not have any rocks that you can date.

That said, new technological advances allow us to directly date fossils. One of the methods is using the Lu-Hf or U-Th-Pb systems on apatite - a mineral that forms teeth and bones. In cases where this method has been applied it showed that biostratigraphy actually works (unsurprisingly and to the dismay of creationists).


What are good metrics to compare climates? I'm interested in visualizing climate data across the conterminous U.S. to determine regions that I would be interested in living in.  So far, I've pulled in NOAA data, and I've:

averaged the maximum daily temperature measurements per location
averaged the minimum daily temperature measurements per location
taken the difference between the average maximum temperature measurements and the average minimum temperature measurements to determine how much weather varies across the year per location
pulled precipitation in tenths of mm per location
pulled snowfall in mm per location

At first, these seemed like "good enough" approximations, but I'm discovering that this approach is somewhat inadequate because it is:

Not appropriately representing swings in daytime-nightime temperatures
Not appropriately representing the annual variance in temperatures between locations
using averages

I was initially seeking to discover areas with a high mean temperature, low variance in temperatures annually and daily, and low rainfall.  What metrics could I be using to improve this investigation?  Thanks!

The Köppen climate classification is a classic metric to classify climates:

Source: Wikimedia Commons
It classifies climates based on the number of months with temperature below and/or above certain thresholds, and on whether rainfall is evenly distributed or concentrated in a particular season.  You will find details on the definitions on Wikipedia.
An alternative is the Trewartha classification:

Source: Wikimedia Commons.
Note that the climate you seek may not exist:

I was initially seeking to discover areas with a high mean temperature, low variance in temperatures annually and daily, and low rainfall.

A low temperature variance tends to happen in humid climates.  Dry climates tend to have large temperature variances.  A subtropical highland climate may come closest to what you seek, although it's not particularly dry.  In the Köppen classification, this would be Cwb.  From the Wikipedia article:

Cwb = Subtropical highland climate or Monsoon-influenced temperate oceanic climate; coldest month averaging above 0 °C (32 °F) (or −3 °C (27 °F)), all months with average temperatures below 22 °C (71.6 °F), and at least four months averaging above 10 °C (50 °F). At least ten times as much rain in the wettest month of summer as in the driest month of winter (an alternative definition is 70% or more of average annual precipitation received in the warmest six months).

I don't think any place with Cwb climate exists in the United States.  Quito is famous for being the city of eternal spring, and some areas of Mexico are classified as Cwb, as in Johannesburg.  I suspect the closest you'll get in the USA will be somewhere not too high, not too low in the Sierra Nevada.


Why would moving the prime meridian hasten the time when it would be necessary to drop a day from the calendar? I'm reading the sci-fi novel Saint Leibowitz and the Wild Horse Woman, and in the story a pope in the post-apocalyptic future moves the prime meridian from England to the U.S. It is an unpopular decision, because according to the author not only would it confuse navigation, but it would decrease the amount of time until it is necessary to drop a day to keep in line with planetary movement. I'm trying to understand the logic of this, but I don't get at all why this would happen.

There is no basis in logic to have to subtract a day due to a change in the prime meridian.

Both the Julian & Gregorian calendars require days to be added, not subtracted. It's why we have leap years.

Also, both the Julian & Gregorian calendars were established centuries before the prime meridian was set in the 19th century. The formula for adding days & creating leap years was set long before the prime meridian was even contemplated.


How are paleomagnetic polarities determined? In magnetostratigraphic logs various chrons are distinguished with either normal or reversed polarity, with the magnetic north pole at the geographic north and south pole, respectively.

How and why can these polarities be determined? Note that I'm not after the quantummechanical reasons for magnetism, but how rocks store the magnetic orientation and how this information can later be retrieved from the rock.

This is a big question: it essentially translates to ‘how do we do palaeomagnetism’? I will try to give a brief overview and links to more detailed explanations. I'm also going to focus on the ‘how’, and leave the ‘why’ to someone else (perhaps it would be best split out into a separate question?). To record the geomagnetic field, you need three things:

A ferromagnetic mineral -- that is, one that can be magnetized like a compass needle.
A situation where grains of this mineral can have their magnetization aligned with the earth's field.
An event that locks the magnetization in place once it's aligned.

There are a surprising number of ways that (2) and (3) can happen, but for this answer I'll just describe the two that tend to be most useful: thermal remanent magnetization (TRM) and depositional remanent magnetization (DRM).

Thermal remanent magnetization is induced when a rock cools from a hot (often molten) state. Here, (2) occurs because, above a certain temperature called the blocking temperature, the magnetization of a mineral is able to change freely to align itself with the earth's magnetic field. As the rock cools, it becomes harder for the magnetization to align, and eventually it is locked in place.

Depositional remanent magnetization occurs in sediments, and is induced when grains of a magnetic mineral fall through the water column and land on the sea floor (or lake bottom). While they are in the water column, the grains are free to move and align themselves with the geomagnetic field. Once on the bottom, they gradually become buried in more layers of sediment, fixing their original orientation.

In principle, recovering the recorded field from a piece of rock is very simple: you record the rock's orientation, cut or drill it from its current situation, then measure its magnetic field in a laboratory magnetometer. In an ideal world, the field you measure would correspond to the Earth's magnetic field when the rock was formed. In practice, it's rarely that simple, and you might need to use heat treatment or alternating-field demagnetization to ‘peel off’ weaker magnetizations that have been layered on top of the original magnetization over the years.

This answer is a gross simplification and glosses over a great deal of theory, practical detail, and possible complication. For more depth, I would direct you to two excellent textbooks which (thanks to the magnanimity of their authors) are freely available online:

Tauxe, L., Banerjee, S. K., Butler, R. F. and van der Voo, R. (2014). Essentials of Paleomagnetism, third web edition. http://earthref.org/MAGIC/books/Tauxe/Essentials/ (accessed 2014-04-17)

Butler, R. F., (2004). Paleomagnetism: Magnetic Domains to Geologic Terranes. electronic edition. http://www.geo.arizona.edu/Paleomag/book/ (accessed 2014-04-17)

Tauxe et al. (2014) is more recent and more extensive; Butler (2004) is an electronic reprint of a 1992 book, but is still an excellent introductory work, and provides (to my mind) a slightly gentler introduction than Tauxe et al. (2014). (While many advances have been made since 1992, the basic theory and techniques have not changed.)

If you are interested in the nitty gritty of how the techniques are actually applied, you might want to look at:

Richter, C., Acton, G., Endris, C. and Radsted, M. (2007). Handbook for shipboard paleomagnetists. ODP Technical Note 34, Texas A&M University, College Station, Texas, USA: Ocean Drilling Program. http://www-odp.tamu.edu/publications/tnotes/tn34/TNOTE_34.PDF (accessed 2014-04-17)


What happens to sea level when a ship sinks? Let's assume that a ship is traveling on the ocean and it sinks, what is the effect on the sea level? Even if the effect is small, would it go up, down or remain the same?

It would go down.

In order to float, an object must displace a volume of fluid that weighs the same as the boat. In the case of a ship, this volume is less than the gross volume of the boat, including the air inside it. That's why it floats with the gunwales comfortably above the water. So when the boat is floating, it displaces some volume V, so relative sea-level goes up (second panel, below).

However, when the ship is submerged and full of seawater, it displaces a smaller volume than it originally did. If it didn't, it wouldn't have sunk (assuming it hasn't changed in weight).

Since it displaces a smaller volume after sinking, relative sea-level must go down. But it will still be higher than it was before the ship was launched.


Is "Carbon Neutral" (roughly) 5 Gt CO₂ equivalent? One key target set out by the IPCC is to be carbon neutral by 2050. That is, the gross green house gas emissions of Humans is less than the carbon absorbed. I'm struggling to find a good source for the value of that second number. What is the volume of GHGs that are absorbed yearly, globally.

Eye-balling the net emissions set out in the IPCC 1.5 special report, and the total gross emissions referenced in this Wikipedia page, puts the number at about of 5Gt CO₂e. Is this correct, and is there a more precise source for this? Or have I misunderstood something?

As Camilo mentioned in the comments, “carbon neutral” in this context means zero net carbon emissions.  This is the gross anthropogenic carbon emissions (fossil fuel burning and land use change) minus the carbon absorbed through managed practices.  That distinction is important; you don’t include the carbon absorbed by the ocean and land through natural processes to offset gross emissions in the calculation.
Since 2010, the UN Environment Programme has published an “Emissions Gap” report each year that includes some relevant emissions numbers:

In 2017 greenhouse gas (GHG) emissions - excluding emissions from land-use change - reached a record 49.2 GtCO2e... Emissions from land-use change... added another 4.2 GtCO2, bringing the total to 53.5 GtCO2e.
Source: UNEP Emissions Gap Report 2018

The following is a nice schematic of various negative emission technologies (NETs) that could be used as mitigation in the overall budget:

Source: Smith et al (2016) “Biophysical and economic limits to negative CO2 emissions”, https://www.nature.com/articles/nclimate2870

Carbon capture and storage (CCS) is done at the point of burning fossil fuels, so reduces gross fossil emissions. Panel (g) is called LULUCF (Land Use, Land Use Change and Forestry) in the Emissions Gap reports and AFOLU (Agriculture, Forestry and Other Land Use) in the IPCC 1.5 Special Report, and that is effectively the +4.2 GtCO2e/year quoted above.  The idea is that in the future land management will have to change to turn managed land from a net source to a net sink of GHGs.  As for Bio-energy Carbon Capture Systems (BECCS), the current levels are about zero, although there are a dozen or so demonstrator projects totalling about 0.001 GtCO2/year.  So at the moment it barely makes a dent in the overall budget, but mitigation scenarios require it rising to an order of 10 GtCO2/year by 2050:

The energy production from the use of BECCS over time in a range of mitigation scenarios.
Source: van Vuuren et al (2018) “Alternative pathways to the 1.5 °C target reduce the need for negative emission technologies”, https://www.nature.com/articles/s41558-018-0119-8

The IPCC special report also has a nice schematic of how NETs contribute to emissions scenarios.  Although there's no timescale on the schematic, most of the actual scenarios don't show any notable BECCS until 2030.

Figure 2.5 | Evolution and break down of global anthropogenic CO2 emissions until 2100
Source: Rogelj et al (2018) "Mitigation Pathways Compatible with 1.5°C in the Context of Sustainable Development", Chapter 2 of the IPCC Special Report on Global Warming of 1.5°C.


Using Range Height Indicator scan of radar I am learning about the several modes of radar that are used to study structure of thunder storms and mesoscale systems. There are three modes of radar scans as documented here - Weather Radar Systems

I have only used the Plan Position Indicator(PPI) mode to track thunder storms.

Could somebody who has used the Range Height Indicator(RHI) mode as a meteorologist or using it as part of their research work put up a sample RHI mode scan for a thunderstorm(can be supercell)  explain the following

What extra information can be gleaned from the RHI mode that is not available with the PPI mode ?
Can phenomena such as back sheared anvil be observed from the RHI mode ?  Also can anvil rain be inferred from RHI mode?

A vertical cross section in RHI mode reveals vertical structure that you can't directly observe in a horizontal PPI scan.  In the image below you can clearly see that there is a significant bounded weak echo region (BWER).  You could put this together from PPI scans at different scan elevations combined for a 3D view but with RHI you can see this from a single scan.  You can also get a sense of the anvil structure as shown in the image below.

Whether you can determine anvil rain or structure is going to be affected by the particular radar and where it is located.  Each radar band has pros/cons related to detection and attenuation but if you take these into account then you could be able to determine the features you are interested in.  You should also be able to observe Doppler winds in RHI and if you are doing this in the field with research radars it is a good bet you have dual-polarimetric data as well.

Here is a presentation of RHI scans in supercells with dual-pol data.


A rough picture about the ground-level ammonia (NH3) Ammonia is the only alkaline gas in the atmosphere. It is one of the key features to control the acidity of aerosols and the formation of ammonium salts.

In the environment of $NH_3$-rich and $NH_3$-poor, the formation pathway of the secondary aerosol would be distinct.

  For example, if $NH_3$ is redundant after the combination with $_2SO_4$, they would continue to react with $HNO_3$ to form $NH_4NO_3$. However, if in the $NH_3$-poor environment, $HNO_3$ would react with the crustal material and thus form nitrate in the coarse mode.

  In this way, the concentration levels of $NH_3$ affect the chemical composition, size distribution of atmospheric aerosols.

However, the ground-level monitoring of $NH_3$ is still limited in China with several published ones in limited spots.

Therefore, I want to learn that:

Is there any method to estimate NH3 concentration by other species?
Is there any dataset (e.g. remote sensing, measurements) offering the distribution of $NH_3$ concentration?

It seems difficult to find a reasonable proxy species for $\mathrm{NH}_3$, since its sources (primarily agriculture) are quite distinct from the sources of more commonly observed pollutants. Some observations of aerosol-bound $\mathrm{NH}_4^+$ might (or might not) be available, but due to the reasons you explain, it is non-trivial to infer the gas-phase $\mathrm{NH}_3$ concentration from the $\mathrm{NH}_4^+$ in aerosols.
There are papers about estimating atmospheric $\mathrm{NH}_3$ from satellite data, see for example here or here. These are for column-integrated and not surface $\mathrm{NH}_3$, however.


Rocks sparking under water I have searched for an answer to this question for years, to verify if it was true.

A man that lived on a river in the rugged part of the northern Washington Cascades told me an interesting story. He actually lived on the upper reaches of the Cascade
River, a tributary, which eventually flows into the Skagit River.

The river is a high energy, steep gradient river full of rocks. Fast moving and cascading.

The man told me during a big flood flow, at night, he could hear the rocks and boulders bouncing around and bumping into each other. The most amazing thing is he
said in the pitch black of night, he saw muted, periodic, random quick light flashes under water - creating an unusual effect. He and I speculated the flashes were produced by rocks colliding with each other.  The rocks in the area were mostly granitic, perhaps with some gneiss.

I did not see it. Is this possible? I know you can get sparks from some rocks and minerals - but granite boulders - underwater!!? Any comments?

Larry

Is this possible?

Definitely.

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

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

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

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

  underwater!!?

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


Educational book on science of climate change with action items? I originally posted this over on Sustainability.SE and someone suggested I try asking over here.

Can anyone recommend a book or books, intended for a non-scientific audience, which covers some (or all) of these elements?

Basic science of global warming
Evidence from ice cores, temp readings, ocean acidity, etc
Climate modeling and simulations
Projected scenarios and impacts
Actions that individuals can take to reduce impact, ranging from simple (eat less meat, adjust thermostat) to more demanding (switch to bike commute, buy electric car)
Corporate actions (policy setting for organizations and companies, what to ask political candidates about, etc)

I am looking for something that emphasizes clarity, an engaging writing style, and a positive attitude about the possibility of averting crisis. After reading this book someone should feel that they have a good general understanding of what causes global warming, and know specific actions they can take which will have a measurable impact.

The intended audience for this book would be people who know (or suspect) that climate change is a big deal, and know they should do something about it, but don't feel personally invested in the problem or solutions.

I recommend following two books. I am not sure it will answer all the questions you have mentioned but I think together they will answer most of them.

The discovery of global warming by Spencer Weart http://www.worldcat.org/title/discovery-of-global-warming/oclc/51505599
The Weather Makers by Tim Flannery http://www.worldcat.org/oclc/80331702

Both the books are highly readable for non-expert audience. Both the books do good job in educating readers about scientific aspect of the problem without bogging down them with equations or technical jargon.  The first book's focus is on science aspect of the climate-change problem and told in highly engaging style, the second book's focus is on mitigation aspect in equally engaging style.