What geophysical instruments should I use to detect water without drilling? How can one detect (preferably artesian) aquifers nowadays that a lot of sensors are available? Should I use ground-penetrating radars, neutron detectors, or any other advanced devices? Can seismic imaging be used to characterize the extent of the aquifers?

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

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

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

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


Why does the earliest sunset time not coincide with the shortest day of the year? I viewed sunset times in some major Eastern U.S. cities including Boston, New York, Philadelphia, Boston / D.C. and Miami. It seems that the earliest sunset time starts around the first week of December, stays the same for the next week, and starts to get later again by December 18.

The winter solstice is around Dec. 22, which is considered the shortest day (i.e. length of sunlight) of the year. So, it seems that the earliest sunset time is a few weeks ahead of the shortest day. Why is that?

Chicago sunset/sunrise from http://www.sciquill.com/analemma/

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

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

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

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


Are fossil fuels really formed from fossils? Hydrocarbons have been found in great abundance elsewhere in the solar system where there is unlikely to be evidence for life past or present.  No fossils involved.

Petroleum and natural gas wells that have gone dry 50 years ago, are found replenishing a fraction of their output.  No fossils involved.

Vast biomass of micro-organisms and extremophiles beneath earth surface estimated to be several times the size of the surface biomass found deriving their chemical energy for life from methane and oxygen pulled from sulfates and ferrous oxides.  The source of methane way too deep to come from fossils.  No fossils involved.

These recent findings and other evidence were foretold by the late scientist and researcher from Cornell, Thomas Gold, who authored "The Deep Hot Biosphere, The Myth of Fossil Fuels".

After seeing evidence of extremeophiles in relative abundance in even the deepest of mines, Gold ties the sub-surface biosphere to the "Deep Earth Gas theory" to show a more plausible primordial explanation of hydrocarbon fuel formation than the generally accepted "fossil" theory.

He posits that
"Hydrocarbons are not biology reworked by geology (as the traditional view would hold), but rather hydrocarbons are geology reworked by biology."  In other words, as in Saturn’s moon Titan and other hydrocarbon rich areas of the solar system, the source of hydrocarbons is primordial; but as they upwell into earth’s outer crust microbial life uses it as energy source.

While the details of the Deep Earth Gas Theory are beyond scope of elaboration in this question area, the main points which Dr. Gold supports, and provides evidence for are:

Hydrocarbons are primordial. IOW, hydrocarbons like elsewhere in the solar systems are here since the planet's birth.
The earth was subjected to only a partial melt.
Hydrocarbons are stable to great depth.  High pressure greatly stabilizes hydrocarbons against thermal dissociation.
Rock at depth contains pores.
Primordial hydrocarbons are still upwelling from the deep earth.

some sub-points worthy of mention:

It more adequately explains why Helium is only present in the earth at any mine-able quantity in natural gas.   There are no pure Helium wells.  Why the strong association of hydrocarbons with Helium, an inert gas that can have no chemical interactions with fossil organic materials or with hydrocarbons?  This is known to geologists as the "Petroleum Paradox" and cannot be explained at all by a sedimentary origin of hydrocarbons.

The presently accepted theory of fossil fuels is that the hydrocarbons formed from the decayed remains of ancient organic matter (fossils) that somehow sank down into the deep earth and got trapped in sedimentary rock formations where increased pressures assisted in converting the organic material over time to hydrocarbons.

Well, hydrocarbons are found in depths where no surface life remains could have possibly geologically submerged to.  The physics of how the ancient organic materials or the resulting hydrocarbons sank deep into the earth have yet to be explained.  Also, hydrocarbons have been found in igneous rock formations, which the accepted surface to sediment theory cannot explain.

Can we still say that fossil fuels are really from fossils?

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

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

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

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

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

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

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

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

Additional Points

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

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


WRF output grid is smaller than input definition I am running some test forecasts using WRF 3.6.1. and am having some problems with my grids. Specifically, I am specifying a parent and nest domain each with 25 points for longitude and latitude (so that there is a point right at the middle of the inner domain and the parent grid points are coincident with inner grid points with a 3:1 nesting ratio).

I would expect an output of 25 by 25 points for each domain. however, I am only getting 24 by 24 points as output. In fact if I look at the geom_em or met_em netcdf files generated by WPS I already get only grids with 24 by 24 points.

What's going on?

Here is the geogrid section of my namelist.wps file:

&geogrid
 parent_id         =   1,   1,
 parent_grid_ratio =   1,   3,
 i_parent_start    =   1,  9,
 j_parent_start    =   1,  9,
 s_we              =   1,  1,
 e_we              =  25, 25,
 s_sn              =   1,  1,
 e_sn              =  25,  25,
 geog_data_res     = '10m','2m',
 dx = 18000,
 dy = 18000,
 map_proj = 'lambert',
 ref_lat   =  53.526,
 ref_lon   =  -113.529,
 truelat1  =  53.526,
 truelat2  =  53.526,
 stand_lon =  -113.529,
 geog_data_path = '/media/data/WRF3.6.1/data/geog/'
/

Your model grid is an Arakawa C grid:

Image from Skamarock et al. A description of the Advanced Research WRF Version 3

It appears the geogrid grid generation uses the 25x25 as the furthest extents of the grid (and this is backed up by the grid maximum needing to be a multiple of the grid ratio +1).  As a result, only the u and v variables will see 25 grid points and each only in one direction, east/west and north/south respectively.  All other variables are located horizontally on the $\theta$, or scalar points in the middle of the grid boxes and there will only be 24 of these points in your setup leaving most of your grids having a horizontal dimensions of 24x24.


How were we able to measure carbon dioxide levels in earlier climates? It is said that carbon dioxide levels were much higher during the Cretaceous and Eocene periods: which proxies are used to determine paleo-pCO2?

One method is through ice cores from the worlds ice caps.

Each year, as small amounts of snow accumulate on ice caps such as on Antarctica and Greenland, bubbled of air gets trapped.  As we drill through the ice, we can identify the air samples in those trapped bubbles, and measure directly the composition of the air in those bubbled.  It tells us much more than the level of CO₂.  For example, the ratio of isotopes of oxygen is a pretty good thermometer.  We can also see pollen, volcanic ash, and other things.

Other methods are listed at the Wikipedia article on climate proxies.  Most famous are ice cores and tree rings, but other methods are lake and ocean sediments, corals, and others.  Those methods are somewhat independent so if they confirm each other, that is good.  Errors on timing may get larger if one gets further back, and sometimes a new analysis leads too a change in timing estimates.  But for the period where we have comparable records (for example, the period for which written historical records exist), results compare pretty well!


Recharge calculation for an aquifer I want to calculate recharge for an aquifer for which I have calculated daily ET by Haude's method and I also have daily precipitation data. How can I calculate recharge per minutes.

This methodology won't work. Haude's method only gives a rough estimate of evaporation. Consider the hydrologic cycle: Rainfall = evaporation (or evapotranspiration) + runoff + surface detention + soil moisture storage + infiltration +/- interbasin transfer. It sounds like you don't have nearly enough data to estimate the aquifer recharge.


Why do cold-core lows slope towards the cold air with heigth? How to show mathematically that wind intensifies with height in this case? I understand that from the hypsometric equation, in a cold core low the pressure gradient must increase with height, because in the center the isobars will be closer together:

quente = hot, frio = cold
What I don't understand is why in practice the low slopes towards the cold air with height:

Also, I wonder how I can show mathematically (I guess from the thermal wind relationship + the hypsometric equation?), that in a cold core low, the wind must increase with height.

I've managed to show why wind speed increases with height in a cold core low, as follows. Considering low is in the Southern Hemisphere, the wind blows clockwise around the low. In natural coordinates, the normal vector points outwards. Since the center is colder than the surroundings, we have
$$ \frac{\partial T}{\partial n}> 0 $$
from the thermal wind relationship,
$$\frac{\partial  V_g}{\partial ln p}\boldsymbol{\widehat{t}}= \frac{-R}{f}\boldsymbol{\widehat{k}} \times\nabla_p{T}=\frac{-R}{f}\boldsymbol{\widehat{k}} \times\frac{\partial T}{\partial n}\boldsymbol{\widehat{n}}=\frac{R}{f}\frac{\partial T}{\partial n}\boldsymbol{\widehat{t}} $$
Where $\boldsymbol{\widehat{t}}$,$\boldsymbol{\widehat{n}}$ and $ \boldsymbol{\widehat{k}}$ are the tangent, normal (in the horizontal plane) and vertical unit vectors.
Since $ f < 0$ and $ \frac{\partial T}{\partial n} > 0 $, we have $\frac{\partial  V_g}{\partial ln p} < 0$, which implies $\frac{\partial  V_g}{\partial z} > 0$, i.e., wind intensifies with height in a cold low.
I still have not understood why the low is displaced towards cold air with height. Since the wind intensifies with height, I would expect the low to be further ahead at higher levels than at the surface.


How to characterize flow of nonreactive tracer in a porous media? About Tracer Experiment
This experiment is conducted by injecting a fluid with nonreactive species of certain concentration inside a column or core composed of sand. The injection of fluid can either be in the form of a pulse or it can be continuous injection. This type of experiment can be useful to characterize the static and dynamic properties of a subsurface and can help us gain a better understanding of the geology and flow dynamics of the fluid.
Known Information
In this type of experiment we typically know the velocity of the tracer through the column, say $v$, the length of the column $L$, the injected concentration of the tracer $C_0$, a time series of the fluid concentration at the column outlet $C$ $\text{vs.}$ $t$, which acts as an output data from this experiment.
Questions

Which equations are typically used to characterize the flow of
nonreactive tracer in a porous media at laboratory scale?
How can we use the known information to estimate the fluid dispersion coefficient (a measure of fluid velocity variance)?

Governing Equation
The constitute equation for a nonreactive tracer test is governed by fluid flow due to advection (viscous flow) and fluid flow due to diffusion. The partial differential equation that governs this process is given as:
$$\frac{\partial C}{\partial t} + \nabla.\left(v  C - D\nabla{C} \right)=0$$
Where, $C$ is concentration of the tracer in space $(x,y,z)$ and time $t$; $v$ is the velocity of the injected tracer fluid, and $D$ is the dispersion coefficient.
1-Dimensional Example
Let's consider a following 1-dimensional core in which tracer is injected at left hand side face (point B) as a heavyside unit step function. The output tracer concentration profile is observed at right hand side face (point A):

The boundary conditions for this general scenario are given as follow:
$$\overline C_B=0, x>0, t=0$$
$$\overline C_B=1, x=0, t>=0$$
$$\overline C_B=0, x\rightarrow\infty, t>=0$$
Now, there exists an analytical solution for this 1-dimensional example that can give you tracer concentration at any place within the column, say $x$, at any time, say $t$. That is, we can estimate $C(x,t)$ using the following analytical solution:
$$\overline C_B=\frac{1}{2}\left[1-{erf}\left(\frac{x-vt}{2\sqrt{Dt}}\right)\right]$$
where, $v$ is the fluid velocity which is known and $D$ is the fluid dispersion coefficient which is unknown.
How to Estimate Dispersion Coefficient
One of the data that we obtain from tracer experiment is the tracer concentration with time at the column output (point A), which is also referred to as effluent concentration. Let's call this data as $C_{measured}$.
Similarly, using the above analytical function, we would estimate the tracer effluent concentration (at $x=L$) by guessing some value of dispersion coefficient $D$. However, since this $D$ is just a guess, so the estimated effluent concentration using the formula is not correct. The correct effluent concentration is the one we have measured i.e .$C_{measured}$. You would have guessed by now that we use the measured concentration in the analytical expression to estimate $D$, and the appropriate way of doing this is by devising an objective function and minimizing its square as follow:
$$f_{obj}=min\left[\sum (C_{measured}-C_{calculated})^2\right]$$
So you find $C_{calculated}$ using multiple guesses of $D$ and stop the iteration for that particular $D$ which gives you minimum $f_{obj}$


Huge netcdf files handling Can any one help me to handle huge netcdf files each of 1gb memory in loop and at least 2 files at a time in ncl or linux or python or matlab.

for example era_interim daily pressure level datasets.

For processing large data it is a good practice to call data into RAM in slices(Either by spliting time axis or spatial domain). In the interest of earth sciences python packages Xarray, iris, netCDF4 and h5py are few of the great tools for handling huge hierarchical data. For handling data in a labeled fashion Xarray and Iris will be useful while netCDf4 and h5py are good to process in a gridded way.

My personal suggestion is h5py which is meant for processing and archiving large datasets. Documentation here explains it. If you have netcdf files and want them in hdf5 format a question at Stack Overflow might help.


Can I average the two RMM values? The RMM values are sometimes quite different. Can I average the values of RMM1 and RMM2 and use it as an index for MJO?

CAN you? Sure, nobody on here is stopping you.
Is it meaningful? Not really.
The RMM indices are two separate metrics corresponding to the phase (interpretable using a phase space diagram)

(Example from CPC)
If you want a more meaningful way to interpret the MJO, you can try $$\sqrt{RMM_1^2+RMM_2^2}$$ which should be the strength of the MJO, or the angle between $RMM_1$ and $RMM_2$ (probably using something like atan2 in your preferred programming language.


Is wind just mainly nitrogen particles moving in one direction? The air is composed of mainly nitrogen.

Therefore, when you feel wind, is it mainly nitrogen particles hitting you that, on average, are moving in one direction?

In a nutshell, you're a little bit right.  The Air pressure is essentially Nitrogen and Oxygen molecules hitting our bodies, but that's true with and without wind.

wind is more easily explained from the macro-scale not the micro-scale.  It's not molecular behavior but governed by forces like high and low pressure systems and weather, or, fans if you're indoors.

The Brownian motion of molecules is pretty consistent like 3d billiard balls, though velocity of the molecules increases with temperature.  This is kind of what air molecules movement looks like:

Wind is, in a nutshell, the entire box moving, not individual particles changing direction, but it could probably be looked at either way.

If all the air molecules, by some strange coincidence, all moved in the same direction 2 things would happen.  One, the air would get very cold as temperature is essentially agitated molecules moving or vibrating against each other, and two, the wind speed would be over 1000 kph.  Roughly the speed of sound.   Fortunately this kind of thing is so statistically improbable it essentially never happens.


Numerical weather forecasting - resources for a programmer? There is a community wiki question over at A good book or source for climate science and meteorology basics? that talks about meteorology basics.

Building on that, but with a slightly different focus, are there "standard texts" for a computer programmer (with engineering background - I get maths, but don't know which math I need to apply) to help understand numerical weather forecasting? If that is too broad, I'm mainly interested in mesoscale and microscale applications.

I've tried building and running some of the forecast models (e.g. WRF) but I'm uncomfortable looking at numbers coming out without understanding at least some of the process.

The resources you want will vary on what level of understanding you are seeking.  For example, knowing the math means you can solve equations or transform them, but it doesn't mean you understand the physics involved.

Some topics you'll want an understanding of to understand the process:

Physics

At the heart of any weather model are our primitive equations.  Navier-stokes, thermodynamic energy, the state equation, and mass continuity.
Differential equations, linear algebra

The math for solving the above equations.
Discretization, numerical stability

How to turn the equations into something than be numerically solved on a 3D grid of points discrete in space and time.  This also involves choices in grid types, grid resolution, boundary conditions and time steps.  Any numeric noise must be accounted for and some artificial diffusion is sometimes used to accomplish this.
Sub-gridscale physics

A consequence of a grid means that processes smaller than about 4x your grid spacing and certainly those entirely contained within a grid volume are not resolvable by the physics in your equations.  These physics must be parameterized.  These process can include convection, radiation, turbulence, moisture, boundary layer processes and more.

Some books that may assist you include:

Numerical Methods for Fluid Dynamics (Durran, 2010) (finite difference methods, time stepping schemes, numerical methods)
Numerical Recipes (implementations of numerical methods)
Paramaterization schemes (Stenstrud 2009) (how to represent sub-gridscale physics in your model)
Modern Fortran Explained (Metcalf, Cohen and Reid, 2011) (in the world of models you will be seeing a lot of Fortran and FORTRAN).
A good text on MPI (not necessarily needed to understand the model, but if you are interested in how it runs across nodes you'll want to understand MPI).

The next step is digging into the source code.  From this perspective I suggest taking a look at CM1, which may be easier to follow than WRF from a programming perspective and will give you a foundation for how the math is applied in code to solve our equations and produce the output you see.


How does the precession of the Earth's apses affect climate? The gravitational influence of the gas giants (plus general-relativistic effects) are known to cause the apses of the Earth's orbit to precess. For an illustration of that process, see this image. Now, it's clear that apsidal precession combined with changes in orbital eccentricity will affect climate - at minimum, this changes the mean (year-averaged) Earth-Sun distance, which one would of course expect to have an effect on climate.

I'm not really following how apsidal precession alone is supposed to affect climate, though. Let us suppose that the Earth's "rotational parameters" (e.g. axial tilt) are held constant, and that the orbit of the Earth is static except for apsidal precession (i.e. no changes in eccentricity, no orbital decay, etc.).

In this case, the total insolation experienced by the Earth over the course of a year should be independent of how much the apses have precessed - indeed, an observer looking at the Sun-Earth system from above the ecliptic plane should not be able to distinguish between, say, a 5-degree precession of the apses and a 5-degree rotation of the observer in the opposite direction. Since the latter cannot affect the Earth's climate, we should neither expect the former to.

Clearly, I'm making some sort of mistake here, but I'm not sure where exactly my thinking has gone wrong. Where is my error?

During the 20th century, the global mean temperature in January was 12°C while it was 15.8°C in July. This is a bit paradoxical as insolation is currently about 7% higher during January than it is in July. So why is July warmer than January?

The solution to this apparent paradox and the answer your question (how does apsidal precession alone affect the climate) are one and the same: The uneven distribution of land and water between the northern and southern hemispheres. The northern hemisphere has about twice as much land as does the southern hemisphere. Continental climates exhibit much more seasonal variability than do maritime climates.

That worldwide insolation is greatest in January and least in July is a bit irrelevant. What is more relevant is the length of the seasons in the northern hemisphere. Right now, summer is longer than is winter in the northern hemisphere because perihelion is in early January. This situation will be reversed in ten thousand years when perihelion and northern hemisphere summer solstice coincide. Looking at precession only, glaciation is much more likely during periods where northern hemisphere summers are short and winters are long.


Does higher hardness means that A cannot scratch B regardless of any other variable? You have object A of hardness 4 and glass B of hardness 6.
Is this information alone enough to determine that, under any circumstances object A will never be able to scratch glass B?

For a more practical example, does this mean that it doesn't matter how hard you press, how fine the point of the object is, how long you keep scratching on B's surface, etc. a cat claw for example will never leave a scratch on a hardness 5 phone glass?
Or is it just like un-noticeable/negligible?

This doesn't seem to make sense on an atomic scale, since both A and B should be losing loose atoms from their interaction.

Welcome.

You're referring to the Mohs hardness scale, a qualitative scale to quickly determine, in the field, whether something scratches (carves a mark into) something else. It states nothing about the opposite direction. Of course, given enough pressure or kinetic energy the scraper can experience deformation as well, but that's not the meaning of the exercise.

One can pretty well scratch Gypsum with the finger nail and feldspar with a steel nail. You don't hammer things and do not scratch over and again or with more force than necessary. It's more like, for instance, cutting wood with a pocket knife. No molecules are counted and no microscopic traces investigated, it is just a superficial visual inspection for use in the field. Laboratory work comes later.

https://geology.com/minerals/mohs-hardness-scale.shtml

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

https://www.nps.gov/articles/mohs-hardness-scale.htm

Edit: To make some sciency disport out of this, here's a work that deals with the force of a large cat's claws and muscles against the bones of its prey.

Even though the claw, being made of keratin (same as horn, hoove, nail, ...), only has a Mohs hardness of 2.5, it can do considerable damage to a bone of hardness 5. That's because of the kinetic energy induced by the sweep of a paw and the chain of muscles at whose end it sits.

The field test based on Mohs hardness is not affected by the application of kinetic energy.


Why does Google maps (in terrain mode) space thier topo lines 80 feet apart? Is 80 feet some sort of standard?

Based on USGS (Department of the Interior – United States Geological Survey) toopgraphic maps, where on a 7.5 min Quadrangle map, the contour interval is commonly 40 feet.  Larger maps 15 min to 1'-2' maps the interval is commonly 80-100 feet.

All maps of the United States are commonly sourced from USGS based maps.  I am certain Google or Google's map provider is using USGS base maps.

Reference:
http://geology.isu.edu/geostac/Field_Exercise/topomaps/vert_scale.htm


Does the heat of reentry affect the reliability of radiometric dating of meteorites? This may be more of an age-dating question. When a meteorite travels through the Earth's atmosphere, I assume that it gets really hot.  Is the temperature of reentry hot enough to effect the radiometric dating process? Does heat influence the quality of radiometric dates, or does the rock have to completely melt to "reset to clock"?

I have found similar questions on Earth Science:

How can radiometric dating of meteorites determine the age of the earth? Wouldn't this only determine the age of the decaying nuclide in each rock?
Why is Earth's age given by dating meteorites rather than its own rocks?
How do we know the asteroids formed at the same time as earth?

But those don't quite answer the question I have.

Current consensus says heat does not affect the rate of radioactive decay and if it does it is due to time dilation, the effect of whihc is very small. Thus the heating of meteorites as they enter Earth's atmosphere will not affect their radiometric dating.


Effects of Centrifugal Force on Gravity Vectors? I've been asked this question twice now from our favourite science denying community, and I don't know how to parse it.  I can do centrifugal force and gravity given mass, but have never tried to even see if there should be any deflection of gravity due to centrifugal force at a given latitude.

I'm guessing I'm being sold a bridge with his numbers, but can't tell for sure.

Here's the numbers he's given me:

Gravitational force (m/s^2) =  9.80576
Latitude (degrees) = 45
Velocity (mph) = 735.64
Centrifugal force (m/s^2) = 0.0239809
Gravity    Direction Vector = (0.707107, 0.707107)
Centrifugal force Direction    Vector = (1, 0)
Combined Force = (-6.90974,-6.93372)
Combined Force    (relative to ground) = (0.016957,-9.7888)
Weight reduction (%)    compared to North pole = 0.172929
Projectile drop (time=4.51 seconds)
Deflection south (cm) = 17.2454
Drop height 100 m.

How on Earth do I go about double checking what he's telling me? I'll be attempting to share the answer on YT as a reference for handling this supposed "Gotcha!"

From the CF he provides, I'm estimating an object at the surface would have a 712 g mass (from CalcTools), and a 17 cm drift for a 100 m drop for that kind of mass seems like he's off by a factor of 10 (from examples at different lats).

https://www.youtube.com/channel/UCHZ2fjTguMMT0EDGSCcPoEw

I'm guessing I'm being sold a bridge with his numbers, but can't tell for sure.

You're being sold a bridge with his numbers. If he had done the math correctly he would have obtained a deflection of 33.58 cm at 45° geocentric latitude rather than 17.245 cm. The youtube comments show a number of errors. Two key errors are that the commenter assumes that

Local vertical points directly toward the center of the Earth.
Gravitational acceleration due to the Earth's mass points in the same direction.

What those youtube comments do show is that the Earth is not quite a sphere. A closer approximation is an oblate spheroid. That said, his comments fall into the wronger than wrong category. Quoting Isaac Asimov,

  When people thought the Earth was flat, they were wrong. When people thought the Earth was spherical, they were wrong. But if you think that thinking the Earth is spherical is just as wrong as thinking the Earth is flat, then your view is wronger than both of them put together.

Note that I qualified latitude in the above as geocentric. Geodesists have multiple concepts of latitude. Geocentric latitude is the angle between a line to the center of the Earth and the Earth's equatorial plane. Geodetic latitude is the angle between the normal to the reference ellipsoid and the Earth's equatorial plane. Yet another concept is astronomical latitude, which is the angle between true vertical and the Earth's equatorial plane.

The difference between geocentric and geodetic latitude is at its greatest at 45°. A geocentric latitude of 45° is equivalent to a geodetic latitude of 45° 11' 32.7". Converting that 11' 32.7" difference to radians and multiplying by 100 meters results in 33.58 cm. The difference between geodetic and astronomical latitude is called the deflection of the vertical (or vertical deflection). The deflection of the vertical is rather small, less than 2' (two minutes of arc) even in extremely mountainous terrain. Typical values are a few tens of arc seconds.

What this means is that an oblate spheroid is a better model of the Earth's shape than a sphere. That does not mean a flat Earth model is correct. The Earth's flattening (how squished the Earth is at the poles versus the at the equator) is rather small. The poles are 22 km closer to the center of the Earth than is the equator. Percentage-wise, that's a 0.345% difference.

The reason an oblate spheroid is a better model of the Earth's shape than a sphere is because the Earth is spinning. That spin does two things: It results in a centrifugal acceleration from the perspective of an observer fixed with respect to the rotating Earth, and it results in an equatorial bulge. If the Earth was a uniform density liquid, the spin would make the Earth naturally relax into an oblate spheroidal shape. "Straight down", the combined effects of gravitational and centrifugal acceleration (geodesists call this "gravity" to distinguish it from gravitation) would be exactly normal to the surface.


What are secondary resources? The Indian Resource Panel shall prepare a strategic roadmap for utilisation of secondary resources for meeting the developmental needs. India is the first country to constitute a National Resource Panel.

An extract from a book am reading on Environment whose author is not internationally known but I’ll still mention his name, Shankar.
The author has it mentioned as a Do You Know.

I ran a google search but couldn’t find any explanation to it.

lets say a water company do deliver water to a city but as the city expands the water source are no longer able to keep up with the demand so the water company have to drill a new well,This is now an alternative source for water the company will still use the primary source for water but will need to use the secondary source in periods of high water demand.

The same is true for building materials if the primary supplier are not able to deliver what you need,You have to get it from an alternative source.

And as i mention in my comment,my primary supplier of electric power is hydro power,So this is the primary source of power for me and if i use more power than they can produce the rest must be supplied from an alternative source,Here this will be wind power or import from other sources.

In denmark the primary source for electric power is wind and the secondary sources is hydro power from norway or coal power from the continental europe.

the comment from fred is an answer to this question too


Given the well known effects of the inverse turbulence cascade for 2D flow, does it make sense to use grid resolutions that resolve turbulence? As is well known, 2D simulations of turbulent flows in the ocean follow an inverse energy cascade, as opposed to a forward energy cascade observed in fully 3D flows. Because in 2D fluid filamentation is enhanced leading to strong density gradients that eventually become grid scale (where most of the mixing is owed to numerical mixing), the dissipation is underpredicted while mixing is overpredicted. As such, is there any value to running a 2D simulation with resolutions that attempt to resolve turbulence?

Any numerical model solution is inherently constrained by the equations being solved. You are probably aware that the inverse turbulence energy cascade exists in predominantly 2D flows. In oceans and atmospheres, this happens at approximate scale of Rossby radius of deformation and larger. Whether or not a numerical model is able to represent a physical process (i.e. 3D turbulence) really depends on the terms in the model equations.

Take for example the simplest 2D model representative of ocean and atmosphere, shallow water equations (SWE, writing non-conservative form for brevity here so don't give me a hard time):

$$
\dfrac{\partial \mathbf{v}}{\partial t} =
-\mathbf{v}\cdot\nabla\mathbf{v} - f\mathbf{k}\times\mathbf{v}
-g\nabla h
$$

$$
\dfrac{\partial h}{\partial t} = -\nabla(h\mathbf{v})
$$

where $\mathbf{v}$ is the 2D velocity, $f$ is Coriolis frequency, $g$ is gravitational acceleration and $h$ is the fluid depth.

The linearized form of the SWE, i.e. $\mathbf{v}\cdot\nabla\mathbf{v}\approx0$ and $\nabla(h\mathbf{v})\approx H\nabla\cdot\mathbf{v}$, where $H$ is the mean fluid depth, has an analytical solution and is well known.

The non-linear term $\mathbf{v}\cdot\nabla\mathbf{v}$ allows for the fast growth of small perturbations, eventually resulting in eddy formation. In this model, the only dissipation is of numerical kind, and the only turbulence is of the 2D kind, supporting inverse energy cascade. In order to allow for 3D turbulence, a prognostic equation for vertical velocity $w$, including non-linear terms $\mathbf{v}\cdot\nabla w$ must be introduced to the model.

  if we know that it is a true 3D flow, is there any point in using highly resolved 2D simulations that attempt to resolve the scales that are typically involved in turbulence?

If by this you mean, can I model 3D turbulence with a very-high resolution 2D model, the answer is no. 2D models are obtained by making an assumption that variations in the 3rd dimension are negligible compared to variations in the other 2 dimensions. It is this assumption that prohibits any 3D process to be part of the model solution. Sure, one can crank up horizontal resolution as much as they like, and the model will produce a solution, however that solution will always be inherently constrained by the initial assumptions made.


Why is there no middle ground between tornadoes and hurricanes? A tornado has an effective area of destruction about the size of a city block.

A hurricane spans several hundred kilometers.

However, there doesn't seem to be a continuum between the two.  Why are there no vortex windstorms on the scale of a city?  Is it because tornadoes and hurricanes have different formation mechanisms?  Or is there a reason why city-sized vortices would be so weak as to be un-newsworthy?

Tornadoes are the result of small-scale effects such as the convergence of updraft/downdraft regions in a single thunderstorm, the stretching or entrainment of vertical vorticity, wind shear profiles, and even friction with the ground.

Hurricanes rely on massive amounts of latent heat release from an atmosphere moistened by warm ocean waters causing rising air and lower pressure over a wide area.  This allows the Coriolis effect to act, sculpting airflow into a spiral pattern.  Under normal conditions, the Coriolis effect is only applicable over a large area (don't get me started on the toilet myth).

There are some intermediate types of circulations.  A mesocyclone is roughly city-sized (and these are often associated with tornadoes).  A mesoscale convective vortex can form out of a thunderstorm complex and are roughly state-sized (usually more of an Indiana than a Texas).  There have been very small hurricanes and typhoons (look up Tropical Storm Marco or Typhoon Tracy).

Extending the scale upward, the normal "synoptic" low pressure systems associated with cold and warm fronts and usually bigger than hurricanes, and upper-level circulations can be continent-sized.


What is the global warming potential (GWP) of any gas over a 1 day time frame? Since in 100 years, the global warming potential (GWP) of methane is 28-36, what will be the GWP in 1 day time frame?
Can it be calculated that way?

It can, but it's not very helpful. A large number of gasses (methane being one) decompose relatively quickly in the atmosphere to form other compounds. A longer time horizon means you capture all of that change in the metric (as compared to CO2), while if you did it for a day you'd end up with a figure that only really made sense for that day. The details of how it's calculated and why the time horizons are where they are is in the IPCC AR5 WG1 CH8 technical supplement (8.SM.11.1 Equations for the Global Warming Potential)


Relationship between illuminance and cloud cover Is there a clear formula or table relating the illuminance in (lux) to status of the sky in terms of cloud cover? For example, mostly cloudy would be 2000-3000 lux.

I don't believe such a formula or table exists (but admittedly, I have not attempted a lit review in this subject).  Sky coverage (cloudy, mostly cloudy, etc) is a the fraction of the sky covered by clouds, not how much light penetrates to the surface.  Even with a mostly cloudy day, all it takes is one break in the clouds between the sun and your instrument to give the same illuminance as a clear sky day.  You might take a time series of illuminance obs and consider the fraction of time with clear sky readings, but this will be faulty unless you can take into account cloud motion.
From the AMS Glossary:

cloud cover
(Also called cloudiness, cloudage.) That portion of the sky cover that is attributed to clouds, usually measured in tenths or eighths of sky covered.

The term "partly cloudy", for example, varies in interpretation but is generally around 0.3 or 0.4 to 0.6 or 0.7 cloud cover (where 0.0 is clear sky and 1.0 is overcast).
The type of cloud will also vary the light transmitted.  A high cirrus or altocirrus cloud layer will transmit light to the surface, whereas a low stratocumulus overcast will only transmit a small fraction of light (note how grey and dreary a northern winter day can be under those clouds).  The fraction of light transmitted will depend on the depth of the cloud layer. The light transmitted will also be a function of time of day and day of the year, both of which determine the position of the sun.
For a look into how these issues play out in a real experiment, take a look at Pfister et. al. (2003) who look at how cloud fraction and irradiance are related over New Zealand.  I think you'll find most of the literature deals with solar irradiance, so it may help you in searches to look for that term rather than illuminance.
Note that the linked Ametsoc article is free to read, as area all Ametsoc articles at least 2 years old.
References
G. Pfister, R. L. McKenzie, J. B. Liley, A. Thomas, B. W. Forgan, and C. N. Long, 2003: Cloud coverage based on all-sky imaging and its impact on surface solar irradiance. J. Appl. Meteor., 42, 1421-1434. doi: http://dx.doi.org/10.1175/1520-0450(2003)042<1421:CCBOAI>2.0.CO;2


Old moon in the new moon's arm I understand the phenomenon I want to explain is something known as Earth Shine. What is Earthshine and what causes Earthshine? Is it really normal? What exactly is the less illuminated part in the diagram?

Yes, earthshine is completely normal. It is simply illumination of that part of the moon that is facing away from the sun. This illumination is sunlight that is reflected towards the moon by the Earth. Strictly speaking, it is that reflected light from the Earth that is itself reflected back to Earth so that we can see it. The intensity of Earthshine is highly variable. If the moon was almost in line between Earth and sun then an observer on the dark side of the moon would see the the whole of Earth's disk brighly illuminated by the sun, and hence the earthshine would be about at its maximum. Conversely, when the Earth is nearly between Moon and Sun, an observer on the moon would only see a crescent Earth (apart from man-made city lights), so the Earthshine would be at a minimum.


Is this particular multiple rainbow unexplained by science? The gist of the BBC News article 'Incredibly rare rainbow' photographed in Highlands is that while it has several familiar features, there are aspects that are still unexplained.
Question: Are there really aspects of this particular multiple rainbow that are currently unexplained by science?
update: there is now a tweet about it

The rainbow was photographed at Loch Lochy in the Highlands, SAXAPHONEJAN/BBC WEATHER WATCHERS
Unusually, the colours of the third rainbow are in the same order as the main one it was attached to.
BBC Weather presenter Simon King said: "This has scratched a few heads as this is something incredibly rare."
The meteorologist said the rainbow had the characteristics of both of what are known as a twinned rainbow and supernumerary rainbow.
Supernumerary bows are formed by small, similar-sized raindrops which then create ripple-like rainbows.

There's nothing inexplicable about that photo.  It's got a few uncommon features, but nothing unknown.  In the image below, I've drastically distorted the brightness curve to make things more obvious:

Primary arc.  This is the classic "internal reflection" rainbow that you learn about in school.
Secondary arc.  This one forms when light is reflected twice within a raindrop, broadening the bow and reversing the order of the colors.
Supernumerary arcs.  These are formed by the wave nature of light: light, even of a single color, spreads out as it passes through a raindrop.  The arcs are interference patterns formed by the spread-out light from many small raindrops, and because of this spreading, they're usually pastel colors rather than the single-frequency colors of the main arcs.  The less variation there is in raindrop size, the sharper the arcs are; these are especially sharp.
Supernumerary arcs on the secondary bow.  These are rarely seen, because they're even more sensitive to variations in raindrop size than the primary arc's supernumeraries.
Possible fifth-order bow.  This faint green patch is in the right place to be the green stripe from light reflecting five times as it passes through a raindrop.  Fifth-order bows are almost never seen because of how faint they are, and are photographed even less often, so this may just be an image artifact.
Primary glow.  Only the light passing through the edges of a raindrop forms the rainbow.  Most of the light passing through the middle just goes straight through to form the zero-order glow (not pictured), but some reflects back to form a glow in the middle of the rainbow.
Alexander's dark band.  The light making up the rainbows has to come from somewhere, and this band is where it comes from.
Reflected rainbow.  This isn't a reflection of the primary arc (rainbows aren't real objects, so they don't have reflections), it's the rainbow you'd see if your position had been reflected across the plane of the water.

All of these have been known to science for quite some time.  The primary arc was the first one to be explained, by Persian astronomers in the 1200s.  Supernumerary arcs were the last one to be explained, by Thomas Young in 1803.

The "third rainbow" the BBC is talking about is probably the first few supernumerary arcs of the primary arc.  Supernumerary arcs have the same color ordering as the arc they're attached to, but because the brightness and width of the arcs varies, and because they're usually pastel colors rather than spectral colors, it can give the appearance of a reversed spectrum.

The "third rainbow" isn't a twinned rainbow, because the second arc of a twinned rainbow (caused by two rainstorms at different distances with different raindrop characteristics) wouldn't be concentric with the first arc.


Confusion on the Nepal earthquake expert statements Nepal hit by second huge earthquake and more are still to come

Equally big earthquake coming in eastern region of Nepal

Nepal quake followed historic pattern

The experts on mentioned on the first and second link says that the big earthquake is coming on the eastern side of Nepal whereas the expert on third link says the big earthquake is coming on the western and southern Nepal.

First of all, I don't understand why experts are predicting a big earthquake in the eastern region once again as the fault there has already ruptured.
According to the expert mentioned in new scientist,the fault zones can be seen like a 3D zipper. If it is so, the one side of the zipper has opened up(in this case eastern side), then it is western and southern ones that remains to be opened up. (1)So then should not it be affecting western and southern sides?

(2)Similarly, if another earthquake does occur, will that earthquake have the same epicenter as that of the previous one? (3)Also will it affect the region where the fault lines running through it have previoulsy been ruptured?

I am confused as well. I asked a question at reddit and a kind guy attempted to answer (it was before the 7.3 "aftershock").

This 2012 study investigated the coupling in the area. You can see that coupling is complete at shallow depths throughout the whole zone. You can also see that coupling tends to decrease at depths towards the eastern termination of the rupture zone of the mainshock, and that coupling was increased in the area of maximum rupture during the mainshock (near Kathmandu). Further towards Bhutan coupling increases but variations are smaller than in subduction zones.

This paper investigates ancient earthquake scarps in Bhutan and tells us what a truly big earthquake looks like in the Himalayan region.

If you see the USGS page, aftershock locations are seen to expand outside the rupture area. There are 2 strong aftershocks of particular interest, both around 6.7 magnitude: one at the north-east corner and one at the north-west corner. The fact that they are towards the north is worrying since this is where coupling changes rapidly from nearly 0% to nearly 100%. As Bilham said, during really strong earthquakes even the deeper uncoupled patches slip and add to magnitude. The western aftershock was in an area of minimal slip during the initial earthquake and this surprised me despite the fact that towards the west there were less strong earthquakes in the recent past (so it theory there was room for a strong one), while towards the east there was the 1934 earthquake (which however was not that huge, and additionally in the 80 years since then a couple meters of convergence have taken place, a significant amount of energy).

If you see the 1st link (figure 7) the most suspicious area is a narrow zone near the location of the 7.3 "aftershock" (and near the eastern aftershock as well). However the second most suspicious zone is in western Nepal. So, there are arguments for both sides, the one claiming that towards the west there is room for a large earthquake, and the side claiming that towards the east there is a large possibility for a perhaps less severe earthquake. The eastwards rupture (that compressed waves and perhaps stimulated more fault patches than in the opposite direction) and the uneven distribution of aftershocks favored the eastern side from the very beginning.

The history of Himalayan earthquakes reminds us that 10% of strong earthquakes were preceded by foreshocks or were stronger-than-usual aftershocks (like in this case). However, to my knowledge, the stronger foreshock even recorded was 8.1 (or was it 8.6) in the case of the most powerful earthquake ever recorded. A Mw 7.8 being a foreshock of something stronger would be very unusual, yet from the first day experts were warning for potential giant shocks near Bangladesh. This was in my opinion not correct. Sure the lack of a truly large earthquake in the whole region is unresting, but why now specifically and why there?

Unfortunately I cannot add more links due to being new here. I hope that, even if not helpful, at least I assured you that you are not the only one in confusion.


Rain Water vs Sprinkler Irrigation During the rainy season, the crops like corn, cotton are found to be growing faster. Studies shows that the thermoelectric fixation of gaseous Nitrogen during rain storm accelerates the plants growth in rainy season.

Can this effect be seen in Sprinkler irrigation ?
Is it possible to mimic this effect in other irrigation methods?

I think what you mean by thermo-electric nitrogen fixation is the nitric oxides created by lightning discharges. This is absorbed by the raindrops as they form and as they fall to earth, and helps to fertilise the soil. You won't get this effect with sprinkler irrigation to any great extent, because the water droplets are exposed to the nitrogen oxides for far less time. In addition, sprinkler use is not usually accompanied by lighting flashes, whereas rain sometimes is.

If your crops are watered mainly by sprinklers and you would like them to have more nitrogen, you should practice rotation of crops. Some years you plant legumes, which fix nitrogen by means of the nitrogen-fixing bacteria which live in the nodules in their roots. In the tropics, a kind of acacia called mimosa, though not related to legumes, has the same nitrogen-fixing capability. This acacia is sometimes called 'the sensitive plant', as when touched its leaves rapidly fold themselves away.


Does climate change cause increase in CO2? My main question is how do we know that increase in global temperature does not CAUSE an increase in CO2 concentration?

I am trying to develop my mental model of what's going on for the climate change issue.  There is definitely a correlation between global temperature and CO2 concentration, this is not disputed.  The general consensus is that CO2 increase causes temperature increase, why is the reverse situation not studied (if it is I could not find any studies).

This thought comes from the statement I've seen that water vapor concentration is more correlated to global temperature  than CO2, but this is intuitive since warmer air holds more water vapor than colder air.  Does the same intuition hold for CO2?

I am not an expert on the subject; so I understand that I may be way off base with my reasoning.  I also openly accept  edits to my question if it is not structured or presented properly.

One reason is that we know exactly where the current increased CO2 comes from.  That is, we know from economic data how much petroleum, natural gas, & coal is extracted and burned.  From that simple chemistry lets us compute the amount of CO2 produced, and we find that (after allowing for factors such as e.g. some being absorbed by the oceans) that the amount created by burning fossil fuels matches the observed increase.

(There are also more subtle measurements, such as isotope ratios, which I'm not qualified to expound in any detail...)

Another reason is that for warming to have caused the observed increase in CO2, there'd have to be some other cause for the warming.  No such cause has been found.  Suggested causes such as variation in solar output have been ruled out by measurements.


Where to start searching to find more radioactive minerals? I'm pretty new to all this...

I've recently purchased a Geiger counter, and am hoping to locate rocks like pitchblende and other radioactive minerals for my collection.

I'm based in the North West of England in Manchester and looking for any hot spots nearby for which to go to and search!

Are there maps available, or any hints as to what types of locations I should be seeking to start my search?

You can try using the locality list at MinDat. Go to places that are easily accessible to you and see what minerals have been reported there. If there's something radioactive, it will probably be listed there.

I would remind you that radioactive minerals are, well, radioactive. These things are dangerous. I strongly recommend you find a different hobby. I deal with radioactive minerals as part of my job, and this is not something that you want to do unless you really know what you're doing. I remind you that a lot of the early researchers who worked on radioactivity died because they did not use the necessary precautions.


How to calculate specific humidity with relative humidity, temperature, and pressure I know there is this question already How do I convert Relative Humidity into specific humidity

but I don't have ρws = density of water vapor (kg/m3) and ρ = density of the moist or humid air (kg/m3).

Is there another way to calculate it? Also I have air pressure but it's in the range of 95000-96000.

I have used the rh2qair function from the PEcAn data.atmosphere R package but I get values such as 1.5463 converts relative humidity to specific humidity

    @title RH to SH
    @param rh relative humidity (proportion, not %)
    @param T absolute temperature (Kelvin)
    @export
    @author Mike Dietze @aliases rh2rv
    rh2qair <- function(rh, T) {
        qair <- rh * 2.541e6 * exp(-5415.0 / T) * 18/29
        return(qair)
    }

It looks like your program is using an approximation based on
$q \approx w = w_s*RH$ with an approximation of Clausius-Clapeyron to find $w_s$.  Looking at a few values of RH,T and P, your approximation is pretty close (+/- 5%) to an analytic answer.  Based on the output you quoted it looks like you are providing incorrect values of RH.  Note in the comments to your routine it says:

@param rh relative humidity (proportion, not %)

This means you need to provide the RH proportion, not the percentage.  E.g. divide by 100 -- RH=1 for 100%, RH=0.5 for 50%, etc.

If you adjust your input data you should be able to use your code as-is.  If you wish to compare it to something, you can reference the solution below.

If you are given $RH$ (in the range [0,1]), $T$ (K) and $p$ (Pa) you can proceed as follows.

Knowing that $$RH = \dfrac{e}{e_s},$$ $$w = \dfrac{e\ R_d}{R_v(p-e)},$$ and $$q = \dfrac{w}{w+1}$$

Then we can solve for specific humidity $q$.

Rather than combining this into a single formula and solving, it is more straightforward to present this incrementally.

First, find $e_s(T)$ where $$e_s(T) = e_{s0}\exp\left[\left(\dfrac{L_v(T)}{R_v}\right)\left(\dfrac{1}{T_0}-\dfrac{1}{T}\right)\right]$$ and then find $e$ from the first formula ($e = RH*e_s$).  Then plug $e$ into the formula for $w$ and then that result into the formula for $q$.

Variables used:

$q$ specific humidity or the mass mixing ratio of water vapor to total air (dimensionless)
$w$ mass mixing ratio of water vapor to dry air (dimensionless)
$e_s(T)$ saturation vapor pressure (Pa)
$e_{s0}$ saturation vapor pressure at $T_0$ (Pa)
$R_d$ specific gas constant for dry air (J kg$^{-1}$ K$^{-1}$)
$R_v$ specific gas constant for water vapor (J kg$^{-1}$ K$^{-1}$)
$p$ pressure (Pa)
$L_v(T)$ specific enthalpy of vaporization (J kg$^{-1}$)
$T$ temperature (K)
$T_0$ reference temperature (typically 273.16 K) (K)


How much did the worst volcanic eruption in human history affect global temperature? According to this,

2018’s Biggest Volcanic Eruption of Sulfur Dioxide

  In extreme cases, like the 1991 eruption of Mount Pinatubo in the
  Philippines, these tiny aerosol particles can scatter so much sunlight
  that they cool the Earth’s surface below.   Mount Pinatubo’s violent
  eruption injected about 15 million tons of sulfur dioxide into the
  stratosphere. The resulting sulfuric acid aerosols remained in the
  stratosphere for about two years, and cooled the Earth’s surface by a
  range of 1 to 2 degrees Fahrenheit.

But according to this, Worst volcanic eruptions in human history

  the worst volcanic eruption in human history injected 400 million tons
  of gas

(26,6 times more than Pinatubo's eruption) though I guess the composition of the gas could be different, and

  the Earth began to cool and 1816 became known as "The Year Without
  Summer" because of the low temperatures, which killed crops and led to
  mass starvation.

Is it know what global temperature Earth had this year and how much in degrees celsius or fahrenheit temperature changed?

The largest volcanic eruption in human history was the Toba eruption on Sumatra about 75,000 years ago. There is still a huge lake, Lake Toba, in the crater. It dwarfed Thera, Krakatoa and Tambora. The Tambora  eruption on the Indonesian island of Sumbawa occurred in 1815, and was the largest eruption in historical times, also dwarfing the other two. It caused bad weather and lower temperatures around the world, including Europe, for about a year. The much larger Toba eruption must have had even more drastic short term effects lasting for years, but strangely enough doesn't seem to have had any major effects on the human population of South East Asia. It may have emitted enough CO2 to have made a minute difference to the ppm figure had there been anyone around able to measure it.


Above average global temperature in March 2016 The question arose when I heard from friends across many countries that March has never been so hot. I myself felt the same in my city (Bangalore, India). Then I tried searching on internet, and I found a link on NASA, which says March 2016 was indeed hot.

I was wondering if experts can explain this rise in temperature? Is it due to higher $\ce{CO_2}$ levels due to human activity, or is it natural? Is it the start of unnatural global warming?

What happens in one city in one month is only a very very small part of the picture. You can make very little inference on global warming based on the weather in one city in one month.

You can make a little more inference on global warming based on the weather around the world in one month.

And we can say a lot about global warming based on the world's weather over a 30-year period.

A lot of heat got released from the ocean last year in the El Niño event: heat that had been accumulating in the oceans for a few years. That heat is now getting distributed around the world, which is why we're seeing rises in global surface temperatures - a similar thing happened back in 1997/8. The Earth has been accumulating a lot of heat for years, and it's now showing up as rises in surface temperatures.

The accumulation of heat is happening because the Earth has been absorbing more energy than it has been radiating away into space. That has happened because of human emissions of greenhouse gases, in particular, but not exclusively, carbon dioxide and methane.

Unnatural global warming started decades ago. Now, it's accelerating.


Is there an atmospheric hydrogen cycle? There are various physical, chemical and biological processes that free up hydrogen from molecules (often hydrocarbons or water).

Once in the atmosphere, the hydrogen is lost to space (the Earth's gravity is too weak to hold onto it). So the Earth is losing hydrogen to space (perhaps at a very slow rate).

Is there any interaction between the Earth's atmosphere and high velocity protons in the solar wind (e.g. protons combining with atmospheric oxygen to form hydroxide) which is capable of balancing the hydrogen loss? How big is the hydrogen loss? Is the amount of hydrogen on Earth in equilibrium?

"Is there any interaction between the Earth's atmosphere and high velocity protons in the solar wind (e.g. protons combining with atmospheric oxygen to form hydroxide) which is capable of balancing the hydrogen loss?" I found Hydrogen ions in the solar wind react with oxygen in interplanetary dust grains to form little packets of water, potentially supplying Earth with its water, but they don't know how much.

"How big is the hydrogen loss?" 3 kilograms per second.

"Is the amount of hydrogen on Earth in equilibrium?" We are also gaining 50,000 tons of matter per year from space dust, but only a small part of that is hydrogen.


Can I just walk around Greenland with a UV light and find rare Earth minerals on the ground? The NPR.org news article and podcast Greenland Is Not For Sale. But It Has The Rare Earth Minerals America Wants is interesting, and it includes a few large GIFs (too large to post here) that appear to show a UV light being waved over some rocks (not really in the dark) and bright red spots lighting up indicating the presence of some mineral containing a rare Earth element.

Compounds containing rare Earth's including oxides have strong transitions in the visible and infrared and some will fluoresce with visible light. When you read what I type over the internet the signal has probably been amplified dozens of times by erbium-doped silica fiber optic amplifiers at the bottom of the ocean (and everywhere else) and those are likely pumped by Nd:YAG lasers (neodymium-doped yttrium aluminum garnet).

But are UV lights really able to so easily find rare Earth-containing rocks on the ground in Iceland, or are these GIFs slightly gratuitous?

Question: Can I just walk around Greenland with a UV light and find rare Earth minerals on the ground?

I think the answer to your question have to be no.

Lots of minerals are fluorescent in UV light,You can take a look here https://geology.com/articles/fluorescent-minerals/

So as you can see in the linked summary of fluorescent minerals it can be hard to tell what you have found unless you know what to look for.

A better way to find Rare Earth Elements might be to use a Geigercounter,Many of the Rare Earth Elements can be found toghether with radioactive minerals.

Here is an example from Norway https://reeminerals.no/fens-field this is an area not far from where i live.

As you can see in the linked article this area can be seen using detectors from an airplane,Maybe not to tell the composition but it can give a hint about where to look.


What would happen if you hypothetically happened to touch an aurora I think that if you touch an aurora it will give you radiation damage? But then the solar winds at -90C would freeze you, so speaking metaphorically what would happen?

Auroras typically happen pretty high. About a century ago, Norwegian scientist triangulated more than 12,000 auroras, and this is the distribution they found:

Figure 1 from Störmer, 1946.

So the fist problem will be to "touch" anything at an elevation of 100 km, where the atmospheric pressure is 0.00006% of the sea level pressure and 0.0002% of the pressure at the top of Mount Everest (pressures estimated using CalcTool).

So let's imagine you use very thin space suit that stop your body from blowing up, and keep you alive.

Even in that case, the air is so thin that its heat capacity and conductivity would be extremely low. Therefore, no matter if the air is at -100°C or +300°C, you wouldn't feel it, and the temperature of your fingers would be dominated by the heat loss through radiation (i.e. your hot fingers would radiate infrared radiation and become very cold pretty soon).

Visually they are diffuse objects, so it will be as disappointing as "touching" a cloud. Where you never really feel you ever get to the "edge" of the cloud and touch it. You just feel that you become shrouded in an increasingly thick fog. That's is at least my experience climbing mountains that from below look like they have their top covered in thick clouds. On airplanes the experience is quite similar. So I think you will just not realize you are at the edge of an aurora and you will just see a subtle glow in the air.

Another important effect would be the radiation. You would get a big dose. I mention a bit of this in my answer to this question, however the formula there is not valid at 100 km. Because radiation increase exponentially the first 10-15 km as you go up, and then flattens (Stozhkov et al, 2001). Under normal conditions, at 100 km you would be receiving approximately 500 times more radiation than in the surface (ref1,ref2), which is pretty much the same dose of outer space. That is not a big deal if you don't stay there very long. But auroras don't happen under normal conditions. However, radiation at surface levels during auroras go up but not by a large amount, so I don't think radiation will kill you.

So, if you get up there with a space suit that keep you alive, I think your quest to touch the aurora will be rather disappointing. However, the view from up there would be amazing.

You might want to see this video of a weather balloon sent up under an aurora. With cameras and radiation sensors. It is pretty cool, but it only got about a fifth of the way towards the aurora. And you can't get much higher with balloons, the world record (unmanned) is 53 km, which is just half way there. These are a couple screenshot from that video:


What method do I use to derive the organic material content (as a percentage) per layer in SoilGrids I am doing soil related calculations for moisture content and the soil characteristics I need (among others) is the content of the soil as a percentage for:

sand
clay
organic matter

I am thinking I take the the sand content (in g) divide by 1000 to get sand percentage content and like wise for clay (except use the clay content value in g). For organic matter do I take the soil organic content they provide in dc/kg and divide by 10000? It seems some areas will have a very high organic material content then. I would expect somewhere between 1% and 6% but some areas if I use that method would be like 44%.

All weight percentages are calculated using the same formula:
Mass Fraction/Total Sample Mass
There are two different values for organic material in a soil and they're derived by different techniques:
If you want to know how much bioavailable organic material is in the soil I was taught to use a chemical reagent to oxidise and strip organic carbon from the soil, saturated soil samples are weighed before and after the test to estimate the weight of organic matter so removed or a titration can be performed on the soil leachate to determine the exact amount of carbon oxidised.
If you want the total soil carbon weigh a dried sample then crush it and put it in a crucible over a Bunsen Burner until it stops smoking, the sample also darkens as it starts to burn and then turns pale once all the carbon has been burned out of it, and reweigh it the difference is all the soil carbon.


What is the reasoning behind the statement "Faulting will occur along the plane where the shear stress is the highest"? In "An Introduction to Seismology, Earthquakes and Earth Structure", authors Seth Stein and Michael Wysession made the statement: "Faulting will occur along the plane where the shear stress is the highest". However, no further clarification was given. What are the implications of this statement? Is the statement true? What are the processes that cause faulting to occur along the plane of maximum shear stress?

This statement is referring to depths within the crust where the lithostatic pressure is sufficiently high to suppress the formation of dilatant fractures. Rock is a brittle material, and if loaded to failure while under little or no confining pressure, it may fail by the growth of mode-I fractures oriented normal to the least compressive stress. At depth in the crust, the overburden weight of rock may cause sufficient pressure to suppress the growth of mode-I fractures, but if the stress is sufficient to cause mode-II fractures, these tend to grow in the plane of maximum shear stress.


Is it theoretically possible to artificially create amber? It is said of amber that it requires thousands of years of time and much pressure to produce amber from tree resin.

This was also said of diamond as well, but we now produce artificial diamonds by the ton.

So the question is, could we not make artificial amber, or is this somehow not possible?

Yes, and this has been done since at least the mid 19th century (Răducanu, 2006) initially it was done to keep up with the demand, but now is a source of scrutiny for valuation of samples (Pederson and Williams, 2011; Răducanu, 2006).

Imitations have been produced by heating the following (Răducanu, 2006):

Polymers, such as polyester and polystyrene
Casein
Glass
Celluloid
Other resins, such as phenolic resin
Copal - this is referred to as 'pre-amber tree resin', a natural intermediary substance between tree resin and amber.

Both Răducanu, 2006 and Pederson and Williams list several techniques as to how to tell them apart from authentic amber.  Pederson and Williams, 2011, also detail that some artificial samples are so close to amber that spectroscopy techniques are required to tell them apart.

References

Pederson and Williams, 2011, Copal vs. amber, Organics

Răducanu, 2006, Actual Exigencies Concerning the Quality of Amber
Pieces Commercialized in Romania, Universităţii Petrol – Gaze din Ploieşti


Where can I download recent precipitation data for Cape Town I need data on monthly precipitation for Cape Town between 1970 and 2018. I found this page: http://cip.csag.uct.ac.za/webclient2/datasets/
But it only seems to offer information until 2000.

It's the same with this: http://worldclim.org

Then there is this one: https://gis.ncdc.noaa.gov/maps/ncei/cdo/alltimes?layers=0
But the data here is very fragmentary. Also the site is currently not working because of the US partial shutdown...

Can anyone give me a good hint of where I should look for good data?

It really depends on what you're looking for and what data formats you want to use. If you're looking for single location direct readings from rain gauges, you might have much better luck contacting the South Africa Weather Service (though this might not be free and is typically not 'Open' in the strictest sense of the word).

Some alternatives to that really depend on what you want (gauges, vs. radar estimates vs. homogenized estimates vs. composite products), the granularity (monthly, daily, hourly; observations or normalized climatologies), the spatial resolution (point locations, grids), and the format (Spreadsheets, GRIB, CF-compliant NetCDF, etc.). It's worth also noting that radar detection of precipitation didn't really become an employed standard until the 1980's (ref.)

For a few options that are open, I would suggest looking over what's available through the NSF's National Center for Atmospheric Research . The CMAP: CPC Merged Analysis of Precipitation or the
GPCP (Monthly): Global Precipitation Climatology Project might work for you.


Strange craters in Afghanistan In this image from 2004 in Afghanistan Kandahar region many small craters are seen. What are they?

These are qanats, a type of antique drainage system common in arid climate regions of the Middle East, particularly in Iran (as mentioned by @Spencer @Winwaed). Some of those are still in use for storage because of lower underground temperature or to access the underground water.

In the picture posted by OP, it further make sense since the underground channels follow linear paths near, around and crossing the small stream, thus providing a remote access to water.

Here is an oblique picture showing the qanats of Bam in Iran (Higher resolution available at the source here).


Can we really travel through earth's core? Inspired by the movie, "The Core".

Can we really travel through earth's core? I will provide 2 sub questions:

Is there any substance that can resist the heat of earth's core?
Between the crust and mantle, and the mantle and outer core is there any "wall" between them? And how hard is the wall (can we go through it)?

As Chris Mueller said, in short: it isn't, or at least highly infeasible. Projects to drill into the mantle, such as the Kola Superdeep Borehole, have all failed because drilling equipment can't withstand the heat at only ~15km deep. Even if we were to come up with some sort of cooling system that's able to cool to 6400km or 12800km deep (depending on whether you would drill from one side only or from both sides at the same time), pressure is the second barrier that holds us from traveling through the earth's core.

According to Lide (2006) the pressure in the inner core is 330 to 360 GPa, at which iron becomes a solid even at the high temperatures in the core. If you could drill as far as the core you would have to build a device that's able to withstand that pressure, because if you can't, the material surrounding your well would immediately become liquid and fill the hole, if not shoot up your well towards the surface.

There are no physical walls between the layers of the Earth, only transition zones where temperature and pressure combinations lead to different behaviour of the materials. An example is the Mohorovičić discontinuity, or Moho, which is the boundary between crust and mantle, below which temperatures are high enough and at the same time the pressure is low enough so that rock becomes either liquid or at least a "flowing" solid. Similarly, at the boundary between the inner and outer core the pressure is so high that even at those temperatures the iron becomes a solid.

Lide, D.R., ed. (2006-2007). CRC Handbook of Chemistry and Physics (87th ed.). pp. j14–13.


Is there a recent global gridded temperature dataset with 0.1 deg resolution? I've been searching for a 2017 or 2018 or 2019 (or any combo) gridded dataset for surface temperature for the globe with a 0.1 degree resolution. Unfortunately even after hours of searching, for this time range, I've only been able to find ones with at most 0.5 degree resolution. Does anyone have any recommendations of where I might be able to find this kind of data?

If gloabal temperature isn't available, I'm specifically searching for Africa, South Asia, and South America (or any combo of those) - so if anyone knows where this data is available, it would be much appreciated!

The most important reanalysis datasets covering until present time (I'm excluding the others that stop some years before present time) currently available are:

ERA5 by ECWMF: 1979-present (soon 1950-present), temporal resolution of 1 hour and spatial resolution quarter degree (0.25 x 0.25);
CRU by the UEA: 1900-present (some variables 1850-present), temporal resolution 3 or 6h, spatial resolution half degree (0.5 x 0.5);
GLDAS by NASA: 1948-present, temporal resolution 3 or 6h, spatial resolution quarter degree (0.25 x 0.25).
ERA5-LAND by ECMWF: 1981-present, temporal resolution of 1 hour and spatial resolution 0.1°x0.1°, global coverage, but only land-covered surface.

(please, feel free to edit the answer to add more)
You could download one of those and process these temperature data using a simple resampling procedure bringing it at the resolution you are interested in by using CDO or another similar software. The procedure could be based on a bilinear interpolation of the original data with a finer grid. This would bring uncertainty because the correct procedure would be to use the reanalysis as boundary conditions in a regional climate model, but it would give a good approximation of the data you are looking for.
The only dataset I am aware of that is providing global data at a resolution of a 0.1 deg. resolution is the MSWEP by JRC and Princeton, but present data are not available for free, and it includes only precipitation data.


How do these cloud forms grow? What conditions would cause these windswept clouds at sunset in Michigan?

Do these cloud forms have a name?

Looks like Cirrus Fibratus (Ci fib) to me.

See e.g. Wolkenatlas or Clouds Online.

Regarding the formation of Ci fib, Name of Clouds says:

  Cirrus fibratus clouds are formed when winds at high altitudes are strong and flow over the cold air from below. The combination of the warm air and the moisture is usually unevenly distributed hence the trail of fine fibers at the ends of such clouds.


Which one is the correct concept of Continental Crust and Oceanic Crust? I knew so far that, the classification of crust as SiAl-SiMa, vs. classification of crust as Continental-Oceanic; are completely different, as told in my school geography and university paleobiology class. (However I'm not a geology student)

Like,

Where Continental crust and oceanic crust placed side-by-side, so, no-part of continental crust can cover-up oceanic crust. Also, in the places of continental crust; both SiAl and SiMa could be found

Now a geology student is telling me, that is wrong. SiAl is Same as Continental crust, and SiMa is same as Oceanic crust. He's Also telling, "SiAl or Continental crust lie upon Sima or Oceanic crust". That implies at the same-place on Earth, continental and oceanic crust occur together, one upon other.

Michael is correct. SIAL and SIMA are very vague and over-simplified summaries of the continental and oceanic crustal compositions. These terms may be OK for school introductions to geology, but you don't have to look far to find many exceptions. There are eroded and fragmented continental remnants, of nominally SIALic composition, in every ocean. Indeed, 100% oceanic crust may include small amounts of highly differentiated plagiogranite (technically SIALic in composition). Then there are bits of oceanic crust, called ophiolites (SIMA) incorporated into continental crust through processes of obduction and terrain accretion, not to mention the many flood basalt terrains (SIMA), which can occur on either continental or oceanic crust. Whether crust is oceanic or continental is a matter of overall rock density, composition and crustal thickness.


Is a glacier advancing or retreating? How to tell? What are the most common ways you would use to tell whether a given mountain glacier is advancing or retreating, judging only by its present state by looking at it? Please list anything you can think of.
Could a stream of water flowing out from under the glacier be a sign of it retreating?

The easiest way is to look a the glacier margins. If the ice is in contact with vegetation or rock covered in lichens or moss, it means it is most likely advancing. If you see a band of life-less rock in between the ice and the first plants/lichens/moss, it means it is retreating.

Some examples I've seen myself:

This glacier in Geenland is advancing, you can see the ice and vegetation in contact

Same glacier, you can see how it is even pushing vegetation, proving it is advancing

However, advancing glaciers are the exception. In most cases they are reatreating and what you see is a band of life-less rock surrounding the ice like this:

Retreating Amalia glacier in Patagonia

The advancing or retreating state of a glacier can have different time-scales. For example a glacier can be retreating on a decade scale, but it might advance every winter, but the recession on summer is large enough to produce a net retreat every year. Small glaciers can also react very quick to weather variations, therefore even if one is receding at a century scale, it can advance one year due to exceptional snow accumulation over few years. So you have to interpret this observations with care, and consider what's the timescale at which the plants/moss/lichens can colonize the rock in the area, which in temperate and low elevations will be between a few years and a decade.
Moraines, trim lines and other features can tell you about the advancing/receding history of a glacier at longer timescales.


How to determine (lost) surface (km²) of a country when both population and population density have changed? I am not sure if the question suits in this stack board, but I give it a try.

Let's assume there is a country with a population of 327 million people and a surface of 9.6 million km², resulting in 34 inhabitants per km².

Now, let's say we have a fictive war scenario, in which the country loses and has to give up land to the victors. The population sunk to 100 million people and 10 inhabitants per km² (still assuming that surface was given to victors, thus the country now has a smaller surface!!). How would I calculate the new surface with these two (now changed) variables or would I need more data?

My question now is:

Is it still possible to determine the new surface of the country when both population and population density changed?

I tried many ways to accomplish that, but I really have no idea how to approach it. Maybe it's possible with a system of linear equations? I have no idea.

$\text{Poulation density} = \frac{\text{Population}}{\text{Surface}}$

Re-arranging

$\text{Surface} = \frac{\text{Population}}{\text{Poulation density}}$

In your case

$\text{Surface} = \frac{100,000,000\, \text{inhabitants}}{10\, \text{inhabitants}\, \text{km}^{-2}}=10,000,000\, \text{km}^2$

So something doesn't make sense, because those numbers suggests that the surface of the country is now larger than before.


Is spectrum of sunlight the same in the summer as in the winter? Of course we receive less sunlight in winter, because the sun is lower in the sky, so the light has to travel through more atmosphere, and loses strength. Does this mean that the blue light is more scattered out?

Are the frequencies we receive in the winter relatively the same as in summer or is there a change in the received spectrum? Are there less UV-B rays in winter than there are in summer relative to UV-A? If so what is the cause of that?

As you suggest, longer the path, larger the proportion of scattered radiation. Since the shorter wavelengths are more strongly affected by the Rayleigh scattering, sunlight appears more red when the sun is low.

Lower solar elevation angle will also result in longer path through the ozone layer, and hence stronger absorption at the UV-B wavelength range. Together with the Rayleigh scattering, this will result in somewhat less UV-B compared to UV-A, all other things being equal.

The online version of NCAR's TUV radiative transfer model can evaluate the clear sky radiation for a given location and time. At noon, 45° north, I get UV-B/UV-A ratio of about 0.03 for 30th June and 0.01 for 30th January.

In addition to the sun elevation, the radiative fluxes will be affected by a number of factors like clouds, surface albedo (snow!), aerosol extinction, and variations in the ozone layer.


How to make, read, and calibrate a ping-pong ball anemometer? I'd like to make a ping-pong ball anemometer to make estimates or approximate measurements of wind and surface air currents at low to moderate speeds. I don't own an anemometer now, but I'd estimate the speeds of interest to be between zero and a maximum of order of 10 or 15 mph (feels similar to riding a (non-racing) bicycle down hill on an otherwise windless day).

If I understand correctly, a ping-pong ball anemometer probably refers to the use of a ping-pong ball or other tell-tale normally used to indicate wind direction to also try to use it to estimate the speed of the wind.

If this were a problem on a test, I'd set up the equations for force and balance the vertical and horizontal forces separately, assuming the wind is horizontal. For the horizontal force, I'd use a simple equation for drag force as a function of velocity from Wikipedia:

$$F_D(v)= \frac{1}{2} \rho v^2 C_D A$$

where the density of air at low elevations and moderate temperature is roughly 1.2 kg/m^3, $A$ is the cross-sectional area of the ping-pong ball $\pi R_{p-pb}^2$ and $C_D$ would be the drag coefficient, which is where all of the reality and the complications of aerodynamics are actually hidden in practice. $C_D$ is not really a constant, and is often plotted against velocity and other parameters. However, for some range of Reynolds numbers, a perfect sphere would have a roughly constant $C_D$ of about 0.47.

But a 2.7 gram, 40mm diameter ping-pong ball anemometer, or similar device is a real-world device. Maybe I should use a heavier ball, but I think the smoothness of the ball is critical if I want to use a theoretical $C_D$ and estimate speeds using equations rather than doing a real calibration against a known anemometer or riding in/on a vehicle at a known speed.

Are there any instructions for how to build, use, and calibrate or interpret results for this kind of simple anemometer? Ideally some dimensions and a suggested scale would be great! Or if this has been actually measured for a pingpong ball or another object, that would also be a great answer as well.

If the concept is good enough for a Mars lander weather station, then it's good enough for me!

above: GIF from images transmitted from Mars. From the The Telltale project page on the Mars Simulation Laboratory. Also archived here.

above: Instrument as delivered to NASA. From the The Telltale project page on the Mars Simulation Laboratory. Also archived here. That's a 45 degree mirror below the telltale providing a simultaneous view from below.

The drag coefficient varies with Reynolds number and hence with wind speed. Most fluid-dynamics textbooks have a graph of the drag coefficient of a sphere versus Reynolds number. Hopefully that could help. (A sphere such as a ping-pong ball is the best shape since its shape is the same in all orientations --- only a sphere has complete omnidirectional symmetry.) Because wind is rarely steady but usually includes gusts and lulls, it may be necessary to account for overshooting. A sudden gust can cause the ping-pong ball to temporarily overshoot to a higher angle than in a steady wind at the same speed as the gust.


Conditions at the bottom of a VERY deep hole I'm a science fiction author looking to describe what conditions might be like at the bottom of a cylindrical shaft ~ 30 meters across and ~ 35 km deep.  It's located somewhere on the edge of Yellowstone national park (if that matters). The top is open to ambient, albeit controlled, conditions in a great big lab room. If you drop a coin down this well, there's nothing man-made in the way of it getting to the bottom.

The shaft itself uses advanced unobtanium wall liners, so the engineering challenge of keeping it from collapsing or otherwise self-destructing has been taken care of. I'm not sure how insulating the unobtanium is from the surrounding rock right now, could be "none" to "completely," depending on how interesting that makes what's happening at the bottom.

I'm pretty sure the atmosphere at the bottom will be amazingly hot and dense, probably quite a bit denser than several hundred feet of water, but I'm hoping someone more knowledgeable can help out with the details.

Contributors will definitely get a mention in the acknowledgements. Big contributions will likely result in a signed copy of the final book. This will be the third book in the Gemini Gambit series, which will likely hit the shelves in late 2017/early 2018.

UPDATE The hole is used as part of a super-massive geothermal power plant, so hot is good. Dense is good. I'm thinking the convection potential would perhaps make mounting ducted fan windmills somewhere also good for generating power.

If it is enclosed and undisturbed there would be a risk of the heavier gasses collecting at the base of the hole, with carbon dioxide, argon, neon and xenon displacing the nitrogen and oxygen. Hence the danger of asphyxiation for any organism at that depth. Mixing, to keep the air homogeneous would also have the effect of heat transfer to further up the hole, so you will need artificial mixing and cooling. There are likely to be traces of helium and hydrogen at such depth, but not enough for the upward flow of such light gasses to have any significant mixing effect. However, hydrogen will be a potentially explosive problem at the enclosed surface environment. At these temperatures water rock reaction at the exposed base of the hole would be rapid. It is not clear whether your hole would have punched through to the mantle. I'm assuming it would, in which case there will be water vapour - hartzburgite reaction to yield more hydrogen. Serpentinization of the rock will proceed, involving about a 17% rock expansion. The rate of such a reaction will be limited by the amount of water vapour in the hole. A by-product of the reaction will be moisture at pH12 which will rapidly react with the high partial pressure of CO2 to produce carbonate encrustation. So it will be a problem to keep the hole clean - unless you prevent any moisture entering the hole from the surface control area.


Database of geological group or formation exposures? Is there any sort of database that provides the locations of exposures of certain geologic groups or formations?

I ask because I have read that halite occurs in the Michigan Basin, and specifically occurs in beds of the Salina Formation (Silurian) and the Detroit River Group (Devonian).  I would love to find a source (preferably a map) that provides locations where these features (or really, halite) are at or near the surface.

Thanks.

You may also find localised geological guides, such as the Roadside Geology series.

http://geology.com/store/roadside-geology.shtml has a listing. While I have not used them, I have seen them crop up fairly often as a nice option when looking for interesting geology in more general terms, including for some outcrops.

(I would have made this a comment, rather than an answer, but have no rep yet.)


How do we apply the Stefan-Boltzmann equation to radiative heat transfer from/to CO2 in the atmosphere? If we can use the Stefan-Boltzman equation to quantify the radiative flux leaving a solid body due to emission of radiation and to do it properly for a solid body we need to include the emissivity term then why, when considering the radiation emitted by the gas CO2 in the atmosphere, do we not use the SB equation utilising the absolute temperature of the atmospheric gas and the emissivity of CO2? The emissivity of CO2 is, I think, something like 0.002 (depends on temperature/pressure).

We don't

Emissivity of CO$_2$

Your claim of low emissivity of CO$_2$ is not entirely true. First off, it matters what the wavelength of emission is when determining emissivity. Carbon dioxide has specific bands of high absorption (which correspond to high emissivity). These bands are crucial for climate modeling, so listing a numerical emissivity value without specifying the wavelength is not a useful measurement.

Secondly, emissivity of a gas isn't as simple as that of a solid surface because solid surfaces are more or less opaque to the IR radiation emitted in accordance with the Stefan-Boltzman equation. Therefore, the surface area of the 'blackbody' is what is important when calculation emission or absorption. For a gas, however, IR radiation will penetrate some distance through it.

The result is that you need to calculate emissivity of a gas as a function of its optical depth. Staley and Jurica, 1970 present calculations where they do that for carbon dioxide in the 15 $\mu$m absorption band (the most important one for climate models). Their results show that at 20 C, CO$_2$ has an emissivity of 0.0823 at an optical depth of 1 cm; 0.244 at an optical depth of 10 m; etc.

Spectrum matters

As I mentioned above, the emission spectra matters a lot. In the case of CO$_2$, there is a specific emission band which corresponds to the absorption band. This means that any radiation emitted by CO$_2$ is emitted at just the perfect wavelength to be reabsorbed by other molecules of CO$_2$.

CO$_2$ also differs from water vapor in that it remains dispersed through the atmosphere and doesn't coalesce into weather formations. Water vapor aggregates into clouds; the emissions from those clouds can be significant because there is much more water vapor emitting in a cloud than in the (drier) air above the cloud. CO$_2$ doesn't exhibit that behavior and thus its emissions are mostly trapped by other CO$_2$, whereas blackbody emission from cloud banks can be significant on the global scale.

What does get emitted to space and lost is heavily attenuated by the presence of other CO$_2$ molecules and is insignificant compared to emissions from the Earth's surface, which pass through the absorption band gaps in water vapor and CO$_2$.

Conclusion

I don't actually know what factors each specific climate model uses. There may be some that account for the emissivity of CO$_2$. It may be that all the models account for it; it has been over a decade since I contributed to those models. However, whether they account for it or not, it is not a significant factor in driving temperature changes the way the emissivity of the Earth's surface is.


Would the Earth function the same spinning the other way? Right, I saw a question about why the Earth spins counter clockwise, and it reminded me of something I would like to know the answer to.

I watched a episode of Futurama. In this episode the Earth stops spinning and they restart the Earth's spin, but going the other way (clockwise).

Would the Earth function in the same way if this was possible to do? What effects could this have?

Note: I'm not even 100% what way we are spinning - it depends how you look at it, right?

That would have many consequences. For example the Coriolis force would change the sign. Thus wind around pressure systems would switch the direction from north and south hemisphere, but also the Ekman spiral in the ocean would be affected. Surface heating at sloped terrain will different, as the sun would rise in the West. This would change thermal induced circulations. And the conservation of angular momentum is important for the general circulation.

I would expect major impacts on the resulting climate, even in an equilibrium mode, which does not account for the acceleration to the oppose rotation velocity.

During the time of stopped rotation additional circulation systems can be expected, which exchange energy between the day and the night side of the earth.


Why is the Atlantic anticyclone an area of high pressure if it's the warmest spot on the planet? I am taking a navigational course and part of it is about meteorology. There is one thing which is, although obvious, quite hard for me to grasp.

Looking at a global weather map like this: https://earth.nullschool.net I can see the High pressure area on the Atlantic pushing air towards Europe and into the Low pressure area in the North pole.

My understanding is that High pressure = Cold air, flowing clockwise and outwards. Viceversa for the Low pressure.

What I don't understand is why there is an area of High (cold) over the Atlantic in the tropics and Low (warm) in the Poles, while I would expect the Atlantic to be warmer than the North pole (and indeed it is, if you look at surface temperature). My expectation would be the opposite should happen.

The Bermuda high is centered near the horse latitudes, where air from the tropical Hadley trade wind cell is sinking. This forced sinking of air can dynamically contribute to high pressure even if the air is warm --- warm air can be forced to sink against its own buoyancy in a Ferrel-type circulation. But the Bermuda high is helped thermally too, at least in summer, because the Atlantic Ocean at those latitudes, at least in summer, is cooler than North America and much cooler than the Sahara at the same latitudes. It is certainly easier for a Ferrel-type circulation to work against cooler surface temperatures than against warmer ones.