Confirmation of historical El Niño events As this year's boreal summer monsoon draws to a close interest automatically centers around forecasts for next summer's monsoon and the likelihood of possibly another El Niño event. This brings about the question of historical El Niños and when I googled for the same I came up with this interesting site - Historical El Niño Events.
I am familiar with the European medieval warming period Medieval Warming Period but my current question deals with the period from 1790 AD to 1799 AD as mentioned in the first link. It appears apart from the year 1798 all other years were El Niño years and that would appear to be a extraordinary period.
My question is

Are there any references from paleoclimatology that talk of the atmosphere during that period ? Are those confirmed El Niño events ?

The best article about the 1789-1793 El Niño is probably Grove (1998) Nature study. There is also a lot more information in Grove's 2007 paper. In the second paper, he explores the global consequences of the El Niño event (some evidence is mostly circumstantial), which he describes as being quite severe: famine ("By November 1792 over 600,000 deaths were being attributed directly to the prolonged droughts"), revolution (French Revolution), economic hardship...
He provides rainfall and temperature records and many historical reports as evidence of the conditions.

  While further archival research is needed to more fully characterise the 1789–93 event, the evidence of a strong global impact already indicates that it was one of the most severe El Niños recorded.

In El Nino History and Crisis Grove talks of the idea of a Mega Niño in relation to the continuous series of El Niño events that occurred during the period 1788-93.

  In terms of severity,the Indian droughts of 1788-1793 surpassed anything
  that  had  occurred  since  the  events  of  1685-88,  and  stand  out  as  having  both an unusually long duration and extraordinarily wide effects,   within and beyond  India. Indian  droughts  that  co-occurred  with  El  Ninos  in  the  interim, in   1701-2,   1707-9,   1737   and   1783,   while   serious,   did   not   approach the ferocity  of  the  years 1685-1687  in  southeast  India and  it  was  not  until  1788—
  1793  that  a  comparable  series  of  extreme  events  took  place.


How could this pyramidal Mountain have been formed? How could this pyramidal peak have been formed in Antarctica? Little is known about it as far as I know but what is known is that its miles away from any existing plate boundary and its shape is also highly atypical, hence I present the above question.

The question bases on two sub-questions really:

A) How did it form so far away from a plate boundary?
B) How did it form in this unusual shape?

https://en.wikipedia.org/wiki/The_Pyramid_(Antarctica)

Such forms tend to be created by glacial activity, which, ahem, the ice-covered continent is known for. Much discussion of this in the related question in Skeptics: Are there three pyramids in Antarctica?

Here's the generic answer in Wikipedia:

  A pyramidal peak, sometimes in its most extreme form called a glacial
  horn, is an angular, sharply pointed mountain peak which results from
  the cirque erosion due to multiple glaciers diverging from a central
  point. It may be an example of a nunatak.

Here's a diagram of the formation process posted on Ace Geography:

Not knowing the specifics of the featured peak, as I understand it there are two general mechanisms of glacial erosion that apply:

Assume we begin with some sort of mounded terrain, or a relatively small protrusion on a larger continental surface like Antarctica. In a very cold environment, precipitation will fall as snow, mound up, and turn into ice. Generally, more ice will form on whatever side of the mound that is sheltered from sunlight (north slopes in the northern hemisphere, south slopes in the southern. Eventually the ice will move under its own weight, abrading the surface as it goes in a manner that will tend to exaggerate the original geometry of the mound. If the mound starts with or develops a slight dip in the slope, ice flowing off the back and side walls will dig a cirque or bowl. Depending on the starting conditions, your mound may develop several cirques; as ice grinds away at the lower elevations, you may wind up with a central, relatively slender peak with several ridges and valleys.
A second mechanism is having a glacier coming down a broader slope and cutting through an existing ridge. (Your ridgeline may begin with a triangular cross-section, or may have developed one from the glacial processes mentioned above.) At some point, ice from a higher elevation will flow across or through your ridgeline (just as a river would), eroding a gorge through the ridge.

Inevitably, given enough material to work from, and even with a relatively smooth starting surface, the erosive power of ice will give you steep slopes and some pyramidal structures.


Are Ice Ages Affected by the Freezing Out of CO2 in Antarctica? The freezing point of carbon dioxide is -78.5 $\small\mathsf{^o}$C. Occasionally this low is exceeded in Antarctica, and small quantities of CO2 are frozen out, but are returned soon after to the atmosphere. Is it possible that during an ice age more substantial quantities of CO2 are frozen out, and could it be enough to affect the climate and worsen the ice age? Could this phenomenon also occur in Siberia?

The freezing point of carbon dioxide is -78.5C.

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

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

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

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

References:

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

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


Are Pompeii and Herculaneum unique? Has anyone ever found or gone looking for similar locations, i.e. volcanic eruption sites in which unfortunate victims – human and non-human –  have been entombed in the volcanic ash, with the possibility of revealing their forms by producing casts from the voids? Such sites, if they exist, could reveal exciting new knowledge about ancient peoples and animals.

Probably the best known is more recent, the 1902 eruption of Mt. Pelée on Martinique, where 30,000 people were killed by pyroclastic flows. I don't know the extent of burial - it appears that the city may have been destroyed more by the ash cloud than the dense part of the flow.


Why are some theories as to the cause of glacation less popular among the scientific community? There are a few theories as to the causes of glaciation.
There's the Milankovitch Theory, which says that there are cyclical changes in Earth's orbit and in the tilt of Earth's axis that occur over thousands of years and cause climate changes.
Some scientists believe that the solar energy made by the sun is not constant and that may be why it gets so cold that glaciers form sometimes.
Others say that when volcanic dust blocks the sun's rays, making it harder for solar radiation to reach Earth's surface.

While the first one can't exactly be proven, it can't be disproven either, and is the theory most go with. So why or why don't the second and third theories work/what makes them less popular?

Your question is framed as if any model of glaciation were only allowed to consider one of those influences. I think practically any palaeoclimatologist would accept that astronomical forcing, solar output, and volcanic eruptions all have effects on glaciation. It's true, however, that on long timescales (tens of kiloyears and up), Milankovitch forcing generally gets more attention than the other two you mention. There are further important drivers of glaciation which you don't mention. Perhaps the most obvious is greenhouse gas concentration: if atmospheric levels of CO2, methane, and other greenhouse gases drop, the Earth cools and glaciation becomes more likely (see e.g. DeConto and Pollard, 2003). Another influence is tectonics and geography, the best-known example perhaps being the theory that Antarctic glaciation was caused by the break-up of Gondwana, which left Antarctica thermally isolated (Kennett, 1977).

To return to your main question, there's a good reason to consider Milankovitch forcing as a (or the) dominant driver of glaciation on longer timescales: it's simply that glaciation (as deduced from δ18O records) varies in time with the astronomical cycles. Hays et al. (1976) is one of the classic papers on this, and they sum the situation up neatly:

  Over the frequency range 10−4 to
  10−5 cycle per year, climatic variance of
  these records is concentrated in three discrete
  spectral peaks at periods of 23,000,
  42,000, and approximately 100,000
  years. These peaks correspond to the
  dominant periods of the earth's solar orbit,
  and contain respectively about 10,
  25, and 50 percent of the climatic variance.

To put it another way: if you want to discount astronomical forcing and attribute those variations to (say) volcanic aerosols, you need to explain why you have volcanoes going off at precise 42,000-year intervals. This isn't to say that we fully understand how these drivers interact with the climate system yet (the 100,000-year problem is perhaps the best-known "wrinkle" in the theory), but the fact remains that if your glaciations are dancing to 23, 42, and 100-kiloyear beats, and your solar system happens to be providing beats at precisely those frequencies, there's probably a pretty strong connection there.

DeConto, R. M., & Pollard, D. (2003). Rapid Cenozoic glaciation of Antarctica induced by declining atmospheric CO2. Nature, 421(6920), 245-249.
Hays, J. D., Imbrie, J., & Shackleton, N. J. (1976). Variations in the Earth's orbit: Pacemaker of the ice ages (PostScript). Science, 192(4270), 1121-1132.
Kennett, J. P. (1977). Cenozoic evolution of Antarctic glaciation, the circum‐Antarctic Ocean, and their impact on global paleoceanography. Journal of Geophysical Research, 82(27), 3843-3860.


How far upstream would severe sea level rise (1m) noticably affect a large river? The projection for sea level rise due to global warming seem to hover about 1m by 2100, let's use this figure. How far upstream would this noticably affect a large river, e.g. the Rhine?

I think it is obvious that the Delta would be changed severely, while it is nigh impossible to say accuratly how exactly (I assume). Upstream, I think the following effects com into play: Less hydraulic head means less flow velocity, more sedimentation and a higher water level in the river bed (the river needs more cross section to achieve the same volume flow with less head). Are these assumptions correct so far?

Now the main question is how far upstream we would notice these changes in river behavior: Only at 1m above new sea level, or 10m, or 100m? Is this stronger determined by linear distance along the river, or by height above (new) sea level?

I prefer the Rhine as an example because it's the closest large river. If someone has a good answer for another large river I'm happy too.

This is both a simple and complex answer.

The simple bit is that a 1m rise in sea level would impact the river to a point 1m higher than the current point (with a slight error margin dependent on flow rates etc)

The rise itself over the next 85 years will not push back along the river (as Michael mentioned) as it's not like a tidal bore such as the Severn Bore.

The complex bit is that the 1m rise could be along an estuary, or across winding wetlands, or a wide delta or other feature, so the change to river flow could actually be quite catastrophic. And these effects could impact very far upstream, especially in the case of a river such as the Rhine, with a heavily populated floodplain. Wikipedia notes the last 50km of the Rhine are at 0m elevation, so that's an incredibly large possible impact area.


Where can I find an anisotropic PREM-like model for Earth's interior? So, I just discovered PREM (the Preliminary reference Earth model) which models the density distribution of matter inside the Earth to any depth.
The PREM is very convenient but since it only depends on the depth I see that is an isotropic model, meaning that it deoesn't matter from which surface coordinates we are digging, it only accounts for radial variations in density from the core. I know that Earth's interior is not distributed in perfect spherical symmetry since there are things like Large low-shear velocity provinces and giant slabs of solid crust floating in the mantle revealed by seismic tomography, and gravitational anomalies.
I was wondering if there is a much more accurate model for the density distribution of Earth that accounts for the aforementioned asymmetries, and where can I download that data?

Here's an extensive list of Earth models, many of which are anisotropic. You'll probably want to focus on tomographic models rather than reference models.
http://ds.iris.edu/spud/earthmodel


largest earthquake not in a subduction zone Whats the largest earthquake since 1900 that was not in a subduction zone (not a megathrust).

Wikipedia says that Since 1900, all earthquakes of magnitude 9.0 or greater have been megathrust earthquakes. No other type of known terrestrial source of tectonic activity has produced earthquakes of this scale.

08/15/1950 Assam, tibet, 8.9 magnitude. according to the USGS, https://earthquake.usgs.gov/earthquakes/browse/largest-world.php

Note you are talking about a very small window of time there are only 5 earthquakes of 9.0 or greater within that time frame.


Result of floating-iron-balls in the mid-pacific? I had an idea to make green islands from mid-pacific plastic: Release a million tons of floating iron balls there, which will stay in the same regions as the plastic and hopefully cause a veritable forest to grow on the plastic, especially if they contain a bit of nitrogen/phosphorus/silica to start the forest, and then seabirds and fish can hopefully do the rest.

What would happen to the iron balls, would they stay with the plastic islands, would they end up on beaches and be a waste of time?

I take it that your iron balls are hollow and made of rust resistant steel. It would be a fiendishly expensive project, but I doubt it would have the result you suggest. The iron balls would have to be linked together by chain or rope to prevent them dispersing in ocean currents and ending up on beaches around the world, like the cargo of plastic ducks which fell overboard from a ship about ten years ago.

Such a contrivance would represent a hazard to shipping, so no government would be willing to spend the huge amount of money it would cost. The whole thing would probably end up on the beach of some Pacific island and cost a fortune to remove.

The problem of plastic in the ocean is certainly a serious one, and something needs to be done about it, but this is not the solution. Perhaps an internationally financed ship dedicated to seeking out rafts of plastic at sea and disposing of them might help, and would certainly be much cheaper and easier to control than your million tons of iron balls.

A world-wide educational campaign aimed at teaching people the damage caused by dumping their rubbish on beaches, in rivers, and from ships might have some effect in reducing the amount of rubbish which ends up in the sea. I always use an ordinary plastic shopping bag a couple of dozen times before it starts to fall to pieces, and then I put it in a bin bag to go to landfill. If everyone did the same it would be a major step in the right direction.


Fault representation In most illustrations and diagrams of the types of faults, there is always something similar. I noticed that there is a side of the hanging wall and foot wall which is slanted.

We're supposed to make a models for each type of fault; however, the material to be used will be difficult to cut diagonally. I'd like to know if it is necessary to have one side slanted? Or if having it vertical fine.

Please mention sources too. Thank you.

Faults are results of stress. The direction of the stress controls what kind of fault that is formed. The most fundamental reason for a fault to occur is horizontal compression or extension, even if it's often more complicated in reality.

Your two examples are dip-slip faults, with a vertical displacement as a result of horizontal stress.

In your first example, the normal fault. The total distance (from left to right) is increased. There has been an extension of the crust. If the fault plane would have been vertical, no distance would have been gained.

In the second example, the reverse fault, the distance is decreased. It's been a horizontal compression of the crust. The dip of a reverse fault is usually rather steep. If the dip is lower, you'll rather form a ramp. Typical for thrust faults.

Vertical fault planes are associated with strike-slip faults or ring faults above collapsing calderas or sinkholes. It's also common, but not for textbook examples of dip-slip faults.

So, unless you are showing a strike-slip fault, you have to find a way to cut diagonally. Do measure the horizontal displacement!

Addition about making fault models:
We made a layer cake for a college some time ago and (of course) wanted to have a fault in it. The simplest way was to make a reverse fault, erode the uppermost layer of the hanging wall block and assume that the lowest exposed layer was of the same lithology (chocolate sandstone reservoir rock). However, it took some geoenginering to make it look good and we decided to make an impact crater next time.


Quality control in Seismic Acquisition - How much data is required? When it comes to land or marine acquisition (oil exploration, for instance), I can see from literature that quality control (QC) is performed during the survey to ensure that the seismic traces obtained are not faulty. However, I see contradicting values for the amount of data that is required for QC. In [1], it is mentioned that just around 10 bytes/minute are sufficient. Meanwhile in [2], it is mentioned that the data collected over the entire day is used for QC.

Can someone point me to a good source where I can understand this aspect better?

[1] - http://home.deib.polimi.it/savazzi/articles/06495774mag.pdf (Page 3, second paragraph under 'Shooting-Blind vs Real Time Telemetry Systems)

[2] - http://www.smngc.ru/en/seismic-surveys/quality-control-of-the-seismic-data/

After a more elaborate literature survey, it turns out that there are two types of quality control that can be performed on seismic data. One is of the acquisition parameters [1], which are just a few bytes per minute. Meanwhile, in [2], the entire data can be screened through QC software before being sent to a central server. This would help report errors in the acquisition process before conducting further sweeps.


Filtered pressured oxygen 80 miilion years ago Was dinosaur blood really red? Was the vegitation really green?Can that filter be used today?

What filter?  Modern vertebrate blood is always red (with just one exception AFAIK: https://en.wikipedia.org/wiki/Channichthyidae ) because it is based on hemoglobin.  Given that birds, which descend from one branch of the dinosaurs, have red blood, it's likely that the dinosaurs did as well.  Likewise plants are mostly green due to the chlorophyll used for photosynthesis, another thing that would be strongly conserved by evolution.


The atmosphere and the dispersion of greenhouse gases I have been researching everywhere. At what level of the atmosphere do carbon dioxide and other greenhouse gases occur?  I can't get a straight answer and am frustrated...

The short answer is that greenhouse gases occur at all levels in the atmosphere. However, the concentrations can vary with altitude. In the case of greenhouse gases that are always in a gaseous state like CO2, Methane and Nitrous oxide, they are evenly distributed throughout the lower atmosphere (i.e. troposphere and stratosphere below ~20km), (this question & answer explain why), with only minor variations in concentration. The only notable exception is water vapour, also a powerful greenhouse gas, water is the only one that do transition between liquid, solid and gaseous states within the atmosphere, something that have as a consequence that its distribution is not homogeneous like it is for the other gases.

The actual distribution of water vapour is highly variable, something that we all know from the daily experiences of a diversity of conditions like dry weather, fog, rain, etc. However, there is some clear patterns:

Vertically, water vapor abundance falls more or less logarithmically, as it can be seen in the following figure:

(taken from AGU WATER VAPOR in the CLIMATE SYSTEM, Special Report. December 1995)

Were it falls from about 3 grams per kilogram of dry air to about 0.003 grams per kilogram of dry air at 15,000 meters of elevation. A big contrast with the tropospheric variations in CO2 for example, that are in the order of ~3-6% across the glove, with a ~1-2% seasonal cycle.

Horizontally, across the surface of the Earth, water it is much more abundant in the tropics than the poles, a pattern mostly controlled by temperature, because the capacity of air to hold dissolved water falls exponentially with temperature (as described by the first equation in my answer to this question). The following figure of the global mean water column derived from satellite data for 2009 will gives you a good sense of the typical distribution

(taken from Retrieval of total precipitable water from GOME-1, SCIAMACHY and GOME-2)

Now, if we consider higher levels of the atmosphere (>20 km), the mixing at that scale is not strong enough to smooth out the variations in concentration that arise due to the existence of sources and sinks for each greenhouse gas.
For example, methane is produced in the surface by natural and anthropocentric sources, and the biggest sink (90%) is the oxidation by hydroxyl radicals (OH) in the stratosphere. This create a fairly large vertical gradient in methane concentration. A gradient that gets smoothed out by strong mixing in the troposphere but becomes very important in the stratosphere and mesosphere. Similar phenomena creates gradients of other greenhouse gases like N2O, Ozone, and to a lesser extent CO2. These processes are nicely explained in this paper, were the following figure gives a great summary of the changes in concentration of most gases in the atmosphere:

Here you can see that, CO2 keeps a relatively fix abundance throughout the atmosphere up to 120 km, while N2O is relatively very scarce above 60 km, and Ozone below 10 km.


How could humans alter storm intensity or direction other than cloud seeding? I am familiar with the concept of cloud seeding, where precipitation can be induced with aerosols, thereby altering storm intensity further downwind.  Are there methods that could be used to drastically alter storm wind intensity or storm direction?  What technology could theoretically be developed in the future that used satellites, ocean networks, balloons, or other devices to curb strong winds (e.g. tornadoes or hurricanes) so that populated areas could be protected.  Or is a strong storm simply too large scale of an event to be altered significantly by humans?

There are numerous ways. Arguably, some we are already doing, but are not intended (such as urbanization and the emission of different pollutants). But I'll suppose you are wondering about intentional modifications. Moreover, this is perhaps too general of a question, as there are a variety of different types of storms, of varying sizes. I'll tackle what I can, in a reasonable fashion. And for the sake of argument, I'll just ignore the downsides.

Let me repeat that, I will ignore the downsides. This may yield a comedic effect.

Extratropical cyclones.

Being that these take the energy from baroclinicity, a good way of disrupting the intensity of these storms is to warm the cold area and cool the warm area. You can do whatever you want to do to accomplish that, be it drop a couple megaton nuclear bombs in the cold region, etc.

Tornadoes

One thing you need to know about tornadoes is that the storms that generate these rely on stability/buoyancy and shear. Leveling everything should reduce the shear. Covering the surface with ice should also promote a more stable atmosphere.

Hurricanes

Hurricanes derive much of their energy from the temperature and entropy difference between the surface and the tropopause. Also, increasing the drag can reduce the wind speed. Different ways to do these can be found in NOAA.

Certainly these aren't all the ways that the weather can be modified. But these are just some. Of course, anything we do may backfire. Extratropical cyclones serve a purpose-transporting energy and momentum. Even hurricanes move water vapor towards the poles. And to that, I'll quote Jeff Goldblum:

  ...[Y]our scientists were so preoccupied with whether or not they could that they didn't stop to think if they should.


Is the lack of aerosols increasing temperatures in 2020? 2020 is predicted to be an unusually warm year and we are already seeing a lot of unusual temperatures. I was wondering, how much of an impact the reduction of aerosol emission from the global lockdown had on this.
I am not a climate scientist, but as far as I understand it: Aerosols are a short lived byproduct of our industries which increases atmospheric reflectivity. Because of this less sunlight reaches the surface of the earth -> less warmth is created in the first place. Because they are so short-lived shutting down industries should result in an almost immediate reduction in atmospheric reflectivity -> more sunlight reaches the earth's surface -> more warmth is created.
That sounds like it makes sense in theory, but does it in praxis?

Depending on type and size of aerosol there can be scattering, (Mie- and Rayleigh- scattering), atmospheric windows filter radiation, we have absorption, transmission and transformation of wavelengths which all influence the amount of energy that's trapped or reflected back.
The lockdown has led to a significant reduction of aerosols and drastic improvement of air quality in some regions (meaning not everywhere), but reliable studies seem to be rare atm. Evaluation is underway, but i think we must wait until a season has passed and activity has returned. A huge effect on temperature has afaik not yet been observed and described and if, it was towards a local decrease in temperature, not an increase. Anyway, the positive effects of lower economic activity are ceasing as no or little attempts are being made to use the reset for a transition to more sustainability.
Two examples I found, so far:
South-East Asia from satellite observation
https://www.sciencedirect.com/science/article/pii/S0048969720331788

... enforced lockdown at different degrees to contain the spread of the disease, which has brought some positive effects on natural environment.

Morocco, a slight (-0.3°C) reduction in temperaure, but higher variablity https://www.sciencedirect.com/science/article/pii/S0048969720330588
... not much for day temperatures for beyond 40°C in the area.

... the emissions from vehicle exhaust and industrial production were significantly reduced, which contribute to the decrease in the concentrations of the studied pollutants ... local emission reductions related to the lockdown were overwhelmed by the contribution of long-range transported aerosols outside areas.

tl, dr:
No, probably not, it may locally temporarily lower the temperature by a tiny bit, but overall this effect seems to be shadowed. But future work will show, it is too early to be definitive because the story still develops.


Sudden Localized Surface Water Temperature Increase In Eastern Lake Superior, Canada As can be seen in the below sequence of NOAA images spanning 15 hours (most recent at top), in extreme eastern Lake Superior the surface water (but not bottom water) temperature increased dramatically in a localized area.  Can anyone confirm or rule out that this is a real event?  If it is real, what is the explanation?

Link to source and additional information (Additional information includes lake-bottom temperature maps and additional time points)

NOAA revised the data.

The map below is for the same date and time as the first map in the question, but with the anomaly gone.  So I'll have to assume the event wasn't real.


What is the most optimal latitude on Earth for the generation of extreme maximum temperatures? First question on this StackExchange, so here goes...

Overall, reaching high temperatures is dependent on 2 factors:

The (maximum) solar angle in the day. The greater the solar angle, the more insolation is received by the surface and air, allowing higher maximum temperatures assuming no thermal inertia.
The length of the day. The longer the day, the more total solar radiation arrives in one 24-hour span, and the shorter the night is to radiate off excess energy, both of which due to the thermal inertia of the atmosphere and ground bias them towards hot temperatures.

(Again due to thermal inertia, it may be dependent on the day length and solar angle of previous days, though this influence is more minor.)

The first factor explains why even though at the summer solstice the poles accumulate more solar energy over 24 hours than any other place on Earth (I know I had a source on this. I can't find it, though.), they are still extremely cold as the low solar angle prevents reaching higher temperatures. The second factor explains why even though the equatorial region has the highest average maximum solar angles throughout the year, they don't get especially hot (even in rare desert areas) as the day length is nearly constant throughout the year.

Ergo, the outer tropics and the subtropics experience the hottest extreme maximum temperatures on Earth. This can be seen in the records for each continent that has a large stretch in that area:

America (South): 48.9 °C in Rivadavia, Argentina (24.18[3]° S)
Africa (South): 50 °C in Dunbrody, South Africa (~33.4° S)
Australia: 50.7 °C in Oodnadatta, South Australia (27.54811° S)
Africa (North): 51.3/53.5 °C in Ouargla, Algeria (31.95° N)
Asia: 53.9 °C in Mitribah, Kuwait (29.81[6]° N)
and lastly, America (North): 54.0/54.4/56.7 °C in Furnace Creek, California, USA at a rather high 36.458056° N.

Presumably, the spread in latitudes is due to the geography in those areas being much more suited to the generation of extreme heat than places at the "absolute ideal latitude". But what is this absolute ideal latitude? At what point from the equator do the combination of day length and solar angle in summer create the most optimal conditions for extreme heat, other factors being equal?

(My scientific wild ass guess is 30°, but I'd like a more educated answer.)

The places that get the hottest temperatures are close to the equator but not necessarily on the equator. They will be low lying places, perhaps below sea level, and 'enjoying' a continental climate. For the record books, they will also need to be places where a climatologist passes through at the right time to measure it. I see you mention some record temperatures in your question, but I don't remember off hand what the absolute world record temperature is. It won't be far short of 55 C, but what amazes me is how the people who measured such temperatures survived to tell the tale. The atmosphere must have been very dry. From the point of view of human wellbeing, in high humidity temperatures well short of world record don't feel well short, and are almost as dangerous.


In a zero carbon future but with increasing energy requirements would Earths oceans continue heating? We’ve completely obliterated our reliance on carbon based fuels. All our energy comes from renewal resources or even fusion. Our energy requirements continue to rise. Taking this to a deliberately ludicrous degree, whereby we’re capturing the sun’s energy, planet wide, via solar panels, we would essentially be diverting large amounts of sunlight that might otherwise have reflected our radiated back into space into our energy networks. Whatever that energy is used for our will ultimately be transformed Into heat. Some of that heat will be emitted into space via radiation, but I can’t help wondering if much of it will just stick around and continue to heat our atmosphere and oceans. Could our energy consumption increase indefinitely without affecting the ability of Earth to support our current ecosystem; or will be ultimately have to limit our energy use?

Edit for disambiguation purposes:
I'm not sure my original question at posed has been understood. Ignoring existing greenhouse gas emissions, in fact ignoring any issue with GHG at all, as civilization advances and our energy requirements continue to rise, the energy that we do use to perform work will ultimately be transformed into heat. We'd basically be pumping heat into the atmosphere instead of GHGs. A hotter atmosphere still holds more energy and moisture. Could we end up overproducing heat via fusion? Or is radiation an effective way for the planet to balance this excess?

Short answer: Yes, the ocean would continue heating for a while if we cut off all greenhouse emissions. Simply because CO2 has a long life span in the atmosphere and its effects will continue to be active for a long time, longer than human life spans.

Also, it may be that thresholds have already been passed that lead to positive feedbacks, like glacier retreat or desertification that amplify the forcing effects of greenhouse gases. Deforestation and wild fires are another such positive feedback, they release a lot of CO2 for immediate warming effect and expose a surface ready to be eroded and not available as a carbon sink any more.


How do you infer what a cross section might look like below sea level? Here is a schematic of a cross section which should represent an anticline:
https://postimg.cc/4HcmmZ26
Below sea level, I have inferred what the units might look like with the dashed lines. As I have interpreted this to be an anticline, it was quite straightforward to understand the possible shape, and by working out true thickness I would represent uniform thickness.
Here is another example of a cross section which should represent a thrust fault system (I may have added these faults at a strange angle, but hopefully this gets my point across):
https://postimg.cc/CRkXJ2Xc
Would I assume these beds are uniformly dipping? How deep should units be represented?

I would say it's reasonable to infer that the strata stay at roughly the same dip angle and thickness in areas not directly visible on the chart you're using.


Forest fuel biochar burial Record fires are blazing in the west coast, huge even compared to California's notorious summers.
Dead plants and debris are crucial to get a fire started. This debris could be collected, carbonized, and buried, say as terra preta.  Biochar burial has been considered as a way to mitigate climate change.
Cleaning up thousands of square miles of brush would be a massive undertaking. But we would avoid the pervasive and persistent loss of air quality on top of an already high health cost as well as tens to hundreds of billions of dollars from property damage, economic disruption i.e. evacuations, and other costs such as fighting fires. Would the combined benefit to cost ratio be competitive compared to the "typical" climate, health, or economic program?

The effects of biochar burial in California would be so minuscule they might be a net negative once you include the CO2 production of the labor involved. Biochar is a very labor intensive process. Consider carbon in fossil fuels was accumulated of millions of years of what is essentially the same process, even industrializing the process will still take comparable amounts of time to resequester that carbon using what is basically the same method. keep in mind fire is a normal part of many of these environmental cycles they are bad because humans kept preventing the normal fire cycles allowing fuels to build up for decades. Normally that fuel would be cleared by the natural fire cycles. Drought is a trigger not the cause.
Large impact estimates assume we would have to be converting land to biochar production, which has many many downsides and still would not be very effective.
It can be particularly confusing since "Bio-char" can mean two different things, the most touted use of biochar (fertilizer) will have no real carbon sequestration effect but can be a way to offset industrial fertilizers. Burial would sequester some carbon, but would also deplete soils and biodiversity. You have to check and see which use of biochar a source is referring to.
A better idea would be to burn the material as fuel, instead of fossil fuels, which would at least be carbon neutral.
source


Why is there no High-Resolution Infrared Radiation Sounder (HIRS) on Metop-C? The weather satellites Metop-A and Metop-B carry copies of the High-Resolution Infrared Radiation Sounder (HIRS), an instrument with a heritage back to 1975.  Considering that Metop-C is part of the same programme as Metop-A and Metop-B, a and operational satellites in the same programme normally carry the same payload, why is there no HIRS on Metop-C?

HIRS is an old NASA heritage design that flew on both European and US weather satellites as part of the EUMETSAT/NOAA Initial Joint Polar System.  The Inrared Atmospheric Sounding Interferometer (IASI) will take over the duties of HIRS, since IASI is a more powerful instrument with European design for a European satellite.  You can see this discussed here:

http://www.esa.int/Our_Activities/Observing_the_Earth/The_Living_Planet_Programme/Meteorological_missions/MetOp/About_HIRS_4/(print)

My perspective on this is that historically the US was the international leader in environmental satellites.  The Europeans now have better designs and more committed plans to environmental satellites over the next couple decades.  So, essentially, they don't need our out-dated hardware anymore.


Can relative humidity be over 100% near (within 30-60m) the surface? I am processing a big meteorological data set, which is a global forcings dataset derived by other datasets and observations, and calculating relative humidity from qair,temperature, and pressure according to these formulas How do I convert specific humidity to relative humidity?

I am noticing that I have a lot of occurrences where RH is slightly higher than 100% and I am wondering if this makes sense or not considering this is air temp from 2m, I would expect that near surface RH over 100% is some errors in the data set.

*I am not a climatologist nor a meteorologist, I use this data to study plants, so I hope for a not too technical answer, thank you.

It is reasonable to assume that air (atmosphere) acting as as a solution could become supersaturated with water vapor.  Supersaturation condition is where the air literally contains more water vapor than is needed to cause saturation. How common these conditions might be, I do not know.


Reciprocal space in the context of x-ray diffraction and a crystal lattice? Could someone please explain what reciprocal space means in the context of of x-ray diffraction of a crystal lattice?

The unit cell space and reciprocal space are fourier transforms of each other. The unit cell indicates the stacking space between crystal elements. The reciprocal space is a similar kind of vectorial representation of the diffracted X-rays. The following reference explains it quite well, although it is not a simple concept. Unless you are smarter than me, you may have to read it 2 or 3 times to 'get it'.

Reciprocal Lattices and Diffraction


What tools allow a quick comparison of NetCDF output from ocean models? I am writing my own MATLAB scripts to do most of the visualization and data analysis of model results. I wonder if there is a quicker way for visual comparison of simulation results gained from different ocean modeling systems. Is there a (preferably free) software package that works with CF (Climate and Forecast Metadata Conventions) compliant NetCDF model output directly or is always some coding required?

For very quick visual comparison I would use Cube Browser or ncview together with a command line tool like the Climate Data Operators. For quick production of nice looking graphics (and animations) Panoply really makes good job. For further analysis or special graphics keep following your approach and script with things like MATLAB, Python (e.g. with Iris), IDL, R, ncl or whatever people around you are using.


Muscovite with pleochroic halos? Is it possible to find pleochroic halos in muscovite ? I would have said that it must be biotite (also, in PPL it is brown!), but then.. why does it have interference colors so similar to muscovite ? Or is it anything else ? Thanks for help !

PPL

In high resolution here: Biotite with pleochroic halos (30 µm thin section, XPL).

XPL

In high resolution here: Biotite with pleochroic halos (30 µm thin section, XPL).

It's biotite. Not muscovite. That's why you have the pleochroic halos in it.

I don't understand why you are saying that the interference colours are like muscovite. First of all, the lack of cleavage suggests you are looking down (or close to) the x axis, so this means the interference colours you see are going to be very low. Let's say 1st order white or brown. And then, it's going to get the anomalous brown colour of the biotite together with it, which is exactly what you see here. Also, muscovite is not brown in ppl. This one is. Therefore, it's biotite.


Are there any metal anomalies other than iridium in the K-Pg boundary? The iridium anomaly marks the elevated concentration of iridium in sedimentary deposits of the Cretaceous-Paleogene boundary. The iridium is said to come from the impactor, which is supposed to have much higher iridium contents than Earth's crust.

What about other metals? Is there an observed increase of other elements as well? For example, osmium is another extremely rare element in the crust. Is there an osmium anomaly as well? If not, why is the anomaly restricted to iridium and not the other metals?

According to the conference article Can Siderophile Element Abundances and Ratios across the K-Pg Boundary be used Discriminate between Possible Types of Projectiles?, (Belza et al. 2013) state that the enrichment is not only in Iridium, but also in the other Platinum Group Elements and siderophile elements.

From the article Platinum-group elements (PGE) and rhenium in marine sediments across the Cretaceous–
Tertiary boundary: Constraints on Re-PGE transport in the marine environment (Lee et al. 2003) elaborates that from

  A traverse
  across the KTB in the South Pacific pelagic clay core found elevated levels of Re, Pt, Ir, Os, and Ru, each of
  which is approximately symmetrically distributed over a distance of 1.8 m across the KTB.

(KTB is a reference to Cretaceous-Tertiary Boundary from the article).

In a re-evaluation of geochemical data in Reevaluation of siderophile element abundances and ratios
across the Cretaceous–Paleogene (K–Pg) boundary:
Implications for the nature of the projectile (Goderis et al. 2013), took into account several more studies (published and unpublished), find that cobalt, chromium and nickel display in some places, an elevated concentration; however, the Co/Cr, Ni/Co, Ni/Cr, Co/Ir, Ni/Ir and Cr/Ir ratio are considerably higher than that of the average continental crust, which the authors suggest is consistent with chondrites.


What is the life-cycle of agricultural water used to grow crops/animals? A là this Slate article:

1 gallon of water is required to grow a single almond
220 gallons to grow a large avocado
5,000 gallons to grow 1 lb of beef

None of these things weighs anywhere near their water weight. So what happened to the water -- was it recycled to ecosystem?

Secondary question: because of the severe drought, California has imposed restrictions on water usage by agriculture. I'm wondering if most of this water ends up as ground water or if it vaporizes up into the atmosphere and blows with the winds... or there's no telling really where it goes?

The water cycle isn't geology, but it's important to pedology, which is an earth science.

Agricultural water can be converted (by photosynthesis) directly into simple carbohydrates that we eat; or converted into carbs and then used as structure or energy that keeps the organism alive and growing, but isn't the mass we finally eat; or used to build more complicated parts of the organism (fats, protein) that we finally eat; or transferred to the atmosphere (mostly) because none of these biological processes are leak-proof; or transferred to the atmosphere or groundwater because we don't get all the water to the plant roots exactly when the plants can use it.

If we eat meat, there's all of the above in making the plants the animal eats, and then even greater inefficiency in turning water-in-plants into animal flesh, and the greater structure and energy costs to keep the animal alive and growing.

The crops listed are not simple carbs, or even self-fertilizing legumes. It takes a lot of tree to make an almond or an avocado. It takes a lot of water to grow the alfalfa and grains that we fatten cows on. There's also water in the processing, the cold chain, often in generating the power that makes nitrogen fertilizer or moves food from California (CA) to the markets.  CA's main ag land is dry and warm and often windy in the summer, so it can lose water really quickly (either through the plants or from flood or overhead irrigation, and even a little bit through mulched soil).

I don't know about all of CA (it's a big place with a lot of different climates), but at least some -- the west side of the Central Valley -- is having soil trouble because they rarely get enough irrigation or rain to flush salts and excess fertilizer out of the root zone, so they at least aren't sending excess water to groundwater. One could check stream gauges to guess whether excess water is making it into surface water -- my guess, not.


What caused peak CO2 to rise, starting about 400,000 years ago? This question assumes the accuracy of this (and similar) charts.

Source of image.

From the image, CO2 peaked at about 260, perhaps 265 ppm during the interglacial periods between 800,000 years ago to the interglacial which ended about 480,000 years ago.    Beginning around 400,000 years ago, CO2 ppm reached about 280 ppm and repeated or exceeded that peak during the next 4 inter-glacial periods.

I understand that CO2 can play a feedback role, where as the oceans warm, less CO2 is absorbed and that can lead to higher CO2 ppm in the atmosphere, but whether the question is focused on the CO2 ppm or ocean temperatures, it's basically the same.   What was the cause for lower peak temperature and/or lower ocean temperature leading to lower peak CO2 in the atmosphere during that time period.

Northern Hemisphere insolation doesn't explain it.   That underwent even wilder swings during the lower peak CO2 period.

First things first: There's nothing per se wrong in science with answering "We don't know" to a vexing problem. This might well be one of those cases.

The question you are asking was asked by Imbrie and Imbrie in 1980. The problem you have noticed (a very strong interglacial despite low Milankovitch forcing) is now known as the "stage 11 problem", and this appears to be closely associated with the transition from a ~41000 year glacial cycle to the ~100000 year cycle we have seen for the last 900000 years.

Why "stage 11"? This is a reference to the concept of Marine Isotope Stages, depicted below. The Marine Isotope Stages refer to the abundance of oxygen 18 relative to oxygen 16. Water made of two protons (hydrogen) and one oxygen 16 atom evaporate more readily than does the slightly heavier water centered on an oxygen 18 atom. This makes the oxygen 18 levels in oceanic deposits a very nice proxy for climate.

Source: https://skepticalscience.com/print.php?n=1703

Three key transitions can be seen in the above graph. The glacial cycle started to change from a ~41000 year period to a ~100000 year period a bit less than one million years ago. The second transition occurred after MIS 17 when glacials shifted to being more extreme. The third transition, the one that you noticed, occurred after MIS 12 when interglacials shifted to being more extreme. This latter shift is the core of the "stage 11 problem".

The key issue with explaining the observed ~100000 year cycle is that the Milankovitch forcings for a 100000 cycle are rather low while the Milankovitch forcings for a ~41000 year cycle are very strong. The stage 11 problem gets at the very heart of the 100000 problem because stages 12 and 11, which mark an extremely large swing in climate, occurred when Milankovitch forcings were very low. One non-solution of this stage 11 problem is that the onset of stage 11 (or possibly the onset of the preceding stage 12) represents when the 100000 year cycle finally took full control. This is essentially the argument made by Berger and Wefer.

So, rhetorically, what did cause this shift from a glacial cycle of ~41000 years to ~100000 years, and why did it take half a million years for this transition to become complete? A partial explanation by Abe-Ouchi et al. is that something happened between 0.4 and 1.0 million years ago that enabled hysteresis loops. Instead of disappearing on a 41000 cycle, ice instead built up to such thick levels that all of the ice didn't melt at what would have ended a 41000 year glaciation. Once that happened, it wasn't much of a jump to survive two 41000 year cycles. But by then the ice had become so very thick that all that was needed was a mild forcing from warming to make the ice melt catastrophically.

This still falls in the "and then magic happens" category. One very plausible hypothesis that has gainied a lot of traction (e.g., Bintanja and Van de Wal) is that those massive ice sheets eventually pushed the built-up regolith from the 200+ million years since the previous ice age (the Karoo) either out to sea in the north or in huge piles of glacial drift to the south.

The initial glaciation events of the current ice age that started about 2.6 million years ago were rather weak in part because regolith makes for a rather nice ice lubricant. Those comparatively weak glaciation events continued for the next 1.6 million years, at a 41000 year interval. Much of the regolith had been pushed out of the way by a million years ago. While regolith is slippery (to ice), bare rock is anything but. This stickiness enabled ice to build up to the extent that those hysteresis loops could start to form, sporadically. It took another half a million years for the transition from a purely Milankovitch-driven 41000 year cycle to a Milankovitch+hysteresis 100000 year cycle.

References:

Imbrie, John, and John Z. Imbrie. "Modeling the climatic response to orbital variations." Science 207, no. 4434 (1980): 943-953.

Berger, W. H., and G. Wefer. "On the dynamics of the ice ages: stage-11 paradox, mid-Brunhes climate shift, and 100-ky cycle." GEOPHYSICAL MONOGRAPH-AMERICAN GEOPHYSICAL UNION 137 (2003): 41-60.

Abe-Ouchi, Ayako, Fuyuki Saito, Kenji Kawamura, Maureen E. Raymo, Jun’ichi Okuno, Kunio Takahashi, and Heinz Blatter. "Insolation-driven 100,000-year glacial cycles and hysteresis of ice-sheet volume." Nature 500, no. 7461 (2013): 190.

Bintanja, R., and R. S. W. Van de Wal. "North American ice-sheet dynamics and the onset of 100,000-year glacial cycles." Nature 454, no. 7206 (2008): 869.


If there's more water in the atmosphere due to global warming, how are there fewer mountain glaciers? As I understand it, moisture condenses at mountain tops to form the mountain glaciers that provide water. The mountain topography doesn't change much in the span of a few decades, so if there's more moisture in the atmosphere due to rising global temperatures, then it seems like there should be more water to condense on these mountains. But somehow, there's even less mountain ice, why?

Indeed some glaciers are growing and gaining mass due to increased precipitation (in part due to climate change and enhanced atmospheric water content). But that's the case only for glaciers in very cold places, like East Antarctica, where most glaciers appear to be growing at increasing rates (1,2). But unfortunately West Antarctica is pretty much a desert; the total precipitation on average is less than in the Sahara Desert. That is usually the case in very cold places. The capacity of air to hold dissolved water decreases exponentially at lower temperatures. Therefore cold glaciers (the ones that are most often growing) account for a small amount of the total global ice mass change.

In contrast, temperate glaciers (i.e. not so cold) constitute the majority of the most well known mountain glaciers (outside Antarctica and the High Arctic). These in many cases are receiving more precipitation, but the increases in accumulation are in most cases offset by the increase in temperature, which have a double impact:

More melting due to higher temperatures
A larger fraction of the precipitation falls as rain instead of snow, therefore promoting melting instead of accumulation.

That last point is not that intuitive, but as explained in this question and answer, warmer air carrying more moisture will develop water droplets quicker, therefore dropping most of the extra moisture at lower elevations. As a consequence, the rain-driven melt in the lower areas of the glacier will overcome the a moderate increase in the accumulation at higher elevations.

Also, there is a positive feedback kicking in against the glaciers: The more the glacier melts, the lower its surface will be, therefore it will be exposed to warmer temperatures leading to further melting, leading to more surface lowering, exposing it to even higher temperatures, producing even more melting and so on.

It is also important to note that glaciers grow due to snow accumulation. It is unclear to me if that's what you meant by "moisture condenses at mountain tops".

Finally, it worth noting that glaciers have been receding since the last ice age about 20,000 years ago (as we have learned from Oxygen isotopes on foraminifera deposits and glacier deposits), the recession slowed down the last ~6,000 years slowly approaching to a steady state. However, recent warming has just accelerated the process a bit, enhancing the extent and speed of the natural deglaciation, but we have to acknowledge that the glaciers were already out of balance and shrinking way before the industrial revolution.


When did wildfires start to occur on earth? An oxidizer, fuel, and heat are needed for a fire.  When considering oxygen as the oxidizer, an oxygen concentration of approximately 16% is required for combustion.  Plant material is the fuel considered when thinking of a wildfire.  A couple examples of natural heat sources could be lightning or lava.

According to the diagram below, plants as a fuel source would not be available until at least 1 billion years ago.  Atmospheric oxygen concentrations of at least 16% did not occur until approximately 500 million years ago.  Therefore, I would guess that there is no evidence of wildfires until within the last 500 million years.  What I'm wondering is what is the earliest known evidence of wildfires?

Source: Oxygen Atmosphere

A definitive statement comes from the abstract of Scott and Glasspool1, 2006:

  Charcoal, a proxy for fire, occurs in the fossil record from the Late Silurian (≈420 Myr) to the present.

One of the tired old truisms you learn is that fire needs three things: Oxygen, fuel, and a source of ignition.

There is little doubt that there has been lightning since Earth's formation. (Wikipedia:Paleolightning). There appears to be evidence of the fossil fulgurite from the Proterozoic Eon.

Oxygen levels were probably sufficient around 470 Myr. (Wikipedia:Fossil record of fire)

So as soon as plant-based fuel appears on land, there is evidence of fire.

Although there is evidence for land plants for as far back as 850 Myr, and some evidence for land-based bryophyta (moss) appears in the Ordovician Period, evidence of widespread plant colonization of the land, and plants with vascular tissue that can dry out into fuel, do not appear until the Silurian period with the appearance of Cooksonia and other early tracheophytes. (Wikipedia: Evolutionary history of plants)

The level of oxygen in the atmosphere does appear to play a role, as there is a gap in the Mid-Devonian period, apparently coincident with a dip in oxygen levels (to about 13%), but there doesn't appear to be a consensus on that. At any rate, fossil charcoal picks up again in the late Devonian as oxygen levels rise again.

1 Andrew C. Scott and Ian J. Glasspool, The diversification of Paleozoic fire systems and fluctuations in atmospheric oxygen concentration,Proc Natl Acad Sci U S A. 2006 Jul 18;103(29):10861-5. Epub 2006 Jul 10.
(Abstract at https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1544139/#!po=0.694444)


How much reduction of insolation (solar energy) would be required to stop global warming? Suppose a giant sheet of semi-reflective mylar (or some other kind of partial sun-screening material) was temporarily placed into space between the Earth and the Sun with the intent to lower the amount of solar energy reaching the surface of the planet.

How much solar radiation (and in what frequency ranges) would need to be filtered to cool the planet to the most-desirable global temperature? Also, would the entire planet need to be shaded or just a key area like the Equatorial region?

Obviously the plan would be to reduce the warming effect without dramatically darkening the day since so many plants require the visible spectrum of sunlight to live.

It's not that hard to make an estimate.

CO2 traps about 2 watts per square meter.   Direct sunlight at 1 Astronomical Unit is about 1,360 watts per square meter, but spread out over the earth, average night and day it's about 1/4th of that about 340 watts per square meter.  (note, Casey's point is valid, it's probably better to use the number of watts that hits the Earth, so, my estimate is likely a bit low)

There may be more detailed and specific ways to look at it, but this is probably pretty close.   If you shade enough sun to reduce 2 watts out of 340, or 1/170th, that should balance out climate change, at least at current levels.

From space, you can view the earth as a disk in terms of area needed for shade, so the 2D area of the earth is about 127 trillion square meters, and 1/170th of that, about 750 billion square meters, or 750,000 square KM, slightly larger than Texas and as you get closer to the sun, the area needed is reduced by the square of the relative distance.

Still, that's no easy task, to put up a shade the size of Texas into space and it's no easy task to keep it there as it would in effect by a huge solar sale and likely enormously heavy.   It's far easier to simply build mirrors on earth than try to build something in space and I've seen that discussed as a possible solution to climate change.   of-course, they'd need to be kept clean to be effective, it would require maintenance, but it's probably doable.

Source (1,360 watts):  http://earthobservatory.nasa.gov/Features/EnergyBalance/page2.php

sources, 1.5-2 watts per square meter, CO2  (I went with the 2 watts estimate cause that includes CH4).   http://www.easterbrook.ca/steve/2012/01/how-much-extra-energy-are-we-adding-to-the-earth-system/ and https://en.wikipedia.org/wiki/Radiative_forcing


What does groundwater consist of? I heard that groundwater is rich in minerals and fluorides, but I have no clear thoughts on what else it contains and whether the ground water differs from area to area.

Can someone please shed some light about what groundwater actually consists of? Is it drinkable?

Groundwater consists mostly of water, obviously.
Usually, "minerals" in water (for example in bottled water) are actually not minerals but rather dissolved ions. Strictly speaking, minerals are solids. Fluoride, then, is also a "mineral", and actually a dissolved ion.

Groundwater usually begin their life as precipitation: rain, melting snow, etc. These are usually clean and pure (as in distilled) waters and once they percolate through the ground they pick up ions from the rocks and from the soil.
For example, groundwater in areas rich in limestone will have high calcium contents. So yes, there are differences in different areas.

Groundwater is mostly safe. However, there are cases where it isn't. Most commonly, groundwater contaminated by man-made sources. Leaks from factories, improper water treatment, etc. Also, some groundwater may be acidic (low pH) or basic (high pH, 1). While this may be desired in natural hot spas, this is not something that would be safe to drink. Groundwater may also be contaminated with arsenic or with radium (2), a radioactive element that occurs naturally in Uranium-bearing rocks (e.g. granite).

References from my local area:

(1) Saines, M., Dickson, P., & Lambert, P. (1980). An occurrence of calcium hydroxide ground water in Jordan. Groundwater, 18(5), 503–503. doi:10.1111/j.1745-6584.1980.tb03427.x

(2) Vengosh, A., Hirschfeld, D., Vinson, D., Dwyer, G., Raanan, H., Rimawi, O., … Ganor, J. (2009). High naturally occurring radioactivity in fossil groundwater from the Middle East. Environmental Science & Technology, 43(6), 1769–1775. doi:10.1021/es802969r


How do we calculate if a meteoroid will completely burn up in the atmosphere? Most meteoroids burn up in the atmosphere, so they don't impact the Earth's surface.  Factors that seem important include:

size and mass of the meteoroid
angle of meteoroid's path through the atmosphere
latitude where meteoroid enters Earth's atmosphere
speed of meteoroid relative to Earth's movement

Are there other factors that are needed to calculate if a meteoroid will burn up in the atmosphere?  How do we calculate if a meteoroid will completely burn up in the atmosphere?

The density & composition of the meteoroid would be important.

There are three main types of meteoroids:

Iron
Stone, &
Iron-Stone

Iron meteoroids are dense & would be somewhat resistant to burning up.

Stone meteoroids are composed of grains of material. The composition of these meteoroids is 75-90 percent silicates. They tend to resemble terrestrial rocks.

Iron-stone meteoroids contain approximately equal amount of iron and stone material.

Another factor to consider is the shape of the meteoroid. A meteoroid that is rounded will have better streamlining properties that a meteoroid that is more angular or elongated in shape. Being more streamlined, less of the meteoroid will be exposed to burning air as it travels through the air at high speed. Also, the more streamlined the meteoroid the more likely one aspect will be exposed to high heating than a meteoroid that is more angular and rotating/tumbling as it travels through the air.


What is a source of worldwide temperature data that also includes extreme weather? I often need to calculate heat balances for large biogas plants, an important factor is outside temperature. I normally use the weather data from Klimadiagramme.de where I can find the mean monthly temperature and precipitation. This allows me to calculate the heat demand of my plant for a given month reasonably well. However, I also need to know extreme weather. I'm not sure what the metric here is, but I'm not looking for "the coldest night in the last 100 years" but "this was the coldest average over 2-3 days in the last x years" or something similiar.

So, what is a good, free source of climate data that gives me information about extreme weather events as described?

CLIMDEX, the "Datasets for Indices of Climate Extremes" is probably the closest you are going to get, for any pre-computed indices. The 27 indices it includes are listed on the indices page of that site.

Unfortunately, it doesn't include anything like "coldest 3-day average per year", let alone "coldest 3-day average over the last 5 years". I doubt there would be any pre-built dataset with exactly that index, and there is unlikely to be online tool that would calculate unusual indices, because the data sets are huge (HadCRUt4 is 20MB for monthly data over the last 150 years), and unusual indices would have to be calculated on the fly - something that's just not feasible on the 'web.

I would guess that you'd have to calculate that yourself, from a raw daily temperature dataset. Unfortunately, I don't think such a thing exists on a global scale. However, a reanalysis product like the NCEP/NCAR Reanalysis is probably good enough for your purposes. However, you'll need to be familiar with large data analysis - the daily surface temperature dataset is over 450MB.

Depending on your exact usage requirements, you might be better off just looking up some of the historical records for neighbouring meteorological stations and using those.


How are Quaternary alluvial deposits differentiated in subglacial latitudes? The USGS maps of coastal California label alluvial deposits as Qyf and Qof — the “younger” and “older” fans of coarse sediments. But in areas of the earth that never saw Quaternary glaciation (like California), does that distinction make any sense?
More generally, in lower latitudes, how is “younger,” meaning Holocene, any different geologically from “Older,” meaning Pleistocene?

They seem to be differentiated according to their morphology, Qof deposits being highly dissected and more consolidated than Qyf, thus older. From a random pamphlet of the map series:

Qyf Alluvial fan deposits (Holocene)—Unconsolidated, heterogeneous layers of sand, silt, and gravel; relatively undissected; deposited by streams emanating from canyons onto alluvial plains; identified primarily by fan morphology and topographic expression. Internal contacts delineate individual alluvial fans
Qof Alluvial fan deposits (Pleistocene)—Discontinuous or highly dissected deposits of semiconsolidated, moderately to poorly sorted layers of silty clay, silt, sand, and gravel

The pamphlet also states that "unit ages [...] reflect local stratigraphic relations", so they are relative ages, not absolute dating.


Dew point variation in a day Is this true?
"If there are no weather front or severe weather systems, then the dew point within a single day is fairly constant, no matter how large the day/night temperature variation."

From a review of weather observations, that statement is false.

Below are  the synoptic weather maps for Australia for 11 August 2015 and  12 August 2015. There are no weather fronts, or adverse weather in the western two-thirds of the continent.

Alice Springs (lat:-23.8, long: 133.89) is in the centre of the continent. It's weather observations for 11 August 2015 reveal the temperature ranged between $5.8$ $^oC$ and $26.0$ $^oC$ and the dew point  range was between $-18.8$ $^oC$ and $-2.5$ $^oC$.

Similarly for Darwin (lat: -12.42, long: 130.89), which is located on the coast in the sub tropics, in the central north of the country, the temperature range for 11 August 2015 was $19.7$ $^oC$ to $30.1$ $^oC$, while the dew point range was $15.4$ $^oC$ to $19.8$ $^oC$.

Perth (lat: -31.93, long: 115.98), on the southern western coast has a temperate Mediterranean climate. It's temperature range was $10.2$ $^oC$ to $17.6$ $^oC$ and the dew point range was $5.7$ $^oC$ to $11.7$ $^oC$.

Adelaide (lat: -34.95, long: 138.52), on the southern coast, in the centre region , also has a temperate climate and its temperature ranged from $7.6$ $^oC$ to $15.4$ $^oC$ and the dew point range was $-0.3$ $^oC$ to $8.5$ $^oC$.

Lastly, Brisbane (lat: -27.39, long: 153.13) which is on the east coast  had temperatures between $8.2$ $^oC$ and $21.9$ $^oC$ and the dew point varied between $6.9$ $^oC$ and $15.8$ $^oC$.

All these weather observations show significant variance in the dew point for these locations given the respective temperature ranges and the lack of weather fronts and adverse weather systems.


Why does the Earth's crust have more aluminum than magnesium while the Sun has more magnesium than aluminum? Magnesium represents 0.07 % of the composition of the Sun's photosphere while aluminum represents 0.006 %. Therefore, there is much more magnesium than aluminum in the Sun's photosphere.

But the same does not happen in the Earth's crust, where magnesium represents 2.9 % of its composition and aluminum represents 8.1 %.

Is there a particular reason why this is so?

On the earth as a whole, there is much more magnesium than aluminium.
Your question is why, specifically in the crust, there is more aluminium than magnesium.
The reason is that Mg is a compatible element whereas Al is an incompatible element. There were several questions here that addressed some aspects of this topic, for example:
What are the high field strength and large ion lithophile (HFS or HFSE & LIL or LILE) elements?
What was the likely composition of Earth's early crust (how did crustal composition evolve)?
Why silicon is abundant in earth surface?
Why do felsic materials have lower melting points than mafic?

Why is there more Al than Mg in the crust?
In earth's (upper) mantle, most Mg is inside the mineral olivine, with some in other minerals such as clinopyroxene and orthopyroxene. In contrast, most Al is in the minerals plagioclase, spinel, and garnet. There could be a tiny amount of Al in the pyroxenes as well.
When you melt the solid mantle rock that is composed of all of the minerals I listed above, some minerals melt at lower temperatures than the others. So the magma composition that is formed more closely resembles those minerals that melted.
As you can guess, the Mg-rich minerals are refractory (that is, they are harder to melt). The Al-rich minerals are usually very easy to melt. So whenever you have magma that comes from the mantle into the crust, it will have more Al than Mg. Over the billions of years of Earth's crustal evolution, quite a lot of Al (along with Na, K, Fe, Ca, and Si) accumulated in the crust, relative to the amount that was in the parental mantle.


How to plot a Hovmoller diagram in MATLAB? Im trying to create a Hovmoller diagram in MATLAB but I'm very new to programming and have no clue what to do. Im trying to do it for vorticity. Below is the code that I have currently. Any input or advice, would be greatly appreciated.

path(path,'/Users/zoleak/Documents/');
lev_name='700';%mb

disp(strcat('calculating mean fields...',lev_name,'mb'))

file1 = '/Users/zoleak/Documents/Datasets/Patricia/ERAi.T.00.2015.1p5.45N45S.nc';
file2 = '/Users/zoleak/Documents/Datasets/Patricia/ERAi.U.00.2015.1p5.45N45S.nc';
file3 =  '/Users/zoleak/Documents/Datasets/Patricia/ERAi.V.00.2015.1p5.45N45S.nc';
file4 =  '/Users/zoleak/Documents/Datasets/Patricia/ERAi.GEO.00.2015.1p5.45N45S.nc';
file5 =  '/Users/zoleak/Documents/Datasets/Patricia/ERAi.VORT.00.2015.1p5.45N45S.nc';
file6 =  '/Users/zoleak/Documents/Datasets/Patricia/ERAi.PV.00.2015.1p5.45N45S.nc';

%Read files in
lat=ncread(file1,'latitude');
lon=ncread(file1,'longitude');
levels=ncread(file1,'level');
u_data=ncread(file2,'u');
v_data=ncread(file3,'v');
vort_data=ncread(file5,'vo');

%Format Files
x=lon(28:121);
y=lat(1:31);
[nlons,nlats,ntimes]=size(vort_data);
u_data=u_data(28:121,1:31,4,:);
v_data=v_data(28:121,1:31,4,:);
vort_data=vort_data(28:121,1:31,4,:);

u_data=squeeze(squeeze(u_data));
v_data=squeeze(squeeze(v_data));
vort_data=squeeze(squeeze(vort_data));

%%

clf;

lat_avg=mean(vort_data(5:15,:,:),1);

LONLIMS=[-139.5 -60];
LATLIMS=[0 30];
[lon_plot,lat_plot]=meshgrid(x,y);
proj('mercator','lon',LONLIMS,'lat',LATLIMS);
%m_quiver(lon_plot,lat_plot,u_data(:,:)',v_data(:,:)','LineStyle','-','Color',[0 0 0],'AutoScaleFactor',2);
hold on;
contourf(lon_plot,lat_plot,lat_avg(:,:)','LevelList',[-6e-4:1e-5:6e-4],'LineColor','none')
coast('patch',[1 1 1],'linewi',2);
grid('linewi',0.5,'tickdir','out','linest','none');
set(gca,'FontSize',14);
set(gcf,'Color','white');
hcb=colorbar('eastoutside');
title(['5N-20N,700mb Vorticity']);
set(hcb,'YTick',[-1e-4:1e-5:1e-4])
caxis([-.5e-4 .5e-4])
save_name1=strcat('/Users/zoleak/Documents/figures/HOVMOLLER/PAT_VORT');
print(save_name1,'dpdf'-r600);

Here is an example using contourf. The trick is in sampling the 3D arrays appropriately:

    x=linspace(0,pi,20);
y=linspace(0,pi,10);
t=0:10:120;
[X3d,Y3d,T3d]=meshgrid(x,y,t);
[X2d,T2dx]=meshgrid(x,t);
[Y2d,T2dy]=meshgrid(y,t);

dat3d=7*sin(X3d)+5*cos(Y3d)+T3d/max(T3d(:))+rand(size(X3d));
dat2dx=7*sin(X2d)+5*cos(y(5))+T2dx/max(T2dx(:))+rand(size(X2d)); % at y(5)
dat2dy=7*sin(x(12))+5*cos(Y2d)+T2dy/max(T2dy(:))+rand(size(Y2d));  % at x(12)
%%
figure(1);clf
contourf(X2d,T2dx,dat2dx);
shading flat; colorbar
ylabel('Time (days)')
xlabel('X distance (km)')
%%
figure(2);clf
contourf(Y2d,T2dy,dat2dy);
shading flat; colorbar
ylabel('Time (days)')
xlabel('Y distance (km)')
%%
figure(3);clf
subplot(221)
contourf(squeeze(X3d(5,:,:)),squeeze(T3d(5,:,:)),squeeze(dat3d(5,:,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('X distance (km)')
title('Hovmoller at y(5)')
subplot(222)
contourf(squeeze(Y3d(:,12,:)),squeeze(T3d(:,12,:)),squeeze(dat3d(:,12,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('Y distance (km)')
title('Hovmoller at x(12)')
subplot(223)
contourf(squeeze(X3d(8,:,:)),squeeze(T3d(8,:,:)),squeeze(dat3d(8,:,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('X distance (km)')
title('Hovmoller at y(8)')
subplot(224)
contourf(squeeze(Y3d(:,17,:)),squeeze(T3d(:,17,:)),squeeze(dat3d(:,17,:)));
shading flat; colorbar
ylabel('Time (days)'); xlabel('Y distance (km)')
title('Hovmoller at x(17)')


Where oil is used for I am trying to study climate change and lately, I am realizing that oil companies were/are drilling for oils at Alaska, Arctic, Antarctica.
Where oil (which oil company drills) is used maximum for?
I am looking for some exhaustive list.
I am reading some sources but they are mostly vague and too shallow like for gas in vehicles , electricity etc.
Any answer which provides exhaustive list or exhaustive material which I can study (even books are cool with me) are appreciated.

OilPrice

Petrochemicals are used to make numerous products.

Source


Surface temperature in early hadean period I am considering earth's internal heat budget for a project in university. For this I need an estimate on the temperature of the earth shortly after it had formed.

In Kelvin's On the Secular cooling of the Earth he estimates the earth's temperature to be around 3800°C initially. This seems to get cited a lot but I have a hard time securing sources for why this value is a logical guess. Any help is appreciated.

It's a can of worms with no definitive answers, not least because, apart from a few ancient zircons, almost all the evidence has been obliterated by later processes.
Critical factors would have been the rate of crustal recycling, the rate and distribution of heat from radioactive decay, the extent and intensity of the greenhouse effect, the onset of plate tectonics, ratyes of magmatic differentiation, and the role of water in the early crust. Develop a model with your own set of assumptions - it's as likely to be as accurate as any of the multitude of models already existing.
The Hadean in total lasted about as long as the Phanerozoic, and even the early Hadean would have been not less than 100 M.a. in duration, over which time conditions changed massively.
Some temperature estimates for the Hadean include:

Early Primitive mantle, about 1650 to 1850 deg C
Mafic zircons 750 to    850 deg C
Late Hadean zircons from Jack Hills, West Australia, 700 deg C
Crustal rocks with plate tectonic under-thrusting, 600 deg C.

So my best guess for the early Hadean surface: Not far short of 2000 deg C.


Dataset for expected sea level rise in case of massive meltdowns (Greenland/Antarctica) Around the time climate change became a 'public issue' (let's say shortly after An inconvenient truth came out), figures started getting published about the expected (global) sea level rise in case of 'catastrophic' meltdowns of the large land ices masses.
Quoting from Table 4.1 in the 2013 IPCC report (Ch. 4, the Cryosphere) these are approximately:

58.3 meters for the Antarctic ice sheet
7.4 meters for the Greenland ice sheet

Other reports quoted similar numbers, e.g. in Poore, R.Z., Williams, R.S., Jr., and Tracey, Christopher, 2000, Sea level and climate: U.S. Geological Survey Fact Sheet 002–00 this was split into:

East Antarctic ice sheet: 64.8
West Antarctic ice sheet: 8.1
Greenland: 6.6

These are world-wide numbers, i.e. sea level rise would be distributed equally over all oceans.

Somewhere in 2013 (IIRC) new research came out, also considering the gravitational effects of the ice masses themselves, which result in a non-uniform distribution of the meltwater (example).
In my country, The Netherlands, the expected sea level rise in case of a Greenland 'meltdown' would not be 6 meters, but less, in the order of 2-3 meters.
IIRC, sea level on the eastern US coast would actually drop in this scenario.

Question: I'm looking for a dataset showing the expected sea level rise, at any place on earth, taking these gravitational effects into consideration, for the 3 scenarios 'melting of Greenland, Western Antactica, entire Antactica'.

I would like to use this to have people indicate where they live, and then show them what would happen at their place.

So this would have the following requirements:

inland data available as deep inland as the land would be affected (that's coastal regions and preferably rivers as well);
input could be longitude/latitude. I would have to convert city names or map coordinates to this;
for practical reasons I'm looking for off-line data that I can download(unreliable Internet available at the place I want to use this).

I'm not sure what scale/resolution would be required, I'm letting that depend on what's available.

Note: I could've asked this question on OpenData, but my guess is I'll have more success here.

You should try to use the equations and maps presented by Mitrovica et al., (2011), entitled On the robustness of predictions of sea level fingerprints.  In this paper they present the history of sea level rise equations and then present their own robust equation with comparisons.  There are maps showing the differences as well.  Soon they will provide fortran code so that you can try it out yourself, which will be published here.


Is there an Existing Model of Computing Rice Sufficiency? I've been researching agricultural systems out of my curiosity.
And so I've been thinking how do the Officials know that the Rice Produce or YIELD, will be satisfiable to a certain country, or small village.

My question is: "Is there an existing model for computing Sufficiency for a place based on Yield of rice, and the Demand of the Population?"

Most likely I aim for a Percentage Output, but anyway I can alter.

If there's none can you enlighten me of some Key terms, That can lead me into building one myself. Can be Studies, articles or Algorithms, and Approaches.

Rice production and yield, like any other agricultural crop depends on a number of factors. These include, but not limited to:

The variety of rice being grown
The fertility of the soil, and this can and does vary between regions
in countries
The availability of water for the variety of rice
Loss due to pests or natural events (ie weather)

When new varieties of rice are developed, test plots are planted in various locations and the yield per area of land, typical tonnes per hectare, are ascertained. Once this has been done for a number of test plots and for a number of growing seasons, average numbers of tonnes per hectare can then be applied to larger/national plantings.

Combine this with data regarding the number of people that need to be fed and the determined average of the amount of rice each person needs it is possible to determine the sufficiency of a rice production.


Why is the north considered as up, and south as down? This question popped up in my head while watching LOTR, in wich a tree says: going south always feels like going down.

There is no good reason. It's simply a convention that someone started a long time ago and that stuck. Like the question whether an hour is divided into 60 minutes and a minute into 60 seconds.

If you go to Australia, you will find plenty of maps for tourists that show Australia at the top and Europe at the bottom.


Why are frontal zones connected to low-pressure systems but not to high-pressure systems? Frontal zones (e. g. a warm or a cold front) are connected to low-pressure systems. But why do high-pressure systems not have frontal zones?

Not only are fronts associated with (extratropical) lows, but by in large, fronts are extensions of those lows, as shown by the following hand analysis (from the US Storm Prediction Center):

There's a lot going on in the image, but try to focus on the many black lines, which show pressure: they're kinked around each front (and even the dryline).  This indicates that the pressure is higher on either side of the front.  (for another good example: this set of images from the 1993 Storm of the Century from the National Weather Service).  Now the kinks in these drawings aren't caused by the actual layout of observation in the image, but added by the understanding of the meteorologist performing the analysis.  Generally observation sites are too widely spread out to see the small pressure kinks.  However, they do sometimes show up in high-resolution numerical weather models forecasts, even despite not being in the initial observation data they run from:

(From Hartung as indicated... note that the kinks are up instead of down, but that's actually the same result, still pointing away from the low, showing lower pressure at the center of the kinks.)

Though pressure troughs can be spatially hard to see without extremely dense observation networks, they can be made out instead in temporal plots at single locations.  After all, falling pressure has been noticed as a sign of bad weather as far back as the the dawn of America (I often hear Benjamin Franklin cited, but it appears it goes back further to Otto von Guericke in the 1600s).  For example, this trace of temperature and pressure from a 1911 cold front in Louisville, Kentucky:

(source: Louisville NWS)

So, WHY are fronts low pressure areas?

It goes to its nature in connection to winds.  Consider the images below:

(ETA images courtesy of Iowa State's MTArchive)

The plots are two days apart.  So how do you get the conditions to change from the left image to the right over such a period?  While clouds, storms, and sunlight differences can help drive small contrasts, the only way to get such a large, widespread boundary... is to have winds develop that draw the contrasting temperatures tighter together...

Indeed, this is exactly what forms and sustains a front.  You can look at surface weather maps and almost always see this convergence, or gathering together of winds, at fronts, even if only slight, as indicated in this idealized diagram set:

(Image modified from OKFirst, the education arm of the Oklahoma Mesonet program.  See comments for modifications I made.)

The thing is, there's only a few basic forces that drive wind formation... and in the lower atmosphere, it turns out that the pressure gradient force outweighs the others enough such that, on the large-scale, air always flows from higher pressure towards lower pressure.

So if you put those two ideas together:

To create/strengthen/sustain a front, you need wind converging together
Air at low-levels flows from high pressure to low pressure...

The resulting conclusion is that the location where winds are flowing together... which is the front itself... must be a low pressure area.

(What causes low formation in the first place?
Winds aloft typically coupled with terrain enhancements or other small-scale perturbations.  The strengthening temperature gradients actually feedback to intensify and favorably realign the winds aloft... such that, despite the influx of air into the low pressure (which one might think would "fill in" the low pressure with more air, dimi), the air is actually ventilated from the system, allowing it to deepen to yet lower pressures values and strengthen further... continuing on until finally the upper-level storm system surges ahead of the surface low and/or the frontal boundary occludes, cutting warm air from continuing to flow into the surface low center.)

Can you get divergent winds near a developed front?
Yes... in fact, there's a name for that process, it's called frontolysis. Divergent wind does indeed work to destroy a frontal gradient.  And so rising pressure is found connected to dissipating fronts.  However, rising pressure has a long ways to go before it's actually a high pressure itself!  Long before it would create a bona fide high, the early pressure rises only REDUCE the strength of that local pressure minimum... and during that time the temperature gradient will very quickly begin to blur out and fall below the strength of which we really notice.  At the same time, even in this period of decrease, note that this dissipating "front" would no longer have any of the other typical conditions we expect with fronts (no more rising air motions [UIllinois], which is what in turn creates the unsettled weather, clouds, strong winds, storms, etc).

Why is a front so quick to dissipate?  Well, in large part because it's not a level situation; indeed, some storm energy is continually lost away to friction.  Because of this, a front actually needs continual reinforcement to even maintain its gradient.  Some times the pattern will permit fronts to continue through repeated periods of weakening and intensification as upper troughs pass by.  As a trough comes by and then shifts by on east (in tandem with the primary surface low), the front will start to weaken some... perhaps gradually becoming stationary... only to reignite when the next upper system comes in from the west [stationary fronts aren't, as may often be suggested, a cold front and warm front "at war", but instead rather more like a lull in the "battle", where the cold front has run out of steam, but readied next for the warm air to start surging back north should another trough/low move in to re-fire the convergence].  Often you can see quite a long chain of fronts (troughs) connecting together lows pressure systems across continents... (which work into the shape and positioning to the polar jet stream).  Other times, when the upper systems come less consistently or the upper flow starts to break down/shift into other regions, the front will quickly fade from existence.  So much so that I don't believe you're ever not going to see anything like a true front anywhere near a formative synoptic high pressure... unless maybe a giant meteor or as-of-yet-unseen-in-size nuclear bomb were precisely set loose upon a front.  And then... well I suggest trying to witness the brief time that the high pressure is connected to the frontal boundaries... should probably be the least of your concerns!

Of course an important note is that not all lows have fronts, not nearly.  Only "extratropical" (baroclinic, cold-core) lows have fronts.  Tropical (barotropic, warm-core) lows are symmetrical, and don't generate their energy from horizontal temperature imbalances, but instead when overall warming temperature, typically in the mid-levels, decreases the amount of air in the entire tropospheric column...

Found on the AOML, but originally adapted from Merrill, R. T., (1993): "Tropical Cyclone Structure" - Chapter 2, Global Guide to Tropical Cyclone Forecasting, WMO/TC-No. 560, Report No. TCP-31, World Meteorological Organization; Geneva, Switzerland

And for those of you better versed in the more rigorous science... while looking for material for this answer, I came across an absolutely great resource that may prove helpful to those looking to dig much more at the mathematical formulations of frontogensis/frontolysis, the consequential flow types involved in them, and how they impact forecasting: this awesome guide from NOAA's Warning Decision Training Branch.


Will the Earth ever stop rotating? It is well known that the Earth's rotation is slowing down and that millions of years ago there was a point in time where there was only a mere 20 hours in a day on Earth.

My question is in two parts.  Firstly why is the Earth's rotation slowing given that angular momentum is conserved, and secondly given that understanding, will the Earth either (a) stop rotating in the future, or (b) eventually begin rotating in the reverse direction to what it is now or will it (c) reach a constant rotational velocity in the same direction it is rotating now and why?

I think the answer to the question will depend on whether the Earth's rotation is slowing at a decreasing rate or at a constant rate.

The short answer is "Probably Yes".

The longer answer is that it is debatable whether Earth's rotation will become tidally locked to the moon due to tidal drag, at which point it will not be rotating relative to the moon, or whether the sun's exhaustion of hydrogen and the fusion of Helium will result in the sun's expansion vaporizing the earth first.  As tidal drag slows the earth's rotation, the moon moves further away, reducing its effect on the earth's rotation, and making the calculations fairly complex.

In either case, unless something really unexpected happens to the earth first, such as it being ejected from the solar system, which is completely improbable, it will stop rotating, if only due to it ceasing to be a planet at all.


How likely is that next big earthquake (and tsunami) will hit Philippines again? We recently had an earthquake in Bali (August 5th 2018), then in Palu, Indonesia (October 1st 2018).

Considering the distance and time between Bali and Palu, is it more likely that it will be near Philipines or it is as likely anywhere else?

How likely is that the next big earthquake (and tsunami) will hit the Philippines again?

How likely is that the next big earthquake (and tsunami) will hit the Philippines again?

The likelihood is 100%, but we don't know when. It could be tomorrow, it could be in a year, or it could be in 100 years. Make sure you are prepared for such an event.

The Philippines are situated above a subduction zone (the Philippine trench), so an earthquake is inevitable. However, it is impossible to predict exactly when and where it will happen.

As for tsunamis, these propagate from earthquake epicentres, so the Philippines are susceptible to tsunamis generated elsewhere in the area.

You are drawing a line between the Bali and Palu events, and suggesting that the next  one will be along that line. This is not how it works. The earthquake could be on the line (by chance), or it could not. There is no way of predicting.


How can I find the nearest point on the coast from an ocean location? Given some location of interest $X$ in a lake or in the ocean with known lat and lon, I'd like to find the lat and lon of the coastal location that is closest to $X$, as well as distance between the two points. Of course, once the lat and lon of the coastal point is found, it's straightforward to compute the distance. I know of this DistFromCoast dataset that has the distance to the nearest coastal point, but it does not provide the nearest coastal point itself.

Would anyone know of datasets, software, or algorithms that may help with my task?

There are public databases with the coastline in lon,lat format. You just need to find the point closest to your coordinates in that coastline. For that you need the formula of the distance between two lon,lat points on an ellipsoid. In this article you can find that and an idea of how to do it:
Garcia-Castellanos, D., & U. Lombardo, 2007. Poles of Inaccessibility: a calculation algorithm for the remotest places on Earth. Scott. Geogr. J., 123, 227-233. doi:10.1080/14702540801897809
available here: https://web.archive.org/web/20140629230429/http://cuba.ija.csic.es/~danielgc/papers/Garcia-Castellanos,%20Lombardo,%202007,%20SGJ.pdf


How did the terms "acidic" and "basic" come to be associated with $SiO_2$ in igneous rocks? Students of geology are introduced to in their petrology course, (or used to be), to the terms "acidic", "basic", and the associated term "intermediate" in relation to %$SiО_{2}$ in igneous rocks, where, depending on whom you read:

Acidic: rocks with above 63%/65% silica (mostly feldspar minerals and
quartz), e.g. granite.
Intermediate: rocks with 50%/55% - 63%/65% silica, e.g. syenite, trachyte.
Basic: rocks that are about 45 to 55% silica
(mostly mafic minerals plus plagioclase feldspar and/or feldspathoid
minerals), e.g. basalt.

Of course, if they go on to work with chemists in, say, an environmental geology practice, this causes no small amount of contention and sometimes confusion between the geo and the chemist, who, of course, understands the terms "acidic", etc. in the classic chemical sense, of $pH = -log [H^+]$, etc.

How did the terms "acidic" and "basic" come to be associated with %$SiO_2$ in igneous rocks, in contrast to the classical chemical definition?

Note to Responders: Apologies for my ignorance. It's been over 30 years since I studied and worked in (exploration) geology. So my knowledge of current terminology is a little rusty, especially since my major experience has been that of an geologist transmogrified into an electronic engineer.

The idea came from the theory that silicic acid was the chief form of silicon occurring in rocks.  Early attempts to classify minerals, placed some mineral specimens in groups based acid-base reactions and the hypothetical acid that mineral was derived.  Sulfates, phosphates, nitrates , and tungstates etc.

This thinking was the result of 19th century chemistry research which attempted to explain chemical reactions in terms of  acid-base reactions.

Much of this terminology is still in use today even though it is considered archaic now.


What can one come to know about a mineral just by knowing name I have been busy learning the components of various minerals for upcoming test....is there any way to predict the components or properties of a mineral just by knowing it's name?
Eg: albite,augite, labradorite,biotite,anorthite

It depends, most of the mineral names we use are derived from old Greek names that were basically comments on the appearance or behaviour of the materials so Galena means literally Lead Ore, which it is, Cassiterite is an ancient word for tin, which it is still be main ore of up to the modern day. On the other hand Pyrite means on fire due to its ancient use as a spark source and Hematite simply means blood and is a comment on the colour of certain European deposits. So if you brush up on your Greek you can tell some things about some minerals but others will remain quite opaque.


Sources of $\ce{CO_2}$ during Carboniferous period It is believed that during the Carboniferous period, fungi and bacteria lacked the biochemical means to decompose lignin and release $\ce{CO_2}$ back to the atmosphere. So dying trees carbon became trapped in coal deposits. But whence came all carbon allowing these plants grow?

The terrestrial vegetation makes ca. 500 PgC (i. e. $500 \times 10^{15}$ grams of Carbon) which is rather small compared to the carbon stored in the ocean of ca. 37 000 PgC, see Fig. 6.1 in Ciais et al. 2013 1.
Even if we assume that the fossil fuels reserves are the remainders of the Carboniferous period, they only add up to no more than ca. 2 000 PgC.

The terrestrial biosphere only makes use of a very small portion of the total available carbon.

1 Ciais, P., C. Sabine, G. Bala, L. Bopp, V. Brovkin, J. Canadell, A. Chhabra, R. DeFries, J. Galloway, M. Heimann, C. Jones, C. Le Quéré, R.B. Myneni, S. Piao and P. Thornton, 2013. Carbon and Other Biogeochemical Cycles. In T. F. Stocker et al. (Eds): Climate Change 2013: The Physical Science Basis. Contribution of Working Group I to the Fifth Assessment Report of the Intergovernmental Panel on Climate Change. Cambridge University Press, Cambridge, United Kingdom and New York, NY, USA.