Factors Affecting Soil Profile Soil forming factors can include climate, parent material, vegetation, animal activity, fire and influence by humans.

I have investigated a podzol soil profile with horizons LFH, AH, AE, BF and parent material.

I can see how climate would affect the LFH, AH AND AE. Precipitation has caused these horizons to be cohesive and climate has provided a growing period for plants, which has caused a presence of organic materials in these layers.

Vegetation has also played a role in the LFH, AH and AE. The roots of plants and trees have caused a presence of organic materials in these horizons.

I am not quite sure if animal activity has played a role in the soil profile. Besides the decomposition of bodies and the fertilization by faeces, I am not sure if animal presence has played any more of a role than this. There was also no evidence of fire in these horizons that I witnessed.

My question is, if animal presence is a contributing factor, what horizons would it play a role in?

Also, I'm not quite sure how humans or parent material have influenced soil profile. Looking for some guidance with this.

Other ways that animals can affect soils is by burrowing, overturning soil through digging or ploughing and also through shallow diggings/scrapings.

Burrows create voids/chambers in soils that can allow air to react with soil beneath the land surface. Likewise they provide easier pathways for water to penetrate soil and affect changes that way.

Overturning soil whether its due to animals looking for food or human agriculture buries soil that was on the surface and brings deeper soil to the surface. It also aerates the top portion of the soil and it allows for easier penetration by water and it provides a greater surface area of soil to be exposed to the air in the atmosphere.

Shallow digging or scrapings by animals, particularly in very hard capped soils can create broken patches that allow water to penetrate a hard impervious cap and allow the water to penetrate deeper in the soil than it would otherwise.

Also, once soil has been overturned and aerated, whether by animals or humans, wind can blow away parts of the soil.


Why are weather service atmospheric pressures systematically different from those I measure in Johannesburg? I live in the northern suburbs of Johannesburg in South Africa.
I have noticed while working with synoptic weather charts in geography class that the isobars indicate that Johannesburg should have atmospheric pressure of around 1010-1020 hPa, just like most cities around the coast, even though Johannesburg is at 1500 m above sea level.
Weather service providers also indicate that Johannesburg's atmospheric pressure should be around that.

What confuses me is that my weather station at home (which I have been monitoring for several years now) never seems to show pressure ratings out of 840-860 hPa.
My outdoor watch gives me the same pressures.
I am convinced that my watch cannot be broken because during my holiday in coastal Cape Town, it gave pressure readings of the expected 1020~ hPa and I can "feel" the higher pressure that I am not used to.

Surely both of my apparatus cannot be wrong.

Is there an explanation for this?

They apply a correction to the actual barometer readings and report what the estimated pressure would be at sea level.

Basically they use an imaginary column of air between the barometer and sea level and add its weight to the pressure measured at the barometer.

This lets them make pressure maps instead of just almost altitude maps.

https://www.faa.gov/regulations_policies/handbooks_manuals/aviation/pilot_handbook/media/PHAK%20-%20Chapter%2011.pdf

https://www.ec.gc.ca/manobs/default.asp?lang=En&n=4349ABDA-1


Source of heat in the center of Earth If I read around most of comments and articles on the Internet give two main reasons for the heat found in the depths of our planet :

Super high pressure at the center of it
Radioactive decay

I need clarification on both points.
Pressure: while it's pretty clear why pressure and temperature are bound in gas (*)  this becomes unclear when matter is in solid or liquid phase. Why pushing on a solid mass would cause its thermal agitation to raise? It looks to me like most of the people takes for granted such point without proper analysis which of course involves more physics than geo-science.
Radioactivity: if I put together radioactive matter it will produce heat by radioactive decay. That's fine. Nevertheless my assumption is that if I take 100kg of any matter here at Earth surface it should contain the same percentage of radioactive isotopes of 100kg of same matter taken from the center of Earth. If this is not the case, then I ask my self why we have higher percentage of radioactive isotopes in the center of Earth rather than in its surface?
I've read somewhere that unstable isotopes are heavier and that explains why they accumulated at the center of Earth, just by gravity; but usually radioactive isotopes have just few neutrons more (or actually less!), and that make the element heavier than just 2 or 3 element next to them in the periodic table. For example Carbon-14 is lighter than Oxygen.
Can someone clarify if these two points are valid or not, and why?
(*): even if with volume and mass constant I would say you can augment pressure by increasing temperature and not the other way round as you can't augment pressure under the constraint of having mass and volume constant

depths of our planet

How deep? "Deep" is a relative thing. You can have 10 kilometres deep, or 5000 kilometres deep.

Super high pressure at the center of it

It's not the pressure per se that's causing the heat, it was the process of getting to the pressure when the Earth's formed. Compression creates heat. That's easy to know - just touch a bicycle air pump after filling up. There's also the issue of gravitational potential energy converting into heat once Earth was accreted. The the pressure and heat are together the result of Earth's formation. It's not that pressure itself makes the heat.

Radioactive decay

According to what we know, the three modern heat producing elements (thorium, uranium and potassium) are actually concentrated in the mantle, with an even greater concentration in the crust, which is just the top few kilometres. It's still deep for us humans, but extremely shallow when compared to the core. There is still some debate on this (see the two other answers), but my own personal opinion is that it's safe to say there's very little U Th and K in the core.
Also read my very relevant answer on the World Building website:
https://worldbuilding.stackexchange.com/a/123951/39999


Equations for Global Temperature Models I'm a volunteer for 350, a grassroots organization that is fighting against climate change through education and advocacy. We're all volunteers, not climate scientists, and I'm looking for some knowledge about the equations that climate scientists use to predict global temperatures with respect to time.

I'm aware that most climate models rely on the Navier-Stokes partial differential equations (Climate Models), but I don't have enough knowledge, nor have I easily found a source online that discusses the resulting approximate solution equations that scientists use to make their predictions. I've only seen graphs.

Do you have any references that contain equations from which one can easily make a prediction of temperature for a given year? (I realize that the derivation of such an equation will be complicated, but I'm not concerned about that.)

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

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

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

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

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


Why are South African mountains short and flat? I drove through South Africa from Cape Town to Mozambique and noticed that almost all heights and mountains were no higher than approx 200-400 meters and had a flat top, just like the iconic Table Mountain. Why is this the case?
Thanks.

I suspect you are referring to the mesas and buttes dotted around the Karoo - the large semi-arid plateau that makes up much of South Africa's interior. These are a product of the glacial and geological history of the region. The flat hills are capped by hard, resistant dolerite. This is solidified lava that was forced between the horizontal strata of the sedimentary rocks (which make up most of the Karoos geology) through high pressure. The dolerite erodes much slower than the surrounding rock and forms a flat cap above the underlying rock.

Most South African mountains are actually not like this - Google "Drakensberg" and you will see that the country's most prominent and highest mountain range is far from flat and short!


How much excess water prevents planting of a crop It's a generic question but was wondering if there is a threshold level of soil water beyond which planting a crop (for e.g. soybean) can be hindered because the soil is too wet or flooded.

As a background, for a given location, I have the soil water content coming out of a water balance model. In a real world, how much excess soil water compared to field capacity would ideally prevent planting of crops.The reason I am asking is because I am making a model on planting days where a day is classified as 'no planting' given excess water in the soil.

Please advise.

Thank you.

EDIT

Adding to this, my water model generates soil water content and surface runoff as well

In practice you really don't want to plant a field that is even close to capacity.  Doing so will result in ruts, soil compaction, breakdown of soil structure and a large increase in fuel consumption.

One of the advantages of zero tillage systems is the ability to get out on the field in wetter (earlier in spring) conditions.  All those roots help reduce the sheering between soil particles.


What ore minerals are likely to be found in a thin section like this? What can we deduce from the structure? The following image is of polished sample of mineral-rich rock. There are two major portions we can see that is ore minerals and rest the grayish material is gangue. The photo was taken with an ore microscope.

Sulfide ore petrography is reflected light is even harder than transmitted light. Unlike transmitted light, colour is actually a very important characteristic feature. But the perception of colour can vary between different light sources, quality and time since polish, microscope lens, and cameras. Therefore, from an image like that it is extremely challenging to tell what the minerals are.

In my opinion you have two of either chalcopyrite, pyrite, pentlandite, pyrrhotite. It is very hard to tell. My guess would be pyrite (the bright one) and chalcopyrite/pentlandite (the golden one).

In cases like this, as a way to move forward, do one or both of the following:

Have thin sections where you know the identity of the minerals so you can compare with your unknown, on exactly the same analytical conditions.
Get access to an EDS-SEM system. I know it's easier said than done, but nowadays these instruments are extremely common in almost every research institution, and once you're experienced it takes literally minutes to identify the minerals.


What effect does concretization (paving/flooring with concrete) has on ground water table I am a newbie for hydrology. If the question seems to have "well known answer", I appreciate if you point me to the resources. I will add details to the question based on comments.

Consider a town of 30km x 30km, nearby a hill, in a place where rain averages 40cm per year. The town is at an average elevation of 30m compared to the surroundings. It gets water mainly from rain. The water table seems to drop off as we walk away from the hill (30m near the hill, 90m once we walk 30km away from the hill).

If we concertize the town (fill every road, every open place with concrete 1m thick), what effect would that have on water table (water availability in earth)? Would the water flow away and sink into outer places (away from the town)?

I found this on the USGS website. It states the effect of increased pavement coverage due to urbanization is to reduce the recharge rate of ground water, because the water is diverted elsewhere.

Also, with urbanization comes the use of storm water drains. The rain water that would have soaked into the ground and recharged the ground water is diverted to streams via the storm water systems (pipes and channels) which can result in flooding elsewhere.


Why is northern Australia unsuitable for agriculture? Northern Australia receives substantial rainfall, but its population is minimal.

For instance the Kimberley region in the state of Western Australia gets more than 20 in. of rainfall per year, but has a population density of less than 1 person per 3 sq. mi.(!)

Is there a reason northern Australia is unattractive for human habitation and agriculture?

Erratic Climate

Lets take Broome, Australia as our example. Broome gets 615mm of rain a year (24 inches), including 58/182/180/102mm in Dec through March. Coupled with average highs in the low 90s, this would be fine for the sort of agriculture you see in South Texas. However, Broome's rainfall is very erratic. For example, in 2016, the rainy season started January 15th, with 23 mm of rain over three days. In 2017 (really 2016, again) the rainy season started December 4th. December 2016 also featured 222mm of rain (remember the average is only 58mm) including 113mm on Dec 23rd and 24th. 2016-2017 featured 222/230/249/114mm of rain, with significant rainfall later into April. 2015-2016 featured 0/119/26/28mm of rain. One year saw too little rainfall to grow even millet, while the next year had enough rain to support paddy rice.

Laterite

Old tropical soils in rainy or monsoonal rainy regions tend to have their soils leached of useful nutrients. The resulting soil is called laterite, and it is heavily enriched in aluminum and iron ore. On the one hand, this explains the mineral wealth of tropical Australia. On the other, laterite (alternately called ferralsols, especially by the UN Food and Agriculture Organization (FAO) ) is hard to farm, with few minerals for the plants, poor moisture retention, and the tendency to form an iron-hardened crust in the dry season.

Not enough people

This is sort of a meta-reason, but Northern Australia is a long way from anywhere. Without very many people, it is hard to build a stable agricultural economy. If a bunch of people where sent there and forced to survive, they'd probably eke something out (for example, like the people who first populated Sydney, or South Africa). But since that never happened...population of the reason never happened. Sort of circular reasoning, but without ever having a reason for a lot of people to show up in Northern Australia (prison colony, religious persecution, etc) no one has ever made the infrastructure that successful farming operations could be based off of.


How old are Pecten fossils in general? Many years ago, I found a piece of rock on a lakeside in Switzerland (see picture below).
I think that it could be a "fossil" from some Pecten species (do you agree?).

  My question is: how old such a fossil can be, approximately? Is it like 1000 years, or rather 1'000'000 years?

I have no idea, that's why I just would be interested to have your opinion on this topic.
I don't know if it is frequent or rather uncommon to find such "fossils".

Thank you for your help!

Pectens seem to have evolved from Chlamys in the late Eocene or early Oligocene. The coarseness and rib spacing of Vertipectens has been slowly evolving since the early and Mid-Miocene, so they have been around for at least 16 million years, maybe up to 20 million years. If you want to be precise you will need to read-up on the fine detail. Pectens are a classic case of 'ontogeny recapitulating phylogeny', and their identification is complicated by parallel and convergent evolution of different species. As fossils, they are quite common, and probably more useful as indicators of the palaeo-environment, than as age indicators. Where you find such fossils you will very likely find associated micro-fossils in the same rock, which are more diagnostic of age.


Do Tectonic Plates Merge? I had a question concerning the nature of continental plates.

When looking at the Eurasian Plate today, for the most part, there is one solid fragment of the Earth's crust. However, having had a look at maps detailing prehistoric Earth, this isn't always the case. Throughout the entire Phanerozoic Eon, Eurasia has been a collection of different landmasses gradually merging together. Baltica, Kazakhstania, all the various regions of East and South-East Asia. Yet, today, only India and Arabia are still situated upon separate plates. All others no longer possess any divisions between them.

Why is this the case? I was under the assumption that it was only oceanic plates that submerge into the mantle due their density. I though that when continental plates collide, neither continent submerges, forming mountains. Shouldn't there still be distinct tectonic plates?

Any answers would be greatly appreciated.

Continental collision as Indian Plate with Eurasia one finish in a merge, but the process is slow. An example of merged plates is Iberian Subplate that is presently considered Eurasian Plate.

The collision creates mountain chains as Himalaya. Presently Indian Plate is a separated system because it has still a big granite root under the mountains. While erosion happens, the new geophysical echillibrium bounces new relief to the chain and the root starts to be sutured. There is stil some decenes of kilometers of granite root under the Himalaya, so the chain is still a plate limit.


How old is Casiquiare canal? Casiquiare canal is the world's largest bifurcation. Since such a large bifurcation seems unlikely to be produced and even less likely to stay for centuries, I wonder how old it is and why all the water didn't just stay in Orinoco.

This is a part answer, as pinning down the actual date that the canal formed is not well framed in the literature.

According to the Texas A&M University web-chapter The Vaupes Arch and Casiquiare Canal Barriers and Passages  (Winemiller and Willis, 2011), are quite vague about exactly pinning down the age of the canal, with

  Extensive alluvial sedimentation and channel
  meandering provided subsequent opportunities for drainage
  capture between the Orinoco and Negro headwaters to the
  east of the Vaupes Arch, and at some point the Río Casiquiare
  formed a connection between the upper Orinoco and upper
  Negro rivers

and by using digital maps based on the topography suggest that

  the upper
  Casiquiare course may have been captured quite recently by
  the Pasiba–Siapa–lower Casiquiare drainage network as a result
  of river meandering on the peneplain.

The article The Casiquiare river acts as a corridor between
the Amazonas and Orinoco river basins: biogeographic
analysis of the genus Cichla (Willis et al. 2001) are more direct in stating that

  Unfortunately, the precise timing of the origin of the
  Casiquiare remains unknown

also stating that in studies of the DNA of species in either basin, there seems to be little dispersal between them through the canal.  Specifically noting that the

  Casiquiare River acts as a selective filter, where only
  some species are able to make the transition from
  stained, acidic water in the Negro River to unstained,
  neutral water in the upper Orinoco River.

Winemiller et al. (2008) state in the article Fish assemblages of the Casiquiare River,
a corridor and zoogeographical filter for
dispersal between the Orinoco and
Amazon basins (2009), that

  Hydrologically, the
  Casiquiare represents a stream capture in progress, but there is
  some debate concerning its formation

Secondly, an answer to your question as to why the water does not stay in the Orinoco, it is a question of elevation, according to Winemiller and Willis, (2011), it is a case of flowing downstream from the western edge of the Guiana Shield, the direction governed by the elevations of the two ends of the bifurcation.

  At its origin at the
  bifurcation of the upper Orinoco, the Casiquiare
  is about 90 m wide and lies at an elevation of 120 meters
  above sea level (m-asl). At its mouth at the upper Rio Negro,
  the Casiquiare is over 500 m wide at an elevation
  of about 90 m-asl.

and passes through what Winemiller et al. (2008) describe as an alluvium filled floodplain, that coupled with the meandering and stream capture (mentioned above) has governed the course of the canal.

The Rio Negro being a major tributary of the Amazon River.

Lujan and Armbruster, authors of the chapter The Guiana Shield (2011) assert that

  In the
  future, it is likely that a new drainage divide will form within
  the Orinoco downstream of the Tama-Tama bifurcation, and
  the current headwaters of the Orinoco will become entirely
  adopted by the Amazon


What is the source of the Big Sur river? While hiking in the Ventana Wilderness in Big Sur, Calfornia, I kept trying to figure out one question: what is the source of the Big Sur river?

Wikipedia reports its tributaries being the Redwood Creek, Lion Creek, Logwood Creek, Terrace Creek, Ventana Creek, Post Creek, Pfeiffer-Redwood Creek, Juan Higuera Creek, and Pheneger Creek, but the source of the water is not described therein.

Does any water from the Salinas Valley make it into the Santa Lucia mountain range, feeding into this river, or is it solely fed by rain fall? Does spring water play any role?

This is the response I received after asking a friend who works as an Hydrologist:

  The river is fed by ground water that is slowly leaking out of the base of the mountains. Rain water slowly percolates through the (elevated) soil, which is why the river still runs many months after the rainy season.

Note to other prospective respondents: if you have a more technical/accurate answer to my question, I am still curious about the mechanics of this process, and am  will mark yours as the correct answer.


Why is the temperature *still* rising? 2015 is the hottest year on record, and the average temperature continues to rise.

I don't understand why this continues, as (over the past twenty years) so much work was put into reducing Global Warming over the past 40 years, yet not only does the temperature not fall, it continues to rise more than it did between 1870-1960.

I don't understand something. The amount of industry went through the roof (literally) between 1870 to 1960, and no one cared about the environment

Now that we do care about it, and (at least somewhat) legislate cleaner cars, factories, etc, I would expect the temperature to even out, yet it doesn't

Why not?

"So much work"? Actually, compared to the global rate of greenhouse gas emissions, it's a case of "so little work"! From a scientific perspective the 'economists' solution' of carbon trading was always unlikely to achieve the required carbon cuts, as has been verified by their ineffectiveness over the last decade or so. As farrenthorpe points out, the rate of increase of CO2 is largely population-driven, and hence there is still an inexorable rise in mean atmospheric CO2. The acid test of human efforts to limit global warming is whether the Hawaiian CO2 monitoring graph is flattening off:

It clearly isn't going to flatten anytime soon. In fact, if anything, it is getting steeper. So all the hot air from 'Paris', and previous talkfests, is evidently too little, too late. Realistically, limiting the average temperature rise to less than 2 °C, is now effectively unattainable. We have yet to see what 'all this work' can achieve. So far, almost nothing.


Would the oceans have boiled off if life (cyanobacteria) hadn't evolved on Earth? The emergence of cyanobacteria caused removal of carbon dioxide from the atmosphere, resulting in Earth becoming cooler. That perhaps implies that the Earth's oceans would have boiled off (in billions of years) if life like cyanobacteria didn't evolve. Is it true?

Short answer: no. The life does contribute to the amount of CO2 in the atmosphere and the temperature on the Earth but mostly not by photosynthetic organisms.

The main mechanism, which regulates the temperature and removes CO2 from the atmosphere is silicate and carbonate weathering cycle. In simple model the more CO2 you have in the atmosphere, the more acidic is rain water. More acidic rain can dissolve more of silicate and carbonate minerals and the dissolved minerals are carried to the ocean, where they either precipitate or are used by living organisms to create shells of CaCO3 (calcite) or SiO2 (opal). When these organisms die, many shells are dissolved but some shells fall all the way to the sea floor and are buried.

In simple words: more CO2 -> more (acidic) rain -> more weathering and C02 removal -> more mineral deposits -> less CO2 in the atmosphere -> lower temperature -> less rain

If you want more information with formulas, I suggest looking up for description of carbonate–silicate geochemical cycle.


Why is the Lithosphere-Asthenosphere Boundary an Isotherm? My understanding of the LAB is that it represents the point in the earth where the mantle undergoes a temperature activated mechanical change. The temperature of the boundary depends on the melting point of the mantle and so one could say that the LAB is an isotherm with temperature given by:
$$T=kT_m,$$
where $T_m$ is the melting point of the mantle and $k$ is some constant.

This is how I have had the situation explained to me, and in sources that I have read that the LAB is an isotherm at $\pu{1300 ^\circ C}$.

My only problem with this is that surely $T_m$ changes with depth, and therefore the Lithosphere-Asthenosphere boundary is not an isotherm at all, but depends on the depth at which the boundary is at (for example at a mid-ocean ridge where the boundary becomes shallower towards the ridge axis).

Reading this question, I'm not sure if you realize what an isotherm is - in this case, imagine peeling rock from the surface of the earth until you reached a temperature of 1300 degrees Celsius. Now, in some areas, such as mid ocean ridges, you wouldn't have to peel back much rock at all, perhaps only a few dozen kilometers. Whereas in regions of old, continental crust, you would have to peel off hundreds of kilometers of rock to get down to rock at 1300 degrees centigrade.

The result would be a lumpy sphere at a constant 1300 degrees, which is your isothermal surface or isotherm. The thickness of the lithosphere is very variable.

Interestingly, the Asthenosphere - Mesosphere boundary is created by a mineral phase transition, which is very pressure-dependent; this makes it far more of a smooth sphere.


Is this series of earthquakes near Broome, Australia normal? There have been a series of earthquakes (some strong) near Broom, Western Australia. See this screenshot of the Geoscience Australia earthquakes map:

I didn't believe there were any faults around this area, or any apparent risk factors for strong earthquakes. Is the strength and number of these earthquakes normal normal, or is something odd happening here?

Are you confusing faults with tectonic plate boundaries?

Australia is in the middle of a tectonic plate, but there are countless faults within the plate, as within all the other plates. Each plate is stressed & eventually rock adjacent to some faults moves resulting in a intraplate earthquakes.

As the Geoscience Australia website states:

  Although Australia is not on the edge of a plate, the continent experiences earthquakes because the Indo-Australian plate is being pushed north and is colliding with the Eurasian, Philippine and Pacific plates. This causes the build up of mainly compressive stress in the interior of the Indo-Australian plate which is released during earthquakes.


How do they know the 2016 Kaikoura (NZ) Earthquake was 'complex', involved six different faults? The BBC news article New Zealand quake: The geological impact of a 'complex' tremor says:

The powerful earthquakes which hit New Zealand were some of the most complex ever recorded, say scientists.
Most earthquakes are the result of rupture on a single fault plane. But the twin quakes led to the rupture of at least six faults, including a newly identified one at Waipapa Bay.

The article describes several resulting changes after the 7.8 magnitude 2016 Kaikoura earthquake, including seabeds raised above the surface, a dangerous 150m-high landslide dam has formed on the Hapuku River, and a town completely cut-off by landslides:

Kaikoura itself was completely cut off by landslides. About 1,000 tourists and locals have been evacuated by sea from the small town...

The image below is one of several from the article.
It's hard for me to understand what happened. It seems there were actually two distinct major earthquakes in rapid succession, and a lot of other motion and changes in nearby related faults. Was seismic data alone used to reach this conclusion, or is it a complex analysis of seismic, satellite, and ground-truth data used to "reconstruct" what actually happened? Is there some more technical description of the analysis available?

You need to see the InSAR data. E.g., see this image which is based on radar data acquired by ESA's Sentinel-1A satellite. For straight faults the pattern is not this complicated.

Using such observations we can estimate which parts of the fault slipped. E.g., take a look at these images. This is done by solving an "inverse problem", i.e., you have some observations and you're trying to estimate what parameters in a (physics-based) model can reproduce the observations. In essence, it is an optimization problem like curve fitting.

Note: Besides InSAR data, we can also use data from seismometers but the former makes it rather obvious.


How do you use the streckeisen (QAPF) classification ternary diagram to identify igneous rocks based on chemical rock composition? I have been given the following diagrams:

and
and a database that is structured like this:

ROCK NAME |SIO2 |TIO2| AL2O3|   CR2O3|  FEOT|   CAO|    MGO|    MNO|    K2O|    NA2O|   P2O5|
WEHRLITE    |45.42| 0.17|   2.57|   0.32|   11.3384|    7.54|   31.93|  0.17|   0.01|   0.24|   0.01|

I want to know how to normalize the data and use these diagrams to identify the rock name based on the IUGS specification. I then am tasked to write a program that will do this automatically meaning that I have to come up with some semi-mathematically-based process to identify these rocks. Any ideas?

Why you should not do it

The QAPF and related diagrams are intended for classification of rocks in the field, or preliminary classification with modal proportions as seen in the optical microscope. They are not designed with the chemical composition of the rocks in the mind. Furthermore, these diagrams are merely descriptive and not genetic. They do not take into account many factors affecting the various characteristics of the rocks. While doing something like this may be interesting for homework exercise, it is not something I would expect to see in a recent research article.

If you want to do it anyway

Your solution should consist of two steps.

Finding what is the norm of the rock. A norm is an estimation of the ideal mineralogy of an igneous rock, based on the chemical composition of the rock. The most common norm calculation method is the CIPW norm, but there are other methods as well. For starters you should do fine with the norm. Instructions on how to calculate the CIPW norm are available in your favourite petrology textbook, here, or here. I've also seen some algorithms that do it for you, but their success varies on the silica undersaturated side of the rock spectrum.
Now that you have the norm, add together anorthite and albite to count how much plagioclase you have. You are also given the rest of the minerals. Now all you need to do is use the normalised relative proportions of each triplet of minerals to place them on the diagram. Here's a refresher on that.


Where can I get archived hourly wind speed data for Germany? Can some one suggest me a web site for archived hourly wind data for Germany.

I have seen here but it was not useful for me.

The MERRA dataset has data for the world from 1979 to date. It updates frequently.

You can get the data as HDF or NETCDF. If your GIS package doesn't read those, there will be translation packages around the web to convert them into a suitable format.

You'll want the U- and V- wind data. You might want pressure too. And possibly even turbulence data.

If you're interested in using this for simulating wind generation, then I highly recommend the paper by Cannon et al on analysing the MERRA data for wind energy simulation.

You might also be interested in the CFSR data, which runs 1979-2010: in connection with using this paper for wind energy simulation, see this paper by Sharp et al.

(I've previously posted this elsewhere on StackExchange)


Other than the South Pole where is the windless place on Earth? For this other question "Would this chambered cylinder be possible", preferably near the equator where is a calmest place from the troposphere to the stratosphere where is the windless place one Earth most of the year?

Truth be told, there is no such place. The atmosphere is a fluid, and a fluid moves. If a fluid did not move, it would not be a fluid.

Proof of concept- If you exhale, the carbon dioxide, water vapor, and other materials that form your breath would need to move, otherwise you would asphyxiate. That movement can be classified as wind, therefore wind exists.

Concerning the reference to your other question, there is no such a location. Consider the surface. Usually we assume the surface is fixed, which is fine over solid land. Because of this, there must be drag on the atmosphere. This drag slows the wind down. Since the air closest to the ground is slower than the air a bit further from the ground, there must be shear. Therefore shear is unavoidable.

For this entire monologue, I have spoken only on the small scales. It is worth noting that on the larger scales, that your linked question is true. A feature of geostrophic theory is the existence of Taylor columns. The Great Red Spot on Jupiter can be considered an example of such a Taylor Column (Ingersoll 1969).


ppmV versus μmol/mol for atmospheric CO2 - how to convert? For a uniform mixture of ideal gases, I think that the concentration of a gas reported in parts per million by volume (ppmV) and micro-moles per mole (μmol/mol) would be the same.

When I see atmospheric CO2 discussed, I have seen both units used, depending on the source. See for example, the comments under this answer.

Since multi-atomic gases like N2, O2, H2O and CO2 are not ideal gases (even monatomic gases are not absolutely ideal) I would guess that for realistic atmospheric samples at different altitudes and times, the CO2 concentrations expressed in ppmV and μmol/mol would not be numerically identical. Further, due to the variations in concentrations of the other constituents they wouldn't even be strictly proportional.

Is there a handy, approximate conversion constant, or function, that is more accurate than unity? Is there a  nearly-exact one?

According to the US Carbon Dioxide Information Analysis Center :
Though in their data table they use the term "ppmv", they explain:

The CO2 mixing ratios are reported as micromoles per mole (µmol/mol = ppmv) of dry air in the World Meteorological Organization (WMO) X85 mole fraction scale, traceable to primary standards at the Scripps Institution of Oceanography (SIO)

This is further explained in The WMO Mole Fraction Scales for CO2 and other greenhouse gases, and uncertainty of the atmospheric measurements:

Abbreviations can be ppm, ppb, etc., whereas widely used abbreviations such as ppmv (the v is for volume) are wrong and should be abandoned. When reviewing papers, or when we are co-authors, we should convince first authors to abandon the ppmv notation. Volume has nothing to do with mole fraction.

Supposing you know the mole fraction, if you literally wanted to calculate the parts per million by volume, first you need to define what that would mean.  Are you interested in the ratio of the volume of CO2 separately isolated relative to the whole volume? Or are you interested in the volume of CO2 separately isolated, relative to the sum of all the gases separately isolated? For either of these methods, you would need to choose a temperature and pressure, such as the actual temperature and pressure of a sample, or standard temperature and pressure.
Then you need an equation of state at least for the CO2, that is more real than the ideal gas law, such as van der Waals.


What is the collective name for the seas of Indonesia? The seas in Indonesia or Sunda Shelf or Southeast Asia separates the Indian Ocean and Pacific Ocean. The seas in Indonesia itself are broken into many parts due to presence of islands such as Sunda islands, Philippines etc. Examples include Java Sea, Celebes Sea, Banda Sea, Flores Sea etc.

Is there a collective term to name the seas of Indonesia as a whole region???

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

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

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


How did CO₂ originate on Earth before there was life? To start life there has to be $\ce{CO2}$.

$\ce{Solar energy + 6CO2 + 6H2O -> C6H12O6 (sugars) + 6O2}$

$C_6H_{12}O_{6} + O_2 \longrightarrow H_2O + {CO}_2 + \text{Energy}$

So to start this cycle, life needs $\text{CO}_2$.
Where did the $\text{CO}_2$ came from?

$C + O_2 + \text{Hot temperature in the Earth} \longrightarrow {CO}_2$

Volcanoes erupt ${CO}_2 \longrightarrow {CO}_2$ in the Atmosphere.

Is this the answer?

The answer is Volcanos. There might be other inorganic processes capable to produce $\text{CO}_2$, but on Earth, the main inorganic source of $\text{CO}_2$ are volcanoes.

In some period of Earth's history, there is evidence of large glaciations events, some of them are thought to have been triggered by the lack of $\text{CO}_2$ (like the Snowball Earth and Permo-carboniferous glaciations), and volcanoes are with no doubt the main candidate to have been responsible of restoring the warm climate by feeding large amounts of $\text{CO}_2$ into the atmosphere over millions of years.

$\text{CO}_2$ is an important component of rocky planets, but it is mostly dissolved (in large quantities) in the magma that exist (or once existed) in the interior of such planets. However, when the magma rises close to the surface, the drop in pressure reduce the solubility of $\text{CO}_2$ and it form bubbles of gaseous $\text{CO}_2$, that can then be expelled into the atmosphere trough volcanic eruptions, that in addition to teprha, and rocks include large amounts of volcanic gases of which $\text{CO}_2$ is one of the main components.
Probably that process of exsolution of $\text{CO}_2$ from hot molten rocks was happening even before the existence of volcanoes as we know them.

The same process happened once in Mars and Venus, whose atmospheres are composed mostly by $\text{CO}_2$ (96% and 96.5% respectively), suggesting that abundant $\text{CO}_2$ was also present in the early Earth's atmosphere.

Currently, it is estimated that volcanoes input to the atmosphere about 100 million tons of carbon in average per year in the form of $\text{CO}_2$, as illustrated by this NASA figure of the Carbon cycle:

(Originally from here)

You can see that many processes move carbon around, but the main reservoir by far is the crust, and that reservoir is tiny compared with all the $\text{CO}_2$ stored deeper in the Earth's interior.

Finally, in addition to be required by photosynthesis, $\text{CO}_2$ is part of the Earth's thermostat, that together with the silicate weathering have been key to keep the Earth's temperature in the range of liquid water. Arguably another very important need for the existence of life as we know it.


Love-Wave Propagation Love-waves cannot exist in a half-space. Layering must be present and there also must be accompanied impedance contrasts associated with the layering.

Because layering naturally induces seismic dispersion (in certain frequency ranges) and layering must be present for Love-wave generation, does that - as a corollary - indicate that Love-waves are naturally and always dispersive?

Note that the motivation for this question primarily comes from the idea that Rayleigh-waves - which can exist in a half-space - are not dispersive when layering is not present.

Your assertion is correct! See e.g. Stein & Wysession An Introduction to Seismology, Earthquakes, and Earth Structure (2003) p. 90 ,section 2.7.3: Love waves in a layer over a halfspace (https://books.google.ch/books?id=-z80yrwFsqoC&lpg=PP1&hl=de&pg=PA90). In particular, for any particular frequency/period, Love waves can only have certain horizontal apparent velocities/wavenumbers. Hence, different frequencies have different apparent velocities, which is what we refer to as dispersion. See for example also the figure 2.8-2 from the book, https://books.google.ch/books?id=-z80yrwFsqoC&lpg=PP1&hl=de&pg=PA96, which shows the dispersion curve for a layer over a halfspace.


Cause for round holes in stones I picked up this stone form a beach on the south coast of England (lancing). How is it possible it has such round holes? Plenty of stones looked similar.

Your image looks very similar to rocks we get here on the West Coast of Vancouver Island.  We have some rock boring bivalves that will effectively drill into the rock which breaks off and erodes into a shape similar to what you are showing.  https://en.wikipedia.org/wiki/Pholadidae or https://the-hazel-tree.com/2013/08/21/piddocks-anything-but-boring/

There are also echinoderms that will bore into rocks, Strongylocentrotus purpuratus, https://en.wikipedia.org/wiki/Strongylocentrotus_purpuratus
https://bmscblog.wordpress.com/2013/01/09/holey-rocks/  but the holes from these creatures tend to be larger than the image you present.

I a confident that the holes are created by some form a boring bivalve.


When was it ever considered that the desert might be "man-made", or otherwise anthropocenically-induced? This answer pointed me to the Wikipedia page for Farouk El-Baz in which the desert research and theories subsection says:

During the past 20 years in his research at Boston University, El-Baz has utilized satellite images to better understand the origin and evolution of desert landforms. He is credited with providing evidence that the desert is not man-made, but the result of major climatic variations. His research uncovered numerous sand-buried rivers and streams in the Sahara based on the interpretation of radar images.
These former water courses lead into depressions in the terrain, which he theorized must contain groundwater. His analysis of these data resulted in the location of groundwater in the arid terrains of Egypt, Oman, and the United Arab Emirates (U.A.E.), and perhaps Darfur in Sudan (unless it dried up).

I was surprised to read that the "origin and evolution of desert landforms" was ever considered to have an anthropocenic component.
Question: When was it ever considered that the desert might be "man-made", or otherwise anthropocenically-induced? Is it possible to know which desert was thought to be man-made that El-Baz proved wasn't? Or does the passage refer to all deserts?

El-Baz has utilized satellite images to better understand the origin
  and evolution of desert landforms. He is credited with providing
  evidence that the desert is not man-made, but the result of major
  climatic variations.

  Does the passage refer to all deserts?

Geolmorphologists classify deserts as zones that take place in climatic arid regions where rainfall is relatively low, there are extreme daily temperature variations and the vegetable cover is reduced or non-existent. The climatic conditions result in desert typical forms as hamadas, caliches, or dunes. (Gutiérrez Elorza, M., 2008).

It is important to note not every arid region is a desert, but every desert, with particular forms, is an arid (or hyperarid) zone.

Source: research.net

The question is: can Climate Change and deforestation create deserts?

Answer is Climate Change and deforestation can create new arid zones. It can create the conditions to expand existant deserts, but the typical desert forms take some time to form, so deserts as El-Baz have not (yet) grow because of our actions on the planet.

However, other deserts as Sahara have expanded his area in the last century (Thomas, N. et al., 2017). The article of this asseveration quotes (anthropological) Climate Change as the main factor of this expansion.

So answering your question the passage you quote does not refer to all deserts if you consider man-made something that result from our emissions of greenhouse gases to the atmosphere.

Gutiérrez Elorza, Mateo (2008): "Geomorfología", Ed. Prentice Hall.

Thomas, Natalie and Nigam, Sumant (2017): "Twentieth-Century Climate Change over Africa: Seasonal Hydroclimate Trends and Sahara Desert Expansion". Journal of Climate, vol 31.


Is COMSOL Multiphysics good for subduction CFD modelling? Are there alternatives? As a beginner for CFD modelling of plate subduction, I heard comsol to be a good software. Can anybody suggests alternatives and the demerits of using COMSOL Multiphysics? Thank you.

numerical modelling is a vast field and the tool to address your problem depends strongly on ... your problem and your approach!
Are you a master student? a PhD student with very short time to wrap up your thesis? A plumber with an intelectual interest in plate tectonics?
In short: Comsol may be an adequate tool. However, with large displacements (larger than the element volumes), you may want to avoid Finite Element method and probably better to have a look at other methods.
You can find a nice description of alternative methods in the book "Introduction to Numerical Geodynamic Modelling" from Professor Taras Gerya. He sugests to use Matlab, but you can probably follow all the book simply with Python.


What is brown carbon? There is a lot of interest in brown carbon in the atmospheric science community these days. There is a paper in the journal, "Atmospheric Chemistry and Physics" titled, "Black carbon or brown carbon? The nature of light-absorbing carbonaceous aerosols" by M.O. Andreae and A. Gelencser, which was published in 2006. However, after reading this paper, I feel more confused than before.

My second question is, "What is the need to separate brown carbon from black carbon?"

Carbonaceous aerosols are formed by a mixture of substances with different chemical, physical, and optical properties.

Certain organic substances are mostly transparent to sunlight and therefore do not contribute to Earth warming or cooling. Other substances are mostly reflective, therefore their presence in the atmosphere contributes to Earth's cooling. Yet there are substances that absorb sunlight thus warming the atmosphere.

Light absorbing carbonaceous aerosols do not form a uniform group either. They include soot particles, smoke, organic compounds such as levoglucosan and the spectre of humic substances all with different optical properties. The figure below shows schematically the absorption spectrum of two compounds representative of different groups of light absorbing materials.

One compound labeled B1 has a more uniform distribution of absorption coefficient across the visible spectrum where the absorption coefficient at the red edge is about half of that at the blue edge. Another compound labeled B2 has a much steeper slope at the blue edge. It would have a yellowish or light brown color. Think of the yellowish fumes that can be seen when a piece of wood is ignited.

Assuming uniform absorption spectrum for light absorbing organic carbon can lead to significant overestimation of light absorption by atmospheric carbon.

On the other hand estimating the carbon content of the atmosphere via measurements in the green or red parts of the spectrum would lead to a significant underestimation of light absorption in the blue and ultraviolet parts of the spectrum.

To reduce the error caused by the non-uniform absorption spectrum of some of light absorbing carbon we could instead think of light absorbing carbonaceous aerosols as two separate groups namely Black Carbon with uniform light absorption spectrum and Brown Carbon with steep increase in light absorption towards the blue edge.

In our example B1 would be assigned to Black Carbon group and B2 would be assigned to the Brown Carbon group.


Why doesn't sea level show seasonality? North-hemisphere ice-shelf melts on summer and grows on winter. I would expect appreciable changes on sea-level between seasons, but sea-level looks equal on winter than on summer.

Why doesn't sea level show seasonality?

Sea level has a strong seasonal signal. The annual variability is less than the daily changes associated with tidal forcing in most locations, but still can be on the order of 5-10 cm (maximum values about 15 cm).

The causes of the seasonal fluctuations are mostly associated with seasonal changes in wind intensity and patterns, changes in temperature that relate to thermal expansion, and in salinity (haline contraction) and river discharge fluctuations. The annual sea level cycle is only partially related to ice melt and this effect tends to be quite local.

The largest sea level seasonal cycles are associated with areas in the vicinity of large rivers with strong seasonal cycles (e.g., Bay of Bengal). Also, there is a lot of spatial variability in the seasonal cycle with the northern hemisphere having a larger signal (likely caused by the stronger seasonality in wind patterns).

An example of the seasonal cycle can be seen in the monthly data from the Permanent Service for Mean Sea Level (PSMSL) for Woods Hole, MA (USA) (in m offset to avoid negative values in the PSMSL database). The monthly data shows strong seasonal variability and also a clear trend. As the data is monthly averaged, the tidal oscillations are filtered out. Most sea level rise graphs tend to use annual data and thus the seasonal information is not included.


High tides at Venice I read somewhere that the new MOSE system can withstand a maximum rise in water of about 3m. I was wondering if that extreme case will happen on the coast line of Lido di Venezia, there will be a rising of the water with a consequent problem at the many beaches along the litoral. What are they expecting? Venice would be, hopefully, saved while Lido will suffer high level of water on the beaches. And more important: how much above the sea level is the highest point of Lido di Venezia?

Added: if the highest point at Lido is 3m that would be the only dry place in case of a tide of 3m. Or I'm wrong?

Venice has plans for a new hydraulic flow controlled by levees and a dam during runoff & tidal events as sealevel continues to rise.

This has a brief summary of progress: https://www.citylab.com/life/2016/09/venices-vast-new-flood-barrier-is-almost-here/498935/

[edit]
The context of Venice has 3 parts, the freshwater seasonal and episodic flow including groundwater in a relic delta, this with enough fetch to sea  allowing winds to pile water for days, and, there are seasonal tides with that.

The almost complete solution deals with sediment compaction separately from defense against high water, those solutions have injection strategies, they're dealing with pore-pressure, flow and having clean water in the canals or they stink.

My view, it's analogous to the high water dam against the North Sea that's closed for storms.

Long-term a dam at Gibraltar Strait, 1200-ft deep has been proposed to save history, otherwise we hit 3mm in a year in 2016 of rise, at 600-ppm Antarctica's land ice begins an unstoppable melt as is going on with submerged valley glaciers.

To the question of littoral habitat that's ok unless there's an oil spill, pollutants in runoff are poisoning it pretty fast being an enclosed sea vs oceanic facing littorals from my reading.


Why does halite have a cubic crystal Why does mineral halite has a cubic crystal ? Is this a result of the way by which sodium ions and chloride ions are held together ?  And what is the relation between the cubic crystal of halite and its cleavage ?

Halite has a cubic structure as a result of its ionic bonds and ion sizes. This means that the positively charged sodium tends to be surrounded by as many negatively charged chlorine ions as possible (and vice versa) but that attraction is working against the repulsion of positive charges from each other and negative charges from each other. It balances nicely with cubic packing of the atoms.

This does control the cleavage direction but there are other cubic minerals where the ion sizes and charge mean the cleavage is stronger in different directions. A good example is fluorite, calcium fluoride, which often forms cubic-shaped crystals but has octahedral cleavage.


What is the appropriate vertical datum to use globally? When studying sea level changes, it is normal to analyze water level with respect to a common vertical datum. The most used datum is Mean Sea Level (MSL), which NOAA defines as "The arithmetic mean of hourly heights observed over the National Tidal Datum Epoch". The issue is that MSL constantly changes, and therefore it needs to be referenced to a different datum. One option is to use an ellipsoid of the entire Earth (for instance WGS 84, like the GPS uses) but the differences with respect to MSL can be big (>100m). The other option is to use a geoid datum. In the US, we normally use the North American Vertical Datum of 1988 (NAVD88), but that only covers the US, Canada and Mexico. What are the options for global geoids?

In a recent study, Talone et al. (2014) compare 4 different geoids and evaluate their effects for oceanographic studies. The four geoids they used are:

  EGM96: The Earth Geopotential Model 1996 embodies ground-based as well as satellite measurements (Lemoine et al. 1998). Remotely sensed data were mainly radar altimeter observations, averaged and transformed in gravity anomalies as expressed in Sandwell and Smith (1997). This geoid may be downloaded from the National Aeronautics and Space Administration (NASA) Goddard Space Flight Center web page (http://cddis.gsfc.nasa.gov/926/egm96/egm96.html). In this study a 360-degree and -order version of the EGM96, included in the GOCE User Toolbox (GUT), was used. GUT is distributed by the ESA at http://earth.esa.int/gut/. In the spatial domain, the geoid is defined on a 0.5° uniform grid. Since the calculation of the EGM96 geoid included altimetry measurements, we may expect that it might have been influenced by some signal from the MSS fields.
  GRACE05: The Gravity Recovery and Climate Experiment (GRACE) (Tapley et al. 2004) is a joint mission by the American (NASA) and the German (DLR) space agencies, launched in March 2002 with the objective of making detailed measurements of the Earth’s gravity field. GRACE’s data are available on the web pages of these two institutions (http://podaac.jpl.nasa.gov/grace and http://isdc.gfz-potsdam.de/grace). As for EGM96, the GRACE05 geoid used in this study is included in the GUT (see Foerste et al. [2008]). It is characterized by a spatial resolution of 0.5° and a spherical harmonic degree and order 360. GRACE05, in the version used for this study, includes altimetry measurements.
  EGM2008: The Earth Gravitational Model 2008 is described in Pavlis et al. (2008) and distributed by the International Centre for Global Gravity Field Models (http://icgem.gfz-potsdam.de/ICGEM/shms/egm2008.gfc). It is available up to spherical harmonic degree and order 2159, and contains additional coefficients extending to degree 2190 and order 2159. For consistency with the EGM96 and GRACE05, the geoid heights have been calculated using up to the spherical harmonic degree and order 360, with a spatial resolution of 0.5°. Like EGM96, EGM2008 is the outcome of fusing different data from several sources, including altimetry data.
  GOCE’s level 2 time-wise product: The time-wise product is obtained using only direct measurements of the gravity field, without any altimetry contribution. Details about the GOCE mission can be found on the ESA web page (http://earth.esa.int/GOCE) and in the ESA (1999) report; data may be accessed on the ESA web page. Three different products are available, namely the direct solution, the space-wise solution and the time-wise solution; the last of these was used in this study as it does not rely on auxiliary information (EGG-C 2012). We used the third release, the last one available at the time of the study, based on 16 months of data collected over 18 months (from November 2009 to April 2011). The spatial resolution of the GOCE level 2 products is 0.5°, with degree and order 250.

Talone, M., Meloni, M., Pelegri, J. L., Rosell-Fieschi, M., & Flobergaghen, R. (2014). Evolution of geoids in recent years and its impact on oceanography. Scientia Marina, 78(2), 155-164.


Does the heating of the oceans due to greenhouse effect negate the acidification due to increased CO2 levels? As I understand, the dissolving of carbon dioxide leads to increased acidification of the oceans, and thus increased atmospheric CO2 levels would lead to more dissolution in the oceans and thus increased levels of carbonic acid.

However, also as CO2 is a gas, it's solubility decreases with temperature, thus as atmospheric CO2 increase leads to higher surface ocean temperatures via greenhouse effect, does this reduce the solubility of CO2 in the oceans to any degree, in some sense limiting the effect of increased gas concentrations on the acidification.

Furthermore on a slight tangent, surely the carbonate buffering system of the ocean is large enough to withstand the effects of more dissolved atmospheric carbon dioxide to maintain a constant pH?

This is a very complex issue, and therefore I'm not entirely convinced I am qualified to answer that, considering how little I understand chemistry, but I'll give it a try.

The Flux of CO2 can be expressed as follows (see e. g. Wanninkhof et al. 2009):

$$F = kK_0(p_{\mathrm{CO}_2sea} - p_{\mathrm{CO}_2air})$$

By convention a negative $F$ means a flux from the atmosphere to the ocean.
$k$ is the transfert velocity and $K_0$ is the solubility which indeed decreases with temperature, as you noted.
$p_{\mathrm{CO}_2sea}$ and $p_{\mathrm{CO}_2air}$ are respectively the partial pressure of CO2 in the sea and in the atmosphere.
Now, with $T$ increasing, $K_0$ (and also $k$ I believe)  decreases, but, as long as the partial pressure of CO2 is larger in the atmosphere than in the ocean there still is a flux toward the ocean.

So worst case scenario, increasing temperature slows down the absorption of CO2 by the ocean but does not negate it. However of course, if the temperature increase to begin with, it is because $p_{\mathrm{CO}_2air}$ is increasing, so this is a bit of a moot point anyway.

As far as the ocean buffer goes, we're talking here of an uptake of ca. 2 Pg (i.e. $2\times10^{15}$g) of carbon dioxide per year (the preindustrial uptake being ca. 0.5 Pg according to Takahashi et al. 2009), which is too much to be buffered. For comparison, phytoplankton net primary productivity is ca. 50 Pg of fixed carbon per year (Falkowski et al. 1998).

Falkowski, P. G., Barber, R. T., Smetacek, V., 1998. Biogeochemical Controls and Feedbacks on Ocean Primary Production. Science, 281: 200-207.
Takahashi, T., et al. 2009. Climatological mean and decadal change in surface ocean pCO2, and net sea–air CO2 ﬂux over the global oceans. Deep Sea Research II, 56: 554-577.
Wanninkhof, R., et al. 2009. Advances in Quantifying
Air-Sea Gas Exchange and Environmental Forcing. Annual Review of Marine Science, 1: 213-244.


What is the difference between nappe and thrust sheet? The titles of many geology articles contain words like "nappes and thrust sheets". Basically these are rather similar and in certain languages can be denoted with one term. The dictionaries tend to mix them giving the same translation for both. Is there any (subtle) difference or can they be considered synonims?

Nappes and thrust sheets are very similar terms.

I agree with definition found on wikipedia:
(except for the 2 km requirement of movement, I would replace 2 km with significant distance.  I am sure you still have a Nappe with only 1.5 km of movement is measured.)

In geology, a nappe or thrust sheet is a large sheetlike body of rock that has been moved more than 2 km (1.2 mi) or 5 km (3.1 mi) above a thrust fault from its original position. Nappes form in compressional tectonic settings like continental collision zones or on the overriding plate in active subduction zones. Nappes form when a mass of rock is forced (or "thrust") over another rock mass, typically on a low angle fault plane. The resulting structure may include large-scale recumbent folds, shearing along the fault plane, imbricate thrust stacks, fensters and klippe.


Is Zealandia really big enough to be called a continent? I was reading this article about Zealandia and got excited that there could be an underwater continent.  However, when viewing the image (below) it appears that Zealandia is much smaller than any other continent.   The article says the bases considered were:

elevation above the surrounding area
distinctive geology
a well-defined area
a crust thicker than the regular ocean floor

Is there some criteria on size that should be met to be classified as a continent? If so, does Zealandia meet that criteria?  Or,  is it possible that Zealandia is a continental fragment?

In the GSA Today article that Michael linked to in the comments, it says:

  The Glossary of Geology defines a continent as “one of the Earth’s major land masses, including both dry land and continental shelves” (Neuendorf et al., 2005). It is generally agreed that continents have all the following attributes:

  high elevation relative to regions floored by oceanic crust;
  a broad range of siliceous igneous, metamorphic, and sedimentary rocks;
  thicker crust and lower seismic velocity structure than oceanic crustal regions; and
  well-defined limits around a large enough area to be considered a continent rather than a microcontinent or continental fragment.

  The first three points are defining elements of continental crust and are explained in many geoscience textbooks and reviews (e.g., Holmes, 1965; Christensen and Mooney, 1995; Levander et al., 2005; Kearey et al., 2009; Condie, 2015). To our knowledge, the last point—how “major” a piece of continental crust has to be to be called a continent—is almost never discussed, Cogley (1984) being an exception.

and goes on to mention:

  Furthermore, the 4.9 Mkm^2 area of continental crust is large and separate enough to be considered not just as a continental fragment or a microcontinent, but as an actual continent—Zealandia. This is not a sudden discovery but a gradual realization; as recently as 10 years ago we would not have had the accumulated data or confidence in interpretation to write this paper.

This part is important too:

  spatial and tectonic separation, along with intervening oceanic crust, means that the Zealandia continental crust is physically separate from that of Australia. If the Cato Trough did not exist, then the content of this paper would be describing the scientific advance that the Australian continent was 4.9 Mkm2 larger than previously thought.

So to wrap it up, they say:

  Being >1 Mkm^2 in area, and bounded by well-defined geologic and geographic limits, Zealandia is, by our definition, large enough to be termed a continent. At 4.9 Mkm^2, Zealandia is substantially bigger than any features termed microcontinents and continental fragments, ~12× the area of Mauritia and ~6× the area of Madagascar. It is also substantially larger than the area of the largest intraoceanic large igneous province, the Ontong Java Plateau (1.9 Mkm^2).


Are the "polar vortex" and "cut-off lows" over/near the Great Lakes new phenomena? In recent years, I've heard weather reporters describe "cut-off" low pressure systems which park over Southern Ontario for days at a time. In summer months, they bring us long stretches of cool cloudy, often rainy days. In only the last couple of years, there was mention of the "polar vortex" which seemed to unusually extend and deepen our winter last year.

I don't recall mention of either term in weather reports for the Southern Ontario region more than a few years ago.

Over the meteorological record for this region, are these new patterns? If they are not new patterns, is it simply a trend in weather reporting to apply these terms?

The polar vortex
The AMS glossary defines the polar vortex as:

A planetary-scale mid- to high-latitude circumpolar cyclonic circulation, extending from the middle troposphere to the stratosphere. The Northern Hemisphere vortex often features two centers—one near Baffin Island and the other over northeast Siberia—with analogous circumpolar asymmetry atypical in the Southern Hemisphere. The westerly airflow is largely a manifestation of the thermal wind above the polar frontal zone of middle and subpolar latitudes. The vortex is strongest during the winter in the upper troposphere and stratosphere when the pole-to-equator temperature gradient is strongest. The stratosphere component of the circulation may be referred to separately as the “polar stratospheric vortex.” In summer, the strongest westerly circulation is largely confined to the troposphere, and the polar stratospheric vortex reverses in the upper stratosphere because of solar heating during the polar day.

This first descriptions of the polar vortex date back to the 1940s.  You'll also note that the description above describes an upper tropospheric and stratospheric circulation e.g. this is is something happening well above the surface of the earth.
The recent popular use of polar vortex to describe any particularly cold air mass can probably be traced back to someone (either a meteorologist of psuedo-meteorologist) on twitter making reference to it and then "going viral".  However the media got a hold of the word, they are quite consistent in misusing it.
The definition above mentions

The westerly airflow is largely a manifestation of the thermal wind above the polar frontal zone of middle and subpolar latitudes

What this means is that the position and strength of polar vortex (the circulation up around the stratosphere) is strongly influenced by the position of strong surface cold fronts coming out of the poles.  The strong cold snaps are not the polar vortex, and the southern push of the high altitude polar vortex is a response of the cold snap, not the other way around.
Cut off lows
Cut off lows are not new either.  A mid-latitude trough can be cut off from the westerly flow and you end up with a cutoff or closed low.  These tend to be persistent, stationary mid and upper level lows that can last for days.  You can see an example of a cut off low in the flow over the US in this video.  Focus over the southern tip of Lake Michigan and you'll see it.  These type of cutoff lows can occur anywhere in the mid-latitudes.


How deep would the nitrogen and oxygen ocean be if cooled to liquid? If the atmosphere were cooled to liquid, say the planet's average atmospheric temperature were reduced to 70K, how deep (above sea level - frozen oceans of water) would the resulting ocean be?

I'm not sure it would be entirely liquefiable as the atmosphere gets thinner and thinner, but if we ignore that, then it's a simple matter of calculating density and ocean cover.

78% Nitrogen, 0.807 g/mL  Source:  Liquid Nitrogen

21% Oxygen, 1.141 g/mL  Source: Liquid Oxygen

Ignoring the 1% of trace gases, average density of liquefied air, 0.87 g/mL, or 87% the density of water.

Mass of air, 1 ATM is equivalent to 33.9 feet of water.   Source:  link

and the Earth is 71% covered by oceans.   From there it's just math.  33.9*(1/.87)*(1/.71) = 54.88 feet.    That's quite a bit less than the oceans would rise by freezing solid (which might not happen given volcanism and warmth coming from the earth, but if even half of the average depth of 14,000 feet of oceans froze, a 9% increase in volume, we'd be looking at some 600 feet of sea level rise by freezing.

Colder temperatures might cause the liquid nitrogen/oxygen to contract a bit further but that's a ballpark answer - 54 feet, 10 1/2 inches.   Some of the air might dissolve into the oceans prior to the oceans turning to ice, cause colder water can hold more gas, so the actual answer might be a little bit less than that.


Which part of solar radiation (VIS, NIR) keeps Earth warm? Which part of solar radiation (visible light vs. infrared radiation) plays main part in keeping Earth's surface warm?

Electromagnetic radiation converts based on frequency and exposure. Visible light and Infrared waves are the predominant energy sources that can penetrate the atmosphere. Higher energy wavelengths (UV and above) do interact but are often bounced by significant portions. Those radiations interact with atmospheric gases; emit infrared waves in the process.


Avoiding fake trinitite I would like to get some trinitite for my rock and mineral collection. The problem is that there is apparently a lot of fake trinitite for sale in the internet.
How do I avoid the fakes, and be sure I purchase real trinitite?

You will probably never know for sure, but the only way to get any confidence is to have any potential specimens analyzed by a mineralogical laboratory that can do Gamma spectroscopy.
Fake trinitite,

use a variety of means to achieve the glassy green silica look as well as mild radioactivity; however, only trinitite from a nuclear explosion will contain certain neutron activation products that are not found in naturally radioactive ores and minerals. Gamma spectroscopy can narrow down the potential nuclear explosions from which the material formed.

Also,

If it's too green, too translucent or too inexpensive to be true, it probably isn't real Trinitite!  So how does the collector know if a specimen is authentic?  Well, usually the only means for the collector to eliminate the fake stuff is to use a sensitive dosimeter and take a reading to verify that residual induced radiation exists.  This will be very small, but it can be detected.  This will not rule out the possibility that clever fakers will not add some small amount of weakly radioactive material to their formula.  The only way to be 100% certain of authenticity is by means of nuclear energy spectroscopy.

One of the radioactive elements to test for is Cesium 137,

This radionuclide has a half life of 30.2 years and is one of several unique byproducts of nuclear fission or atomic detonations.  It is present in all authentic Trinitite specimens.

All radioactive elements have a half life. The radioactive elements produced by the Trinity Test on 16 July 1945 are also well know. To increase the confidence of testing, the amount of each radionuclide in each sample would need to be detected and compared with the expected amount that would be in true Trinitite given the elapsed time since 16 July 1945.
If the specimens have a report from testing laboratory, get a copy of the report and verify it with the laboratory. Ideally, such reports should had a picture of the sample that was tested. If so, ensure it matches what is being offered for sale.


Is the Principle of Original Horizontality a good indicator? Still reading a course on datation over multiple stratums that may have setting up the Earth's crust, I'm meeting for the first time the principle of original horizontality Steno.

Is this theory safe?

Logically, if multiple stratums squeeze, the last one to squeeze will be the youngest. It makes sense to me. But isn't Earth's crust affected by inner perturbations that may disrupt the stratums pile? Is it safe to date stratums this way then?

No, Steno's principle of original horizontality (I'll call it the POOH) is not 'safe'. It is not a useful theory.

Don't confuse it with the law of superposition (also due to Steno), which is useful. That law is, in a general sense, a foundation stone (ha!) of stratigraphy... with some caveats due to resedimentation and other processes.

Why is the POOH dodgy? On small and large scales, the concept of 'layer-cake' stratigraphy does not hold up. Indeed, it's probably rather unhelpful. Brian Romans wrote a nice essay on this subject in 52 Things... Geology (edited by me, 2014) — see the link below. In it, he refers to Bailey (1998), who described sedimentary bodies as 'lenticles' with complex 3D geometries. And you just have to look at some seismic reflection data from the continental shelf to appreciate that this principle applies to even an outwardly rather continuous environment (excerpt of a line in the Virtual Seismic Atlas):

References

Bailey, R (1998). Review: Stratigraphy, Meta-Stratigraphy, and Chaos. Terra Nova 10, 222-230. DOI: 10.1046/j.1365- 3121.1998.00192.x

Romans, B (2014). Strata are not flat. In: M Hall, ed., 52 Things You Should Know About Geology. Agile Libre, Nova Scotia, 132 pp. ISBN 978-0-9879594-2-3. Available online.


How did sand dunes appear in the midst of a fertile region? I recently visited a place called Talakad/Talakadu about 40 km from Mysore, India. Its an amazing place where a whole city has been covered by sand about 15 m deep. The local myth is that a curse turned the once thriving town to a barren dune. Does anyone have any scientific explanations?

It appears the sands at Talakad are the result of a ecological disaster that occurred in the 17th Century. At the time, a dam was constructed north of Talakad on Kaveri River which caused the river to be diverted. This exposed a sand deposit in the river which was subsequently moved to Talakad by monsoonal winds. The following quote is from this source AB Roy & MS Sethumadhav, 2014:

  It is thought to have originated due to an ‘eco-disaster’ that
  lashed the region during the 17th century. That was the
  time when the normal flow of the Kaveri River was
  impeded because of the construction of a dam on the up-
  stream side, north of Talakad and subsequent diversion of
  water in a different direction. As a result, the water level
  at the point bar on the concave side of the Kaveri meander southwest of Talakad was significantly lowered leading to the buildup of sand at this place. The accumulated
  sand was then actively reworked and carried by the
  northeasterly monsoon winds, which were subsequently
  deposited around Talakad engulfing the temples and other
  settlements in the region. The yellow coloured, uniformly fine-grained and homogeneous nature of the sand
  without any clay material in it provides further proof that
  the air-borne sand deposited as dunes


What is limestone made of? I know that it is calcium carbonate (CaCO3). I also know that these are the dead bodies of microorganisms.

My question is, where do they procure the building material? The limestone seems to cover the whole Planet with a multimeter-thick layer. How is this possible - after we assume the conservation of atoms? Where did the limestone molecules come from? How long can the process of sediment formation last? Is the building material coming from space or due to Universe Expansion (black matter)? Is it right that the Planet becomes thicker and thicker with every year if we assume conservation of matter?

The building material comes from minerals dissolved in the ocean, mainly $\mathrm{Ca}^{2+}$, $\mathrm{Mg}^{2+}$, and $\mathrm{HCO}_3^{–}$, but of course there are all sorts of biochemical details. Most limestone originated as the skeletons of micro- and macro-organisms, such as plankton and coral.

The minerals come in turn from the erosion of older rocks (among other places). For example, here are the famous white cliffs near Dover, UK, where massive amounts of calcium carbonate, mostly stable since the Cretaceous, are falling into the sea, where it will be re-used:

This attrition is part of the rock cycle and a very slow-moving part of the carbon cycle. These are well-studied and reasonably well-understood.

You seem to suggest there is a paradox, that there's just constant deposition and no erosion or dissolution. But there is no paradox. The earth is not becoming thicker and thicker, material is not coming from space (not in substantial quantities anyway), and there's no need to invoke any processes we don't understand sufficiently to explain our large-scale observations. We know this because those processes would have a measurable effect on all sorts of things: the earth's orbit, climate, plate tectonics, and so on. There would be, I suggest, a strong low-frequency trend in all sorts of signals (stable isotopes, organism growth rates, sedimentation rates, volcanism rates, and so on).

The image is by Flickr/Harvey Barrison, CC-BY-SA.


Have there ever been significant events of ecological or geological disasters occurring simultaneously alongside extreme meterological disasters? e.g.

A major earthquake hitting an area over which a large tropical cyclone is passing by (Haiti, Mexico (either coast), Taiwan/Japan/Philippines)
Major tornado outbreak hitting an area inundated by wildfires (southeastern U.S. in November-December)

The text in brackets represents areas where I think such scenarios could happen.

Here's an amazing one:

In June 1991 category 3 Typhoon Yunya made landfall in central Luzon in the Philippines and gradually weakened as it moved across the island... however as it was near exiting the island... Mount Pinatubo sustained the largest volcanic eruption in our lifetimes -- almost directly in the center of the storm!

Here is a remarkable satellite loop showing the event unfold.

Screen cap shortly before the event unfolder showing the locations, from UW CIMSS

The CIMSS Satellite Blog has a nice post writing up the event, along with a collection of additional satellite data.


How much water does a wave transport into a sea cave? How much water is transported (volume) as a wave travels into a sea cave?

The wave has a height of 1 m and a period of 12 seconds. The average water depth at the cave mouth it 5 m and the width is 15 m.

How do I calculate this? This is a real-world problem and if there is any other information needed for this problem I will happily collect it.

This isn't a homework problem. This is a real cave and I assumed water is transported because it does pile up in the back of the cave until the wave is reflected and exits the cave in the opposite direction. Just as on beaches where waves push water up on to the beach and gravity pulls the water back to ocean creating the nearshore current. I understand that deep water waves have an almost circular orbit but due to Stokes drift a particle will be slightly displaced in the direction the swell is moving. In this cave we can assume the wave is well with in the shallow water wave criteria and almost at the critical depth in which the wave deformation is extreme and wave energy is about to be converted into turbulent kinetic energy as the wave breaks. The orbit therefore would be linear, as the wave moves in and out. The net change would be 0 m$^3$, but how much water flows in and then flows back out of the cave?

The time-averaged material transport by water waves is quantified by Stokes drift, which is the residual Lagrangian drift due to sub-surface orbits not being closed:

$$
u_{St} = \dfrac{\omega k^2 a \cosh[2k(z+d)]}{2\sinh(kd)^2}
$$
where $\omega$ is the angular frequency, $k$ is the wavenumber, $a$ is the wave amplitude, $d$ is mean water depth, and $z$ is the displacement from water surface, positive upward.

Because the cave is closed, there is build-up of water in the cave which results in pressure gradient-induced Eulerian backflow which opposes the Stokes drift. This backflow is barotropic in nature and equals:

$$
u_E = -\dfrac{1}{d}\int_{-d}^{0}u_{St}(z)dz
$$

The transport velocity is the sum of mean Eulerian velocity and Stokes drift:

$$
u_L = u_E + u_{St}
$$

For the case of $T = 12\ s$, $a = 1\ m$, and $d = 5\ m$, the resulting transport looks like this:

Because the Stokes drift is not uniform in the vertical but compensating Eulerian backflow is, the resulting transport is into the cave in the upper 2 m, and out of the cave below that depth.

Assumptions made:

Inviscid ($\mu\nabla^2\mathbf{u}=0$), irrotational ($\nabla \times \mathbf{u} = 0$), and incompressible ($\nabla\cdot \mathbf{u}=0$) flow.
Small amplitude for the linear wave theory to hold.
All wave energy is dissipated at the cave wall (no reflection). If there is some reflection of waves out of the cave, then the Stokes drift and the corresponding Eulerian backflow would be reduced in magnitude, but the answer for the net transport would be qualitatively the same.
Shallow water dispersion relationship ($\omega^2 = gk^2d$).

And here is the Python code:

import numpy as np
import matplotlib.pyplot as plt

T = 12. # wave period [s]
d = 5.  # mean water depth [m]
a = 1.  # wave amplitude [m]
g = 9.8 # gravitational acceleration [m/s]

omega = 2*np.pi/T # angular frequency [rad/s]
k = np.sqrt(omega**2/(g*d)) # wavenumber [rad/m]

z = np.linspace(0,-d,501.) # depth array [m]
dz = -np.gradient(z) # depth increment [m]

# Stokes drift in arbitrary depth
ust = 0.5*omega*k*a**2*np.cosh(2*k*(z+d))/np.sinh(k*d)**2

# Eulerian backflow is the vertical integral of Stokes drift
ue = -np.ones(z.size)*np.sum(ust*dz)/d

fig = plt.figure(figsize=(8,6))
ax = fig.add_subplot(111,xlim=(-0.2,0.2),ylim=(5,0))
ax.tick_params(axis='both',which='major',labelsize=16)
plt.plot(ust,-z,'r-',lw=3,label='Stokes drift')
plt.plot(ue,-z,'g-',lw=3,label='Eulerian backflow')
plt.plot(ust+ue,-z,'k-',lw=3,label='Lagrangian velocity')
plt.plot([0,0],[5,0],'k--')
plt.legend(loc='lower left',shadow=True,fancybox=True)
plt.grid(True)
plt.xlabel('Velocity [m/s]',fontsize=16)
plt.ylabel('Depth [m]',fontsize=16)
plt.savefig('transport.png',dpi=100)
plt.close(fig)


How would I use data to find specific humidity and mixing ratio? I keep reviewing this table to compare and contrast my results:

The parcel of air is at 35°C and a relative humidity of 43%.

I used this online calculator and it stated that with these two factors it would be 16.01 g/kg. Is this correct? What is the formula for this answer?

If that is right how would one use that information in order to find the specific humidity? If the atmospheric pressure is at 1000 mb, what would its mixing ratio be?

The online calculator is giving you the specific humidity, which at a relative humidity of 43% is 43% of the saturation specific humidity at that temperature.

Reading from the chart, a rough estimate for the saturation specific humidity is ~37.5 g/kg at 35°C. 43% of this is 16.1 g/kg, which is close to the value given by the calculator.


Why don't toilets use saltwater? My question is in the header. It would seem to be a major environmental benefit if toilets used saltwater in stead of drinkable fresh water, right?

This question has tenuous links to Earth Sciences, but the answer is simply that, historically, freshwater has been used to flush toilets, and hence the sewage treatment plants have been developed to treat non-saline sewage. The water can be (and frequently is) recycled for domestic use, whilst sewage sludge can be used to enrich farmland. No such benefits accrue to flushing effluent with saline water. It is then pollution, whether it is disposed of on land or at sea.

In many estuaries and deltas around the world sewage sludge does end up in the sea where it accumulates as tidal mud flats with an unnaturally high lipid content. Give this sediment a few tens of millions of years of compression and maturation and it will doubtless yield oil shale.


How much wind power is there roughly in Britain and its surrounding? Given the prominence of the climate crisis, it's important to get some estimates of how much wind power is available in Britain as part of a renewably energised future.
Q. What is yearly average of wind energy available on the landmass on Britain.
And how much does this work per metre squared?
More, given that for some they can be unsightly, how much yearly wind energy is available on the island shelf around Britain, say up to 30 km; and again what is the average per square metre? How does this compare with the yearly energy consumption in Britain?
Thank you.

2.2TWe on average in the seas...
The uk uses less than 350 Gigawatts every year, so the sea can provide about 6 times the current UK energy consumption:
80 GW in shallow waters (0-25 m)
270 GW in seas of depth 25-50m
(up to there is sufficient to meet all of the UK's 2016 energy consumption)... There is also:
790GW in seas of 50-100m
1030GW at 100m-700m
https://claverton-energy.com/two-terawatts-average-power-output-the-uk-offshore-wind-resource.html
https://www.statista.com/statistics/323381/total-demand-for-electricity-in-the-united-kingdom-uk/
For onshore resources, you can add another 100GWh.


Need help understanding what an "isostatic model minimizing crustal deviatoric stress" means Despite the background information coming from another body besides the Earth, the terms I would like to understand are historically geophysical in nature.

Background:

I just read today's news "Saturn's moon Dione harbors a subsurface ocean" at Phys.org and this seems to bring the number of sub-surface oceans in the Solar System to about six (the number might vary depending on the level of certainty).

This news about Saturn's moon Dione comes from a model which uses gravitational data from recent flyby's of the Cassini spacecraft. The model is simultaneously applied to another one of Saturn's moons Enceladus.

Question:

My question is about the terms in the abstract of the recently published paper on the subject in Geophysical Research Letters and my question is limited to these terms which I believe come from Earth Science and apply to the understanding of the Earth's crust floating on it's magma "ocean" interaction with the hot and slightly viscous mantle below.

What is an isostatic model and what is deviatoric stress in the context of geophysics?

  Enceladus' gravity and shape have been explained in terms of a thick isostatic ice shell floating on a global ocean, in contradiction of the thin shell implied by librations. Here we propose a new isostatic model minimizing crustal deviatoric stress, and demonstrate that gravity and shape data predict a 38 ± 4km-thick ocean beneath a 23 ± 4km-thick shell agreeing with – but independent from – libration data. Isostatic and tidal stresses are comparable in magnitude. South polar crust is only 7 ± 4km thick, facilitating the opening of water conduits and enhancing tidal dissipation through stress concentration. Enceladus' resonant companion, Dione, is in a similar state of minimum stress isostasy. Its gravity and shape can be explained in terms of a 99 ± 23km-thick isostatic shell overlying a 65 ± 30km-thick global ocean, thus providing the first clear evidence for a present-day ocean within Dione.

Isostatic means the equilibrium between the components of the crust in regards to their vertical movement owing to differences in density.

Deviatoric stress is the kinda sideways stress that particles in a larger system under stress, impose on each other. It's what keeps objects from crumbling to dust when exert vertical stress on them.

So, there model simulates the vertical stress on the crust more than it does the horizontal stresses. Enceladus is a puzzle because it's squished down at the poles much more than any other known moon or planet.


Please help identify I have had this rock in my yard for close to 10 years. It was left behind by the previous tenant. Can you help identify it?
It has layers, a mixture of soft and hard, and is tan to white in color.
Thanks in advance,
Monica

My best guess is a weathered dolostone. These are called dolomites in parts of the country (as around where I grew up) but dolomite is technically the name of the primary mineral in dolostones.  The visual clues I used were 1) it looks like weathered cobbles of the Alibates Dolomite which is common where I live, it is white which is a good color for a reasonably pure sample of dolomite, though I have no idea what the black stain or inclusion is), it is fine grain texture, appears to have a  laminar or bedded structure (but not the horizontal laminations or planer laminations of clastic sedimentary rocks), it appears to be chemically susceptible to chemical weathering but not so much so that there are big holes or gaps in it. The dark areas could be flint or chert.  I believe flint/chert is a common rock type in at least some dolomites, I know they are in the Alibates.
   Yes, try a drop or two of dilute hydrochloric acid if you have some,use vinegar if you don't. In fact  vinegar is probably the better choice for a person no accustomed to working with acids on rocks.  If the rock is limestone it will effervesce if it is dolomite it might dissolve a bit after a few minutes.  If you use they HCL and the  rock is limestone it will effervesce rapidly, if it is dolomite it may bubble a bit.
If you have HCL around the house it may be called muriatic acid and have been purchased at swimming pool supply store.  If you use that, be very,very careful!!. In fact I would not recommend you use it at all.  vinegar is much safer.


Why is the part of the earth tilted towards the sun warmer? Which factors matter more? The part of the earth tilted towards the sun is warmer. For example, in the Northern hemisphere, the earth is tilted towards the sun in the months around June and tilted away from it in the months around December.

This has the effect of increasing the exposure of the earth to the sun for the latitudes tilted towards the sun.
Also, the more tropical the latitude, the more energy is received per unit area.

These two ideas are illustrated by the figure below:

There are other effects, too...

If the sun's energy must pass through more atmosphere, there is greater opportunity for it to scatter into space before reaching the earth
When the sun strikes the earth, if it strikes it obliquely there is greater chance for the light to be reflected rather than absorbed.
Finally, whether the sun strikes water or land or ice has an effect, because each has a different degree of absorption and reflectivity.

In total there seem to be 5 different major factors in how much energy is absorbed by the earth from the sun.

My question is what is the relative importance of each of these factors? Is there a set of equations or measurements that describe the total energy received by the sun in terms of these 5 different factors?

The 5 factors you mention are not nearly as important to the effect you're asking about as another, more fundamental factor: time.

If you've read my answer to this other question, you should understand that all of the factors you mention would create temperature differences at different latitudes whether the Earth is tilted on its axis or not.

But because the Earth's axis is tilted, at some parts of the year the regions of the Earth tilted towards the Sun (in "summer") receive sunlight a greater proportion of the day than the regions pointed away (in "winter").

Not only that, because of the more direct angle of the Sun the factors you list mean that the regions in "summer" are heated better during the day than the regions in "winter".
And this adds up over all the days of summer or winter until the Earth's orbit reorients the axis relative to the Sun.

Or even more succinctly, summer is hotter because the Sun is higher in the sky for more of the day.


Deep sea pumps that work on wind power, can they control the weather? If they used wind power to bring up cold water from far under the ocean in the day time and spray it on prevailing winds going into land, could they make it rain more in arid regions? What weather control can be done by bringing up cold water from the deep sea?

Here are some maths: If 1cm of rain for 1 kilometer is equivalent to a cubic meter of water. 1kwh can lift 1 cubic meter by 100 meters, so an average wind turbine can lift about 6 million square kilometers of 1cm rain every year. Australia is 8 million square kilometers, so 300 wind turbines can logically make Australia rainforest if clouds worked like rivers, without the salt problem?

In theory your idea is not bad,But it needs to be placed as far from land as possible this is to avoid the soil on land from being contaminated by saltwater.

So spraying saltwater into the air is not usefull for creating rain over land,But it can be used to cool the ocean and the planet.

Salt water spraying into the air can possibly help creating condensation nucleus,And help clouds to form and these clouds can shade the ocean and limit the heat absorption.

But this is not as simple as it sounds,Clouds tend to form more in the evening and night when the temparature drops and not as easy in the daytime when they are needed.

Clouds can limit the heating in the daytime,But they will trap or reflect heat in the night time,And then the positive effect is limited.

I think it is best to use the hotter water from the surface of the ocean as it will evaporate faster and probably create clouds faster.


Analyzing composition of a mineral using SEM If I have a mineral in which I did a SEM analysis on and got the data (elements and their wt% with  Std. Dev., MDL, atomic % oxide % and k ratio) how would I go about quantifying the sample's composition? I know I would need standards to do so but I not sure how to go about this. Can someone please assist? Thank you!

You would be lucky if you could identify it with only elemental composition. XRD would be the best method to identify material ( the elemental composition is also needed ). Our lab normally used XRD and XRF , and only went to the SEM when special information was needed.