How is the concentration of particulate matter calculated per cubic meter I have some data about PM10, PM2.5, i.e, how much is generated per day (in kilotonnes) by some sector, say from vehicular emissions. It can be converted to micrograms but I don't know how standard procedures/appliances calculate these values per cubic meter. Is it the mass divided by the volume of the region for which these components are to determined? If yes, then how is it possible in an open space? The area of a city makes sense, but volume doesn't.

The data that you are having are called emission fluxes. If these data are available as global averages then one can calculate global mean concentration by multiplying the residence time of the species with emission flux.
However, at the city or grid level, it is not straightforward to calculate concentration from emission fluxes. In order to calculate, concentration, one requires information of rate of dispersion in three dimensions as well as species amount brought-in by the wind. The dispersion is generally estimated using atmospheric transport models. See for example Gadhavi et al. (2015) have estimated concentration from emission fluxes for black carbon particles.
Technically speaking, one can calculate concentration by first dividing the region where the concentration is needed in three dimensional grid-boxes and by calculating mass fluxes at each interface of the grid-boxes as well as chemical transformation within box. The chemical transformation for species like PM10 or PM2.5 may not be significant but it can be significant for species like SO2. The mass flux calculations will require knowledge on wind velocities across interfaces, diffusion mixing and turbulent mixing within the box as well as removal processes such as dry deposition and wet deposition.
Here, a confusing issue is the size of grid-boxes. A different size may lead to a different concentration number. Though, there is no hard and fast rule about size of grid-boxes, the decision often depends on resolution of available flux and meteorological data as well as end purpose. Suppose, one is looking for comparing satellite based columnar concentration, he/she may take grid-box height that covers entire atmosphere but if one is planning to compare a surface mass concentration measurement typically obtained by air pollution monitoring stations, vertical height of grid-box should be as small as possible preferably less than boundary layer height.
Most emission flux data or emission inventories are available for the emission near Earth's surface. They should be considered as emission flux across the bottom face of the lowest grid-box. The grid box that one but the lowest grid-box will have emission fluxes from top of the lowest grid-box dictated by meteorology and dispersion physics. And the gain of this grid-box will be losses (or negative flux) of the lowest grid box. Besides, losing mass to above, the lowest grid-boxes will also loose mass through process called dry deposition. If the grid-boxes covers the region with rain, then all the grid-boxes from cloud level to surface will also have wet deposition or wet removal. Same applies to mass fluxes in horizontal direction. The lowest grid-box gains mass from bottom face because of emissions but looses to neighboring boxes by horizontal wind. A balance between mass fluxes across all the faces will be concentration of given grid-box.
A crude estimation of surface concentration can be obtained by making a certain assumptions, like by taking grid-box height equal to mixing layer height and assuming horizontally uniform emission fluxes across large region. Under this assumptions one can calculate concentration by multiplying emission fluxes with characteristic time period say 24 hour and dividing it by volume of grid-box. The scientific rational behind this assumption is that mixing height is the height of the atmosphere were turbulence is very high and the loss process becomes dominant only after this volume is filled. Also, when the emission region is sufficiently large, horizontal movement of mass will cancel out across opposing face of the grid-box.
Reference
Gadhavi, H. S., Renuka, K., Ravi Kiran, V., Jayaraman, A., Stohl, A., Klimont, Z., and Beig, G.: Evaluation of black carbon emission inventories using a Lagrangian dispersion model – a case study over southern India, Atmos. Chem. Phys., 15, 1447–1461, https://doi.org/10.5194/acp-15-1447-2015, 2015.
Chapter 2 Atmospheric Trace Constituents in Atmospheric Chemistry and Physics by Seinfeld and Pandis, 2006.


Elemental ratios in rocks and stream water I have chemical analysis of one catchment which can be considered more or less homogeneous and also stream water analysis, I would like to know how elemental ratios (to Na for example) are related both in the geology and in the water. The rocks are mostly andesites. Can I expect the ratios to be similar, and based on your expertise can you recommend a methodology to relate both variables?

There's no simple answer to this. The elemental ratios are a function of proximity to the ocean (Na, Cl, Br, I, etc), relative abundance and mode of weathering of feldspar, rate of weathering, rock Mg-Fe ratio and redox state (especially in relation to iron), the degree of rock mineralization (SO4, Cl, F), rock heterogeneity, and how close the rock-water system is to thermodynamic equilibrium.
There are many good books on the subject, of which my long-standing favorite is John Hem's classic US Geological Survey Water Supply Paper 2254, Study and Interpretation of the Chemical Characteristics of Natural Water, 3rd Edition, available online as a PDF.


Rate of climate change with and without humans? I was watching this interview of Bill Nye on Fox News. Bill claimed that the earth's climate is never in equilibrium, but human activity has caused the gradient to be much higher than it would've been in the absence of humans.

Does this mean that $\dfrac {\Delta\text{avg. global temperature}}{\text{year}}$ is higher than it should be? Is this even a sensible way to measure the impact of global warming? If so, what is the current number, and do we have an estimate of what the number would have been naturally in the absence of humans?

The Earth should probably be cooling, at least, that's what the Milankovich cycles and historical variation and recent temperature charts all indicate.

See XKCD and related question on XKCD chart, and temperature chart over the last 800,000 years.  Source.

Now, it should be pointed out that the Milankovich cycles don't line up in perfect synchronicity, so no two warm periods and no two ice ages should be exactly alike, but there are similarities, like a steady cooling after a warm period.   Earth has been gradually cooling for roughly the last 7,000 years, and this is due to the gradual changes in the Earth's orbit per XKCD.   (scroll to 5,000 bce - see note).

If Earth cooled 1°C in 6,500 years and is due to cool 4°C in the next 10-30,000 years as the next ice age comes along, we can ballpark estimate 1 degree of cooling per 5,000 years, and if we use an estimate of 2 degrees warming by 2,100 and climate change took hold in the 1980s, that's 1 degree every 60 years current rate of warming.

So, by my estimate, man is responsible for 101% of the current warming and Earth's natural cycles are shaving about 1% off man made climate change.   To say it's all us is accurate enough for me.   There's currently no natural warming of the Earth as far as I can tell, Earth should be cooling.   Granted there's variation, like the current solar cycle is a few tenths of a degree warmer than the maunder minimum that is believed to be the cause of the little ice age and our relative lack of major volcanic activity for much of this century might have a slight warming effect, so precise numbers are hard to pin down, but I think 101% man, -1% natural is pretty close to accurate.

That part of the video begins about 2 minutes in, goes on for about 3 minutes, then it moves onto "how would the Earth be different"

If I may rant, there's several things I don't like about the interview.
Tucker Carson says 1:18  "The essence of science is extreme skepticism" - that just ain't so.   Skeptisism doesn't equal scientific discovery.   Bart Simpson is a skeptic - I don't think we should listen to his views on science.  Skeptisism is important to science but it is absolutely NOT the essence of science.   The essence of science is asking the right question and working out an answer through evidence and testing and peer review.   Peer review doesn't mean denial.  For Peer review to be meaningful, evidence or solid counter argument must be presented - not just empty skepticism.   Skepticism that ignores the evidence is about as valuable as a restaurant that doesn't serve any food.   Skeptics must respect and understand the evidence if they are going to provide intelligent skeptical arguments on why the evidence might mean something else.  If they don't do that, it's just noise.  Intelligent skepticism that respects the evidence and data is always welcome.   Uneducated skepticism is a pointless and senseless distraction.    It's like trying to form sentences without using any words.

But try explaining that to a skeptic sometime who thinks he doesn't need to be educated because skepticism is his education.

Tucker then says, about 1:50 "the climate has always changed" - again, not really.  There are periods of what might be called climate consistency and periods of climate change.   The climate isn't "always" changing, but it does change fairly frequently.   There's also some clarity on what constitutes a change - weather changes during the seasons, but that's not climate, not really.   Climate incorporates the seasons and year to year variations.  Real climate change, by my definition, happens every few thousand years - give or take, and big changes, with the current ice age cycle on a 100,000 year time-frame, big changes happen twice every 100,000 years, with the rise and fall of ice ages.   There's some room for opinion in this though, but "always changing", a common phrase by deniers - but simply not accurate, not if you're talking about real change.   Now if you're talking about irrelevant change then, sure.

Pretty much everything is always changing.   A human's height changes about 1/2 inch from when they wake up to when they go to bed,   A human in space grows a full inch, but, . . . I still say I'm 5'10 when asked and I'd say I'm 5'10 if I lived on the space station.  I don't say 5"10 1/2 cause I just woke up.   Even though my height is always changing depending on how long I've been standing up, 5'10 is close enough.   Relevant, significant change is worth identifying.   Incidental or irrelevant change based on fluctuations that go back and forth mostly doesn't need to be identified.

So, no, the CLIMATE is NOT always changing.   Weather is always changing, climate goes through periods of decades, centuries, sometimes Millennia, where it remains consistent enough that we can say it isn't changing.   "The climate is always changing" is a red herring.

Everything Bill said is true, though I wasn't crazy about his initial time scales "change used to happen over millions of years" and "now it happens over decades and years" - that's iffy, but mostly everything he said was true, but he didn't handle the interview very well.    Tucker's Gish Gallop was successful.

When Tucker moves onto "how would the Earth be different", Bill does answer him with specifics, but Tucker just pretends those aren't good answers and interrupts Bill or goes back to the first question when he doesn't like that his 2nd question is being answered.    Overall it's a terrible interview designed to sell disinformation, not inform.   Painful to watch and I hate Fox News for that reason.

OK, rant finished.

There's no right answer.    101% - by my estimate.   100% if you believe the Earth isn't getting cooler.  102% or more if you set the rate of cooling a little higher, with the next ice age due in 10,000 years not 20,000 years.    (as of now, the next ice age is on indefinite delay - but that's another story).

Or, the answer could be, 70-90% if you believe there's an un-accounted for natural warming period over the last 30-40 years.  That's one of Judith Curry's arguments that climate change has gotten a natural push to make it look bigger than it is, but, she has no good proof, which is why she's mostly alone in that argument.  It's just something she's claiming.

100% is a good answer too, and if you listen, Bill does say 100% at one point, but it's during an interruption and hard to hear.   "We aren't sure but close to 100% is also a good answer".

If Tucker had asked me what percentage.   I'd have showed him XKCD's chart and said "see this point here, the cooling began shortly after 5,000 BCE, at a rate about 100 times slower than the current warming.  101% is relatively consistent with past Milankovich cycles and past periods of cooling following a warm period between ice ages.  So, that's my answer.   101% of the current warming is man-made.


Predicting school closures with historical weather prediction data? I'm interested in predicting when the local schools will be closed due to snow and other winter weather. I have a list of school closure dates and a rough sense of the criteria used to determine the closing of schools including, temperature, wind, precipitation, and their interactions.  Using a statistical technique (classical, Bayesian, or machine learning), I'd like to use both the actual weather the day before (t-1) and the predicted weather for the the day (t) to predict the county's decision.

I want to use the predicted weather at t and not the actual because that's the information known to the deciders when they have to make their decisions. For the actual, realized weather for t-1, I was planning on using the NOAA API. But I'm at a loss on where to find weather prediction data. While I could do what @MarkRovetta suggests in the question on Statistical weather prediction and roll my own prediction model, that is harder than using a database and my lousy prediction model won't compare with the National Weather Service predictions available to the country officials. At best that will act like noise that will reduce the quality of my predictions. My primary question is therefore what sources are available for local weather predictions at various lags to the realized weather?

Additionally, are there tables of the predictive quality of forecasts at various time horizons? If, for example, the daily weather was predicted with 99% accuracy by 4 am that day, maybe there isn't an important difference between the predictions and the realized values.

I'm not aware of any datasets that are quite what you want (archived point forecasts for the next day).  There is less digestible data out there though.

NOAA NCDC archived messages
This website has archives of all messages that NOAA transmits.  The vast majority are unrelated to your needs, but if you look through the message types you might find something worthwile.

NCDC NOMADS
This site has archived GFS model grids.  This model is run 4 times per day and each run will have an analysis grid (current weather) and forecasts every 6 hours through the first few days of forecast time.

Most other archived data I could find are either observations or model reanalysis datasets, which won't work for your needs (except to better define the initial day t).  With the above datasets you could potentially put together the current weather at a specific place at 4 different times on day (t) and from each time have forecasts data for the next day, e.g.:

Observations / model analysis 12Z day t: 24 hour forecast for 12Z day t+1
Observations / model analysis 18Z day t: 18 hour forecast for 12Z, 24 hour forecast for 18Z day t+1
Observations / model analysis 00Z day t: 12 hour forecast for 12Z, 18 hour for 18Z and 24 hour for 00Z day t+1

From these you could then do your statistical analysis overall and explore how it may change as the day progresses and the model forecasts are shorter term.
If wading through this data is not something you want to deal with, an alternative is to start archiving forecast data yourself going forward and building up a database over time.
Some caveats...
The NOMADS GFS data is pure model data, no forecaster input.  This is not what decision makers will be using directly.  This data will be made more consumable and be tweaked by forecasters before dissemination to the public.  If the NOAA message archive contains suitable forecasts data, that data will have likely been filtered through a forecaster and close to what would be displayed on the NWS website as a forecast.
School closings are chaotic.  The same weather will not yeild the same closures.  Sometimes schools will stay open when faced with a worse forecast than a time they recently closed.  The criteria for closing may be a moving target as usable "snow days" are used up.  School closing thresholds will vary regionally (Florida schools would be closed Dec - March if subjected to a Michigan winter).  You may come up with a good forecast for when a school should close, but don't be surprised if it doesn't correlate well with actual closings.


Can humanity help reinforce the ozone layer? The ozone layer has been weakened by humans over the last century, but is slowly recovering.  Can humanity help undo the damage faster by manufacturing and releasing ozone?
Would it be enough to simply vent ozone at point of manufacture, or would it be better released at the 10 km height?
Would the latitude of release have an effect?   IE, would ozone release be faster/more effective at the poles?

Inspired by how does the ozone layer "stay in place"? which says (paraphrased) "the ozone layer is 10km thick at height which would be 3mm thick at sea level"
and by Has a reduction in car use ever had an effect on the ozone layer? which suggests total recovery is at least 30 years away for mid latitudes and longer for the antarctic hole.

Would it be enough to simply vent ozone at point of manufacture, or would it be better released at the 10 km height?

Neither. The right answer is not to do it at all. Surface level ozone is deemed to be a pollutant. It is highly irritating to people. Ten kilometers is still in the troposphere. Ozone in the troposphere rarely makes its way to the stratosphere. Ozone is highly reactive, and there is plenty of stuff in the troposphere that ozone can readily oxidize. If this was to be done (which is a bad idea), the ozone would have to be released into the stratosphere. Ozone concentration peaks at about twenty kilometers altitude.
Why not at all? There are three billion metric tons of ozone in the stratosphere. Think of how much effort augmenting that would take, and how much ozone depleting chemicals would be deposited into the stratosphere while doing so. Jet engine and rocket exhaust contain chemicals that deplete ozone.


Why is Earth's outer-core liquid? The Earth's inner core is solid because despite the enormous temperature in this region, there is also enormous pressure there, which in turn raises the melting point of iron and nickel to a value above the Earth's core temperature.

Now as we move out from the solid inner core, temperature drops, and pressure also decreases.  Obviously because the inner core is solid but the outer core is liquid, we must conclude that the drop in temperature vs the drop in pressure must be lower than the gradient of 16 degrees/GPa shown in the diagram below (link to source), given that at the outer-core temperature has exceeded the melting point of iron/nickel, which is a function of pressure.

In other words, the drop in pressure must be quite significant compared to the drop in temperature as radius increases from the core.

So how is it that pressure drops off fast enough relative to temperature to give rise to the liquid outer-core.  A good answer will explain how temperature drops off with radius and how pressure drops off with radius and how these compare to give rise to the liquid outer-core.

First, you need a phase diagram that goes to higher pressure. The pressure at the inner/outer core boundary is over 300 GPa. The one in the question would only get us into the mantle:

(link to source)

A typical temperature and pressure at the outermost part of the core would be 3750K and 135GPa, which is in the liquid region of the phase diagram.

For more data on pressure and temperature as a function of depth see this University of Arizona source.  All appropriate credit to Marcus Origlieri.


Calculating/estimating volatiles based on other representative samples I am currently working on a set of geochemical data representing calc-alkaline igneous intrusions from central Canada.  The samples were analyzed in ~2013-2014.  These samples have been tested for LOI wt%, but not H2O, CO2...etc.  Historical sampling from the same area representing the same suite of rocks (but different sample locations) have results for H2O and CO2 wt%.  I need H2O wt% values for my samples in order to complete a calculation for viscosity of the intrusions, but I won't be doing any more testing.  Am I able to estimate H2O in my samples using the historical data?  And if so, how would I go about doing that?  And how would I correct for (if possible) the difference in quality of the measurements due to more advanced and accurate/precise instrumentation?

If you are sure that the samples for which you have H$_2$O data are from the same intrusion than yours, then I don't see a problem for using these values for viscosity modelling, as long as it is clearly mentioned in the paper. After all, a sample is supposed to representative of the rock unit, and science is done by standing on the shoulders of giants!
If you have several historical samples with different H$_2$O contents, this gives you a range of water contents. Do you intend to use a model like Giordano et al. (2008) ? If so, you also need a temperature estimate, which you may have by geothermometry. These temperature estimates have an uncertainty, see Putirka (2008) for a review. For example, if you use the two-feldspar thermometer, it gives you $T$ to $\pm$30 °C.
So, what you could do is to model two scenarios: one "cool and dry", with the lowest $T$ and H$_2$O content, which gives you the highest viscosity; and one "hot and wet", with the highest $T$ and H$_2$O content, which gives you the lowest viscosity. This way you can be quite confident that the viscosity was somewhere between these two values. Usually a $\pm$30 °C interval will change your result by half a log unit, and a $\pm$0.2 wt% H$_2$O interval will change it by one log unit, so you'd get something like $\log \eta = X \pm 0.75$ Pa s, which is not that bad.


Is Earth an organism? According to Wikipedia, "all known types of organism are capable of some degree of response to stimuli, reproduction, growth and development and self-regulation via homeostasis." Further, watching a video like the "Earth Breathes as Seasons Change" (which is from NASA) - superficially gives the sense that the "Earth is alive" so to speak.

Is Earth an organism? Since there is no unequivocal definition of life, the current understanding is descriptive. To define Earth as an organism, your answer most show either via observed phenomena or theoretically observable phenomena that Earth exhibits all or most of the following traits: Homeostasis, Organization, Metabolism, Growth, Adaptation, Response to stimuli, and Reproduction.

[I am going to preface this by saying that I am not in one camp or the other in this discussion, as I think there are pros and cons to each side]

This links to the "Gaia Theory" proposed by James Lovelock, wherein the Earth is considered a self regulating organism.

In this hypothesis, Earth is an organism in that it will try to maintain certain conditions.  These conditions include temperature (within a range suitable for life as we currently understand it), oxygen content of the atmosphere, water availability etc.

This does not mean that the ball of rock we are flying through space on is a living organism as we understand it, but rather that the various spheres of life (These are usually the biosphere (ecosystems), the atmosphere, the cryosphere (the poles, and other ice-bound areas), the hydrosphere(oceans), and the pedosphere(soil)) interact with each other in such a way that optimal conditions are maintained.

Whilst the theory as a whole is not used today, it is recognised that feedbacks and interactions between different spheres occur, and are an important part of understanding Earth systems, and is studied in an area of science known as Earth System Science

One of the initial arguments for this theory was that our atmosphere is not in chemical equilibrium, and that there must therefore be processes active to maintain oxygen levels at a steady state outside of equilibrium.

This is a difficult topic, as it is important to stress that the Gaia hypothesis does not state the Earth is some sentient being consciously doing anything, rather that a complex set of interactions, abiotic and biotic, combine to maintain and regulate the planets temperature and atmospheric composition.

An example of this regulation is chemical weathering, whereby carbon dioxide in the atmosphere falls in rain, and reacts with rocks, to form calcium bicarbonate, removing carbon from the short term carbon cycles.  The more surface rocks there are which are capable of this reaction, the more CO2 is removed from the atmosphere.
There is a hypothesis which says that at least once, the Earth has been covered largely in ice and snow, and this reaction (known as carbonation) is suspected to have played a part in the recovery of Earth.
The hypothesis (Snowball Earth) goes like this:

The Earth became cooler, whether due to Milankovich cycles, volcanic activity, or solar output changes.  As this happened, ice began to form at the poles, changing the albedo, and reflecting more radiation back to space, this caused local cooling, and allowed for the growth of the ice sheets. As they spread, the albedo became higher on a larger scale, and the ice sheets eventually covered the two hemispheres, with a band of open ocean at the equator.
The earth was now very cold, but not completely empty of life, or without volcanic activity.  Life continued to respire CO2, and volcanoes continued releasing CO2.  Without rocks to remove it from rain, or ocean to absorb it, Carbon dioxide began to build up in the atmosphere.
As it built up (over millions of years), it began to warm the planet, which in turn began to melt the snow. As the snow and ice began to retreat to the poles, rocks, and open ocean were again available to remove the carbon dioxide from the atmosphere, and more photosynthetic organisms were able to survive, and remove more CO2 through photosynthesis.

This lead to a stabilisation of the planets systems again, although, it may have gone too far, and swung back to a glacial period (although not a frozen earth), then moving back to a warm period before stabilising due to the tectonic movement of the continents northwards The break-up of Rodinia, birth of Gondwana, true polar
wander and the snowball Earth

I hope this long ramble illustrates how there are a number of complex systems which all interact with each other to maintain conditions.  Whether we consider the sum of these systems an organism is an ongoing discussion, but, all organisms have the ability to regulate via various systems, and each of these systems has the potential to lead to chaotic positive feedbacks, and spiral out of control, although negative feedbacks usually keep everything running as normal.

I have linked the Gaia theory webpage, and if you search for Daisyworld model, you will find a model which you can run to simulate feedbacks
It is up to you whether you think this collection of feedback systems is an organism, and this debate will likely run for decades more.

Gaia Theory Site


What would happen if magma flows into a very large oil deposit? If there were an earthquake that somehow cause a crack in the earth and allowed a significant amount of magma to flow into a very large oil deposit. With that high amount of explosive energy that would be produced, could it cause an earthquake or even a volcano? Does this usually happen?

An oil deposit is gravel and rock mixed with oil, capped by rock - like this:

My guess is that if somehow, likely from below or sideways, magma would intrude into this deposit, oil (and posibly water) would evaporate. The pressure rises, slowing the magma intrusion. If enough magma and enough heat is provided, the vapor pressure of the oil may be enough to crack the rock layer at places, oil would escape and condense in the shale layer.

My gut feeling is that we are talking about processes that take years to decades to play out.


What causes the semi-annual mesospheric meteoric potassium variability? In a recent study presented in the article First global observations of the mesospheric potassium layer (Dawkins et al. 2014), space-borne resonance fluorescence observations confirmed previous LIDAR observations of a semi-annual variability of mesospheric meteoric $\ce{K}$, which is very different from the annual (seasonal) pattern observed for other metals such as $\ce{Na}$ and $\ce{Fe}$.

What causes the semi-annual mesospheric meteoric potassium variability?

Recent observations and modelling by Plane et al. (2015) and Plane et al. (2014) have described the most likely mechanisms for why potassium has its unique semi-annual variability, with a small summertime maximum and minima occurring at the equinoxes (Plane et al. 2015).  The semi-annual variability is consistent across the globe (Plane et al. 2014).

In both papers, the cause of the unique semi-annual variability are narrowed down to 2 main atmospheric chemical dynamics, based in no small part on unique K chemical properties:

(Note: MLT = Mesosphere-Lower Thermosphere)

In summertime, the maxima observed is due to the cooler MLT temperatures being low enough to neutralise K+ ions to K.
During the equinoxes, O is at a minima, while CO2 and H2 exhibit a maxima - so, according to Plane et al. (2015)'s model, decreasing O, while increasing CO2 and H2 causes a reaction with K to form KHCO3, thus resulting in K being at a minima.

According to their models, KHCO3 returns to K by largely temperature independent photolysis.

Plane et al. (2014) describe there is a slight decrease in K in high latitudes in the presence of polar mesospheric clouds.

References

Plane et al. 2015, Resolving the strange behavior of extraterrestrial potassium in the upper atmosphere, Geophysical Research Letters

Plane et al. 2014, The Mesosphere and Metals: Chemistry and Changes, Chemical Reviews


In which state of matter exactly are the clouds? The state of the clouds and it can only be one of the three states, solid, liquid, or gas. Which one are clouds?

Clouds consist of suspended (floating) liquid water droplets ("liquid clouds"), frozen (solid) ice particles ("ice clouds"), or a mixture of both ("mixed phase clouds").  In-between those droplets or ice particles (meteorologists use the phrase hydrometeor to encompass both) is air which will contain water vapour, but what you are seeing is the liquid and solid parts.  Some people believe that when they're seeing clouds, they're seeing water vapour.  They are wrong.  Don't feel bad about sharing this belief, I've known an atmospheric (!!) scientist at a national research institute have the same misconception.  Whether the humid air between the droplets or particles is part of the cloud is a matter of definition, but ice particles may contain air bubbles so I think it would be unreasonable to say there is no water vapour in a cloud.

One way to tell this by yourself is experiencing fog.  Fog is nothing else than a cloud that is connected to the ground.  If you walk through fog (preferably dense fog) and look carefully, you will notice it consists of many tiny water droplets (or ice particles, but then it should be very cold, as small cloud particles will not freeze immediately at -5°C or -10°C).

Tall clouds such as Cumulonimbus usually consist of liquid droplets near the bottom, ice particles in the anvil or incus (the top part that may spread out horizontally), and mixed in-between.  Mixed phase clouds are pretty difficult to model or even measure accurately, as the exact proportion between liquid and solid depends on many (unknown) factors.

See also Ice and Mixed Phase Clouds at the Centre for Atmospheric Science, University of Manchester (UK).


Every 202,500 years, Earth wanders in a new direction; does it affect climate? I refer to this article on nytimes.com: Every 202,500 Years, Earth Wanders in a New Direction

TLDR: Scientists believe the earth's orbit oscillates between circular
and more elliptical due to the gravitational pull from Jupiter (big)
and Venus (close). It takes 405k years to complete a cycle.

The big question: could this affect climate-change? Could it make colder winters, hotter summers or just more extreme weathers? Changing Gulf stream?

Milankovitch cycles do affect climate on Earth. There are several cycles.

  "Variations in eccentricity, axial tilt, and precession of the Earth's
  orbit resulted in cyclical variation in the solar radiation reaching
  the Earth, and that this orbital forcing strongly influenced climatic
  patterns on Earth."
  source: wikipedia

Scientists of Pleistocene's climate evolution strongly correlate Milankovitch cycles with glacial/interglacial periods, affecting the Gulf Stream Current.
Other factors of Earth's internal system, such as volcanic events do affect climate, but changes in the magnitude of solar radiation are a well known climatic variability generator.


Over which surface will the albedo changes due to clear and overcast skies have the greatest impact? With respect to climate change, will the changes in albedos due to clear skies and overcast skies have the greatest impact on incoming solar radiation over ocean, sea ice, or land?

My thoughts:

On a scale, the ocean has the lowest albedo, nearing on 0, land is much higher with an average of 0.3, and sea ice has the greatest with average of 0.6.  Since the oceans absorb almost all the incoming radiation, an increase in cloud cover will greatly change the albedo, since clouds tend toward 1, and much less energy will be absorbed.  Looking at sea ice, it already reflects 60%, adding clouds with similar albedos, the change won’t be much.

Note: I picked these crude numbers from the internet for sake of argument.

Is my reasoning correct, or am I missing piece of puzzle?

You should also consider that fresh snow atop the sea ice increases the albedo significantly. So the albedo for sea ice can fluctuate during a season. More clouds implies more precipitation, something we are seeing in a changing climate, so it’s fair to assume that changes in snow cover atop the sea ice will change as well. It may also make the change in seasonal albedo more dramatic, from sea ice to darker oceans. It depends on the weather patterns and the regions.
 Also, first-year sea ice will have a lower albedo than multi-year ice that has does not melt each season - though in the Arctic is type of ice is now very rare.

If cloud cover increases over the oceans the albedo as seen from space will not change significantly, but again, the cloud types and heights will affect the albedo. But more cloud cover generally will trap more outgoing radiation enhancing the greenhouse effect. In a positive feedback loop. So, using you numbers, the albedo would increase, but the greenhouse effect would enhance, overall leading to a temperature increase.

Land cover also varies, mid latitude regions are likely to see more cloud cover and more intense storms with climate change. An increase in cloud cover would again lead to changes in the greenhouse effect. With the albedo likely increasing (dark greens of forests, fields, etc having lower albedos etc).

Overall your reasoning is sound, but it overlooks the effect cloud cover has on outgoing radiation from the Earth’s surface, more of which will be trapped and re-radiated by the extra water vapor.


The spiraling cyclone track - Cyclone Nathan In the northern part of Queensland, Cyclone Nathan has had a spiral type of track, as can be seen below:

Image credit: Tropical Cyclone NATHAN Forecast Track (Joint Typhoon Warning Center)

As can be seen in the diagram, it tracked in from the Coral Sea, stopped short of making landfall on the Cape York Peninsula, went back out to sea and has tracked back inland  -and is expected to make landfall and cross into the Gulf of Carpentaria (where it may re-intensify).

What meteorological mechanisms would cause the spiraling track of a cyclone?

Hurricanes backtracking and looping seem to be quite common in the Atlantic (Nadine, Jeanne, Alberto, Dennis), and West Pacific (Ernie, Nari, Fung Wong, Parma, Roke) but not so much in the East Pacific (where the tracks are way more linear, with much less latitudinal change).

In general, tropical cyclones are steered by the global wind field. The environmental wind field (winds that surround a hurricane) guides a cyclone along its path. Hurricanes are steered predominantly by winds in the upper atmosphere, especially winds from about 3000 to 10000 meters above sea level. High-pressure and low-pressure systems often cause cyclones to divert from their initially east-to-west movement. When a high- or low-pressure system is located to the west and extends far enough latitudinally, storms are blocked and a change in direction may occur.

In the case of Tropical Cyclone Nathan, there seems to have been a stationary high over southwestern Australia on 12 March 2015 that connected with another high to the north and prevented the movement of the cyclone. The presence of Tropical Cyclones Olwyn and Pam probably influenced the change in path.

.

Nathan started to move north as Pam was moving south (13 March) and then went east without that much obstruction (14-15 March). As the high pressure to the south moved east, there was a clear path for Nathan to continue moving west (18-March).


What would happend in distant future if we didn't extract fossil fuels I'm sorry if that is stupid question. Geology is not my thing, but I'm curios about this.

Let's assume that mankind has never extracted fossil fuels (or existed in the first place) and for millions of years fossil fuels just stacked up in the earth's crust.
Then, let's fast forward time absurdly huge amount of time ahead, assuming there's no astronomical catastrophes.

What will happen with the pockets of fossil fuels when they grow absurdly huge?
Would they surface earth to form seas of oil or release all the gas into atmosphere?
Or would they grow in opposite direction - to the center of earth, then what would it become?

Obviously if all fossil fuels had been left in the Earth it would greatly lessen the climate warming problem. You ask what would happen to these fossil fuels in the course of time if we left them alone. The coal would remain inert and fairly well behaved; some would be exposed by erosion, but would do no harm. Some would be buried even deeper as new deposits of sediment were laid on top of them.

Most of the oil would remain buried out of harm's way, but some would be exposed by erosion and geological faults to form tar pits or asphalt lakes (which are both much the same thing). Oil seepages are a nuisance, because they pollute the sea and fresh water on land. Fortunately they do not occur very often. On land, the volatile fraction evaporates quickly and leaves a thick, sticky residue called tar or asphalt, the latter being slightly thicker.

Well known examples are the La Brea tar pits in Los Angeles, famous for the fossils of extinct animals trapped by the tar, and the asphalt lake in Trinidad which has long been mined for surfacing roads etc. There are several other tar pits in California, and a large asphalt lake in Venezuela.

Looking into the future, a few more oil reservoirs would be caused to leak in the course of time by geological faults, but most would stay safely in the ground. Meanwhile the old processes would be at work, transforming vegetable matter into peat, peat and wood into lignite, and lignite into coal. Plankton and vegetable matter in the ocean would form more oil reservoirs.

Present fossil fuel deposits will become buried more and more deeply in the course of millions of years, when man has vanished from the scene, with new layers of sediment and new fossil fuels laid down on top of them, but they will never be buried deep enough to reach the asthenosphere, never mind the centre of the Earth. They will just, in some cases, have another kilometre or two of rock placed on top of them.


Splitting the Earth's emerged land in two equal parts Is there a meridian that has exactly as much emerged land area 180° on its East than 180° on its West (on the assumption that it could exist...)? If there is no meridian, is there any other great circle with that property?

Edit: Since David Hammen proved that such a median exists, which one is it?

And what is the latitude that has as much emerged land on its North than on its South (that one necessarily exists)?

I found this Wikipedia article but it doesn't really answers the question.

TL;DR: It depends on how one defines land area. With a sensible definition, such a meridian (along with its completion on the other side of the globe) must necessarily exist by virtue of the intermediate value theorem. The same goes for the line of latitude.

Defining the functions

$\operatorname{A}_{\text{E}}(\lambda)$ is the area of the land projected onto the reference ellipsoid of the hemisphere to the east of the line of longitude $\lambda$.
$\operatorname{A}_{\text{W}}(\lambda)$ is the area of the land projected onto the reference ellipsoid of the hemisphere to the west of the line of longitude $\lambda$.
$\operatorname{\Delta A}_{\text{lon}}(\lambda)$ is the difference between $\operatorname{A}_{\text{E}}(\lambda)$ and $\operatorname{A}_{\text{W}}(\lambda)$.
$\operatorname{A}_{\text{N}}(\phi)$ is the area of the land projected onto the reference ellipsoid of the hemisphere to the north of the line of latitude $\phi$.
$\operatorname{A}_{\text{S}}(\phi)$ is the area of the land projected onto the reference ellipsoid of the hemisphere to the west of the line of longitude $\phi$.
$\operatorname{\Delta A}_{\text{lat}}(\phi)$ is the difference between $\operatorname{A}_{\text{N}}(\phi)$ and $\operatorname{A}_{\text{S}}(\phi)$.

My definitions make each of these functions continuous. Note well: Other definitions of land area might result in non-continuous functions. Imagine a perfectly vertical cliff that runs north to south. If the area of that cliff face counted as land area then $\operatorname{\Delta A}_{\text{lon}}(\lambda)$ will not be continuous. The same goes for $\operatorname{\Delta A}_{\text{lat}}(\phi)$ for a perfectly vertical cliff that run east to west.

Proving that the latitude line must exist is easy, so I'll do that first. All of the Earth's land area is north of 90° south latitude, making $\operatorname{\Delta A}_{\text{lat}}(-90)$ a large positive number. All of the Earth's land area is south of 90° north latitude, making $\operatorname{\Delta A}_{\text{lat}}(90)$ a large negative number. Because zero is between this large negative number and large positive number, and because $\operatorname{\Delta A}_{\text{lat}}(\phi)$ is continuous, there must necessarily exist at least one line of latitude $\phi$ for which $\operatorname{\Delta A}_{\text{lat}}(\phi)$ is zero.

Regarding longitude, Pick an arbitrary longitude $\lambda$. If $\operatorname{\Delta A}_{\text{lon}}(\lambda)$ is zero we have a winner. If it's not zero, then since $\operatorname{\Delta A}_{\text{lon}}(\lambda +180°) = -\operatorname{\Delta A}_{\text{lon}}(\lambda)$, there exists at least one longitude $\lambda_0$ between $\lambda$ and $\lambda+180°$ where $\operatorname{\Delta A}_{\text{lon}}(\lambda_0)$ is zero.


Why are oceans so deep? Some areas of oceans are about 11 km deep. Is it because continental plates were moving away because of troughs in the middle from where new rock is formed? If so, why did it become deep? If not, what are other reasons?

The deep zones in the ocean are not where new rock is formed. The trenches are the areas where rock is subducted back into the mantle. Here's a picture to visualise it:

USGS/USGov, modified by Eurico Zimbres

New rock is formed at mid ocean ridges (for example 12 in the image). Those are areas that are less deep than the rest of the ocean. This rocky plate sinks underneath another plate (either continental or oceanic) and by doing so "pulls" that plate down (for example 13 and 18 in the image). This is what causes the extreme depth of those areas.


What is the fastest ocean deep current? The Gulf Stream is the fastest ocean current in the world with peak
velocities near 2m/s.
Source: marine.coastal.edu

What about deep currents, North Atlantic Deep Water, Antarctic Bottom Water, etc?
What is the fastest ocean deep current?
My guess is Antarctic Bottom Water must be the fastest because Antarctic Circumpolar Current receives not salty water from ice melt, and salinity gradient moves deep currents.
Is Antarctica Bottom Water the fastest?

This article in Fox News points to this paper and asserts that the fastest deep current measured is the Antarctic.

Rintoul, of the Antarctic Climate and Ecosystems Cooperative Research
Center in Hobart, said it proved to be the fastest deep ocean current
yet found, with an average speed of 7.9 inches a second (0.20 m/s).

I have no access to the paper, I can only read the abstract. I guess Fox News didn't lie this time as they are sourcing a scientifical paper of Nature Geoscience.
Fukamachi, Y., Rintoul, S., Church, J. et al. Strong export of Antarctic Bottom Water east of the Kerguelen plateau. Nature Geosci 3, 327–331 (2010). https://doi.org/10.1038/ngeo842


Could the extraction of energy by wind turbines be harmful to the environment? Wind turbines work by converting some of the energy from wind to electrical energy. Is it possible to have too many turbines, leading to them removing too much energy from the wind?  I'm not an environmental scientist, but I'm guessing the energy in wind plays some vital role in the environment.

So what would happen if we removed too much of that energy?

The short answer is yes, it's possible. And it can also reduce harm.
Summary of the changes
Here's a brief summary of the changes that happen when electricity is generated from a wind turbine, rather than from a fossil or nuclear plant:

energy is taken out of the wind further upwind than it would otherwise be
there is more turbulence just downwind from the wind turbine
less low-grade heat is put into the environment around the fossil or nuclear plant that has been turned down, or off, because the electricity is supplied from wind now.

Global impacts
As far as we can tell it's unlikely that there would be global effects at any plausible levels of global deployment (let's say, up to terawatts of mean power, but below tens of terawatts). But a single row of turbines can be enough to cause very local effects, and those could be positive or negative.
There is an open discussion in the literature about what the impact of removing terawatts of wind power would be.  But it's a theoretical discussion, and not really meaningful, because it would absolutely depend on where the power was extracted.
What happens to the wind's energy?
Ultimately, pretty much all energy in the wind ends up as low-grade heat. And that's regardless of whether or not it gets there via a wind turbine or not. If not, it will eventually dissipate due to friction, where it becomes ambient low-grade heat. If it is, then it will get converted into electricity, then some energy service (e.g. lighting), and then ambient low-grade heat.
So deploying lots of wind turbines just moves where that energy gets taken out of the wind, but not how much.
An unshrouded turbine can extract at most 16/27ths (59.3%) of the wind's kinetic energy - that's the Betz limit. In practice, it's more like 20-50%. Here's the power curve for an E82-Enercon 3MW turbine, from the Enercon brochure:

The lighter curve, plotted against the vertical axis on the right, shows the proportion of the wind's kinetic energy that is converted to electricity. At around 9 m/s wind speeds, that proportion maxes out at about 50%. A further small (~2) percentage goes to internal conversion losses within the turbine.
What are the energy changes, and where?
The full picture is more complicated. Whether switching from fossil/nuclear to wind would change patterns of energy service demand, and energy efficiency, is an open question, so there are plenty of ripple effects. But, putting those aside to simplify things, just switching from fossil/nuclear to wind wouldn't create new sinks for the low-grade heat: lighting would carry on getting used at the same time and place as it does at the moment. What would happen is that energy would be extracted from the wind in new places: at turbines, rather than further downwind where the energy would be dissipated by friction. The other thing that would change is that there would no longer be additional sources of low-grade heat at all those fossil and nuclear power stations. Now, they're pretty intense sources of heat: nuclear or coal plants typically push out 150% - 200% as much energy as local heat, as they do electricity. So that's a significant input of heat into a local weather system, which would no longer be there when they're turned off because the electricity is being supplied from wind instead.
A quick romp through the literature
Smith, Barthelmie & Prior used In situ observations of the influence of a large onshore wind farm on near-surface temperature, turbulence intensity and wind speed profiles. They found that in the daytime, there was no observable change in temperatures once they were more than 2km downwind from turbines. However, there was an increase in night-time temperatures at 2.5m above ground (hence the use by farmers of wind turbines for frost prevention)
On top of what I've written above, we've also got a bunch of modelling in the literature. Now, this is largely an argument between different assumptions: pick the answer you want, and tune your assumptions accordingly. However, these papers are written by people with different underlying positions, so you'll find a range of possible outcomes, and you can decide for yourself which assumptions are more or less likely.
Mark Z Jacobson wrote the book on the Fundamentals of Atmospheric Modelling, and tends to build up from the micro level. A recent paper of his shows potential benefits of reducing the energy in hurricanes that reach the shore, and we know that the first-order impacts of that would be positive.
Roy & Traiteur looked at Impacts of wind farms on surface air temperatures and found significant very local effects, and options for mitigation.
Wang & Prinn looked at potential long-term global impacts of multi-terawatt-scale installations and found that massive onshore wind turbines might cause some warming over land (though less than the coal & gas plants they would replace), and massive offshore wind turbines might cause some global cooling. The modelling was done by assuming the turbine interactions would behave like a generic increase in surface roughness; the other key assumption is that the loss of detail from meso-scale modelling did not significantly impact the results.
Kirk-Davidoff and Keith, like Wang and Prinn, used coarse meso-scale modelling by adding anomalies to surface roughness coefficients. With continental-scale windfarms, they found very little change in global temperatures, but local changes could be up to 2 Kelvin.
Rooijmans' Masters' thesis (Universiteit Utrecht, 2004) looked at the impact of a huge (9 000 km2) offshore wind farm on patterns of rainfall, using a mesoscale circulation model, and found that the distribution of precipitation could change, with more rain at sea, and less onshore. That modelled windfarm would be about four times the size of the largest envisaged offshore wind farm.
Consequences and conclusions
Distributions of heat affect weather and climate. So, deploying lots of wind turbines can change local patterns of evaporation and rainfall. They can also change patterns of frost: the turbines increase the turbulence in the flow, close to the ground, reducing frosts: there are farms that deploy turbines in order to harness that frost-prevention: you can even (HT scruss) buy wind machines dedicated to producing that turbulence in no-wind conditions (these wind machines, ironically, are typically powered by fossil fuels).
So that's the ultimate change: energy would be extracted from the wind further upstream than it was previously; and there's less heat put into the system from the cooling systems at fossil and nuclear power stations. These are all local weather effects, and could be beneficial, harmful, or neutral.


What can we learn by studying lunar atmospheric tides? Lunar atmospheric tides are likely insignificant for weather, although Guoqing (2005) asserts that The lunar revolution around the earth strongly influences the atmospheric circulation.  They don't seem to be studied terribly much.  What insights can we gain from the study of lunar atmospheric tides?

This is a partial answer detailing some of the recent research in lunar atmospheric tides.  Many of which go beyond the 27.3 and 13.6 day cycles discussed in the Guoqing, 2005 paper, referenced in your question.  There has been some considerable research in this in recent years (an example is this list from Google Scholar of research since 2013).

A couple of examples are explained below that show that all manner of lunar cycles seem to have an effect on the Earth's atmosphere, generating a complexity of tides that tidally affect all layers of the atmosphere.  As we've been able to take long term measurements of various atmospheric parameters (most notably temperature, pressure and velocity) we have been able to come across patterns that suggest that several lunar cycles have made an imprint on them - in a way, suggesting that all lunar cycles have an affect on our atmosphere.

The lunar semi-diurnal cycle has been found to have a definite signature in the amplitude and phases of the temperature field of parts of the atmosphere between 20-120km altitude, according to research presented in the article A global view of the atmospheric lunar semidiurnal tide (Paulino et al. 2013) with the most pronounced signature observed in the lower thermosphere region.

Observations made between 1947-1994 in the article Long-Term Lunar Atmospheric Tides in the Southern Hemisphere (Wilson and Siderankov, 2013) have detected 4 roughly equidistant standing-wave summertime patterns with mean sea level pressure (MSLP) and sea-surface temperature (SST) consistent with being influenced by the 18.6 year Draconic lunar atmospheric cycle.  Superimposed on these is evidence of the SST's being affected longterm by the Perigee-Syzygy (or 'supermoon') lunar cycle.

A consequence is that the standing-wave pattern of the MSLP will interact and cause abnormal atmospheric pressure when passing over the semi-permanent South Pacific subtropical high roughly every 4.5 years, the consequences are that these affect the strength of the East-Pacific trade winds and according to the authors, may lead to conditions that "preferentially favor the onset of La Niña/El Niño events."


How do Rossby Waves in the ocean form? So on land, I believe that one factor in their formation is due to inhomogeneities in surface heating between land and ocean (and also inhomogeneities in surface heating due to terrain effects like the Rocky Mountains).

But what about in the ocean, where we don't see such inhomogeneities? How is the formation and movement of Rossby Waves in ocean different from that of land?

First, inhomogeneities in the ocean are in fact quite common. There are density gradients in both horizontal and vertical directions and those gradients result in the baroclinic circulation of the ocean. The density gradients in the ocean are caused by salinity and temperature differences.

Rossby waves are common in the ocean. They propagate along lines of latitude with the waves traveling along the Equator being the most obvious example and the most thoroughly studied. As in the case of atmospheric Rossby waves, their formation and propagation is related to the conservation of (potential) vorticity (rotational movement, angular momentum). A parcel of water has two sources of vorticity: its own spin and the planetary spin. When a parcel of water moves across a latitudinal line, its planetary spin (planetary vorticity) changes (as the Coriolis effect is latitudinally dependent) and, in order to conserve vorticity, it changes its own spin (relative vorticity). The water parcel tends to swing back and forth around the original latitude resulting in a wave-like motion. A Rossby wave is characterized by a westward phase velocity (that of the wave crests).


Where to find reliable snowfall rate data? Would you please let me know where I can find/download reliable snowfall rate datasets?
I am looking for multiple weather stations (in different regions) or field measured data, that contain both solid/liquid precipitation data.
Thank you.

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


Paleogene transantarctic seaway Lawver & Gahagan (1998; 2003) hypothesized, based on sea level records and the isostatically adjusted bedrock surface of Antarctica, the existence of a Trans-Antarctic Seaway linking the Ross Sea and the Weddell Sea, between the Antarctic peninsula and the Ellsworth Mountains, in the Paleogene.

Has any other evidence confirming or infirming the existence of such a seaway been found since then? If so, do we have an idea of when it opened and closed?

Source:
Lawver, L. A., Gahagan, L. M., 1998. Opening of Drake Passage and and its impact on Cenozoic ocean circulation. In Crowley, T. C. & Burke, K. C., Tectonic boundary conditions for climate reconstructions, Oxford monographs on geology and geophysics, 39: 212-227.
Lawver, L. A., Gahagan, L. M., 2003. Evolution of Cenozoic seaways in the circum-Antarctic region. Palaeogeography, Palaeoclimatology, Palaeoecology, 198: 11-37.

Barnes & Hillenbrand (2010) argue that there is faunal evidence for a late-Quaternary trans-Antarctic seaway. From the abstract:

  We investigated biological evidence for past connectivity between different regions of Antarctica by comparing the composition of modern bryozoan assemblages from the continental margin around Antarctica. Surprisingly, we found most similarity between two areas which are not currently connected – the shelves of the Weddell Sea (WS) and Ross Sea (RS). We evaluated three hypotheses to explain this and conclude that bryozoans most likely dispersed through a trans-Antarctic seaway that opened in response to a WAIS collapse and connected the WS and RS shelves. These bryozoans must have survived glaciations(s) during subsequent ice ages in refuges, whereas they were wiped out in most other regions of the Antarctic shelf. After the last glacial period, bryozoan assemblages could freely disperse between many of the regions we examined (e.g. Antarctic Peninsula and South Shetland Islands), which has allowed recolonization of areas in which bryozoans had been eradicated during the last ice age. For the bryozoans on the WS and RS shelves to be more similar than those which are in close proximity means the trans-Antarctic seaway may have been as late as the last few interglacials.

There are some other folk in agreement, in particular Strugnell et al. (2012) on the topic of genetics of an Antarctic octopus (yes, really); and Vaughan et al. (2011) review available data and find strong biogeographical evidence for the existence of such a trans-Antarctic seaway, with four possible candidates and extensive discussion of when it might most recently have been open:

  The methods currently at our disposal do not allow us to constrain, with confidence, which recent interglacial saw the last open West Antarctic seaways. However, given that during the last interglacial (MIS 5e), air temperature in Antarctica was substantially warmer than present for several thousand years [Sime et al., 2009] and at the same time, ice-loss from Antarctica almost certainly contributed to higher global sea levels [Kopp et al., 2009], it would appear that MIS 5e is a strong candidate.

In summary: biogeography and octopuses say yes.


What happens when a mid-ocean ridge sub-ducts underneath continental crust? I'm aware that oceanic crust always sub-ducts to continental crust, but surely the geologic forces pushing the ridge apart in the first place isn't just going to turn off, right?
Any answers would be greatly appreciated.

We probably can't say that any one thing will happen in every instance.  The particular effects of any one such subduction will probably depend on the event's geometry and the continental rocks doing the subducting.
That said, we can talk about a famous instance of this, when parts of the East Pacific Rise (between the Pacific and Farallon plates) first started going under North America about 30 Ma ago.
Subduction itself is a destructive process: oceanic sediments and water lower the melting point of the crust being subducted, so the subducted plate melts.
So, for the most part, the Pacific-Farallon rifting centers were just swallowed up, and we don't consider the Farallon plate to exist anymore, just its remnants, such as the Juan de Fuca and Cocos plates.  A large transform fault, the San Andreas Fault, formed in the gap.
However, the tendency to rift is still there: A bunch of previously North American continental crust was rifted off onto the underlying Pacific Plate oceanic crust, forming Baja California, and the San Andreas Fault adjusted itself to meet the rift. This was more likely a recent extension of the rift north from the Rivera triple junction than remnant Farallon slab pull under North America.

Source: USGS via Wikimedia Commons - Public Domain


Why does warm air "hold" more moisture? It is often explained that warm air holds more water because warmer water is less likely to condense. This and other explanations just seem to be circular arguments.  If the warmer air picks up enough moisture it will saturate and then water will still condense at 100% humidity.

Given two cubic feet of air with one warmer than the other and the warmer holding more water, where/how do all those extra water molecules invisibly fit in the warmer cubic foot? What is the deep physics or chemistry reason this happens?

Saying that warm air "holds" more moisture is technically incorrect, but is a common colloquialism. Let's break it down to the technicalities.

Let's consider a glass of water with a vacuum (no air) above it. What will happen? The molecules that are at the top most layer of the water will evaporate. At what rate will the water evaporate? Better yet, what is evaporation?

Evaporation is when the water molecules gain enough kinetic energy (how fast they vibrate) to break the bonds that hold them to one another. Kinetic energy is dependent on temperature. So the molecules vibrate faster, break their bonds, and enter the vacuum as a vapor. Some molecules will stay as a vapor in the vacuum, but others will reenter the liquid. When the molecules enter the liquid as fast as they are leaving, then it is saturated.

If the air is cooled down, then the rate at which molecules leave the liquid slows down. The molecules entering the liquid do not slow down at the same rate, causing the liquid to grow toward it's initial state.

Note that I specifically said it is a vacuum. Instead of a glass of water, picture the water as little drops. The atmosphere can act to warm or cool these drops, and vice-versa.

In the more nitty-gritty aspect of this, the equation that describes the vapor pressure as a function of temperature is called the Clausius-Clapeyeron equation/relation. The American Meteorological Society has one approximate solution, but I prefer this equation: $$e_{sat}(T)=611 Pa \exp[\frac{L_v}{R_v}(273.15^{-1}-T^{-1})]$$, where $L_v$ is the latent heat of vaporization, $R_v$ is the specific gas constant for water vapor, and $T$ is the absolute temperature in Kelvin. Combined with the ideal gas law for water vapor (assuming saturation) $$e_{sat}(T)V=m_vR_vT$$, and given the volume ($V$) we can write an expression for the mass of water vapor $m_v$. The equation comes out to $$m_v=611 Pa \exp[\frac{L_v}{R_v}(273.15^{-1}-T^{-1})]V R_v^{-1}T^{-1}$$

To answer your final question, the molecules are approximated as being infintessimally small, per the ideal gas law. To be more specific, one molecule of water is about 7.08$\times$ 10$^{-19}$ cubic feet (after some math), so the added volume is considered negligible. In short, the molecules are treated as point masses.


How to understand the bizarre high level for both PM2.5 and Ozone Background

Eastern China now (2017.01) are suffering severe haze with striking concentration of PM2.5.
Haze, with low visibility and complex chemical components threatens billions of persons' health.

But when I look through the pollutants concentration all over the country, I found some phenomenon interesting.

General

Here is a snapshot of PM2.5 concentration distribution map of eastern china (clipped from aqistudy.cn).

The circle with red and purple color represent the high ground-level loading of PM2.5.

  From the figure above, we can identify the locations with high PM2.5 conc.

Meanwhile, I also clipped the O3 concentration distribution at the same time.

  From the figure above, we can observe that O3 pollution are not severe in haze zone.
  Actually, the conc of Ozone are lower in the area which the PM2.5 conc are higher.

The real-time data are also presented here a supplement. I choose Beijing, Xi'an (two large city in China), Zhoushan(an island in Eastern China Sea), Sanya(nearby the southern China Sea)

City     | PM2.5 |   NO2  | SO2  | O3
-------------------------------------
Beijing  |  229  |  109   |  30  |  7
Xi'an    |  381  |  147   |  34  |  12
Zhoushan |  20   |  28    |  14  |  70
Sanya    |  16   |   9    |   2  |  77

 ###  units: ug/m3

IMHO, the high conc of PM2.5 and low conc of O3 can be explained as follows:

  High loading of Aerosol -> strong extinction effect -> week solar radiation -> O3 formation slow down

Here is another figure I clipped from Cheng et al. Sci. Adv. 2016. It depicts the NO2 and O3 conc in different PM2.5 level.

An Special case

Look at the city of Anqing (30.5319° N, 117.1151° E), its PM2.5 and O3 concentration has a strange phenomenon. I clipped some figure of its air quality status (2016-01-04 local 12:00:00)

Fig 1 Anqing City and Chizhou City

These two nearby cities are in the distance less than 60 Km, has the similar PM2.5 conc with different O3 conc

Fig 2 Anqing City and its surrounding area

  What attract me is the high conc O3 of Anqing City comparing with its nearby area. And I found this feature is rare in China.

Anyone has some theory to explain that? Any discussion or advises would be great!

I think it is important to keep in mind the mechanisms that form PM$_{2.5}$ are different than the mechanisms that form O$_3$.

From the data your provided you can draw some simple conclusions:

Increasing SO$_2$ increases PM$_{2.5}$
Increasing NO$_2$ increases PM$_{2.5}$
Increasing NO$_2$ doesn't necessarily increase O$_{3}$

The last point is what you seem to be struggling with. I think what you see here is 'the weekend effect' where lowering the NO$_2$ concentration increases O$_3$ concentration. In this effect, the generation of nitric acid and the destruction of O$_3$ by NO ($\ce{O_3 + NO → O_2 + NO_2}$) decreases the ozone, but increases NO$_2$. I think this explains the phenomenon seen.


Will another big earthquake hit Kathmandu? Recently, we got the news that the western part of Nepal may be hit by a larger earthquake than that of April 25, because it did release all of its energy. During the earthquake, only the eastern part of Nepal was affected. So I want to know if Kathmandu, i.e. the central part of Nepal, could also be affected by the anticipated earthquake.

The partial release of strain energy makes another major earthquake in the same area less likely - in the near future.

That said, there is not just a single slip plane between the converging Indian and Tibetan tectonic plates. Rather, the nappes (slabs of rock) are stacked about 12 layers deep, with Tibet over-thrusting India at a low angle.

The main Himalayan thrust fault slipped at an average depth of about 8 kilometers. There is still unreleased strain energy accumulating in thrust faults above this level. Geographically, an area 120 kilometers long by 60 kilometers wide slipped three metres southwards and one meter upwards in just over 20 seconds.

The adjacent Himalayan regions, east and west, will eventually rupture in more or less similar manner. Bear in mind that the mean rate of tectonic convergence across the Nepalese Himalayas in the vicinity of Kathmandu is 17.5 +/- 2 mm per year, whereas the overall rate of convergence of the Indian and Tibetan (Eurasian) tectonic plates is between 26 and 36 mm per year.

The Kathmandu earthquake locally released 86 years' worth of strain energy, equivalent to 35 mm per year, so is very unlikely to slip that much again for decades to come. But if I was living in north India, west Nepal or Bhutan, I'd be worried. The recent earthquake was magnitude 7.8 according to seismometers on the Indian side, and magnitude 8.1 according to Chinese seismometers (counter-intuitively both could be right). For those parts of the Himalayas that haven't experienced a major quake for centuries the accumulating strain could be phenomenal. For these areas a magnitude 8.5 is plausible.


At least by theoretical biology - could there be, or should there have been, or was a "southern Taiga" on earth? All data I have ever encountered about the Taiga "pole surrounding", vast, cold forests comprised mainly of Pinophyta trees, was about the northern pole surrounding forests ranging from northern Scandinavia and northern European Russia to northern Siberia and northern Canada.

Considering woodland of areas a little bit close to the southern pole, south Patagonia (extreme south of south america) reminds me a bit of the northern forests; the vegetation at and New Zealand and in Norfolk island (which might be mostly artificial in that island) a bit too, and perhaps paleoentological findings about trees in Antarctica in the past will even more resemble a "Taiga".

At least by theoretical biology - could there be, or should there have been, or was a "southern Taiga" on earth?

I'll define a boreal forest as a place that

Has trees, i.e., long-lived woody plants that are capable of growing at least ten meters tall and that grow both upward by extending new branches and outward by widening of the trunk. Amongst other things, this rules out times before ~380 million years ago, which was when the first trees formed.
Has sufficient trees so as to constitute a forest, which I'll define as a largish area where trees grow sufficiently dense so as to form a more or less closed canopy. This distinguishes forests from areas with only  a few trees such as savannas and krummholz.
Has very harsh winters, with at least one month where the average temperature is well below freezing, and temperatures of -40° C are not rare. This distinguishes boreal forests from cold oceanic forests such as the Magellanic subpolar forests in southern Chile and Argentina.
Has mild summers, with only a few months where the average temperature exceeds 10° C. This distinguishes boreal forests from hemiboreal and temperate forests. Note that some scientists do not make this distinction, classifying Köppen climate zone Dfb as boreal.
Is extensive. This distinguishes large boreal forests from high altitude subalpine forests that would locally pass the above tests. Subalpine forests can occur at any latitude, including Australia's Snow Mountains, New Zealand's Southern Alps, and parts of the Andes.  This is not a clear-cut boundary. As a climate cools, subalpine forests may spread to the valleys between mountains and then spread out beyond the mountains. At some point, such montane forests becomes boreal forests.

The need for very harsh winters coupled with the need for extensiveness means that boreal forests did not exist between the start of the Triassic ~252 million years ago to the end of the Eocene ~34 million years ago. The Earth was in its greenhouse phase during that long stretch of time, with balmy temperatures year round even at the poles. A boreal forest can only exist when the Earth is in its icehouse phase. This includes the last 34 million years, and also the period between 340 to 250, the late Paleozoic glaciation. Unlike the current ice age, the Earth in the late Paleozoic had land (Gondwana) surrounding the South Pole.

The question then is whether either of those intervals (the last ~34 million years, and the late Paleozoic glaciation) have supported a southern boreal forest. Per Rees-Owens et al., the answer is a possible yes to the more recent interval. Forests existed on Antarctica until as recently as 2.5 million years ago. Whether these were Köppen climate zone Cfc (subpolar) or Dfc (continental boreal) is very hard to say. If one relaxes the requirement for cold winters a bit, then those recent forests almost certainly were boreal.

Per Horton, et al., and also per the authors of several related papers, the answer is an unequivocal yes to the more ancient interval. Moreover, the boreal forest of that ancient time would have been very much like the boreal forest of present time: One of the largest ecozones on the planet.

References:

Horton, D.E., Poulsen, C.J. and Pollard, D., 2010. Influence of high-latitude vegetation feedbacks on late Palaeozoic glacial cycles. Nature Geoscience, 3(8), p.572.

Pross, J., Contreras, L., Bijl, P.K., Greenwood, D.R., Bohaty, S.M., Schouten, S., Bendle, J.A., Röhl, U., Tauxe, L., Raine, J.I. and Huck, C.E., 2012. Persistent near-tropical warmth on the Antarctic continent during the early Eocene epoch. Nature, 488(7409), p.73.

Rees-Owen, R.L., Gill, F.L., Newton, R.J., Ivanović, R.F., Francis, J.E., Riding, J.B., Vane, C.H. and dos Santos, R.A.L., 2018. The last forests on Antarctica: Reconstructing flora and temperature from the Neogene Sirius Group, Transantarctic Mountains. Organic Geochemistry, 118, pp.4-14.


What is 'dissection rate'? I am looking for a definition of this term for wikipedia, with a reference.

It's mentioned on Franz Josef Land where it's indicated that the units are km-2/km. I'm curious about how this would be measured.

I've found precious few mentions of this unit in the usual sources.

Thanks in advance!

In geological terms, "dissection" appears to refer to the creation of cuts in a landscape due to erosion e.g. by the flowing of streams. Dissection rate would then be the rate at which such cuts in the landscape form.

https://books.google.com/books?id=AIyIAAAAMAAJ&pg=PA221&lpg=PA221&dq=dissection+rate+geology&source=bl&ots=bFXfYFDmt3&sig=CiiKojDNHIkyQxzqVkBuSyL1Zr0&hl=en&sa=X&ved=0ahUKEwiVgpOLm8TZAhUKnOAKHXQQBMMQ6AEIUjAI#v=onepage&q=dissection%20rate%20geology&f=false


Why does the "Ring of Fire" pretty much define "Pacific Rim" The Pacific Rim is pretty much defined by the so-called "Ring of Fire." It consists of the "stomping ground" for a disproportionate number of earthquakes and volcanoes, and the affected territory extends up and down the coast of North and South America, up and down the East Asian coast, and into the "Australasian" islands like Indonesia, the Philippines, and New Zealand. Apparently it has something to do with the presence (or absence) of tectonic plates  there.

Why is there such a configuration of tectonic plates, and the resulting earthquakes and volcanoes in the Pacific, and not to the other oceans?

There isn't a concentration of tectonic plates - rather the opposite!

The "Ring of Fire" is a pattern really. It is marked by subduction zones. So the question becomes, "Why is the Pacific Ocean surrounded by subduction zones?".

Think back to Pangaea. This was a supercontinent that formed in the late Palaeozoic. Virtually all of the Earth's land masses were concentrated in one large supercontinent. When this broke up, the new continents moved away from each other. Fast forward 200Ma or so, and you find that the continents have moved so far apart that they are now converging on a point on the other side of the planet - the continents are moving towards each other! Hence the remains of the super ocean (which was actually multiple ocean plates - today's Pacific & Nazca plates, plus the Farrallon plate (RIP),etc ) is shrinking as the continental plates move towards it.
This destruction of the ocean plate(s) occurs at subduction zones.

This is a big picture generalisation. Not all of the Pacific's boundaries are marked with subduction zones (e.g. North America has two large strike slip systems + a new spreading ridge). Also, not all of the continents are converging on each other. Africa is doing a pirouette, India is moving northwards, etc.


Is there any significance of lacustrine gastropoda fossils regarding paleoenviroment interpretation? How to interpret lots of gastropoda fossils seen in lacustrine marls? Do they indicate any paleoenvironment conditions? Depth, temperature, chemistry, ph?

Shell stable isotopes, for oxygen and carbon reveals, if the gastropoda had lived in brackish, lacustrine or palustrine environment.

For discussion please see paper below.

Latal, C., Piller, W. E., & Harzhauser, M. (2004). Palaeoenvironmental reconstructions by stable isotopes of Middle Miocene gastropods of the Central Paratethys. Palaeogeography, Palaeoclimatology, Palaeoecology, 211(1-2), 157-169.


Is there limestone under the Oregon Coast Range? I've found some diagrams of the Oregon Coast Range, but they are very basic. An friend said he thinks there is limestone deep underground, but my understanding of the formation of these mountains is that there is not. Where can I find information to settle this question? (or, if you know the answer, I'd be glad to hear it)

I'm not familiar with the Oregon Coast Range, but limestone is such a ubiquitous and widespread rock that your friend is almost certainly right. For strata to be limestone, they need to have been under the sea when they were laid down. The fact that some are found today near the tops of mountains only means that plate movements have uplifted them since they were formed. They might easily have become overlaid with igneous rock, volcanic tuffs, sandstone etc,but if you go down deep enough the probability is that you'll find limestone somewhere. You usually don't have to go down very far, and there are usually exposures that reveal it. Limestone (calcium carbonate) is often a good place to find fossils.


Why can I look directly at the sun during a sunset but not at noon? Why can I look directly at the sun during a sunset (with a lot less pain and unconfort) but not at noon?

At Noon, sunlight is coming from nearly directly above you, and goes through ~2 miles (4km) of reasonably dense atmosphere to reach you (Atmospheric pressure at 2 miles is about one half of sea level pressure). At sunset (and sunrise), since the sunlight is traveling mostly parallel to the surface, it travels through dense atmosphere for considerably longer. When traveling through dense atmosphere it's subjected to more scattering, which decreases the observed intensity of the light.

Or, considered a different way, when looking at a sunset/sunrise, you don't see the sun as a single well defined point. It's hazy, with the bits of sky near to the sun also giving off a fair amount of light. That additional light is some of the light that was scattered from an otherwise direct beam. If it were all re concentrated to a single point, it would be brighter/more painful to look at (though not as bright as the noon sunlight- for shaky statistical and light absorption reasons).

Using an Earth Curvature Calculator, sunlight at the horizon travels through ~120 miles of 'dense' atmosphere (ie has an altitude <2 miles). That will fall off rather quickly the higher above the horizon the sun is.

(dense atmosphere in this refers partly to just thicker air; but also to particulates/dust in the air, haze, mist, fog, etc)


What is the meaning of step in ERA reanalysis data? The webpage to download ERA data includes an option called "time" which is intuitive, but also an option called "step". I can't find an explanation of the meaning of this. It can't be a time step because it has also 0.

The "step" is the number of hours the ERA re-forecast has been run into the future from the "time" of the re-analysis.

For example, asking for ERA data with time = 12:00 and step = 0 means asking for data valid at 12:00 based on a re-analysis for 12:00. But asking for data with time = 12:00 and step = 6 means asking for data valid at 18:00, i.e. for data produced by a 6 h model run based on the 12:00 re-analysis.

To fill the gaps between the analysis times one can use steps from a forward run. Forward runs are needed to get parameters like time accumulated precipitation, which would not be available from an analysis. Sometimes a combination of steps and times might be appropriate for a joint analysis of instantaneous and time averaged parameters, i.e. to stagger them correctly in time.

Data valid 00:00 deviate less from the observations if they come from a 00:00 analysis compared to data from step 12 of the 12:00 analysis. But a series of steps from one initialization time should be more consistent in time compared to a series of independent analyses.


How many buildings in tornado prone-areas have storm shelters? I did a quick search, but couldn't pull any statistics from it.  On tornado risk days, many I interact with in Oklahoma become concerned or panicked that they don't have a shelter.  I am guessing the percentage of people with shelters is actually pretty low, and in such situations a statistic like that might be encouraging to folks.  Does anybody know where I can find such statistics?

Have you perhaps contact the National Weather Service or FEMA about that ? If not, then maybe find out from real estate that they might have data for each houses in your state. They may have the data or not, but it is hard to know. All I know is that each state has different types of soils that can or can't built storm shelter. I heard in Texas almost 1/2 of the buildings there do not have a storm shelter, because the soil in Texas are not strong enough to withstand against the flooding. That kind of thing ...

I do not know if you have seen this, https://stateimpact.npr.org/oklahoma/2013/09/27/mapped-which-oklahoma-schools-have-storm-shelters/

http://www.esri.com/news/arcuser/0104/storm.html

Another one is the reason why an individual passed away from flooding in a storm shelter
http://mashable.com/2015/05/07/oklahoma-city-storm-fatality/#KGEHNAxU5sqq


Did global warming cause the extreme cold 2013-14 winter in North America? There have been some claims made (example) that global warming had something to do with why the 2013-2014 winter was so cold in the Midwest area of America.

If this is true then how did global warming make the winter so cold? Shouldn't it make the temperature rise in all parts of the world, during all seasons?

I bet you live on the eastern half of North America, which had a cold winter of 2013-2014, Europe and Alaska had a very warm winter, and China had its second warmest January.

Jennifer Francis of Rutgers has been advocating the Arctic or Polar Amplification theory (Wikipedia). In which she hypothesises that warming of the Arctic has been greater than lower latitudes, and this lowers the temperature contrast between the poles and the equator. This in turn weakens the jet stream which becomes slow and meandering. This weakened and meandering jet stream then is less able to hold back cold polar air, the so called "polar vortex" which can then bring outbreaks of cold air from the poles to the mid latitudes.(BBC Article outlining the theory)

However, the theory is not without some problems...

  One problem is that the changes in atmospheric thickness and wind
  speed observed have become apparent only since the mid-1990s, which
  gives fewer than 20 years of data to work with. Another difficulty
  concerns the blocking patterns. Dr Francis’s theory suggests there
  will be more of them in future, as the world warms. But climate models
  unanimously disagree, saying that global warming will produce fewer of
  them...(The Economist)

and...

Tim Woollings, an atmospheric dynamics researcher at Oxford University pointed out in an email exchange that over the Atlantic the jet stream was stuck, but was not meandering or slowed, however he did concede that the jet stream over the Pacific did match the hypothesis.(Yale Environment 360) The jet stream over the Atlantic reached sustained speeds over 230 miles per hour (370 km/h) during the winter,(Liam Dutton) reaching  275 miles per hour (443 km/h) on 22 December 2013. 30% stronger than the normal jet stream.

So yes, there is a theory which describes how warming can bring locally colder winters, but also, the science isn't exactly settled yet.

Addendum: here's a link to a good blog post on the matter Polar Amplification, Vortex Disruption to Set off Extreme Weather Events For US, UK Yet Again

An overview of the debate as of 2016:Wapo 2016


Will a country that cares for its environment be affected by climate change due to other countries' pollution? Let's say my country is very environment conscious, has lots of trees and animals, protects the forest, uses clean/green energy, and has all kinds of environment friendly policies you can imagine. Will my country be safe from climate change?

Or will that be useless when other countries don't take those measures, because we all share the same atmosphere?

The main driver for anthropogenic climate change is carbon dioxide because it is very long-lived and hence relatively evenly distributed within the atmosphere. And even if you'd somehow manage to keep reduced levels of $CO_2$ in your country's atmosphere, you'd still be affected by large-scale weather changes. So yes, your country would be affected just like any other country.

Of course other benefits from climate-friendly policies, such as better air quality due to reduced combustion or better public transport due to investments in that sector, have a stronger local impact.


Is the representation of Earth oriented correctly in this image? Is there something wrong with this image?

I found it in Wikipedia's article Ecliptic coordinate system and the image's source page is here.

What bothers me is the orientation of the Earth's surface (continents).

The horizontal plane with the red line around the sphere represents the plane of the ecliptic. The ecliptic is basically the plane of Earth's orbit around the Sun, in as much as that can be considered to be a plane. (caveats, details, mumble, mumble J2000.0 mumble...)
The inclined plane with the blue line is the Celestial Equator, which basically coincides with the Equator of the Earth (...mumble...).

If I understand correctly then, the North pole of the Earth should point in a direction that is perpendicular to the Earth's equator and celestial equator, but it looks to me like this is drawn with the north pole pointing directly up.

Am I wrong, or confused, or both?

The way "I see the diagram" it looks weird, but it is probably correct.

My perception is that it is about frames of reference. We are used to seeing the Earth with Earth's north at the top, not at 23.5 deg from the vertical.

This picture has the ecliptic pole at the top. As you state, Earth's equator matches the celestial equator. The Earth's poles would be at right angles to it and the north pole would be in the middle of the white mass at the top of the Earth - representing the Arctic ice sheet

If you imagine a line from this point, perpendicular with the celestial equator it matches zero degrees latitude and is sort of sub parallel with the west coast of Africa.

The other thing that might be confusing our perception is the representation of the land masses is not accurate.

Looking at the representation for Europe, Italy is not present, neither is the Balkan Peninsular or the islands of Britain & Ireland. Scandinavia just looks wrong! Iceland is present and the Arctic ice extends too far southwards. The last time I looked there wasn't an ice sheet between Iceland & Greenland. Also, the Red Sea isn't represented.


Does the position of the Earth's axis affect the position and shape of its continents? If somehow we were to move the Earth's axis of rotation to, say, Mexico, making some spot in Mexico  effectively the North Pole, would this change how the continental plates drift over time, thereby changing the shape of a World Map a hundred million years from now (as compared to how that map would look had we not changed the axis)?
I'm wondering about the effects of so called centrifugal forces and so on, or any other effects I might not be thinking of.

This is an idea that we can consider "wild".
Or even better, untamed. Every then and now there are researchers trying to address the questions, but the proof have not been conclusive up to now (as far as I know).
If you have sufficient knowledge, you may try to go through this peer-reviewed paper
Riguzzi et al, (2009) Can Earth's rotation and tidal despinning drive plate tectonics?
https://www.sciencedirect.com/science/article/abs/pii/S0040195109003321#!
It has been cited 67 times, which is a small number, but not negligible.
I would say your question at the moment has only a possible answer: maybe.
But it is a good question and maybe someone can provide a better answer!


What was the likely composition of Earth's early crust (how did crustal composition evolve)? Was the first crust entirely mafic (oceanic) crust which was later distilled via volcanic arcs along subduction zones to make felsic rocks or did the earth start with bits of felsic crust?

Are the ancient zircons most likely from felsic or mafic rocks?

Gordon's answer is correct to a first order approximation.

However, the zircons that were found in Jack Hills are from the Hadean, more than 4 billion years ago. The fact that zircons that old exist is interesting - zircon is not a mineral you find in mafic rocks. Zirconium is an incompatible element in the mantle, so to get enough of it to form its own mineral you need some partial melting events. This may also be of interest:

What are the high field strength and large ion lithophile (HFS or HFSE & LIL or LILE) elements?

When you melt the mantle, you end up having basalt or more felsic rocks. If you have enough zircon in mafic rocks, you form baddeleyite: ZrO2. Zircon, ZrSiO4 will only form in more felsic rocks, where you have enough Si. This alone suggests that some parts of the early crust was somewhat more felsic than a basalt.

There's more to it: inclusions of quartz and oxygen isotope data indicate that not only the zircon was in a felsic rock, it has evidence to suggest liquid water and hydrothermal alteration.

This entire thing is heavily debated, because there's only so much you can tell from a few grains of zircon. However, the basics are there - some felsic rocks existed as far as the Hadean.


Probability distribution of fault throw displacement and height limiting mechanisms First, what is the probability distribution of fault throw displacement. Uniform distribution seems unlikely, since then small changes would add up to huge huge elevation differences that require a large amount of by erosion to reduce. But the same holds for a Gaussian. Are there any other mechanisms that limits these large differences, like gravity pull-back and pressure from the magma? How can these be described in terms of free-fall, damping etc?

This is a very interesting question, and one that many people have explored. It's also a very complex question, as geology is inherently complex. A complete answer would probably require you attending a semester or mores worth of structural geology lectures, so below is only a very brief introduction.

To answer the first part of your question, there is a general consensus that fault-throw is proportional to fault length, which can be modelled by a power-law relationship. The paper presented by Joe Kington is very useful. Another paper which may be of interest is Kolyukhin, D., and A. Torabi (2012), Statistical analysis of the relationships between faults attributes, J. Geophys. Res., 117, B05406, doi:10.1029/2011JB008880.
They show that fault throw is proportional to fault length, fault type (e.g. normal, reverse/thrust) and rheology of the rock and fault zone. So to get an understanding of the probability distribution of fault-throw, you would have to explore the effects that these variables have. I couldn't find papers that explicitly deal with fault-throw probability distribution (they mainly look at predictive models and reasons), so unfortunately cannot help in giving a precise answer.

The second part of your question seems to deal with ways that stress (pressure caused by whatever: tectonic plates moving around, magma moving around, things moving downslope under force of gravity, etc) is accommodated by some Earth response, generally either faulting or magma emplacement. Take a look at the Andersonian theory of faulting to get an understanding of how different stress regimes (in what direction is the prinicipal stress oriented) effect creation/reactivation of faults. This theory will give you some insight into how the Earth accommodates stresses by extending/shortening. The direction and magnitude of faults is explained by the interplay of different stress components. When you were talking about free-fall, I assume that you mean gravity, which is generally reformed as overburden stress, which is an important stress component.

Magma can accommodate stress (as well as induce it!). Take a look at examples from the East African rift system around Afar. Here the fault-throw versus length relationships mentioned above do not hold, because introduction of magma into the area reduces the need for the rock to extend/stretch in the horizontal and shorten in the vertical directions. I don't have any papers on hand, but the examples are very interesting.


Volcanic activity in Taiwan, ever in recorded history, much chance in the near future? News of Hawaii has got me thinking...

I've lived in Taiwan for many years and hiked many kinds geologically interesting mountain and seashore rock formations, seen steaming, sulfury fumaroles, even ate my lunch in a (presumably long extinct) volcano crater.

From what I've learned from others, volcanism has a significant contribution to Taiwan's geology and geography.

But is this very old and no longer a factor?

Question: Is there any historical reference to volcanic activity in Taiwan? Is there much chance of it again in the near future?

Screenshots from Google maps:

left: Da You Keng Fumarole (Chinese), right (向天池山) Xiang Tian Chi Mountain (can't find a link), great for a caldera picnic. Images are screenshots from google maps. Click for larger size.

There are at least 9 old centres of volcanic activity in Taiwan:

The Tatun Volcano Group 15km north of Taipei, they think there are active magmatic systems there but the last eruption was 200,000 years ago.

The Chilung Volcano Group in the north is extinct, with no magmatic activity and hasn't erupted in 800,000 years.

Mount Guanyin is listed as extinct but not a lot of work seems to have been published on it as a volcano.

Caoling Mountain is similarly extinct and no-one seems to have done any real work about it's eruptive history at all.

Guishan Island is still active and last erupted in 1795, it could start a new eruption at any stage.

The Hai'an Range on the Eastern Coast is tectonically active and has experienced volcanism in the past which could recur at any time depending on the movement along that plate boundary.

Green Island and Orchid Island off the East Coast are old volcanoes of the Luzon volcanic Arc and haven't erupted in hundreds of millions of years.

Lastly there are the Pescadores out west, 90 odd volcanic atolls and small islands probably all monogenetic in origin (the individual volcanoes erupted only once in a given location but the area has experienced repeated eruptive cycles over geological time) none of the existing members is likely to erupt ever again but new volcanism in the region is likely at some stage.

So the long and short is that while it's been pretty quiet in Taiwan in the last couple of centuries there are areas where new eruptive cycles could start at any time at existing sites or new ones.

Please note any dates given are pretty approximate.